Friday, April 11, 2008

MESO: Mesoscale Discussion 0642

ACUS11 KWNS 112257
SWOMCD
SPC MCD 112256
VAZ000-WVZ000-120000-

MESOSCALE DISCUSSION 0642
NWS STORM PREDICTION CENTER NORMAN OK
0556 PM CDT FRI APR 11 2008

AREAS AFFECTED...SERN WV INTO W-CNTRL VA

CONCERNING...SEVERE THUNDERSTORM WATCH 200...

VALID 112256Z - 120000Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 200
CONTINUES.

THE POTENTIAL FOR LOCALLY DAMAGING WIND GUSTS AND SOME HAIL IS
EXPECTED TO CONTINUE WITH ONGOING BOW ECHO. TERRAIN EFFECTS AND
DIURNAL COOLING OF BOUNDARY LAYER MAY TEND TO MITIGATE THIS THREAT
WITH TIME.

AS OF 2245Z...RADAR IMAGERY INDICATED A FAST-MOVING...SHORT SEGMENT
BOW ECHO OVER WEBSTER...NICHOLAS...GREENBRIER AND SUMMER COUNTIES WV
MOVING 260/45 KT. THIS SYSTEM HAS A HISTORY OF PRODUCING DAMAGING
WINDS OVER THE PAST HOUR OR SO. HOWEVER...THIS BOW ECHO IS MOVING
INTO MORE COMPLEX TERRAIN WHICH COULD DISRUPT THE STABILITY OF THE
SYSTEM. DOWNSTREAM OBSERVATIONS ACROSS PARTS OF WRN AND NRN VA
INDICATE THE PRESENCE OF A WELL-MIXED BOUNDARY LAYER WITH
TEMPERATURES IN THE UPPER 70S TO LOWER 80S WITH AT LEAST MARGINAL
SURFACE-BASED CONVECTIVE INSTABILITY.

CURRENT EXTRAPOLATION PLACES BOW AT ERN EDGE OF WW 200 BY 2330Z.
THERE IS SOME POTENTIAL THAT THIS SYSTEM MAY CONTINUE EWD WITH AT
LEAST AN ISOLATED DAMAGING WIND AND/OR HAIL THREAT. HOWEVER...THE
BOUNDARY LAYER SHOULD BEGIN TO COOL/STABILIZE WITHIN THE NEXT 1 TO 2
HOURS...EFFECTIVELY REDUCING ANY LONGER-LIVED SEVERE WEATHER THREAT.

.MEAD.. 04/11/2008

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...LWX...RNK...RLX...

38378042 38638016 38757970 38637910 38307879 37807902
37517951 37557997 37668031

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