The Storm Prediction Center is forecasting a potentially significant severe weather episode for the ARKLATEX and much of the lower Mississippi Valley region of the US from this afternoon through the overnight hours.  While the main area of concern is well to the northeast of southeast Texas the significance is that this event has the potential to be a mini-outbreak of tornadoes across a fairly large area; a rare event in itself, but even rarer for January.

Here is the SPC’s risk map for this severe event; note the MDT (Moderate) risk area in red:

Parts of SE Texas are included in the yellow (SLIGHT RISK) area, but read below for impacts in our area.

Map of the Tornado Potential:

The Black Hatched area in the image above indicates a 10% or greater probability of a significant tornado (EF2 – EF5) to occur within 25 miles of a point within that area.  The overall percentage is the probability of a tornado within 25 miles of a point.

Map of Damaging Wind Probability:

The setup for this event consists of a very strong upper level trough, a very strong jet streak (area of very strong upper level winds within the jet stream) which will generate a strong surface low pressure center, and attendant cold front (lift).  The airmass ahead of the front is very unstable as warm gulf air and moisture is transported northward into the area beneath the strongest lift and forcing.  The strong lower and upper level winds create wind shear which will enhance rotation within the thunderstorms.  There will be storms ahead of the front which will have a tendency to move very quickly and generate strong tornadoes, hail, and strong winds.  Also, the front itself will generate thunderstorms along the leading edge (a squall line) which will have a damaging wind, hail, and tornado threat as well.  It’s essentially a double whammy.  Severe storms ahead of the front followed by severe storms along the front. Again, the main area that will by under the gun is the ARKLATEX and Lower MS Valley region.

Map showing the jet stream and strong jet streak (forecast for midnight tonight):

The green area is an area of 115 mph winds aloft (~30,000 feet).

Map of current watches:

Red boxes are tornado watches and blue is severe thunderstorm watch.  These will expand east as the storm progresses into this evening and overnight.

Current Texas Radar showing from draped across middle OK and into north central Texas:

Map of weather in Texas showing temperatures 10-15 degrees cooler behind the front:

For example in Austin, the temperature (red number) is in the mid 70′s while it is in the mid to lower 60′s west of Austin where the front has moved through.  The wind barbs point in the direction the wind is blowing towards.  Northwest/westerly winds behind the front and southerly winds ahead.

SE TEXAS IMPACTS

The front will approach SE Texas later tonight (10pm) and some storms ahead of the front are possible as moisture streams from the Gulf of Mexico.  Storms are expected along the front itself as it passes through.  Some storms could produce damaging winds, but the chances are much less than areas north and east of SE Texas.  This will not be a huge rain maker of a system either, but spring will return to SE Texas (even though it’s technically winter) after the frontal passage and for the remainder of the week.

Hope those in the areas of highest severe weather risk are spared the worst and remain safe and prepared.