MESO: Mesoscale Discussion 0726

ACUS11 KWNS 060431
SWOMCD
SPC MCD 060431
MNZ000-IAZ000-SDZ000-NEZ000-060600-

MESOSCALE DISCUSSION 0726
NWS STORM PREDICTION CENTER NORMAN OK
1131 PM CDT SAT MAY 05 2012

AREAS AFFECTED...PARTS OF CNTRL/SRN MN...SERN SOUTH DAKOTA...NWRN
IA....INTO CNTRL NEBRASKA

CONCERNING...SEVERE THUNDERSTORM WATCH 252...253...254...

VALID 060431Z - 060600Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
252...253...254...CONTINUES.

SUMMARY...TRENDS WILL CONTINUE TO BE MONITORED. IT IS NOT CERTAIN
THAT A NEW WW WILL BE NEEDED...BUT THIS WILL BE COORDINATED WITH WFO
MINNEAPOLIS PRIOR TO 05Z.

DISCUSSION...AIDED BY MID/UPPER FORCING FOR UPWARD VERTICAL MOTION
DOWNSTREAM OF THE LARGE-SCALE UPPER TROUGH LIFTING NORTHEAST OF THE
NORTHERN ROCKIES...INTENSE STORMS ASSOCIATED WITH A COUPLE OF
CONVECTIVE CLUSTERS ARE LINKING UP INTO ONE ELONGATED SQUALL LINE
EXTENDING FROM CENTRAL MINNESOTA SOUTHWESTWARD THROUGH SOUTHEASTERN
SOUTH DAKOTA INTO CENTRAL NEBRASKA. ACTIVITY APPEARS LIKELY TO
REMAIN ROOTED IN A LAYER OF LOWER/MID TROPOSPHERIC WARM
ADVECTION...ABOVE A DEEPENING NEAR SURFACE STABLE LAYER ASSOCIATED
WITH A COLD FRONT ADVANCING SOUTHEASTWARD THROUGH THE CENTRAL
PLAINS...AND ABOVE A RESIDUAL COOL STABLE BOUNDARY LAYER TO THE
NORTH OF A STATIONARY FRONT EXTENDING EAST SOUTHEASTWARD FROM THE
MIDDLE MISSOURI VALLEY.

DESPITE THE PRESENCE OF A 30-40 KT SOUTHERLY 850 MB JET STREAK
PROGGED TO NOSE NORTHWARD THROUGH CENTRAL MINNESOTA DURING THE NEXT
FEW HOURS...FORECAST SOUNDINGS SUGGEST THAT THE SURFACE BASED LAYER
ACROSS MUCH OF CENTRAL/SOUTHERN MINNESOTA MAY BE TOO STABLE FOR
DOWNDRAFTS REACHING THE SURFACE WITH DAMAGING WIND POTENTIAL.
HOWEVER...30 KT EASTERLY SYSTEM RELATIVE FLOW IN THIS LAYER COULD
STILL CONTRIBUTE TO AT LEAST LOCALIZED GUSTS APPROACHING SEVERE
LIMITS AS STORMS PROGRESS INTO THE MINNEAPOLIS AREA BETWEEN NOW AND
06-08Z.

OTHERWISE...THE RISK FOR LARGE HAIL PROBABLY WILL REMAIN THE PRIMARY
SEVERE THREAT WITH STORMS EXTENDING SOUTHWESTWARD INTO CENTRAL
NEBRASKA...AND EVEN THIS THREAT ALREADY SEEMS TO BE IN THE PROCESS
OF GRADUALLY WANING.

..KERR.. 05/06/2012

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

ATTN...WFO...MPX...FSD...OAX...GID...LBF...

LAT...LON 41290039 41849945 42809885 43639821 44059635 44679521
45589440 45689346 45269288 44619323 43849457 43269630
42049783 41060004 41290039

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