MESO: Mesoscale Discussion 0479

ACUS11 KWNS 210938
SWOMCD
SPC MCD 210937
ILZ000-WIZ000-IAZ000-MNZ000-211400-

MESOSCALE DISCUSSION 0479
NWS STORM PREDICTION CENTER NORMAN OK
0437 AM CDT FRI MAR 21 2008

AREAS AFFECTED...PARTS OF CENTRAL/SERN MN...FAR NERN IA...SRN
WI...AND FAR NRN IL

CONCERNING...HEAVY SNOW

VALID 210937Z - 211400Z

SNOWFALL RATES OF AT LEAST 1 IN/HR ARE EXPECTED TO DEVELOP AND
SPREAD SEWD ACROSS THE SRN TWIN CITIES METRO AREA TO SERN MN/NERN IA
THROUGH 12-15Z AND INTO SRN WI/FAR NRN IL BY 12-15Z. LOCALIZED
RATES UP TO 2 IN/HR SHOULD OCCUR ACROSS SRN WI INCLUDING MADISON AS
INDICATED BY LATEST SHORT TERM MODELS /SREF AND RUC/. THE HEAVY
SNOWFALL RATES ARE EXPECTED TO REACH SERN WI/FAR NERN IL INCLUDING
PARTS OF THE MILWAUKEE/CHICAGO METRO AREAS LATER THIS MORNING.

REGIONAL RADAR DATA INDICATED INCREASING REFLECTIVITY VALUES ACROSS
PARTS OF EAST CENTRAL MN /SRN TWIN CITIES METRO/ SEWD ACROSS NERN IA
INTO SRN WI AND FAR NRN IL. WIND PROFILERS/WSR-88D VAD DATA
INDICATED A STRONG 50-60 KT WSWLY MID LEVEL JET NOSING INTO IA ATTM.
THIS FEATURE ATTENDANT TO MID/UPPER LEVEL ERN DAKOTAS/SWRN MN SHORT
WAVE TROUGH WILL TRANSLATE EWD THIS MORNING...WITH LEFT EXIT REGION
OF THIS JET SPREADING ACROSS SERN MN/NERN IA TO SRN WI/NRN IL.
ASCENT WITHIN EXIT REGION OF MID LEVEL JET COUPLED WITH STRONG LOW
LEVEL WAA ALONG NOSE OF 55 KT SWLY LLJ TRANSLATING FROM IA TO IL BY
18Z ARE EXPECTED TO FURTHER ENHANCE SNOWFALL RATES FROM THE TWIN
CITIES METRO SEWD TO SRN WI/FAR NRN IL. COOLING OF THE COLUMN AS A
RESULT OF STRENGTHENING UVVS COMBINED WITH ELY LOW LEVEL FLOW WILL
SUPPORT COOL BOUNDARY LAYER CONDITIONS TO MAINTAIN A P-TYPE OF SNOW.
THE UVVS COMBINED WITH FURTHER SATURATION OF THE COLUMN ACROSS NERN
IL AND SURFACE WET BULB ZERO TEMPERATURES FORECAST TO REMAIN BELOW
32 F IN THIS AREA SHOULD ALLOW LOCATIONS CURRENTLY REPORTING RAIN TO
CHANGE OVER TO SNOW BY 12-15Z.

.PETERS.. 03/21/2008

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

ATTN...WFO...LOT...MKX...DVN...ARX...MPX...

44489451 44869444 45189424 45369392 45019288 44699185
44189092 43728993 43178809 42568747 41958759 41248781
41688928 42569106 42869161 43659280

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@PO.UIUC.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.