Ramblings of a Graduate Student

A big warm-up is coming to the southern plains and very well could extend northward into the central and northern plains as well.  The image above and below were generated from tonight’s 00 UTC (7 PM CDT) initialization of the North American Model (NAM).  The color fill in both of these images is the forecast surface temperatures at 21 UTC (4 PM CDT) on Monday (top) and Tuesday (bottom).

A big warm-up is underway, with temperatures approaching lower 80sF across far western Oklahoma and the eastern Texas panhandle on Monday.  By Tuesday, the warmth expands even more, and the NAM forecasts temperatures above 90F in the Childress, Texas area.  Temperatures could very well approach and even exceed 70F across portions of southern Canada!

This warm-up is the result of a strong low that is developing along the west coast of the United States.  This will help to warm the central United States, and should begin to draw up moisture by the end of the week.  As the west coast trough (low) moves into the central United States, severe weather chances should increase.

The spring severe weather season could very well be about to begin…

Yesterday, much of Oklahoma spent the day with temperatures in the 20s and 30s (F), dealing with strong northerly winds, and watching snow fall.  Today, snow is still falling across the eastern sections of the state, while the western half of the state enjoys a spring thaw.  As of 2:45 PM CDT, there was a 23F temperature change throughout the state!  56F in portions of the panhandle to 33F in several places in the east.

If we compare today’s temperatures to what was occurring yesterday at the same time, some areas are 20F warmer today (panhandle) whereas others are 5F cooler (far southeast).  So why such a rapid warm-up?

Normally, rapid warm-ups after snowfall is the result of strong southerly winds bringing the warm air northward.  However, as the image above indicates, northerly winds persist across almost the entire state.  So, southerly winds can’t be the reason for the warm-up across the southern plains.

The actual reason for such a rapid warm-up has to do with what time of year it is.  As we continue into the spring and summer months, the sun angle continues to increase in the sky, and is present longer than during the winter months.  The image above is a measure of how much sunlight is reaching the ground.  Warmer colors indicates areas where more sunlight is reaching the ground and cooler colors indicate less sunlight.  Notice the sharp gradient between western and central Oklahoma?  Also, notice how it matches up quite nicely the with sharpest temperature gradient in the first image?  This is where the edge of the clouds associated with the departing winter storm can be found.  Areas in western Oklahoma are free of clouds and are enjoying maximum sunlight, whereas places to the east have thick clouds and snow is still falling.

Tomorrow, the winter storm will be well to the east of the southern plains.  As such, the late March sun will act quickly to warm the area back to seasonable levels.  The exception to this will be in far eastern Oklahoma, where 12-18″ of snow will have fallen over the weekend.  Before all of the sun’s energy can go toward warming the atmosphere, in these places, it must first work to melt some of the snow.  Don’t get me wrong, these places will still be a lot warmer than they have been this weekend, but they won’t be as warm as they could have been.

So just how impressive is the warm-up across the southern plains?  Check out the following two visible satellite images from today.

The image above is valid this morning at 1545 UTC (10:45 AM CDT).  Notice the white areas that stretch from southwest Oklahoma and northwest Texas northeast into southcentral Iowa.  Most of this white is actually not clouds, but snow on the ground from the previous two days.  Now, take a look at the image below, which is valid this afternoon at 1945 UTC (2:45 PM CDT).  The white areas described previously have faded considerably or disappeared altogether.  In the span of four hours, most of the snow that fell yesterday has melted.  Eastern Oklahoma and western Arkansas will have this kind of rapid melting to look forward to in the coming days.

(PS…Look how classic this storm is!  Very clear comma shape, with the comma-head over eastern Oklahoma and western Arkansas and a very pronounced dry-slot extending from the Gulf of Mexico, northeast into the western Florida panhandle and southern Alabama!  If you look close enough, you can follow the dry-slot from southern Alabama, north then northwest then west then southwest all the way into eastern Arkansas!!)

Anyone outside last night across Oklahoma may have noticed a slight chill in the air compared to temperatures from earlier in the week.  Tonight, however, temperatures are running anywhere from 5-15F throughout a large part of Oklahoma – in fact, some areas of southeast Oklahoma are almost 20F warmer tonight!  The warmer temperatures should last a few more days before actually increasing even more before next weekend.

Late in the week, into next weekend, models have hinted at the possibility of a pattern change back to colder temperatures.  I’m sure this will be the focus of blog posts in the coming days…

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.

The forecast warm-up for the central United States is well underway.  In fact, the high temperature in Norman, OK was 57F today.  Contrast that with a high temperature of 56F in Key West, FL.  As was pointed out by a friend, for one of those cities, the high temperature was quite pleasant and for the other city the high temperature was very unpleasant.

(Image courtesy of Unisys Corporation.  Current temperatures can be found here.)

Note:  Read the following to put into perspective the severity of the recent cold air outbreak.  This is taken from the National Weather Service office in Key West, FL.

THE LOW TEMPERATURE TODAY AT KEY WEST INTERNATIONAL AIRPORT WAS 42
DEGREES. THIS SHATTERED THE DAILY RECORD FOR MINIMUM TEMPERATURE
MEASURED IN KEY WEST ON JANUARY 11TH. THE PREVIOUS RECORD WAS 48
DEGREES SET IN 1970. THIS LOW TEMPERATURE OF 42 DEGREES IS ONLY ONE
DEGREE AWAY FROM THE ALL TIME RECORD MINIMUM TEMPERATURE IN KEY WEST
OF 41 DEGREES SET IN 1886 AND TIED IN 1981.

IN ADDITION...THE LOW TEMPERATURE OF 42 DEGREES MAKES TODAY THE 5TH
CONSECUTIVE DAY OF MINIMUM TEMPERATURES BELOW 50 DEGREES...THE
SECOND LONGEST STRETCH OF CONSECUTIVE DAYS WITH MINIMUM TEMPERATURES
BELOW 50 DEGREES IN KEY WEST SINCE TEMPERATURE RECORDS BEGAN IN
1872. THE LONGEST STRETCH OF DAYS WITH LOW TEMPERATURES BELOW 50
DEGREES IN KEY WEST OCCURRED FROM DECEMBER 1ST THROUGH DECEMBER 6TH
OF 1876. THIS RECORD WILL LIKELY BE TIED TONIGHT...AS THE LOW
TEMPERATURE IS EXPECTED TO BE BELOW 50 DEGREES AT KEY WEST

INTERNATIONAL AIRPORT.