Monday, September 22, 2008

MESO: Mesoscale Discussion 2276

ACUS11 KWNS 230128
SWOMCD
SPC MCD 230127
SDZ000-NEZ000-230300-

MESOSCALE DISCUSSION 2276
NWS STORM PREDICTION CENTER NORMAN OK
0827 PM CDT MON SEP 22 2008

AREAS AFFECTED...PARTS OF W CNTRL NEB THRU CNTRL SD

CONCERNING...SEVERE THUNDERSTORM WATCH 906...

VALID 230127Z - 230300Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 906
CONTINUES.

AN ADDITIONAL WW MAY NOT BE NEEDED...BUT TRENDS WILL BE MONITORED
FOR THIS POSSIBILITY...PARTICULARLY NORTH NORTHWEST OF BROKEN BOW
NEB INTO THE ABERDEEN SD VICINITY.

POTENTIAL FOR PRE-FRONTAL STORM DEVELOPMENT APPEARS TO BE
DIMINISHING. PRIMARY ACTIVITY NOW APPEARS TO BE OCCURRING IN
RESPONSE TO A ZONE OF LOW-LEVEL FRONTOGENETIC FORCING WHICH HAS
ADVANCED INTO THE NORTH CENTRAL HIGH PLAINS...SOUTH OF A WEAK
FRONTAL WAVE TO THE SOUTH/SOUTHWEST OF PIERRE. RUC GUIDANCE
SUGGESTS THAT THIS FORCING WILL BEGIN TO WEAKEN AFTER 03Z...BUT THE
SEVERE POTENTIAL IN LINGERING CONVECTION ACROSS EASTERN PORTIONS OF
THE WW AREA MAY BE A BIT SLOWER TO DIMINISH.

INTENSIFICATION OF THE PRE-FRONTAL LOW-LEVEL JET IS UNDERWAY...AND
MODELS SUGGEST THAT THIS COULD STRENGTHEN IN EXCESS OF 50 KTS...AS
BOUNDARY LAYER DECOUPLING CONTINUES THIS EVENING. AS THE DEVELOPING
LINE OF STORMS APPROACHES THE JET CORE...EVAPORATIVE COOLING
ASSOCIATED WITH DRY-SUB CLOUD AIR WITHIN THE REMNANT ELEVATED MIXED
LAYER COULD AID DOWNWARD TRANSPORT OF HIGHER MOMENTUM AIR TO THE
SURFACE. SO...THE RISK FOR DAMAGING WIND GUSTS MAY INCREASE DURING
THE NEXT COUPLE OF HOURS...AND POSSIBLY PERSIST THROUGH LATE
EVENING.

..KERR.. 09/23/2008

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

ATTN...WFO...FSD...ABR...LBF...UNR...

41510255 42720217 43880181 45360063 45769938 45429823
42779906 41250002 40960176

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