366  
ACUS02 KWNS 221807  
SWODY2  
SPC AC 221807  
 
DAY 2 CONVECTIVE OUTLOOK CORR 1  
NWS STORM PREDICTION CENTER NORMAN OK  
0107 PM CDT WED MAY 22 2019  
 
VALID 231200Z - 241200Z  
 
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE OH  
VALLEY/MIDDLE ATLANTIC AND SOUTHERN/CENTRAL PLAINS...  
 
CORRECTED FOR MISSING THUNDER LINE  
   
..SUMMARY
 
 
SEVERE STORMS WITH LARGE HAIL, DAMAGING WIND AND TORNADOES WILL BE  
POSSIBLE OVER A PART OF THE CENTRAL AND SOUTHERN PLAINS THURSDAY.  
OTHER SEVERE STORMS WITH A THREAT FOR MAINLY DAMAGING WIND AND LARGE  
HAIL ARE EXPECTED FROM A PORTION OF THE OHIO VALLEY INTO THE  
NORTHERN MIDDLE ATLANTIC.  
   
..UPPER OH VALLEY/NORTHERN MIDDLE ATLANTIC
 
 
CENTRAL US SHORT-WAVE TROUGH IS FORECAST TO EJECT NORTHEAST ACROSS  
THE GREAT LAKES AND FLATTEN THE EASTERN RIDGE AS 80KT 500MB SPEED  
MAX TRANSLATES ACROSS LAKE ERIE. THIS FEATURE IS EXPECTED TO AID  
EARLY-MORNING CONVECTION ACROSS THE OH VALLEY WHICH WILL PROPAGATE  
INTO EASTERN OH/WESTERN PA BY 18Z. DEPENDING ON THE EVOLUTION OF  
THIS CONVECTION IT APPEARS ENVIRONMENTAL SHEAR WILL BECOME FAVORABLE  
FOR SUSTAINING FAST-MOVING ORGANIZED UPDRAFTS. LATEST MODEL GUIDANCE  
SUGGESTS UPWARD-EVOLVING THUNDERSTORMS BY EARLY AFTERNOON WITHIN  
STRENGTHENING WESTERLY FLOW REGIME. BOUNDARY-LAYER HEATING IS  
EXPECTED TO BE MAXIMIZED FROM SOUTH-CENTRAL PA, SOUTH ALONG THE LEE  
OF THE CENTRAL APPALACHIANS. IF A COLD POOL DEVELOPS EARLY, SEVERE  
THUNDERSTORMS SHOULD INITIATE ALONG THE  
EASTERN-SOUTHERN-SOUTHWESTERN FLANK OF THIS ACTIVITY THEN  
SPREAD/DEVELOP EAST-SOUTHEAST TOWARD THE DELMARVA. SEVERAL CAMS  
SOLUTIONS SUPPORT THIS SCENARIO AND WILL EXTEND HIGHER SEVERE PROBS  
INTO NORTHERN MD TO ACCOUNT FOR THE MORE SOUTHEAST PROPAGATIONAL  
COMPONENT. DAMAGING WINDS, AND SOME HAIL, ARE EXPECTED WITH  
CONVECTION AS IT SPREADS ACROSS EASTERN OH/PA TOWARD NORTHERN MD BY  
LATE AFTERNOON.  
   
..CENTRAL/SOUTHERN PLAINS
 
 
STRONG MID-LEVEL FLOW IS FORECAST TO ROUND THE BASE OF WESTERN US  
TROUGH OVER NORTHERN MEXICO LATE DAY1 INTO EARLY DAY2, THEN  
TRANSLATE INTO THE CENTRAL HIGH PLAINS BY 24/00Z. IN RESPONSE TO  
THIS FEATURE, LLJ SHOULD STRENGTHEN ACROSS THE TX SOUTH PLAINS LATE  
WEDNESDAY. THIS WILL ALLOW FOR A SUBSTANTIAL MOISTURE SURGE TO AT  
LEAST 102W LONGITUDE WHERE HIGHER TERRAIN AND HEATING ALONG THE  
WESTERN EDGE OF THIS MOIST PLUME SHOULD CONTRIBUTE TO ROBUST  
CONVECTION. THERE IS SOME CONCERN THAT CONVECTION COULD DEVELOP  
EARLY IN THE PERIOD ALONG THE NOSE OF THE LLJ. THIS ACTIVITY IS MOST  
LIKELY ACROSS THE NORTHERN TX PANHANDLE INTO WESTERN KS ATOP COOLER  
BOUNDARY AIR MASS THAT WILL SAG SOUTH ACROSS THE HIGH PLAINS. THIS  
EARLY-DAY CONVECTION WILL LIKELY BE ELEVATED AND POSE PRIMARILY A  
LARGE HAIL THREAT. HOWEVER, STRONG SURFACE HEATING NEAR THE NM/TX  
BORDER WILL CONTRIBUTE TO SUBSTANTIAL BUOYANCY THAT WILL BECOME  
UNCAPPED BY LATE AFTERNOON. FORECAST SHEAR PROFILES STRONGLY FAVOR  
SUPERCELLS AND A FAIR NUMBER OF STORMS SHOULD ULTIMATELY EVOLVE  
ACROSS THE ENH RISK. HIGH-PW AIR MASS SHOULD SURGE INTO THIS REGION  
SUCH THAT LONG-LIVED SUPERCELLS ARE EXPECTED. VERY LARGE HAIL AND  
TORNADOES CAN BE EXPECTED WITH SUPERCELLS SOUTH OF THE COLD FRONT  
THAT WILL ORIENT ITSELF ACROSS SOUTHWEST-CENTRAL KS. IF EARLY-DAY  
CONVECTION IS LESS THAN CURRENTLY EXPECTED, A CORRIDOR OF HIGHER  
SEVERE PROBS MAY ULTIMATELY NEED TO BE CONSIDERED ACROSS THE HIGH  
PLAINS SOUTH OF THE FRONT.  
   
..MAXIMUM RISK BY HAZARD
 
 
TORNADO: 10% - ENHANCED  
WIND: 30% - ENHANCED  
HAIL: 30% SIG - ENHANCED  
 
..DARROW.. 05/22/2019  
 

 
 
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