860
ACUS11 KWNS 180725
SWOMCD
SPC MCD 180725
OKZ000-TXZ000-180930-
MESOSCALE DISCUSSION 2229
NWS STORM PREDICTION CENTER NORMAN OK
0125 AM CST MON NOV 18 2024
AREAS AFFECTED...MUCH OF NORTHWESTERN TEXAS INTO SOUTHWESTERN
OKLAHOMA
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY
VALID 180725Z - 180930Z
PROBABILITY OF WATCH ISSUANCE...80 PERCENT
SUMMARY...POTENTIAL FOR DAMAGING WIND GUSTS AND PERHAPS A FEW
TORNADOES MAY BEGIN TO INCREASE WITH AN EVOLVING SQUALL LINE
ACCELERATING NORTHEAST OF THE TEXAS SOUTH PLAINS THROUGH MUCH OF
NORTHWESTERN TEXAS AND SOUTHWESTERN OKLAHOMA BY 3-5 AM CDT.
DISCUSSION...DOWNSTREAM OF A 90+ KT 500 MB JET STREAK BEGINNING TO
NOSE NORTHEAST OF THE TEXAS BIG BEND INTO THE PECOS VALLEY, STRONG
FORCING FOR ASCENT CONTINUES TO AID THE EVOLUTION OF A SQUALL LINE
IN ADVANCE OF A DEEPENING SURFACE LOW NOW NEAR/SOUTHWEST OF LUBBOCK.
INSTABILITY IS STILL RATHER WEAK IN THE PRESENCE OF THERMODYNAMIC
PROFILES CHARACTERIZED BY MODEST MID-LEVEL LAPSE RATES, BUT WEAK
LOW-LEVEL LAPSE RATES AND MODEST MOISTURE. HOWEVER, LOW-LEVEL AND
DEEP-LAYER SHEAR IS STRONG, AND AN ILL-DEFINED MESO-BETA SCALE
MID-LEVEL CYCLONIC CIRCULATION IS NOW PROGRESSING NORTHEAST OF
LUBBOCK.
A NUMBER OF BETTER DEFINED MESO-GAMMA SCALE CYCLONIC CIRCULATIONS
ARE EVIDENT ALONG THE LINE, WHICH HAS BEEN SURGING NORTHEASTWARD
AROUND 30 KT, TO THE NORTHEAST OF THE MID-LEVEL CIRCULATION. THIS
APPEARS LIKELY TO PROPAGATE INTO THE ALTUS OK VICINITY THROUGH
09-11Z, WITH THE SOUTHERN FLANK OF THE LINE PROGRESSING ACROSS THE
ABILENE TX VICINITY.
IN RESPONSE TO THE DEEPENING SURFACE TROUGHING, A GRADUAL
NORTH-NORTHWESTWARD ADVECTION OF MID 60S TO NEAR 70F SURFACE DEW
POINTS TOWARD THE UPSTREAM SQUALL LINE WILL GRADUALLY CONTRIBUTE TO
SOMEWHAT MORE UNSTABLE UPDRAFT INFLOW. THIS MAY ALSO CONTRIBUTE TO
A BOUNDARY-LAYER AT LEAST MARGINALLY MORE SUPPORTIVE OF DOWNWARD
MOMENTUM TRANSFER TO THE SURFACE AND POTENTIAL FOR TORNADOES, AS
LOW-LEVEL SHEAR INTENSIFIES BENEATH AN 850 MB JET FORECAST TO
STRENGTHEN IN EXCESS OF 50 KT.
..KERR/GLEASON.. 11/18/2024
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...FWD...OUN...SJT...LUB...AMA...MAF...
LAT...LON 33610035 34130064 35169968 35239810 34159800 32049873
31479966 31470050 32160084 33610035
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