Monday, September 22, 2008

MESO: Mesoscale Discussion 2274

ACUS11 KWNS 222211
SWOMCD
SPC MCD 222210
NDZ000-SDZ000-222315-

MESOSCALE DISCUSSION 2274
NWS STORM PREDICTION CENTER NORMAN OK
0510 PM CDT MON SEP 22 2008

AREAS AFFECTED...CNTRL AND ERN ND...FAR CNTRL SD

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 222210Z - 222315Z

A FEW SEVERE STORMS ARE LIKELY TO DEVELOP BEFORE 00Z. LARGE HAIL
WILL BE LIKELY...WITH A LESSER CHANCE OF AN ISOLATED TORNADO AND
DAMAGING WINDS.

SURFACE ANALYSIS SHOWS A WEAK TROUGH ACROSS WRN ND..EXTENDING SWD
INTO WRN SD WHERE A LOW IS DEVELOPING. EARLIER ELEVATED CONVECTION
ACROSS NW SD/CNTRL ND HAS CREATED A RELATIVELY COOL AIR MASS AT THE
SURFACE...BUT A WEAK WARM FRONT WAS FORMING ACROSS NWRN SD AS WELL
AS CNTRL ND.

CONVERGENCE ALONG THIS WARM FRONT WILL BE THE FOCUS FOR NEW STORM
DEVELOPMENT...FROM EXTREME N CNTRL SD INTO SRN ND. THE 18Z BIS
SOUNDING SHOWED RELATIVELY COOL AIR ALOFT IN ADVANCE OF THE UPPER
TROUGH...WITH AMPLE WIND FIELDS FOR SUPERCELLS. AS THE UPPER TROUGH
APPROACHES...SO WILL LIFT AND STORM COVERAGE.

THE COOL AIR ALOFT ALONG WITH LONG HODOGRAPHS WILL EASILY SUPPORT
LARGE HAIL. LOW LEVEL WIND FIELDS ARE MARGINAL ACROSS CNTRL ND AND
NWRN SD...BUT INCREASE IN SPEED FARTHER E WHERE THE LOW LEVEL JET
AXIS WILL SET UP. THUS...A TORNADO THREAT WILL EXIST WITH SUPERCELLS
THAT TRAVEL EWD INTO ERN ND/NERN SD WHERE LOW LEVEL SHEAR IS
STRONGEST. WARMER SURFACE AIR WITH TEMPERATURES IN THE UPPER 70S
ACROSS ERN PORTIONS OF THE AREA FURTHER SUGGESTS THE LIKELIHOOD THAT
ACTIVITY WILL REMAIN SURFACE BASED.

..JEWELL.. 09/22/2008

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

ATTN...WFO...FGF...ABR...BIS...

45360073 45410106 46280122 47960049 48659951 48739842
48479751 47819717 46619741 45859829 45539920

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