tag:blogger.com,1999:blog-86882086629325274092012-02-23T11:25:29.310-08:00A commentary on weather-related topics by Luke Madaus.Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.comBlogger1391100tag:blogger.com,1999:blog-8688208662932527409.post-80140544520233533652012-02-23T11:25:00.002-08:002012-02-23T11:25:29.328-08:00

As most people in the central US are probably well aware, a powerful winter storm will be moving across the area over the next few days.  In fact, it's already pretty well developed.  Here's the surface analysis at 17Z this morning (11 AM CST): We see a very well-developed low over western Missouri, with strong pressure gradients to the northwest and southeast of the low.  Strong pressure

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-57177414637196643382012-02-16T11:57:00.000-08:002012-02-16T11:57:35.704-08:00

Last weekend's massive high pressure system brought some cooler air to the middle of the country, getting us slightly closer to more winter-like weather.  Compare the temperature anomalies from the first week of February nationally (from NCDC)... ...to the temperature anomalies from the second week of February. This shows a significant change in temperatures across the central part of the

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-90733697459205085262012-02-10T10:42:00.000-08:002012-02-10T10:42:08.958-08:00

A lot of snow and rain is currently impacting the eastern third of the country.  This morning's radar composite sums it up nicely. Heavy rain for southern Louisiana with scattered heavy showers throughout the southeast.  Further north where it's colder, snow (enhanced by the lake effect) is being reported in the Chicago area and northern Michigan. All this active weather...but where is the

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-68147404135912064012012-02-02T11:36:00.001-08:002012-02-02T11:36:56.124-08:00

Last week I was talking about a slow moving storm that was pushing through the southern US.  This week we're looking at another cyclone, currently developing over the desert southwest, that looks to slowly push eastward into the central plains into this weekend. Let's start by looking at the GFS model 500mb forecasts.  At the moment, the Oklahoma HOOT site where I usually get my model graphics

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-22643088566408053192012-01-26T10:59:00.000-08:002012-01-26T10:59:14.718-08:00

It's been a while since I last posted on the blog as we've scrambled to recover from last week's winter weather here in Seattle.  I had a grand total of four inches of snow at my place, topped with a quarter inch of freezing rain, topped by another two inches of snow.  All in all, a pretty good storm--enough to close down the university for a few days.  However now we're returning to more

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-10652414739724538692012-01-18T09:37:00.000-08:002012-01-18T09:38:20.670-08:00

A lot can change overnight.  Yesterday evening's model runs were increasingly pessimistic about how much snow would fall in the Seattle area.  However, this morning's projections are looking more on the optimistic sie for seeing 4-6 inches of snow in the Seattle area.  So what changed? In my last blog post I talked about how the location of the surface low moving in off the coast would be

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com2tag:blogger.com,1999:blog-8688208662932527409.post-88448993166292756812012-01-17T15:10:00.000-08:002012-01-17T15:10:57.894-08:00

As much of the nationwide media is now proclaiming, there is a potential for a major winter weather event in western Washington tonight and tomorrow.  Here's what we're looking at. Snow showers continue over western Washington this afternoon as cool, moist air streams in off the Pacific.  Portland and the northern Willamette valley are really getting hammered.  Here's the latest composite radar

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-38387899804775218562012-01-13T10:25:00.000-08:002012-01-13T10:25:44.557-08:00

Yesterday's snowstorm across the upper midwest is well on its way to moving out of the area.  I thought I'd take a quick minute to look at what the final snowfall pattern looked like and compare it to the model outputs I was showing yesterday. First, final totals from around the Chicago area are now in.Most areas got at least three inches of snow, with totals up to 8 inches being reported in

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-83957703265727711112012-01-12T11:26:00.000-08:002012-01-12T11:36:06.880-08:00

As I talked about in yesterday's blog, the first significant snowfall event of the season is underway across much of the upper midwest.  The areas around Lake Michigan look to be the hardest hit with this storm in terms of snowfall amounts today.  Here's the latest regional radar image: Lots of precipitation falling throughout the area, and it's pretty much all snow once you get west of

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com1tag:blogger.com,1999:blog-8688208662932527409.post-23452743014504899862012-01-11T11:05:00.000-08:002012-01-11T11:05:05.688-08:00

In my last blog post I talked about the evolution of the upper-air pattern for the rest of this week.  I noted that there looked to be a shortwave trough forecast to dive south from Canada and later strengthen as it approached the east coast.  It looks like this is indeed what's going to happen, and as this trough brings in colder air, winter weather advisories are going up across the upper

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-26836274444361673982012-01-09T11:05:00.000-08:002012-01-09T11:05:23.832-08:00

A cut-off low over the desert southwest is slowly churning eastward through Texas and into the deep South.  In response to the low-level cyclonic motion generated by this low, southerly winds have helped pull lots of moist air out from over the Gulf of Mexico and into Texas.  The result?  Heavy rains today throughout much of the state. According to the Houston forecast office, they're

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-87120331067978831172012-01-03T10:52:00.000-08:002012-01-03T10:52:51.707-08:00

As we begin this new year, I thought it might be interesting to look at the longer-range forecasts from the Climate Prediction Center for the next several months.  Our longer-term prediction like this is somewhat different from what we're used to in normal weather prediction.  We aren't very specific--no forecasts of "it will rain on this day and not on this day" or "the high on February 10th

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-1163053670002686702011-12-22T21:23:00.000-08:002011-12-22T21:23:13.064-08:00

This evening, the Chicago area looked to be just on the northern edge of a shield of precipitation over much of the Ohio River Valley.  In fact, the base reflectivity looked like this around 5:30 PM CST: You'll notice a wide area of rather light reflectivity, including a large area of light returns to the east of the radar. The radar was scanning in a pattern called VCP 31, which is one of the

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-56841057125383992182011-12-19T13:57:00.000-08:002011-12-19T13:57:49.926-08:00

Heavy rain is falling over central Oklahoma, southern Kansas and north Texas right now as a powerful surface low is deepening over the Texas Panhandle.  Here's the latest map of surface observations from the area. There's a lot going on with this map, so I brought it into Powerpoint and have done a quick analysis of what I feel are the key features going on here. This is a classic pattern--

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-12053966567926331852011-12-14T10:27:00.000-08:002011-12-14T10:27:43.164-08:00

Today an upper-level shortwave moving across the Great Plains (as seen in this 500 mb map)...  ...and associated lift with this feature is helping to bring lots of rainy weather to much of the central part of the country.  A surface low is trying to develop along the baroclinic zone (a zone of horizontal temperature gradients) that is interacting with the jet streak aloft.  Here's the radar

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-37075755917937354772011-12-09T11:44:00.001-08:002011-12-09T12:07:30.148-08:00

Today we have an interesting and somewhat busy visible satellite image over the midwestern United States.  Here's what the view was at 11:15 AM PST.  I've labeled some of the more salient features.  You can click the image to get a bigger view. The first thing that stands out (to me, at least) is the large swath of snow covering a wide band from eastern Nebraska up through northwestern Iowa,

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-44773333207479079092011-12-07T11:48:00.001-08:002011-12-07T12:12:03.169-08:00

I've noticed over the past few days that there's been a curious dry spot in the central Pacific water vapor imagery.  It starts at around 8Z on Monday.  You can see the development of a structure sometimes loosely referred to as a "baroclinic leaf" in the area I've circled.  This often marks the initial formation of a surface low pressure center.  Notice the strong gradient between drier air (the

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com1tag:blogger.com,1999:blog-8688208662932527409.post-90392489847892965892011-12-01T12:35:00.001-08:002011-12-01T13:02:05.002-08:00

I haven't posted in a while, mostly because I've been busy traveling and teaching.  But I'd like to get back to the current weather today briefly, as we have an unusual set of circumstances that's causing some unique weather. First, anyone who has followed my Facebook status may have noted that Seattle (or, rather, SeaTac airport) reached a record high pressure of 1043.4 mb last night.  This

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-54052280588123581932011-11-22T12:19:00.001-08:002011-11-22T13:26:04.931-08:00

After a brief reprieve here in Seattle (and an inch or so of rain last night), another shortwave trough is moving up through the area and rain is on its way in again.  So the rain will continue.  But, it's going to be a rainy week or so ahead as well.  Why is this?  A particular weather event known as a Pineapple Express (not the movie...the real thing).  Let's look at what makes a Pineapple

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-74181155879210823062011-11-21T16:19:00.001-08:002011-11-21T16:27:40.900-08:00

The rainy season is here in Seattle.  The forecast for the next few days says it all... A series of upper-level disturbances moving over the Seattle area combined with a favorable flow pattern aloft are helping to bring in copious amounts of moisture to the Pacific Northwest over the next few days.  Here's a capture of the satellite water vapor image from late this afternoon.  You can see a

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-61701104151262077892011-11-15T13:55:00.001-08:002011-11-15T14:26:49.662-08:00

A quick look at the infrared satellite image over the eastern US today shows an elongated area of high clouds and deep convection stretching from Texas up through the eastern Great Lakes. Looking at the radar composite also confirms that there's a lot of convection and rain going on associated with these clouds.  The Storm Prediction Center even has a slight risk for severe weather out for the

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com1tag:blogger.com,1999:blog-8688208662932527409.post-29752744576432192202011-11-09T12:36:00.000-08:002011-11-09T12:51:57.194-08:00

1) The extremely deep low in the Bering Sea An unusually deep low pressure center moved through the Bering Sea last night and is now moving northward through the Chukchi Sea in western Alaska.  At its peak intensity, the low was down to 943 mb (or so we assume).  It was still at 946 mb, at least according to this morning's 12Z surface analysis from the NAM-WRF model over Alaska:

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com1tag:blogger.com,1999:blog-8688208662932527409.post-58083518477998317452011-11-07T12:19:00.000-08:002011-11-07T12:19:58.480-08:00

It's been a busy two weeks for me, so I apologize for not doing more blog posts.  Hopefully this week I'll be able to get back into the regular swing of things. Today we have an interesting weather event setting up for the southern plains.  In an upper-air scenario that looks more like what we see in springtime, we have an upper-level trough across the desert southwest this morning. The jet

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-26864252185108152632011-10-31T09:48:00.000-07:002011-11-01T12:20:28.024-07:00

Just an announcement today for those of you interested in learning about the new dual-pol radar systems that have no been installed in all Washington State radars and are continuing to be installed in radars across the country.  I will be giving a talk for the Puget Sound chapter of the American Meteorological Society about these new radar systems, how they work, what new products they'll include

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-71066007072174910082011-10-25T14:04:00.000-07:002011-10-25T14:04:30.414-07:00

The "official" hurricane season lasts from the beginning of June through the end of November, so we're beginning to near the end of it.  In fact, we're getting to a time of the year when there are fewer hurricanes forming in the Atlantic.  Here's a chart from the National Hurricane Center showing the annual distribution of Atlantic hurricane frequency: You can see that the number of tropical

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-60304717200823516592011-10-20T12:08:00.000-07:002011-10-20T12:10:12.191-07:00

Chicago (and much of the upper midwest) had quite the rainy and windy weather starting yesterday and into today.  So what's causing all this? First, let's check the upper-level pattern.  Below is last night's 300mb analysis.  You can see that there is a deep, cut-off trough over the Mississippi River valley.  Strong jet streaks are notable on either side of the trough axis. Most notably, the

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0Chicago, IL, USA41.8781136 -87.629798241.6889521 -87.94565519999999 42.067275099999996 -87.3139412tag:blogger.com,1999:blog-8688208662932527409.post-57630545010380771502011-10-18T11:55:00.000-07:002011-10-18T11:55:58.040-07:00

Today is forecast to be a very warm day in Seattle--probably our last time to get into the upper 60s this year.  So what's causing this climatologically unusual day of warmth? It starts with the upper-air pattern.  We're under a ridge at the moment, and with that ridge is a pool of very warm temperatures aloft along the coast.  Here's this morning's 700mb analysis: Warm temperatures and high

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-90155952617121040302011-10-12T14:35:00.000-07:002011-10-12T14:35:26.039-07:00

Showers and thunderstorms are currently moving across the central US with another area of rain in the northeast.  These areas of rain are associated with two different surface lows and we're expecting clearing skies in their wake. However, I want to look at the longer-range forecasts from the global weather models for the rest of this week and into next week.  Let's start by setting the stage. 

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com1tag:blogger.com,1999:blog-8688208662932527409.post-89725406667591237092011-10-08T22:42:00.000-07:002011-10-08T22:42:06.201-07:00

If you remember, during the late summer there was a lot of talk about the wildfires in central and west Texas.  That area has been stuck in extreme or exceptional drought conditions for much of this year. Here's the official drought monitor image from NOAA as of October 4th: You can see that pretty much all of Texas is in some pretty dire straits when it comes to needing rainfall.  But it

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-59232140004475225642011-10-04T15:57:00.000-07:002011-10-04T15:57:13.512-07:00

One of the simplest variables that we often look at to predict the weather is the atmospheric pressure.  In and of itself, pressure can tell us a lot about what kind of weather to expect.  For instance, I'm sure most of you have seen barometers like this one (taken from the barometer Wikipedia page...): You've seen that the pressure scale is often accompanied by weather descriptions (and in

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-34586532316275605412011-09-27T12:04:00.000-07:002011-09-27T12:04:16.781-07:00

We have an aesthetically beautiful storm system (at least, from a satellite perspective) over the midwest that has been lingering around for the last few days. GOES-E IR satellite image from 1815Z, Sept. 27 2011 A nice spiral shape is visible over the Chicago area, indicative of what we call a stacked low--a situation where the center of low pressure (or the lowest heights of all pressure

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-45735852341780637002011-09-21T17:13:00.000-07:002011-09-21T17:13:50.211-07:00

Today, the newest radar in the NEXRAD system began publicly transmitting its data.  This radar is known as the Langley Hill radar (KLGX) and it's located in Grays Harbor County in western Washington.  Here's a sample reflectivity image from this evening: As you can see, the radar's position on the coast affords us the new ability to watch storm systems and rainfall before they reach the coast--

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-57635933787775993082011-09-19T10:13:00.000-07:002011-09-19T10:13:45.636-07:00

This will be a short post, describing a few changes in the content of this blog that we'll hopefully see over the next three months. I know that the audience of this blog is a mix of people with greatly different backgrounds.  Each new blog post I have generates, on average, about 150 views after it is posted.  Of those people, I know many are fellow friends and colleagues who are also

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-78726408532858625722011-09-16T10:25:00.000-07:002011-09-16T10:25:12.084-07:00

Hurricane Maria is currently up near Newfoundland and is undergoing a period of its life known as the "extratropical transition". GOES-E wide view infrared satellite image from 1615Z Sept. 16, 2011.  Maria is in the top right corner. What does this mean?  In the classification of large-scale cyclones, we usually think of two broad classes: tropical and extratropical (that is, "outside the

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-79000033361716925382011-09-14T13:00:00.000-07:002011-09-14T13:00:08.388-07:00

As anyone who has been in Seattle over the past few days knows that we've returned to more "normal" conditions for fall.  Which includes a sky that perpetually looks like this: Webcam image looking across Hood Canal to the west on Sept. 14, 2011.  From Dr. Dale Ireland's page. The marine layer is in constantly and so far we haven't had enough heating to erode it away.  Upper-level troughing is

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-31390280389801015232011-09-12T10:37:00.000-07:002011-09-12T10:39:43.616-07:00

It's that time of year--time to start looking ahead to the cooler temperatures that are inevitably on their way.  A taste of more fall-like temperatures is due this week for much of the central part of the country. Right now, we still have the same general upper-air pattern that I talked about a week ago--a ridge over the west with troughing in the east: GFS analysis of 500mb heights and winds

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-25302246711687314392011-09-08T11:06:00.000-07:002011-09-08T11:06:49.306-07:00

I have decided to stay local today (at least local for me) and talk about a wildfire that's ongoing in the Olympic Mountains of western Washington.  With the huge wildfires in Texas, it seemed like a good topic to briefly talk about. I know...there are three tropical cyclones in the Atlantic that would also be worthy subjects. However, I feel like I've somewhat neglected my many blog readers who

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-60629704716950205412011-09-06T10:57:00.000-07:002011-09-06T10:57:47.856-07:00

I thought I'd do a quick look at what the GFS model is saying for the weather over the next week.  Let's start with this morning's analysis. GFS 500mb analysis from 12Z, Sept. 6, 2011.  Annotations by LM. This is this morning's 500mb analysis from the GFS model.  We can see the remnants of Tropical Storm Lee as marked by the deep trough with a small cutoff area in the south.  Lee's remnants are

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-16585168102692480252011-09-01T11:24:00.000-07:002011-09-01T11:24:30.817-07:00

Let's look at the tropics today.  As most people are aware by now, Hurricane Katia has formed in the eastern tropical Atlantic and is chugging along westward, forecast to become a major hurricane.  Katia is a Cape Verde type hurricane, which means that it formed just off the coast of Africa (near the Cape Verde Islands).  Because of this, it will go through a long, slow trek across the tropical

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-51675070404317096742011-08-31T00:24:00.000-07:002011-08-31T00:24:34.548-07:00

One of the simplest and most predictable patterns in meteorology is what is called the "diurnal cycle", meaning the cycle of what happens every day.  Our weather is governed by the sun, so naturally the sun's rising and setting creates a repeated cycle of events every day.  Here's a 24-hour meteogram for several important weather variables at my weather station from several days ago: Nighttime

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-44410752556889182872011-08-29T11:52:00.000-07:002011-08-29T11:52:13.689-07:00

It's been a week and a half since my last post, as I've been on vacation in northern California during that time.  But what a week to miss--a strong hurricane moving up the east coast with lots of media hype surrounding this storm.  I wanted to just briefly cover some highlights of the fallout from this storm by looking at what other people are saying. 1) Irene caused/is causing major flooding

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com1tag:blogger.com,1999:blog-8688208662932527409.post-70440041335701092442011-08-17T15:50:00.000-07:002011-08-17T15:50:17.939-07:00

I often use complex, 4-dimensional weather models and show their output here as an indication of what our weather forecasts look like.  But today I wanted to show how a much simpler weather model works--and how sensitive these models can be to their parameters. I wrote up what would be considered a small surface parameterization scheme to simply forecast the air temperature at the surface at a

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com1tag:blogger.com,1999:blog-8688208662932527409.post-63050674526825188662011-08-15T12:30:00.000-07:002011-08-15T12:30:19.694-07:00

I don't often write about the northeast in this blog.  It's probably because I've never lived there and therefore haven't really experienced their annual weather patterns firsthand.  I've lived in the upper midwest, the southern plains, and now the Pacific northwest, so that's where I tend to focus my writings. But today I am indeed going to talk about the northeast.  As you can see in a radar

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-16847448357994850882011-08-11T10:41:00.000-07:002011-08-11T10:41:29.725-07:00

As reports from people I know in Oklahoma keep streaming in on Facebook, it looks like today is going to be one of the cooler days in the past several weeks in that area.  For a place that has seen daily highs above 100 for much of the past month, the fact that it's only 70 degrees in Norman, OK, around noon is quite spectacular.  That's more Seattle-like in terms of the weather... But we can

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-36943915195391626432011-08-08T12:31:00.000-07:002011-08-08T12:31:05.706-07:00

Just a quick post today looking at the upper-air pattern forecast for this week. It continues to be warm in the central part of the country.  The Climate Prediction Center outlook for the next 6-10 days continues that trend: CPC 6-10 day outlook of temperature probability as of Aug. 7, 2011. In the meantime, though, cooler-than-normal temperatures are expected for the Pacific Northwest and

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-75380081245131852382011-08-01T12:24:00.000-07:002011-08-01T14:47:22.238-07:00

Looking out into the tropics today.  Last week, Tropical Storm Don failed to live up to expectations in south Texas.  The rainfall associated with the storm dissipated rather quickly, bringing little relief to that drought-stricken area. However, we have a new disturbance in the tropical Atlantic, labeled by the National Hurricane Center (NHC) as Invest 91L.  Here's how it looked early this

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-57671926672110462982011-07-28T10:45:00.000-07:002011-07-28T10:45:13.775-07:00

Repeated rounds of storms around the periphery of the still-persisting ridge in the southern US have contributed to rainfall totals that are well above climatology for the last few weeks in some locations.  In Chicago this is the wettest July on record with 9.75 inches so far this month.  Furthermore, this month is now the 9th wettest month of all months in Chicago since records began--pretty

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-3803472857182767592011-07-25T10:44:00.000-07:002011-07-25T10:44:59.531-07:00

I awoke this morning to the sound of what I thought were airplanes flying over my house periodically.  It's not uncommon--the main northerly approach to Sea-Tac airport goes right over my house.  And they don't call Seattle "Jet City" for nothing.  But the sound wasn't quite right--and it was occuring way too frequently.  Turns out it was something far more exciting--thunderstorms. KATX 0.5

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-34137682936569295862011-07-20T13:31:00.000-07:002011-07-20T13:31:38.244-07:00

As most people in the central US are well aware, it has been extremely hot and humid for the past several days.  Model forecasts indicate that we'll be staying this way for a little while longer, too. This morning's 500mb analysis shows the ridge that has been promoting these hot, stagnant conditions rather clearly: GFS 500mb analysis at 12Z, July 20, 2011. There is pronounced ridging with the

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-59805678192649686832011-07-11T10:42:00.000-07:002011-07-11T10:42:05.524-07:00

Last night we had two MCCs merge together over Wisconsin to form a very potent MCC with a leading convective line in southern Michigan this morning.  Here's the IR satellite image from earlier this morning: GOES-E IR image from 1015Z, July 11, 2011. You can see the characteristic circular "blob" pattern in the IR imagery that is the hallmark of MCCs.  It seems that the particular route these

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-91619152983074028432011-07-07T10:25:00.000-07:002011-07-07T10:25:52.742-07:00

I was pleasantly surprised to see the University of Wisconsin -- Cooperative Institute for Mesoscale Satellite Studies (CIMSS) blog post on July 6th.  It discusses a mesoscale convective vortex that just occured over the southwestern US on July 5th and 6th.  Moreover, they have a stunning GIF animation of visible and IR satellite images that shows how the storms first organized as a mesoscale

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-50876644181375222702011-07-05T11:36:00.000-07:002011-07-05T11:36:09.669-07:00

For my last post in this series about different kinds of mesoscale convective systems (MCSs), I'm going to briefly talk about one of the rarer types of MCSs--the mesoscale convective vortex (MCV).  These sorts of storms usually form from parent mesoscale convective complexes (MCCs), so we have a full line of mesoscale convective classification: MCS --> MCC --> MCV In trying to trace the history

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-91926201386005666142011-06-30T11:30:00.000-07:002011-06-30T11:30:47.629-07:00

Fittingly enough, as I began this discussion on mesoscale convective systems (MCSs), our first tropical storm of the Atlantic hurricane season formed off the east coast of Mexico.  Tropical Storm Arlene made landfall this morning near Cabo Rojo, Mexico.  Here's the an IR satellite image shortly after landfall: GOES IR satellite image of TS Arlene at 1715Z, Jun 30, 2011. I find it fascinating

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-49230120522862719472011-06-28T14:12:00.000-07:002011-06-28T14:12:25.063-07:00

As I mentioned in my last post, I want to go into some detail about the definition and structure of several classes of storms.  We use the term mesoscale convective system to describe any collection of storms (or other convective activity) that is organized on a scale larger than a single storm.  Today I want to focus on one particular type of mesoscale convective system--the mesoscale convective

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-18362710513914843312011-06-26T20:30:00.000-07:002011-06-26T20:30:32.005-07:00

This evening's radar composite was quite the sight. Fig 1 -- NEXRAD composite base reflectivity from 0228Z, June 27, 2011. There are three areas of storms moving across the northern plains and upper midwest.  The leading batch at this time was crossing the Iowa-Illinois border.  The next line was in western Iowa and southeastern Nebraska, and the furthest west group was in western Nebraska and

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-6018346481305810652011-06-20T15:45:00.000-07:002011-06-20T15:47:47.337-07:00

There's a moderate risk of severe storms with a PDS (particularly dangerous situation) tornado watch out for parts of Nebraska and Kansas this afternoon.  And storms are indeed exploding across the central plains.  Here's a reflectivity image from earlier this afternoon in southern Nebraska. Fig 1 -- 0.5 degree base reflectivity from KUEX at 2121Z, June 20, 2011. Several powerful storms are

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-11801692332692895092011-06-16T16:21:00.000-07:002011-06-16T16:21:55.993-07:00

Continuing from my previous post, I mentioned that there was another mechanism that helped explain why there was this maximum of winds just above the surface starting in the evening and persisting through the night.  This other mechanism would work to explain why the nocturnal boundary layer wind maximum seemed to be stronger and more frequent over the Great Plains and other selected locations

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-76332895957098583722011-06-14T21:08:00.000-07:002011-06-14T21:08:31.452-07:00

Tonight's topic is a bit more elaborate and complex than a lot of what I usually talk about here.  However, it's a subject I enjoy a lot and I hope people will find it useful.  I've made several drawings to try to illustrate what I'm talking about, so hopefully things won't seem too complicated.  I'm also splitting my discussion over two blog posts so as not to seem too overwhelming. So, as we

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-12357834003431930162011-06-08T14:55:00.000-07:002011-06-08T14:55:19.474-07:00

Switching gears a bit, I wanted to talk a bit about El Nino and why it's such a big deal for us. When we talk about El Nino (or, as it is usually called these days, the El Nino-Southern Oscillation (ENSO)), we're talking about a periodic shift in the sea-surface temperature pattern over the eastern and central equatorial Pacific.  This in turn affects pressure patterns throughout the world,

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com1tag:blogger.com,1999:blog-8688208662932527409.post-50431915928797865442011-06-07T19:10:00.000-07:002011-06-07T19:10:34.826-07:00

Large-scale ridging continues across the central and eastern US through the middle of this week, with some storms firing around the northern (and Gulf Coast) periphery of this sprawling surface high.  With clear skies and general subsidence, near record-high temperatures are being reported across much of the central part of the country. But, that's not what I want to talk about tonight.  When

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-21376378066568451652011-06-04T21:31:00.000-07:002011-06-04T21:31:21.431-07:00

In my last post I talked about how it looked like this weekend would be rather quiet weather-wise across the eastern half of the country due to hints at a building ridge across the region.  Well, this has turned out to be partially correct.  A surface high-pressure ridge has built across the southern US with a secondary ridge maximum further north in Canada.  There's week troughing in between

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-39028687612072999642011-05-31T15:21:00.000-07:002011-05-31T15:21:24.785-07:00

Sorry about the delay in updates.  I've been rather busy and went up to Canada over the long weekend, so I'm just now getting back into the swing of things. Nothing too technical today, just a look at some medium- to long-range model forecasts for the end of this week.  The active weather continues today across the upper midwest with a shortwave trough present over the northern plains: Fig 1 -

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-26879783121790235052011-05-23T18:49:00.000-07:002011-05-23T18:49:37.034-07:00

As most people are well aware by now, a horribly strong tornado ripped through the heart of Joplin, Missouri on Sunday evening.  With 116 people confirmed as killed so far, this is the deadliest tornado to strike the US since the 1940s.  The photos and videos of the aftermath of this storm are everywhere. I had a very slight acquaintance with Joplin.  Every time I would drive between my home in

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-36490277886579000942011-05-21T19:40:00.000-07:002011-05-21T19:40:35.245-07:00

This evening there are severe weather watches across several parts of the central US, including a tornado watch across eastern Oklahoma.  Early this evening, a few storms fired to the east of the I-35 corridor--including a couple tornadic ones.  Here's the radar image from 0103Z.  I noted the locations of the tornadic storms with white arrows. Fig 1 -- 0.5 degree base reflectivity from KOUN at

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-92105095676874396982011-05-18T11:20:00.000-07:002011-05-18T11:20:22.783-07:00

This will be a short post today.  I recently had to install Unidata's Integrated Data Viewer program on a computer and thought I'd use some of the program's capabilities to remind  us what we're actually looking at when we look at upper-level height charts. Take the 300mb chart for instance.  I often will show charts like this: Fig 1 -- NAM 6 hour forecast of 300mb height (contours) and winds

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-69505108904873948412011-05-14T15:59:00.000-07:002011-05-14T15:59:43.125-07:00

Recently I've read a few claims by people online that something funny is going on with our NEXRAD Doppler radars. What is this strangeness?  Apparently some people believe that the appearance of certain "spikes" on the national radar mosaics are evidence of a government-led weather modification program.  They believe that the radars are picking up high-energy pulses from some secret government

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-90430661244210678862011-05-11T15:49:00.000-07:002011-05-11T15:49:13.600-07:00

Many people I know were discussing the moderate risk of severe weather that the Storm Prediction Center had issued last night for today in western Oklahoma: Fig 1 -- SPC Day 1 convective outlook as of 12Z, May 11, 2011. From the SPC. However, by mid-morning, that moderate risk had gone away (and the slight risk had expanded considerably further north)... Fig 2 -- SPC Day 1 convective outlook

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-45705947169804243912011-05-08T16:52:00.000-07:002011-05-08T16:52:18.692-07:00

Back to a general synopsis of the weather conditions to expect in the coming week... The SPC has a slight risk of severe weather out for various isolated spots in the upper midwest with even more conditional possibilities of severe weather in the southern plains over the next few days. So, let's look at the overall setup.  Here's Sunday morning's 12Z 300mb upper air analysis: Fig 1 -- 300mb

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-79537267355359667722011-05-04T18:32:00.000-07:002011-05-04T18:32:13.280-07:00

One of the first rules of thumb that novice weather forecasters learn (or, at least, one of the first rules of thumb that I learned) was that when forecasting the overnight low temperature, it should never be more than a degree or two cooler than the dewpoint temperature.  This rule of thumb applies very broadly--it's very hard to cool temperatures down below the dewpoint temperature.  Why is

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-1282582183842084712011-05-01T21:02:00.000-07:002011-05-01T21:02:35.087-07:00

As we saw last week, sometimes these severe weather events can be incredibly destructive.  Last week's tornado outbreak in the south was the largest since the 1930s--around 350 have been confirmed killed so far. And, unfortunately, there's a risk of another round of severe storms for that part of the country on Monday.  The SPC has a slight risk out for a narrow corridor of the southern US.

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-86805611280787363832011-04-27T18:22:00.000-07:002011-04-27T18:22:51.380-07:00

Nothing technical here tonight--just awe at how terrible the fury of nature can be. Currently, the majority of the eastern US is under a tornado watch: Fig 1 -- SPC tornado watches (red) and severe thunderstorm watches (blue) as of 0041Z, April 27, 2011. With dozens and dozens of tornado reports so far.  Mississippi and Alabama have been particularly hit hard this afternoon--and storms are

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-31722611943400695522011-04-25T20:55:00.000-07:002011-04-25T20:55:01.273-07:00

I've been away for a week--and what a week it has been.  Repeated rounds of tornadoes, including one that destroyed dozens of homes and part of Lambert International Airport in Saint Louis. Unfortunately, it's not over yet.  The SPC convective outlooks currently have moderate risks of severe weather posted for the next three days.  It's round after round of severe weather. I want to quickly

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com1tag:blogger.com,1999:blog-8688208662932527409.post-22438208228882493692011-04-19T12:11:00.000-07:002011-04-19T12:11:00.496-07:00

As many people know by now, the SPC has issued a moderate risk of severe storms this afternoon for parts of the midwest from Arkansas up through the lower Ohio River valley. Fig 1 -- SPC Day 1 convective outlook for April 19, 2011. SPC surface mesoanalysis at 1PM CDT (18Z) shows a low pressure centered over central Missouri with a large warm, moist sector extending to the east.  This warm

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-57624442928489266082011-04-16T15:48:00.000-07:002011-04-16T15:48:03.381-07:00

One of the most frequent questions I am asked by people is how we can see tornadoes on our Doppler radar.  Given that the shortwave that has trekked across the southern US the last few days has produced (and is still producing...) dozens of tornadoes, I collected a few images from radars to try and show the different signatures associated with tornadoes.  I believe that the more people know about

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com3tag:blogger.com,1999:blog-8688208662932527409.post-78996229246409605672011-04-14T12:19:00.000-07:002011-04-14T12:19:39.288-07:00

We're definitely entering the heart of the spring severe weather season now.  In the wake of last weekend's moderate risks in northern Iowa and Wisconsin where several large and damaging tornadoes were reported, yet another potent shortwave is digging into the central part of the country. The SPC has issued a moderate risk for eastern Oklahoma and western Arkansas today: Fig 1 -- SPC day 1

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-17044211542069826432011-04-10T14:25:00.000-07:002011-04-10T14:27:14.201-07:00

Last night was a lot more active than I expected.  Several tornadic supercells did severe damage in northern Iowa.  These storms fed off of convergence associated with the warm front that was lifting north through the state at the time.  I'll admit that in my last blog post I wasn't really looking at the warm front at all.  But, it is a front and there is convergence along it--enough to force

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-58467067597204712622011-04-08T22:42:00.000-07:002011-04-08T22:42:07.663-07:00

I shouldn't necessarily say "upcoming"--there are some ongoing severe storms in northern Oklahoma and eastern Kansas even late this Friday evening: Fig 1 -- KICT 0.5 degree base reflectivity from 0345Z, April 9, 2011. Several reports of large hail were associated with these storms as they moved through the area.  No tornadoes reported with these storms.  There were possible tornado reports with

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-61657292572178367852011-04-07T18:34:00.000-07:002011-04-07T18:34:53.483-07:00

First, let's get one thing out of the way.  Yes--there is pretty good agreement among the global models (the GFS and the ECMWF) that a severe weather event will impact the central US on Sunday and Monday.  I plan to talk about this upcoming event soon...but not this evening. This evening I want to talk about this amazing storm impacting southern Alaska.  Here's a visible satellite image from a

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-67641245057238300082011-04-03T15:06:00.000-07:002011-04-03T15:06:42.207-07:00

Well, the day of severe weather is upon us.  And it's now around 4:30 PM central time and we're still waiting for storms to fire. In my last post, I talked about how a feature called the "capping inversion" would work to inhibit thunderstorm development throughout the afternoon until this cap could be broken so that air could more easily rise.  Remember that the capping inversion can be seen as

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-23657718874698759972011-04-02T18:37:00.000-07:002011-04-02T18:37:41.361-07:00

Now that I'm back again, to continue the discussion.  I already noted in part one how the upper-air pattern seemed somewhat chaotic in the forecast and that would also reflect on the surface pattern.  It's the surface and low-level variables that really have people worked up about this event.  Remember how we saw a strengthening pressure gradient due to pressure rises and falls across the middle

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-77640766336285994112011-04-02T12:42:00.000-07:002011-04-02T12:42:58.053-07:00

That shortwave trough that is forecast to move through the central United States on Sunday into Monday is well on its way--we're finally beginning to clear out here in Seattle as the trough axis (and the accompanying cold front) has moved through.  Now it's out into the mountains and headed toward the plains... In my last post I talked about how there was some ambiguity in the models with

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-16972240011493008212011-03-31T12:11:00.000-07:002011-03-31T12:11:17.679-07:00

As many people have noted recently, the end of March has been unusually cool across much of the northern part of the country, as arctic air has settled in.  Here's this morning's approximate low temperatures across the country: Fig 1 -- Surface temperature (colors) and pressure (contours) at 11Z, March 31, 2011. From the HOOT website. Note that 40 degree Fahrenheit lows exteded all the way down

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-28146719873095822562011-03-29T11:32:00.000-07:002011-03-29T11:32:10.925-07:00

We currently have relatively weak flow across the Rocky Mountains and central US, so it's a bad time to be looking for lee-side cyclogenesis.  So, in the meantime, I'll turn to more current weather to discuss. Spring has definitely arrived here in the Pacific Northwest--the trees are blooming, leaves are starting to appear, and high temperatures are consistently in the 50s.  However, with spring

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-60724208907353954482011-03-27T15:32:00.000-07:002011-03-27T15:32:34.840-07:00

It's been a week since my last blog post and that's mostly because I've been away on spring break this past week.  But I am back now, so I should start posting things regularly again. A few people have asked me recently about the dynamics behind mountain flow--why we get this "rain shadow" effect among other things.  There are several excellent resources out there that explain this, but I'll do

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com2tag:blogger.com,1999:blog-8688208662932527409.post-2155549152520433662011-03-20T23:06:00.000-07:002011-03-20T23:06:45.507-07:00

It's been a while since I actually looked at a week-long forecast of what's up in the weather, so I thought I'd begin the week by taking a quick look at that. A look at tonight's 00Z 300mb analysis shows the upper-air pattern: Fig 1 -- 300mb objective analysis valid 00Z, March 21, 2011.  From the HOOT website. Features of note include the rather deep trough just off the California coast, with

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-59216691243333198632011-03-16T16:35:00.000-07:002011-03-16T16:35:05.463-07:00

In reviewing all the weather blogs I read this morning, I noticed this line in WGN-Chicago's Weather Blog: "...Powerful southwest winds predicted to gust to 35 mph Thursday afternoon combined with jet stream-induced warming produced as air sinks and compresses beneath the nose of powerhouse 170 mph upper winds should more than compensate for the reduction of sunshine and allow warming to proceed

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-77787855187846854922011-03-11T18:44:00.000-08:002011-03-11T18:44:45.974-08:00

Usually I talk about the weather in this blog.  The fact is, a lot of the dynamics of weather are derived from basic fluid dynamics which apply not only to air, but to water as well.  We talk about waves in the atmosphere all the time--short waves, long waves, buoyant waves, etc.--and the same mechanics describe water waves.  So today I'm going to give a brief look at some of the simple

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com1tag:blogger.com,1999:blog-8688208662932527409.post-86825906854018431962011-03-06T13:41:00.000-08:002011-03-06T13:41:46.596-08:00

Flooding concerns are going to be big this spring after all of the huge snowfalls we've had in the northern part of the country. For instance, here's today's watches, warnings and advisories map from the National Weather Service. Fig 1 --  NWS watches, warnings and advisories for 2010Z, March 6, 2011. We're in between two storm systems in the country at the moment.  Up in the northeast we can

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-59342763157607121272011-03-03T15:31:00.000-08:002011-03-03T15:31:48.727-08:00

This will be a quick little post.  We've been getting a lot of rain recently in the Seattle area, and the mountains have been seeing a lot of snow.  So, the radar has been pretty active with lots of precipitation moving through.  The other day I was checking to see if there were any showers moving through the area and this was the radar view south of Seattle. Fig 1 -  KATX 0.5 degree base

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-44539701250072720512011-02-28T11:42:00.000-08:002011-02-28T11:42:25.789-08:00

Last night was quite the night for severe weather--several quasi-linear convective systems moved across the southern US.  There's another moderate risk out for today in the central Appalachians associated with this same powerful cyclone.  I didn't even mention the snowfall potential on the northern side of the cyclone...  Lots going on with this one. But today I wanted to cover a more

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-82063366295814092642011-02-26T14:14:00.000-08:002011-02-26T14:14:21.360-08:00

Another day, another moderate risk of severe weather in the southern US forecast for tomorrow.  Severe weather season seems to be here... Fig 1 -- SPC day 2 convective outlook from 1730Z, Saturday, Feb. 26, 2011. The evolution of this system seems to be straightforward--at first.  We start with the current upper-level conditions.  Like we saw with the last severe weather system, we start out

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-10534543021566984762011-02-23T18:39:00.000-08:002011-02-23T18:53:30.227-08:00

Quick post tonight as I have some other things I need to take care of.  But, I promised to talk about snow in Seattle today... First, as many people have noted, the SPC has upgraded to a moderate risk for the severe weather potential tomorrow in the southern US: Fig 1 -- SPC day 2 convective outlook as of 1730Z, Feb. 23, 2011.  From the SPC website. So things are continuing to shape up there..

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-34748590357801427312011-02-22T19:08:00.000-08:002011-02-22T19:08:53.379-08:00

A lot is happening in the weather across the country over the next few days.  Today I'm going to focus on the severe weather threat Thursday into Thursday night for the south-central part of the country.  Tomorrow I'm going to talk about the snow event that is shaping up for Wednesday night into Thursday here in Seattle. The shortwave trough that moved through a week or so ago that initially

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-11510023870627235972011-02-19T12:16:00.000-08:002011-02-19T12:16:41.074-08:00

We're getting into one time of year (another is in the mid to late summer) when we start to see a fair number of Red Flag Warnings crop up across the country. Fig 1 -- US Warnings, watches and advisories as of 1918Z, Feb 19, 2011. In the warnings and advisories map above, the dark pink areas in the trans-Pecos region of western Texas and southern New Mexico and also in southern Virginia and

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-4531735078877079932011-02-12T13:13:00.000-08:002011-02-12T13:13:59.810-08:00

The first half of February has been one major snowfall after another.  This includes several snowfalls in places that aren't used to seeing a lot of snow--like central Oklahoma.  The bitter cold weather and several snow events in the central US have been due to a persistent pattern aloft since the beginning of February. Fig 1 -- Hemispheric plot of 500mb heights (shaded) and mean sea level

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-57924234454099631732011-02-07T18:28:00.000-08:002011-02-07T18:28:55.144-08:00

Ok--I was going to do a post about the large scale pattern in upper-air features over the past two weeks and how that will hopefully start breaking down by the end of this week.  But then on the way back from the University today, I started getting text messages from people... "Was that hail that just fell?"  "Hail?  Graupel?"  "Is it supposed to snow today?" Hmm...we were in the upper 40s

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-61063542672219903552011-02-04T22:41:00.000-08:002011-02-04T22:41:11.718-08:00

Just a quick post tonight showing how much of the central part of the country is covered by snow--and we can see it on satellite images.  Snow is usually very bright, and because of this we say it has a high "albedo".  The albedo of an object is how effectively it reflects any incoming radiation.  The higher the albedo, the more reflective the surface.  Snow and ice, being bright white (usually),

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-85894181117456044092011-02-01T23:46:00.000-08:002011-02-01T23:46:38.009-08:00

Well, it's around midnight central time now--and the snow is still falling for many people.  But it ended rather soon for many as well--too soon, given some of the forecasts.  However, earlier Tuesday it was a very, very impressive looking storm-- Fig 1 -- Radar mosaic from 2008Z, February 1st, 2011. This storm has a very well-defined structure.  The center of the low pressure at this point (

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-47006385272784726362011-01-31T20:56:00.000-08:002011-01-31T20:57:06.894-08:00

In reading a lot of the forecast discussions from WFOs across the upper midwest, I noted several references comparing this coming winter weather event to the blizzard of January 2-4th, 1999.  Though I apparently lived right through the middle of it, I honestly didn't remember this particular event.  So, I thought I'd see what all this hubub was about and quickly, qualitatively compare the two

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0tag:blogger.com,1999:blog-8688208662932527409.post-89699826211732383642011-01-30T16:00:00.000-08:002011-01-30T16:00:39.564-08:00

It's been a week or so since I last posted on here.  The annual meeting of the American Meteorological Society was here in Seattle last week and needless to say I was very busy during that time.  But now that's done and my schedule can resume something more normal... Today's National Weather Service summary map looks pretty spectacular: Fig 1 -- NWS watches and warnings as of 2300Z, January 30

Luke Madaushttp://www.blogger.com/profile/00342287184407373669noreply@blogger.com0