#2410 Postby srainhoutx » Wed Dec 18, 2013 6:24 am
It looks like the cap may be too strong for surface based storms to develop as the Euro and Canadian have slowed the cut off upper low a bit and SW flow aloft keeps the cap large and strong across Central and SE Texas via the GFS, but the Euro/Canadian suggest a bit more negative tilt and better dynamics for severe weather and are much 'wetter' and even suggest training showers/storms across Central Texas as a surface low develops. Further N in the cold sector, icy conditions with freezing rain look likely across portions of the Panhandle and Oklahoma and locations further NE. Warm sector heavy training rains may be possible across Arkansas/Tennessee and on E where severe storms have a better chance to develop extending into the SE Region. Another freeze may be possible early next week as well. Late Christmas Day looks changeable as yet another SW upper low approaches from our W and a secondary re enforcing shot of 'colder air' drops S into the Southern Plains on Christmas Eve. It may take another day or two to sort out any severe weather potential for Texas as the short wave that will develop into a robust upper low across Southern California/Baja late Thursday into Friday is further sampled by the RAOB network.
The longer range beyond Christmas Day looks very unsettled with several disturbance crossing our Region and perhaps much colder air drops S from Canada into the Inter Mountain West and Plains and a strong storm system ejects out of Mexico with a noisy sub tropical jet. We will see.
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0400 AM CST WED DEC 18 2013
VALID 211200Z - 261200Z
...DISCUSSION...
...TX...ARKLATEX...LOWER MS/LOWER OH VALLEY ON SAT/D4...
THE VARIOUS MODELS AND ENSEMBLE MEMBERS ARE IN DECENT AGREEMENT IN
SHOWING THE LOCATION OF GREATEST SEVERE POTENTIAL FROM TX INTO THE
LOWER MS VALLEY ON SAT/D4 AS THE SWRN UPPER LOW/TROUGH EJECTS
RAPIDLY NEWD ALONG WITH A DEVELOPING SURFACE LOW/WAVE ALONG THE
STATIONARY/WARM FRONT. S OF THIS FRONT...AMPLE LOW LEVEL MOISTURE
WILL EXIST WITH MID TO UPPER 60S F DEWPOINTS.
NUMEROUS THUNDERSTORMS SHOULD BE ONGOING ALONG AND N OF A STATIONARY
FRONT EARLY ON SAT/D4...FROM WRN TX NEWD ACROSS THE RED RIVER VALLEY
AND INTO SERN MO...WHERE STRONG WARM AND MOIST ADVECTION WILL EXIST
COURTESY OF A 60 KT SLY LOW LEVEL JET. RAPID COOLING ALOFT...A
VEER/BACK SIGNAL IN THE WIND PROFILE IN THE 850-700 MB LAYER...A
RATHER MERIDIONAL UPPER FLOW REGIME AS WELL AS A SEMI-CAPPED WARM
SECTOR SUGGEST THAT A STRONGLY FORCED QLCS WILL BE LIKELY...CAPABLE
OF DAMAGING WINDS AND A FEW TORNADOES. THE GREATEST THREAT AREA IS
EXPECTED TO BE NEAR THE SURFACE LOW TRACK ALONG THE DEVELOPING WARM
FRONT...OR THE NRN HALF OF THE OUTLOOK AREA.
...SUN/D5 AND BEYOND...
THE SHORTWAVE TROUGH IS FORECAST TO BE LOCATED OVER THE MID MS
VALLEY/LOWER OH VALLEY SUNDAY MORNING WITH LOSS OF AMPLITUDE
COMPARED TO PREVIOUS DAY. AT THE SURFACE...THE COLD FRONT WITH
ONGOING STORMS SHOULD TRAIL APPROXIMATELY FROM IND/OH SWWD ACROSS
TN/AL/MS WITH SOME ONGOING THREAT. GIVEN TIMING ISSUES AS WELL AS
THE LOSS OF THE SHORTWAVE TROUGH TO THE N...WILL DEFER ANY SEVERE
AREAS TO LATER OUTLOOKS. AT THIS TIME...IT APPEARS THE GREATEST
POTENTIAL FOR DAMAGING WINDS AND/OR A FEW TORNADOES WOULD BE ACROSS
ERN MS/AL/GA AND TN IN PROXIMITY TO THE MOST ROBUST MOISTURE AND
MARGINAL INSTABILITY...WITH LINEAR STORM MODE MOST LIKELY.
..JEWELL.. 12/18/2013
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