Severe Weather In Store For South/Tennessee Valley

RIO GRANDE VALLEY:

Today’s high and low temperatures around the RGV:

Brownsville: 78/70
Harlingen:  78/70
McAllen:  79/72
Weslaco:  78/71
Edinburg:  79/72

It was a very pleasant Tuesday.  Winds were much calmer today than previous days.  However, winds will begin to pick up again tomorrow afternoon.  A stalled frontal boundary, just north of the Valley will begin to dissipate over the next 24 hours.  Once it dissipates, clouds will begin to thin out and clear.  For tonight, cloudy skies with patchy fog developing after midnight.  Lows will be in the middle 60s; winds will be out of the south east at 5-10 mph.

(2/23/2011): Clouds will slowly begin to decrease after noon, but still remain partly cloudy tomorrow.  Afternoon temperature will be warmer and winds will be windier.  Highs will be in the lower to middle 80s and winds will range from 15-20 mph.  Clouds will return again on Wednesday night, with lows in the middle to upper 60s; southeast winds at 10-15 mph.

(2/24/2011): Thursday morning will start off cloudy but will once again clear by afternoon hours.  Afternoon highs will be in the lower to middle 80s.  A cold front will be passing through the RGV Thursday night into Friday morning, bringing drier air for the Valley.  Winds will also begin to die down as the front passes.  Thursday night will be slightly cooler, with lows in the lower to middle 60s and will feel less humid.  Winds will be shifting out of the northeast at 5-10 mph.

(2/25/2011): Friday will start off with patchy fog, but then turning sunny after 9 am.  Winds will start off out of the northeast then shift out of the east at 5-10 mph.  Though a cold front will pass through late Thursday evening, afternoon high temperatures will range from the lower 80s in the lower Valley to the upper 80s in the upper Valley.  Friday evening will be partly to mostly cloudy with lows in the lower 60s.  Winds will pick up a bit from the southeast at 10-15 mph.

Edinburg 3-day Forecast:

(2/23/2011): 86/66….Decreasing clouds….SE winds at 15-20 mph
(2/24/2011): 85/68….Clouds…SE winds turning NE at 5-15 mph
(2/25/2011): 87/60…Mostly sunny…N winds turning E at 5-15 mph

REST OF THE NATION:

An intense 500mb closed low height will be lifting into the Southern Plains as a shortwave trough on Thursday afternoon and evening.  Cyclogenesis will spawn at the surface beginning Thursday morning in NW TX.  The low will deepen over central OK Thursday afternoon and continue moving northeast.  Southerly flow from the warm sector of the low will increase temperatures and dewpoints ahead of the low.   With relatively high surface dewpoints and  80+ wind knots in the mid-levels, instability will increase and severe weather is prominent from eastern OK to the OH Valley on Thursday, into Friday.   Most storms that develop in the warm sector of the low (and along the dryline) will be elevated and severe.  Storms that develop north of the warm front will not be as elevated, therefore not severe.

The Storm Prediction Center has already issued out a “Slight Risk” for the areas I was talking about for Thursday and Thursday evening.  Tornadoes (EF0-EF2) and even isolated large tornadoes (EF3+) are very much possible, but the main threat looks to be large hail and high winds.  NAM and GFS forecast soundings show significant shear near the low 00Z Friday.  If you live in these areas, please use extreme caution Thursday and Friday and please stay informed on the upcoming weather conditions.

SPC Day 3 outlook. Slight Risk of severe thunderstorms.

About Brian

University of Oklahoma graduate with a degree in Meteorology. Follow me on Twitter: @WeatherInformer
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