805  
ACUS02 KWNS 261737  
SWODY2  
SPC AC 261736  
 
DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1236 PM CDT FRI MAY 26 2017  
 
VALID 271200Z - 281200Z  
 
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR THE OZARK  
PLATEAU INTO THE LOWER OHIO VALLEY...  
 
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERN  
OKLAHOMA AND KANSAS EASTWARD INTO MUCH OF KENTUCKY...  
 
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE  
CENTRAL-SOUTHERN GREAT PLAINS INTO THE SOUTHERN APPALACHIAN  
STATES...  
 
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE  
SLIGHT RISK...  
   
..SUMMARY
 
 
WIDESPREAD SEVERE GUSTS ARE LIKELY FROM THE OZARK PLATEAU INTO THE  
LOWER OHIO VALLEY. LARGE TO GIANT HAIL, TORNADOES, AND WIND DAMAGE  
ARE POSSIBLE FOR PARTS OF OKLAHOMA, KANSAS, AND EASTWARD INTO  
PORTIONS OF THE OHIO VALLEY.  
   
..SYNOPSIS
 
 
A CLOSED 500-MB LOW WILL MEANDER SOUTHEAST ACROSS MANITOBA WHILE A  
MID-LEVEL TROUGH WILL MOVE FROM WY/UT EAST INTO THE CENTRAL HIGH  
PLAINS BY SATURDAY EVENING AND INTO THE UPPER MIDWEST/CENTRAL PLAINS  
BY EARLY SUNDAY. A BELT OF STRONG WEST-SOUTHWESTERLY MID- TO  
HIGH-LEVEL FLOW WILL EXTEND FROM OK/TX EASTWARD THROUGH THE OZARKS  
AND INTO THE OH VALLEY/SOUTHERN APPALACHIANS. AT THE SURFACE, A LOW  
NEAR THE OK/KS BORDER WILL DEVELOP EAST INTO THE LOWER MO VALLEY  
DURING THE AFTERNOON WITH A COLD FRONT EXTENDING FROM EASTERN KS  
SOUTHWEST INTO NORTHERN OK AND ARCING WEST INTO THE TX PANHANDLE. A  
TRIPLE POINT NEAR NORTH-CENTRAL/NORTHEAST OK IS FORECAST WITH A  
DRYLINE EXTENDING SOUTH NEAR I-35 IN OK/TX DURING THE LATE  
AFTERNOON.  
   
..OZARK PLATEAU INTO THE LOWER OH VALLEY
 
 
VERY RICH LOW-LEVEL MOISTURE WILL ADVECT NORTHWARD INTO THE REGION  
SOUTH OF A WEST-EAST FRONTAL ZONE. A VERY UNSTABLE TO EXTREMELY  
UNSTABLE AIRMASS WILL LIKELY DEVELOP ACROSS AT LEAST THE SOUTHERN  
PORTION OF THIS REGION. SEVERAL SCENARIOS ARE POSSIBLE REGARDING  
THE SEVERE THREAT FOR THIS REGION, ESPECIALLY OVER MO. MODEL  
GUIDANCE APPEARS TO BE CONVERGING TOWARDS THE DEVELOPMENT OF A  
SEVERE MCS MOVING EAST FROM MO INTO THE LOWER OH VALLEY. DETAILS  
REGARDING TIMING AND EVOLUTION ARE STILL SOMEWHAT UNCERTAIN AT THIS  
TIME AND POSSIBILITIES INCLUDE THE FOLLOWING:  
1) A REMNANT MCV FROM OVERNIGHT FRIDAY STORM ACTIVITY MAY SERVE AS  
AN INITIATING FEATURE FOR A THUNDERSTORM CLUSTER TO GROW UPSCALE.  
2) SUPERCELLS WITH ALL SEVERE HAZARDS (INCLUDING TORNADOES)  
TRANSITIONING TO A SEVERE CONVECTIVE WINDSTORM ACROSS THE OZARKS.  
GIVEN THE OVERALL ENVIRONMENT, IT APPEARS SIGNIFICANT SEVERE WITH  
ALL HAZARDS IS POSSIBLE. THE VEERING OF A SOUTHWESTERLY LLJ INTO  
THE OH VALLEY DURING THE EVENING WILL LIKELY AID IN MAINTAINING A  
SEVERE THREAT INTO THE EVENING.  
   
..OK-TX DRYLINE
 
 
AN INITIAL STRONG CAPPING INVERSION WILL LEAD TO EXTREME INSTABILITY  
DEVELOPING BY MID AFTERNOON TO THE EAST OF THE DRYLINE OVER EASTERN  
OK INTO NORTHEAST TX. RICH LOW-LEVEL MOISTURE CHARACTERIZED BY  
LOWEST 100-MB MEAN MIXING RATIOS 17-19 G/KG BENEATH VERY STEEP  
700-500 MB LAPSE RATES (8-9 DEGREES C/KM) WILL RESULT IN (4500-6500  
J/KG MLCAPE PER FORECAST SOUNDINGS. DESPITE GENERALLY WEAK FORCING  
FOR ASCENT, THE COMBINATION OF ERODING MLCINH DUE TO STRONG HEATING  
AND PERHAPS SOME CONTRIBUTION DUE TO A 55-KT 500 MB SPEED MAX MOVING  
OVER OK DURING THE LATE AFTERNOON WILL CONTRIBUTE TO THE CAP LOCALLY  
ERODING AND ISOLATED THUNDERSTORM DEVELOPMENT FROM NORTHEAST OK  
SOUTH INTO NORTH-CENTRAL TX BETWEEN 21-02Z. STRONG EFFECTIVE SHEAR  
(50 KT) AND EXTREME BUOYANCY WILL RAPIDLY FAVOR SUPERCELL  
DEVELOPMENT EARLY IN THE CONVECTIVE LIFE CYCLE. GIANT HAIL (3.0-4.5  
INCHES IN DIAMETER) IS POSSIBLE WITH ANY ESTABLISHED SUPERCELL.  
NAM/GFS FORECAST SOUNDINGS SHOW GRADUAL VEERING AND STRENGTHENING OF  
THE WIND PROFILE IN THE LOWEST 2-3 KM --- YIELDING 100-250 M2/S2 0-1  
KM SRH FROM SOUTH TO NORTH ACROSS THIS REGION. THE POSSIBILITY  
EXISTS FOR SIGNIFICANT TORNADOES WITH SUPERCELLS, ESPECIALLY ACROSS  
THE NORTHEASTERN QUARTER OF OK INTO SOUTHEASTERN KS AND INTO MO. A  
CLUSTER OF STORMS WILL PROBABLY EVOLVE DURING THE EVENING WITH  
HAIL/WIND BECOMING THE PREDOMINANT RISK LATE SATURDAY NIGHT AS  
ACTIVITY MOVES EAST INTO AR.  
   
..SOUTHERN APPALACHIANS
 
 
MODELS SHOW MODERATE BUOYANCY DEVELOPING DURING THE DAY WITH  
DEEP-LAYER SHEAR SUPPORTIVE OF ORGANIZED THUNDERSTORMS. HAIL/WIND  
WILL BE THE PRIMARY HAZARDS WITH WEAKENING OF THE STORMS AND A  
CORRESPONDING DECREASE IN SEVERE RISK ASSOCIATED WITH COOLING DURING  
OF THE BOUNDARY LAYER DURING THE EVENING.  
 
..SMITH.. 05/26/2017  
 

 
 
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