Sunday, August 23, 2009

MESO: Mesoscale Discussion 1960

ACUS11 KWNS 240102
SWOMCD
SPC MCD 240102
NDZ000-MTZ000-240230-

MESOSCALE DISCUSSION 1960
NWS STORM PREDICTION CENTER NORMAN OK
0802 PM CDT SUN AUG 23 2009

AREAS AFFECTED...ERN MT INTO WRN ND

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 240102Z - 240230Z

TRENDS ARE BEING MONITORED FOR AN INCREASING SEVERE THREAT AND THE
POSSIBILITY OF WW WHICH MAY BE REQUIRED WITHIN THE NEXT HOUR OR TWO.


RECENT DEVELOPMENT OF SCATTERED THUNDERSTORM ACTIVITY ACROSS
NORTHEAST MONTANA APPEARS TO BE IN RESPONSE TO FORCING ASSOCIATED
WITH LOWER/MID TROPOSPHERIC WARM ADVECTION...AS AN INCREASINGLY
DIVERGENT UPPER FLOW FIELD OVERSPREADS REGION IN ASSOCIATION WITH AN
UPPER IMPULSE EMANATING FROM THE GREAT BASIN. CONVECTION CURRENTLY
APPEARS BASED ABOVE A VERY WARM AND CAPPING ELEVATED MIXED LAYER
WHICH HAS ADVECTED OFF THE PLATEAU/ROCKIES REGION. HOWEVER...DURING
THE COURSE OF THE NEXT FEW HOURS...PERSISTENT AND STRENGTHENING WARM
ADVECTION WITHIN AND BELOW THE CAPPING LAYER... ASSOCIATED WITH A
DEVELOPING LOW-LEVEL JET...COUPLED WITH UPPER FORCING...LIKELY WILL
CONTRIBUTE TO AN INCREASE IN STORMS ROOTED CLOSER TO THE SURFACE.
AS THIS OCCURS...MUCH LARGER CAPE...IN THE PRESENCE OF STRONG
VERTICAL SHEAR BENEATH 30-50 KT SOUTHWESTERLY 500 MB FLOW...IS
EXPECTED TO SUPPORT A FEW SEVERE THUNDERSTORMS WITH THE RISK FOR
LARGE HAIL/DAMAGING WIND GUSTS. ISOLATED SUPERCELLS ARE POSSIBLE BY
02-04Z...BEFORE UPSCALE CONVECTIVE GROWTH OCCURS LATER THIS EVENING.

..KERR.. 08/24/2009

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

ATTN...WFO...BIS...BYZ...GGW...

LAT...LON 49000151 48480116 46610167 46200290 45860458 46350591
47310615 48050587 48680572 49080536 49000151

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