National Weather Service United States Department of Commerce

A Change in the Weather Pattern

The Atmospheric River event has ended for the Northwest, and conditions will be drier for a couple of days. A strong cold front in the East may produce damaging high winds in the central Appalachians and critical fire weather threats. Bitter wind chills across Northeast Alaska and heavy snow in the Southeast will continue, and blizzard conditions are expected to develop in far west-central Alaska. Read More >

Mesoscale Discussion #0622 issued at 1651 UTC 27 April 2011
MESOSCALE DISCUSSION 0622
NWS STORM PREDICTION CENTER NORMAN OK
1151 AM CDT WED APR 27 2011
   
AREAS AFFECTED...MUCH OF SC...CNTRL/ERN NC...CNTRL/ERN VA
   
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
VALID 271651Z - 271815Z
   
PORTIONS OF SC...CNTRL/ERN NC...AND CNTRL/ERN VA WILL EXPERIENCE AN
INCREASE IN THUNDERSTORM COVERAGE DURING THE NEXT FEW HOURS. THIS
ACTIVITY WILL POSE A SVR WEATHER RISK...AND THE AREA WILL LIKELY
REQUIRE A WW ISSUANCE.
   
DEEP LAYER S-SWLY FLOW RESIDES ACROSS THE SERN ATLANTIC AND MID
ATLANTIC REGION...CHARACTERIZED BY 40 KT SLY LLJ OVERLAYED BY
STRENGTHENING SWLY MIDLEVEL FLOW /APPROACHING 40 KT/. IN
ADDITION...VERY MOIST BOUNDARY LAYER /SURFACE DEWPOINTS IN THE UPPER
60S TO LOW 70S/ COINCIDES WITH STRONG DAYTIME HEATING /TEMPERATURES
WARMING INTO THE 80S/. THE WARM/MOIST CONDITIONS ARE LEADING TO
RAPID DESTABILIZATION AND THUNDERSTORM INITIATION. GIVEN MLCAPE
VALUES FROM 1000-2000 J/KG...FAVORABLY STEEP LAPSE RATES...AND
STRENGTHENING VERTICAL WIND SHEAR PROFILES /EFFECTIVE SHEAR
INCREASING TO 35-50 KT...AND ENLARGING LOW-LEVEL HODOGRAPH
STRUCTURE/...THE THREAT FOR DAMAGING WINDS AND LARGE HAIL WILL EXIST
ACROSS THE AREA THIS AFTERNOON. IN ADDITION...A FEW TORNADOES WILL
ALSO BE POSSIBLE.
   
..GARNER.. 04/27/2011
   
   
ATTN...WFO...AKQ...MHX...LWX...RAH...ILM...RNK...CHS...CAE...
GSP...
   
LAT...LON   35658107 38147891 38127673 36527643 34697776 33018019
            33038123 34018169 35658107