Monday, August 4, 2008

MESO: Mesoscale Discussion 2023

ACUS11 KWNS 040647
SWOMCD
SPC MCD 040646 COR
WIZ000-MNZ000-040815-

MESOSCALE DISCUSSION 2023
NWS STORM PREDICTION CENTER NORMAN OK
0146 AM CDT MON AUG 04 2008

AREAS AFFECTED...SERN MN THROUGH CNTRL AND SRN WI

CONCERNING...TORNADO WATCH 804...

VALID 040646Z - 040815Z

CORRECTED FOR TYPE OF WATCH

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 804 CONTINUES.

THREAT FOR MAINLY ISOLATED LARGE HAIL WILL PERSIST NEXT FEW HOURS
FROM SERN MN SPREADING ESEWD THROUGH CNTRL AND SRN WI. SOME STORMS
ARE BEGINNING MOVE OUT OF WW 804 INTO CNTRL WI...BUT STORMS SO FAR
APPEAR ONLY LOOSELY ORGANIZED WITH ALGORITHMS INDICATING MARGINALLY
SEVERE HAIL. A WW DOWNSTREAM OF WW 804 WILL PROBABLY NOT BE NEEDED
UNLESS STORMS BEGIN TO SHOW SIGNS OF INTENSIFICATION OR BETTER
ORGANIZATION.

EARLY THIS MORNING A WARM FRONT EXTENDS FROM A SURFACE LOW NEAR THE
IA-MN BORDER SEWD THROUGH ERN IA. COLD FRONT EXTENDS SWWD FROM THE
LOW THROUGH NW IA AND ERN NEB. SWLY LOW LEVEL JET EXTENDING FROM THE
CNTRL PLAINS NEWD THROUGH IA IS FORECAST TO VEER TO WLY WITH TIME AS
A SHORTWAVE TROUGH MOVES EWD THROUGH MN AND CRESTS UPPER RIDGE. THIS
WILL RESULT IN PRIMARY ZONE OF WARM ADVECTION AND ISENTROPIC LIFT
SHIFTING EWD AND SEWD INTO CNTRL AND SRN WI. THUS STORMS WILL LIKELY
SPREAD ESEWD ALONG INSTABILITY GRADIENT THROUGH WI NEXT SEVERAL
HOURS. RUC PFCS SHOW MODERATE TO STRONG MUCAPE AND STEEP MID LEVEL
LAPSE RATES IN THIS REGION SUFFICIENT FOR A THREAT OF ISOLATED LARGE
HAIL. HOWEVER...EFFECTIVE SHEAR FOR ELEVATED STORMS IS RATHER MODEST
WITH EWD AND SWD EXTENT INTO WI...AND THIS MAY PROVIDE A LIMITING
FACTOR FOR SUSTAINED LONG LIVED UPDRAFTS AND OVERALL SEVERE THREAT.

..DIAL.. 08/04/2008

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

ATTN...WFO...GRB...MKX...ARX...MPX...

42939001 43419088 44079189 44249278 44599319 45069289
45349144 45228979 44778884 44108846 43298882

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