Tuesday, September 25, 2007

MESO: Mesoscale Discussion 2017

ACUS11 KWNS 260004
SWOMCD
SPC MCD 260003
MIZ000-260130-

MESOSCALE DISCUSSION 2017
NWS STORM PREDICTION CENTER NORMAN OK
0703 PM CDT TUE SEP 25 2007

AREAS AFFECTED...SOUTHEAST LOWER MICHIGAN...INTO THE THUMB OF
MICHIGAN

CONCERNING...SEVERE THUNDERSTORM WATCH 689...

VALID 260003Z - 260130Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 689
CONTINUES.

AN ADDITIONAL WW IS NOT ANTICIPATED.

ALTHOUGH BOUNDARY LAYER BASED INSTABILITY IS BEGINNING TO WANE...
STORM DEVELOPMENT ACROSS LOWER MICHIGAN MAY BE SLOWEST TO WEAKEN
THIS EVENING...PERHAPS DUE TO ENHANCED FORCING FOR UPWARD VERTICAL
MOTION ASSOCIATED WITH SIGNIFICANT UPSTREAM SHORT WAVE TROUGH NOW
LIFTING INTO THE UPPER GREAT LAKES REGION. 40-50 KT SOUTHWESTERLY
500 MB FLOW TO THE SOUTHEAST OF THIS FEATURE IS CONTRIBUTING TO
STRONG DEEP LAYER SHEAR...SUPPORTIVE OF UPDRAFT ROTATION AND THE
PRODUCTION OF SMALL TO MARGINALLY SEVERE HAIL IN RELATIVELY HIGH
MOISTURE CONTENT AIR MASS WITH PRECIPITABLE WATER NEAR 1.8 INCHES
AND CAPE IN EXCESS OF 1000 J/KG.

DESPITE NEAR SATURATED PROFILES AND WEAK TO MODERATE LOW-LEVEL FLOW
FIELDS...MELTING HAIL MAY BE ENHANCING DOWNDRAFTS...AND...IN
CONJUNCTION WITH FAST STORM MOTIONS...CONTRIBUTING TO THE DAMAGING
WIND POTENTIAL IN STRONGEST ACTIVITY. THIS MAY CONTINUE ACROSS
SOUTHEAST LOWER MICHIGAN...INCLUDING THE THUMB AREA...POSSIBLY THE
DETROIT METROPOLITAN AREA...THROUGH 02-03Z. THEREAFTER...SEVERE
POTENTIAL IS EXPECTED TO DIMINISH WITH FURTHER STABILIZATION...AND
PRIMARY CONVECTIVE DEVELOPMENT WILL SHIFT EASTWARD INTO ONTARIO.

.KERR.. 09/26/2007

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

ATTN...WFO...DTX...IWX...GRR...

41958334 41858421 42098495 42438501 42798432 43148380
43448329 43558275 43518218 42878196 42308264

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