764  
ACUS48 KWNS 210902  
SWOD48  
SPC AC 210900  
 
DAY 4-8 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0400 AM CDT TUE OCT 21 2025  
 
VALID 241200Z - 291200Z  
   
..DISCUSSION  
   
..D4/FRIDAY-D5/SATURDAY SOUTHERN PLAINS/ARKLATEX  
 
THE SHORTWAVE TROUGH OVER THE SOUTHERN PLAINS AND ASSOCIATED SURFACE  
LOW/PACIFIC FRONT WILL GRADUALLY MOVE EASTWARD FRIDAY SUPPORTING  
SCATTERED THUNDERSTORMS OVER PARTS OF TX/OK. OVERNIGHT CONVECTION  
AND CONTINUED LOW-LEVEL WARM AIR ADVECTION IS LIKELY TO IMPACT THE  
ENVIRONMENT TO SOME DEGREE. THIS SUGGESTS VERY LOW PREDICTABILITY  
FOR ANY ORGANIZED SEVERE THREAT. STILL, BROAD ASCENT, MODERATE  
DEEP-LAYER SHEAR, AND THE POTENTIAL FOR DESTABILIZATION SUGGESTS AT  
LEAST SOME SEVERE RISK MAY DEVELOP FROM CENTRAL OK SOUTHWARD TOWARD  
THE RED RIVER AND CENTRAL TX VICINITY FRIDAY.  
 
LOW-END SEVERE POTENTIAL WILL LIKELY SHIFT EASTWARD INTO THE  
ARKLATEX AND LOWER MS VALLEY D5/SATURDAY AS THE UPPER LOW MOVES  
FARTHER EASTWARD. MOST GUIDANCE SHOWS THE UPPER TROUGH BEGINNING TO  
WEAKEN WITH THE SURFACE FEATURES ALSO BECOMING MORE ILL DEFINED WITH  
TIME. WHILE THE GENERAL ENVIRONMENT LIKELY WILL REMAIN SUPPORTIVE OF  
THUNDERSTORMS AND ISOLATED SEVERE POTENTIAL, DETAILS ARE SPARSE.  
   
..EASTERN PLAINS AND MID MS VALLEY D6/SUNDAY-D7 MONDAY  
 
HIGHER SEVERE POTENTIAL MAY DEVELOP TOWARDS THE END OF THE EXTENDED  
FORECAST PERIOD AS A PACIFIC TROUGH AND AMPLIFIED WESTERLY FLOW  
DEVELOP OVER THE WESTERN US D6/SUNDAY AND MOVE INTO THE PLAINS AND  
MIDWEST D7/MONDAY. SUBSTANTIAL VARIABILITY EXISTS BETWEEN MULTIPLE  
ENSEMBLE AND DETERMINISTIC MODELS REGARDING THE EVOLUTION OF THE  
TROUGH AND RESULTING SURFACE PATTERN. MORE AMPLIFIED AND LESS  
PROGRESSIVE SOLUTIONS, ALONG WITH SOME ML GUIDANCE, SHOW THE  
POTENTIAL FOR A DEEP SURFACE LOW AND STRONG COLD FRONT TO DEVELOP  
AND SWEEP EASTWARD. SHOULD THIS OCCUR, ROBUST MOISTURE RETURN FOR  
FALL IS LIKELY TO DEVELOP ALONG WITH STRONG LOW AND MID-LEVEL WIND  
FIELDS ACROSS MUCH OF THE CENTRAL US. A FAVORABLE SYNOPTIC REGIME  
COULD SUPPORT WIDESPREAD SEVERE STORM DEVELOPMENT WITH SUFFICIENT  
INSTABILITY/SHEAR OVERLAP FOR ALL HAZARDS FROM THE EASTERN PLAINS  
INTO THE MS VALLEY AND MIDWEST.  
 
THIS SCENARIO REMAINS HIGHLY UNCERTAIN WITH LARGE VARIANCE NOTED  
BETWEEN BOTH ENSEMBLE AND DETERMINISTIC SOLUTIONS REGARDING THE  
STRUCTURE AND TIMING OF THE UPPER TROUGH. GIVEN THE DEGREE OF  
SPATIAL AND TEMPORAL VARIANCE, PREDICTABILITY REMAINS TOO LOW TO  
JUSTIFY PROBABILITIES IN THE EXTENDED FORECAST. HOWEVER, 15% OR  
HIGHER SEVERE PROBABILITIES COULD BE NEEDED IN FUTURE OUTLOOK CYCLES  
SHOULD GUIDANCE TREND TOWARDS A MORE UNIFIED/HIGHER-END SOLUTION.  
 
..LYONS.. 10/21/2025  
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