890  
ACUS01 KWNS 231954  
SWODY1  
SPC AC 231953  
 
DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0153 PM CST FRI FEB 23 2018  
 
VALID 232000Z - 241200Z  
 
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL AND  
NORTH TEXAS LATE TONIGHT...  
   
..SUMMARY
 
 
AN ISOLATED SEVERE STORM OR TWO IS POSSIBLE OVER PORTIONS OF  
CENTRAL/NORTH TEXAS LATE TONIGHT.  
   
..DISCUSSION
 
 
NO CHANGES HAVE BEEN MADE TO THE ONGOING FORECAST. ACROSS PARTS OF  
TEXAS, A HIGHLY CONDITIONAL LARGE-HAIL THREAT REMAINS FOR LATE  
TONIGHT/EARLY SATURDAY MORNING. AS THE LOW-LEVEL JET INTENSIFIES  
OVERNIGHT, INCREASING ASCENT WILL FOCUS SHOWERY DEVELOPMENT OVER  
CENTRAL/NORTH TEXAS. ISOLATED UPDRAFTS MAY DEEPEN SUFFICIENTLY FOR A  
FEW THUNDERSTORMS, AND FORECAST MID-LEVEL LAPSE RATES/SHEAR PROFILES  
SUGGEST A LARGE HAIL THREAT COULD EXIST WITH ANY SUCH STORM.  
 
ELSEWHERE, A STRONGER STORM OR TWO MAY DEVELOP THROUGH TONIGHT FROM  
THE LOWER MISSISSIPPI VALLEY NORTHEASTWARD TO WEST VIRGINIA,  
GENERALLY ALONG THE NORTHWESTERN FLANK OF THE SOUTHEAST SUB-TROPICAL  
RIDGE. WHILE A LACK OF A CLEAR FOCUSING MECHANISM IS EXPECTED TO  
KEEP ANY COVERAGE SPARSE ENOUGH TO PRECLUDE PROBABILITIES, AN  
INSTANCE OR TWO OF STRONGER WIND GUSTS/MARGINALLY SEVERE HAIL IS  
POSSIBLE.  
 
..PICCA.. 02/23/2018  
   
PREV DISCUSSION
 
/ISSUED 1022 AM CST FRI FEB 23 2018/  
   
..OK/TX INTO THE MID MS VALLEY
 
 
MORNING WATER VAPOR LOOP SHOWS TWO IMPORTANT UPPER FEATURES  
CONTRIBUTING TO THE FORECAST FOR THUNDERSTORMS. THE FIRST SHORTWAVE  
TROUGH IS CURRENTLY OVER NORTH TX, AND IS ASSOCIATED WITH A CLUSTER  
OF SHOWERS AND THUNDERSTORMS ALONG THE RED RIVER. THIS ACTIVITY  
WILL DEVELOP NORTHEASTWARD INTO THE MID MS VALLEY THROUGH THE DAY,  
WITH A CONTINUED RISK OF THUNDERSTORMS. WHILE MARGINALLY SEVERE  
HAIL IS NOT OUT OF THE QUESTION, THE RISK IS VERY LOW.  
   
..CENTRAL/NORTH TX LATE TONIGHT
 
 
A SECOND AND MORE INTENSE UPPER TROUGH IS CURRENTLY OVER THE GREAT  
BASIN. THIS FEATURE WILL DIG INTO THE SOUTHERN ROCKIES BY SATURDAY  
MORNING. INCREASING LARGE-SCALE LIFT AHEAD OF THE TROUGH WILL  
OVERSPREAD TX BY DAYBREAK, POSSIBLY LEADING TO SCATTERED  
THUNDERSTORM DEVELOPMENT. ONLY A MINORITY OF MORNING CAM GUIDANCE  
SHOWS THIS ACTIVITY FORMING BEFORE 12Z, SO CONFIDENCE THAT THIS  
THREAT DEVELOPS DURING THE DAY1 PERIOD IS LOW. NEVERTHELESS, WILL  
MAINTAIN THE ONGOING MARGINAL HAIL PROBABILITY AREA.  
   
..SOUTHEAST AR/NORTHEAST MS THIS AFTERNOON
 
 
ONE FINAL AREA OF LOW CONCERN THIS AFTERNOON IS OVER PARTS OF THE  
LOWER MS VALLEY. VISIBLE SATELLITE IMAGERY SHOWS BROKEN CLOUDS IN  
THIS AREA, WHICH MAY CONTRIBUTE TO SLOW DESTABILIZATION TODAY. A  
CLUSTER OF SHOWERS AND THUNDERSTORMS CURRENTLY OVER SOUTHEAST LA  
WILL SPREAD NORTHWARD AND INTO THIS SLIGHTLY MORE UNSTABLE AIR MASS.  
VERTICAL SHEAR IS RATHER WEAK, BUT A STRONG STORM CAPABLE OF HAIL  
IS POSSIBLE LATER TODAY. THE CURRENT THOUGHT IS THAT THIS THREAT IS  
BELOW THE 5% THRESHOLD.  
 

 
 
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