

094 

WWUS20 KWNS 220842

SEL0

SPC WW 220842

DCZ000-MDZ000-PAZ000-VAZ000-WVZ000-CWZ000-221500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 590

NWS STORM PREDICTION CENTER NORMAN OK

335 AM EST SUN DEC 22 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  DISTRICT OF COLUMBIA

  WESTERN AND CENTRAL MARYLAND

  CENTRAL AND SOUTHERN PENNSYLVANIA

  NORTHERN AND CENTRAL VIRGINIA

  THE EASTERN PANHANDLE OF WEST VIRGINIA

  COASTAL WATERS



* EFFECTIVE THIS SUNDAY MORNING FROM 335 AM UNTIL 1000 AM EST.



* PRIMARY THREATS INCLUDE...

  SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 75

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES NORTH

NORTHWEST OF WILLIAMSPORT PENNSYLVANIA TO 30 MILES EAST OF

STAUNTON VIRGINIA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE

FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY

DO PRODUCE TORNADOES.



&&



OTHER WATCH INFORMATION...CONTINUE...WW 588...WW 589...



DISCUSSION...NARROW...BROKEN SQLN LINE WITH EMBEDDED LEWPS/SMALL

BOWS NOW OVER WRN PA/CNTRL WV EXPECTED TO CONTINUE E AT 50+ KTS

THROUGH LATER THIS MORNING. CONVECTIVE SYSTEM SHOULD MOVE WITH 70+

KT WSWLY 700 MB JET STREAK LOOSELY ASSOCIATED WITH POTENT MID-MS VLY

VORT MAX. VWP DATA SHOW THIS SPEED MAX TRACKING THROUGH NRN MD AND

SRN/CNTRL PA THROUGH MID-MORNING. WHILE OVERALL TREND SHOULD BE FOR

THE CONVECTIVE BAND TO GRADUALLY WEAKEN...STRENGTH OF LWR

TROPOSPHERIC WIND FIELD AND SEASONABLY WARM/MOIST LOW-LVL

ENVIRONMENT IN PLACE TO ITS EAST SUGGEST A CONTINUED RISK FOR

DOWNWARD MOMENTUM TRANSFER/LOCALLY DMGG GUSTS DESPITE TIME OF DAY

AND DISTANCE OF THE CONVECTION FROM LARGE SCALE FORCING /DCVA/ THAT

HELPED INITIATE IT.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 250. MEAN STORM

MOTION VECTOR 24055.





...CORFIDI

