MESO: Mesoscale Discussion 1502

ACUS11 KWNS 092021
SWOMCD
SPC MCD 092020
MNZ000-092145-

MESOSCALE DISCUSSION 1502
NWS STORM PREDICTION CENTER NORMAN OK
0320 PM CDT THU JUL 09 2009

AREAS AFFECTED...NRN/CNTRL MN

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 092020Z - 092145Z

TSTMS MAY INITIATE ALONG COLD FRONT AND CONFLUENCE BANDS ORIENTED
PARALLEL TO THE FRONT NE OF THE BUFFALO RIDGE. STRONG DEEP-LAYER
SHEAR WOULD PROVE FAVORABLE FOR SUPERCELLS. HOWEVER...SURFACE-BASED
DESTABILIZATION HAS BEEN RETARDED DOWNSTREAM ACROSS CNTRL MN DUE TO
REMNANT MCS CLOUD DEBRIS AND THIS BREEDS UNCERTAINTY OVER WHETHER A
WW WILL BE NEEDED THIS AFTERNOON.

20Z SUBJECTIVE SURFACE ANALYSIS PLACED AN OCCLUDED FRONT FROM LAKE
OF THE WOODS S/SWWD TO NEAR HON. RECENT VISIBLE SATELLITE IMAGERY
DEPICTED INCREASINGLY AGITATED CU ALONG THIS BOUNDARY AND IN BANDS
ORIENTED PARALLEL TO THE FRONT NE OF THE BUFFALO RIDGE IN W-CNTRL
MN. IN THESE AREAS...SURFACE TEMPERATURES HAVE WARMED INTO THE LOWER
TO MIDDLE 80S WITH A PLUME OF 60S SURFACE DEW POINTS. MODIFYING THE
12Z ABR RAOB SUGGESTS LITTLE IF ANY REMAINING MLCIN SHOULD REMAIN.
ALTHOUGH THE REGION MAY STILL BE IN SOME DEGREE OF SUBSIDENCE IN THE
WAKE OF VIGOROUS SHORT WAVE TROUGH SHIFTING ACROSS WRN ONTARIO...A
WEAK IMPULSE APPEARS TO BE EJECTING ACROSS THE NRN PLAINS /PER
INCREASING CI IN SATELLITE IMAGERY/ AND MAY ENHANCE LARGER-SCALE
ASCENT WITH AT LEAST ISOLATED TSTM DEVELOPMENT BY LATE AFTERNOON.

ALTHOUGH LOW-LEVEL S/SWLYS SHOULD GRADUALLY VEER AND WEAKEN...STRONG
MID-LEVEL WLYS /AS SAMPLED BY THE WDL PROFILER AND THE 17Z WINNIPEG
RAOB/...WILL BE FAVORABLE FOR SUPERCELLS PRODUCING LARGE HAIL. THE
OVERALL EXTENT OF THIS THREAT IS STILL UNCERTAIN GIVEN EXTENSIVE
SC/CI FIELD ACROSS MOST OF CNTRL MN WHICH HAS SLOWED SURFACE-BASED
DESTABILIZATION.

..GRAMS.. 07/09/2009

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

ATTN...WFO...DLH...MPX...FGF...ABR...

LAT...LON 46349330 45619373 45199441 45079510 45229631 45959638
47519566 48709506 48859436 48559278 46349330

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