SWOMCD
SPC MCD 032358
MNZ000-IAZ000-NEZ000-SDZ000-040200-
MESOSCALE DISCUSSION 1763
NWS STORM PREDICTION CENTER NORMAN OK
0658 PM CDT MON AUG 03 2009
AREAS AFFECTED...PORTIONS SRN...CENTRAL AND ERN SD...CENTRAL/WRN
MN...N-CENTRAL/NERN NEB...EXTREME NWRN IA.
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 032358Z - 040200Z
BKN LINE OF CONVECTION -- INCLUDING SEVERAL SMALL CB - IS DEVELOPING
INVOF SFC COLD FRONT MOVING SEWD ACROSS CENTRAL MN...AND NERN
THROUGH W-CENTRAL SD. WHILE AT LEAST ISOLATED SVR WIND/HAIL MAY
OCCUR WITH ANY TSTMS IN THIS BAND DURING NEXT FEW HOURS...MOST
PROLONGED/ORGANIZED SVR THREAT RESULTING FROM THIS DEVELOPMENT
APPEARS TO BE IN CORRIDOR FROM CENTRAL/ERN SD SSEWD ACROSS NERN NEB
AND NWRN IA.
AT 23Z...SFC MESOANALYSIS SHOWED COLD FRONT FROM CASS COUNTY MN
WSWWD ACROSS ABR AREA AND ACROSS MEADE COUNTY SD. FRONT IS MOVING
SEWD 25-30 KT. ALTHOUGH PREFRONTAL SFC WINDS ARE WEAK -- GENERALLY
LESS THAN 10 KT AND SWLY TO WLY...COMBINATION OF DIABATICALLY
WEAKENED MLCINH AND FRONTAL ASCENT SHOULD CONTINUE TO AID TSTM
FORMATION. THIS WILL BE AUGMENTED DURING EVENING BY COLD POOLS FROM
ANY ORGANIZED MULTICELL CLUSTERING OF FRONTAL CONVECTION. SFC
MOISTURE ANALYSIS...MODIFIED RUC SOUNDINGS AND ABR GPS PW DATA
INDICATES STG GRADIENT IN LOW LEVEL MOISTURE AND BUOYANCY FROM NEAR
MN/SD BORDER SWD TOWARD IA/SD BORDER...THEN SSEWD OVER WRN IA. THIS
GRADIENT -- AT LEAST PARTIALLY AN AFTEREFFECT F PRIOR/OVERNIGHT
ACTIVITY -- MAY DRIFT NEWD...AND WILL FORM EFFECTIVE ERN BOUND TO
MOST SUBSTANTIAL CONVECTIVE POTENTIAL. CENTRAL MN FRONTAL ACTIVITY
WILL MOVE INTO RELATIVELY LOW SFC-BASED INSTABILITY E OF GRADIENT
THAT ALSO SHOULD WEAKEN WITH TIME. MEANWHILE COMPLEX OF TSTMS MAY
ORGANIZE OVER CENTRAL/ERN SD AND MOVE TOWARD NERN NEB...WITH
DAMAGING GUSTS AND LARGE HAIL POSSIBLE. SFC MOIST AXIS IS ANALYZED
ROUGHLY FROM HON-MHE-OLU AND INTO BROADER FIELD OF RICH MOISTURE
ACROSS SRN/ERN NEB AND WRN IA...WITH MLCAPE GENERALLY IN 1500-2000
J/KG RANGE. ALTHOUGH LOW LEVEL HODOGRAPHS SHOULD REMAIN
SMALL...DEEP-LAYER SHEAR WILL FAVOR BOTH SUPERCELL AND BOW
STRUCTURES...I.E. EFFECTIVE SHEAR MAGNITUDES 30-50 KT.
..EDWARDS.. 08/03/2009
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MPX...FGF...FSD...OAX...ABR...GID...LBF...UNR...
LAT...LON 44330238 44700058 45549764 45979578 46149386 45859352
45379393 45139471 44639600 43909649 42999606 42339614
41679694 41629832 42110104 42980208 44330238
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