[MCD] SWOMCD

Mon Jan 15 01:05:14 UTC 2007

ACUS11 KWNS 150108
SWOMCD
SPC MCD 150107 
MIZ000-OHZ000-INZ000-ILZ000-WIZ000-150600-

MESOSCALE DISCUSSION 0065
NWS STORM PREDICTION CENTER NORMAN OK
0707 PM CST SUN JAN 14 2007

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

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 150107Z - 150600Z

NEWD MOVING AREA OF PRECIP NOW OVER CENTRAL PORTIONS INDIANA/IL WILL
MOVE ATOP FREEZING SFC TEMPS IN MI/INDIANA AND ERN WI/IL BORDER
REGIONS...AND PORTIONS N-CENTRAL/NERN IL...THROUGH 230Z.  THIS
ACTIVITY WILL BE PRIMARILY IN FORM OF LIGHT FREEZING RAIN WITH RATES
GENERALLY AOB .10 INCH HOUR...BUT LOCALLY TO .25 INCH/HOUR.  BETWEEN
3Z-6Z...FREEZING RAIN WITH RATES LOCALLY NEAR .25-.5 INCH/HOUR MAY
MOVE NEWD ACROSS SRN LOWER MI.  TRANSITION THROUGH MIXED PHASE WITH
SLEET...THEN TO SLEET/SNOW MIX...IS POSSIBLE WITH NWD EXTENT ACROSS
S-CENTRAL TO CENTRAL LOWER MI.  ISOLATED SNOW RATES 1-2 INCH/HOUR
MAY DEVELOP BY 6Z W-CENTRAL LOWER MI.

LOW LEVEL WAA AND MOISTURE TRANSPORT WILL STRENGTHEN ACROSS THIS
AREA FROM SW-NE AS MID-UPPER LEVEL PERTURBATION NOW OVER CENTRAL
HIGH PLAINS CONTINUES TO EJECT NEWD.  NRN PORTION OF MOST INTENSE
ISENTROPIC ASCENT IN 291-297K LAYER WILL OVERLAP SFC FREEZING TEMPS
ACROSS NERN IL...NRN INDIANA AND SRN LOWER MI BETWEEN 3Z AND
6Z...CONCURRENT WITH INCREASE IN 850 MB LLJ TO 40-50 KT JUST S OF
AREA ACROSS CENTRAL/SRN INDIANA AND SRN IL.  850-750 MB LAYER
FRONTOGENESIS REASONABLY IS PROGGED TO STRENGTHEN OVER THIS AREA
THROUGH 6Z...AIDING LIFT.  AT SFC...FREEZING LINE IS ANALYZED AT 0Z
NEAR TOL...SBN...VPZ...NWD ACROSS RELATIVELY WARM LM WATERS...THEN
SWWD AGAIN ACROSS NRN FRINGES CHI METRO...TO ABOUT 10 N PIA.  PRIND
CAA AND WEAK WET BULB EFFECTS WILL HELP TO DRIFT THIS LINE SWD OVER
NRN INDIANA.  HOWEVER FREEZING LINE MAY NOT CHANGE MUCH OVER IL DUE
TO LACK OF SFC CAA...COMBINED WITH SENSIBLE WARMING FROM DESCENT OF
RELATIVELY WARM PRECIP THROUGH SATURATED AIR.

RUC FCST SOUNDINGS INDICATE THIS WILL LEAD TO SATURATED...ROUGHLY 7
KFT DEEP SUPERFREEZING LAYER ACROSS NRN INDIANA...ABOVE SHALLOW
FREEZING LAYER NEAR SFC.  SUPERFREEZING LAYER SHOULD TRANSITION TO
4-5 KFT DEPTH OVER SRN LOWER MI...ATOP DEEPER SUBFREEZING BOUNDARY
LAYER MORE CONDUCIVE FOR SLEET.  WITH NWWD EXTENT IN LOWER
MI...THERMAL PROFILES ALOFT WILL SUPPORT SNOW.  STEEP LAPSE RATES OF
6-7 DEG C/KM...IN PORTIONS OF MOST FAVORABLE THERMAL ZONES FOR
DENDRITIC GROWTH...INDICATE SOME CONVECTIVE SNOW IS POSSIBLE WITH
LOCALIZED HEAVY RATES.

..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...APX...IWX...GRR...LOT...MKX...DVN...

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