Ramblings of a Graduate Student

Friday night I discussed the possibility of setting up another southern snow storm.  All current indications are the are suggesting another Texas snow storm late Monday night into early Wednesday.  This will be the second snow storm for portions of central and northern Texas in less than two weeks.  (Remember, 11-12 February portions of northern Texas – including the Dallas-Fort Worth metropolitan area – received over a foot of snow.)

The image above is from the National Weather Service’s Hydrometeorological Prediction Center.  It is the probability of a given point receiving over 8″ of snow between 00Z Tuesday (6 PM CST Monday) and 00Z Wednesday (6 PM CST Tuesday).  Notice how areas south of the Dallas-Fort Worth metropolitan area have a 10% chance of receiving 8″ or more of snow – including the Waco, TX area.  Per the NWS office in Fort Worth, the last time Waco, TX received 4″ of snow was 1982.  This has been one of the greatest winters ever!

The first of several shortwave troughs (middle-to-upper level lows) is beginning to impact the southern plains.  In response to this shortwave trough, warm, moist air has surged northward over a stationary front.  This warm, moist air is being lifted (isentropically, for my meteorology students) over the stationary front resulting in widely scattered thunderstorms in the Texas Panhandle.  It’s amazing to think there are thunderstorms in places where last week  a fresh snow was covering the ground!

Last night I mentioned that the models were indicating that the warm up that portions of the southern United States has experienced over the last day or so was going to be relatively short lived.  Model forecasts have been persistent in bringing south cold air was pooling in northern Canada.  Tonight, I thought I would show you from where the cold air was originating.  The image above is a hemispheric plot.  The United States is in the bottom center and Europe/Asia in on the top center.  The white circle in the very middle of the image is the North Pole.  The black lines represent surface pressure features and the colored shading is the height at which the 500 mb pressure surface would be found.  (The 500 mb pressure surface could be thought of as the middle of the troposphere.)

So what does all this mean?  Well, in the image above, the cooler (blue) colors tend to be associated with cooler atmospheric temperatures and warmer (red) colors tend to be associated with warmer atmospheric temperatures.  Notice the warmer colors over the western portion of North America.  This is because of the ridge (upper-level high) over the area.  The warmer temperatures throughout the atmosphere associated with this upper-level high have wreaked havoc with the Winter Olympics.

Of interest for the upcoming week is the pocket of cooler colors in central Canada.  If one were to look at a loop of this map, it would be readily apparent that the colors (and atmospheric temperatures as well) have been trending even cooler and expanding in central Canada.  Over the next few days this pocket of cooler atmospheric air will surge south into the United States.  This will effectively return much of the southern United States back to below average temperatures.

And, as the title alludes to, the potential exists for another southern United States snow storm by mid-week.  With the cold air in place, an upper-level low will move from the eastern Pacific Ocean into southern California then into Texas.  Depending on the exact track of this upper-low, snow will be possible in portions of the southern plains.

Oh, and the models have consistently taken this potential mid-week southern plains snow storm and developed a Nor’easter by late next week.  It looks like more snow will be possible for areas along the east coast that have already seen a lot of snow this winter.  People from Washington D.C. to Boston will need to watch the forecast closely over the coming week.

Thanks to the hard work by Carnegie Mellon Civil Engineering student, Nick Doiron, I am pleased to announce that a method of efficiently moving the 1000+ photographs from email to Google Maps has been found!  The website that will host all of the Snow Shot of America photographs can be viewed here: Snow Shot of America.  Please know that we are still debugging and testing things so expect some problems in the short term.  With this said, photographs should begin to start appearing in the coming days.  It will take a while to get through all of them, but through the website above, people can start to view the photographs just as soon as they have been uploaded.

If you have any suggestions or notice any problems, please don’t hesitate to let me know via the comments!

Lastly, Laban West of Yukon, OK has provided me with this overview image displaying photographs from each state in a single image.  Thanks, Laban!

After spending a good portion of February below normal, much of the eastern two thirds of the country will experience a brief warmup tomorrow.  Temperatures throughout the southern United States will reach the 60s and possibly even 70s in some areas.  If you have the ability to get out and enjoy it, please do.  This warmup does not look to last as models continue to suggest, and observations support, a return back to below normal temperatures (at least for the south) by next week.

Not a lot is happening across most of the country tonight, at least in terms of precipitation.  The image above is a mosaic (composite) of the National Weather Service’s radars.  Areas that are shaded in blue and/or green indicate areas where a radar is detecting possible precipitation.  These areas include the eastern Great Lakes, western spine of the Appalachians,  and the eastern Rockies.  The precipitation across the eastern Great Lakes is the result of weak/light lake effect snow and the snow along the western spine of the Appalachians is the result of orographic lift.  The precipitation in the eastern Rockies is being aided by an upper-level low that will move into the plains by late week.

People throughout the eastern United States should enjoy the relatively tranquil pattern while it lasts.  Long range models continue to hint at a return to an active pattern as early as this upcoming weekend!

Last night I mentioned the persistent upper-level high (referred to as an upper-level ridge) that was redeveloping across the western United States.  In that post I mentioned that one result of this upper-level high would be warmer than normal temperatures across portions of the west.  Another impact is a lack of precipitation.

The image above displays the current “Drought Monitor” for the United States, including Alaska and Hawaii, produced by the National Drought Mitigation Center.  Areas shaded in yellow (bad) to red (worst) indicate areas where there is an ongoing drought.  Notice how for most of the country, little to no drought is found – including places in southern Texas that were experiencing an extreme drought just last summer.  One place where drought is a developing concern is the western United States, which has been under the west coast ridge for a good portion of the winter. This west coast ridge extends all the way up into Alaska, and the beginnings of a drought are observed there as well.

Another place that is experiencing a drought is Hawaii.  This is the result of a different upper-level high (also the result of an El Nino winter).  This upper-level high over Hawaii made my Snow Shot of America project “interesting” as the lack of Hawaiian precipitation has resulted in less snow on the peaks than is normally expected.