[MCD] SWOMCD

Mon Jan 15 05:31:39 UTC 2007

ACUS11 KWNS 150534
SWOMCD
SPC MCD 150534 
MIZ000-OHZ000-INZ000-ILZ000-WIZ000-151030-

MESOSCALE DISCUSSION 0067
NWS STORM PREDICTION CENTER NORMAN OK
1134 PM CST SUN JAN 14 2007

AREAS AFFECTED...PORTIONS CENTRAL/SRN LOWER MI...EXTREME SERN
WI...EXTREME NWRN OH...EXTREME NRN INDIANA...SRN LM...AND NRN IL.

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 150534Z - 151030Z

MAJOR SFC ICING EVENT POSSIBLE THROUGH 12Z ACROSS PORTIONS
S-CENTRAL/SERN LOWER MI...EXTREME NRN INDIANA AND NWRN OH...WITH
FREEZING RAIN CONTINUING THROUGH MUCH OF DISCUSSION PERIOD.  RATES
LOCALLY EXCEEDING .25 INCH/HOUR ARE POSSIBLE BRIEFLY...WITH .10-.25
INCH RATES COMMON.  TRANSITION TO LIGHTER FREEZING RAIN RATES IS
EXPECTED WITH WWD EXTENT ACROSS EXTREME SWRN LOWER MI...SRN LM INTO
NRN IL...WHERE PRECIP SHOULD WEAKEN FROM SW-NE DURING NEXT 4-6
HOURS.  MEANWHILE MIXED-PHASE TRANSITION IS EXPECTED FROM FREEZING
RAIN TO SLEET TO SNOW -- FROM S-N ACROSS S-CENTRAL AND ERN LOWER MI.

5Z SFC MESOANALYSIS SHOWED FREEZING LINE NEAR NRN SHORE LE...THEN
INVOF MI/OH AND MI/INDIANA BORDERS...ARCHING NWD OVER SRN LM...THEN
WINDING ERRATICALLY SWWD ACROSS NRN IL.  MODIFIED RAOBS AND RUC
SOUNDINGS INDICATE 5-8 KFT DEEP SUPERFREEZING AIR MASS ABOVE SHALLOW
NEAR-SFC FREEZING LAYER FROM MI/INDIANA AND MI/OH BORDER REGIONS NWD
OVER S-CENTRAL/SWRN LOWER MI.  THIS PROFILE GRADUALLY WILL COOL WITH
TIME...AS APPARENT TOP-DOWN PRECIP COOLING OCCURS IN WARM LAYER
THROUGH MELTING AND RELATED LATENT HEAT ABSORPTION PROCESSES.  THIS
WILL MAINTAIN FREEZING RAIN FOR SEVERAL MORE HOURS OVER SERN LOWER
MI BUT AID IN TRANSITION TO MORE FROZEN PRECIP FARTHER W AND NW. 
MEANWHILE...WITH BOUNDARY LAYER NEARLY SATURATED...WET BULB COOLING
EFFECTS NEAR SFC SHOULD BE MINIMAL...AND FREEZING LINE SHOULD MOVE
LITTLE OVER MOST OF AREA THROUGH REMAINDER OVERNIGHT HOURS. 
STRONGEST ISENTROPIC ASCENT IN 288-294 K LAYER...AND GREATEST
FRONTOGENETIC FORCING IN 800-850 MB PRESSURE LAYER...ARE FCST TO
MOVE NEWD ACROSS REGION THROUGH 9Z...THEN DIMINISH THEREAFTER AS
BULK OF STRONGEST FORCING SHIFTS EWD OVER SRN ONT AND INTO UPSTATE
NY.  REF SPC MESOSCALE DISCUSSION 676 FOR MORE DETAILS ON DOWNSTREAM
FREEZING RAIN POTENTIAL.

..EDWARDS.. 01/15/2007

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

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A
SCHEDULED BASIS FROM DECEMBER 1 THROUGH FEBRUARY 28...FOUR
TIMES A DAY...AROUND 00 UTC...06 UTC...12 UTC...AND 18 UTC
FOR SIGNIFICANT SHORT RANGE WINTER WEATHER EVENTS.

ATTN...WFO...CLE...DTX...IWX...GRR...LOT...MKX...DVN...

42948787 43538557 43598409 43868251 43168234 41858309
41558342 41548499 41678653 42238670 42488728 42028825
41388844 41528968 41758988 