Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 301229
SWODY1
SPC AC 301227

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0727 AM CDT SAT JUL 30 2016

VALID 301300Z - 311200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY
TONIGHT NEAR THE BLACK HILLS IN SD...

...THERE IS A MRGL RISK OF SVR TSTMS FROM ERN WY TO CENTRAL NEB/NRN
KS THROUGH TONIGHT...

...THERE IS A MRGL RISK OF SVR TSTMS THIS AFTERNOON FOR CENTRAL VA
AND VICINITY...

...SUMMARY...
ISOLATED STRONG TO LOCALLY SEVERE THUNDERSTORMS ARE POSSIBLE FROM
NEAR THE BLACK HILLS INTO THE CENTRAL HIGH PLAINS AND MID-ATLANTIC
REGION THIS AFTERNOON AND EVENING.  A FEW STRONG STORMS ARE POSSIBLE
LATE TONIGHT OVER THE CENTRAL PLAINS.

...SYNOPSIS...
A MIDLEVEL TROUGH WILL PROGRESS SEWD OVER BC TO WA AND THE NRN
ROCKIES BY THE END OF THE PERIOD.  DOWNSTREAM...WEAK SHORTWAVE
RIDGING IS EXPECTED OVER THE NRN HIGH PLAINS...WITH A TROUGH OVER
THE OH VALLEY.  A DIFFUSE SURFACE CYCLONE INVOF OH WILL ACCOMPANY
THE MIDLEVEL TROUGH...AND A WEAK SURFACE FRONT WILL EXTEND WWD FROM
THE OH VALLEY TO THE OZARK PLATEAU AND CENTRAL PLAINS.  A FEW STRONG
THUNDERSTORMS WITH GUSTY OUTFLOW WINDS WILL BE POSSIBLE THIS
AFTERNOON IN THE WARM SECTOR AHEAD OF THE WEAK FRONT FROM PARTS OF
THE UPPER OH VALLEY TO VA. STORMS SHOULD FORM OVER THE HIGH TERRAIN
THIS AFTERNOON AND SPREAD EWD INTO VA...WHERE MLCAPE OF 1000-1500
J/KG AND EFFECTIVE BULK SHEAR AROUND 30 KT COULD SUPPORT ORGANIZED
MULTICELL CLUSTERS CAPABLE OF PRODUCING ISOLATED DOWNBURSTS.

...CENTRAL PLAINS THROUGH TONIGHT...
LOW-LEVEL SELY FLOW AND A WEAK WAA REGIME WILL BE MAINTAINED THROUGH
TONIGHT TO THE N OF THE SOMEWHAT DIFFUSE FRONT ACROSS KS.  BOUNDARY
LAYER DEWPOINTS IN THE MID 50S-LOW 60S BENEATH A PLUME OF STEEP
MIDLEVEL LAPSE RATES WILL CONTRIBUTE TO MLCAPE OF 1500-2500 J/KG
THIS AFTERNOON INVOF THE BLACK HILLS...AS SURFACE TEMPERATURES WARM
WELL INTO THE 80S.  A FEW STORMS ARE EXPECTED TO FORM OVER THE BLACK
HILLS LATE AFTERNOON AND SUBSEQUENTLY SPREAD TO THE SE.  DEEP-LAYER
VERTICAL SHEAR WILL BE SUFFICIENT FOR SUPERCELLS...WITH LARGE HAIL
THE PRIMARY RISK.

FARTHER E...STORM INITIATION IS A BIT LESS CERTAIN. THE ONGOING WAA
STORMS ACROSS CENTRAL NEB SHOULD WEAKEN BY MIDDAY-EARLY
AFTERNOON...WHILE OTHER WAA STORMS MAY FORM AGAIN TONIGHT.
SURFACE-BASED CONVECTION THIS AFTERNOON MAY OCCUR ON LINGERING
BOUNDARIES FROM THE MORNING CONVECTION...THOUGH CONFIDENCE IS LOW.
ISOLATED LARGE HAIL WILL BE POSSIBLE WITH ANY SURFACE-BASED STORMS
THAT MANAGE TO FORM THIS AFTERNOON...AND WITH THE ADDITIONAL STORMS
TONIGHT.

..THOMPSON/LEITMAN.. 07/30/2016

$$


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