[MCD] SWOMCD

Sat Jan 13 00:30:40 UTC 2007

ACUS11 KWNS 130033
SWOMCD
SPC MCD 130033 
ILZ000-MOZ000-IAZ000-ARZ000-OKZ000-KSZ000-130530-

MESOSCALE DISCUSSION 0046
NWS STORM PREDICTION CENTER NORMAN OK
0633 PM CST FRI JAN 12 2007

AREAS AFFECTED...CNTRL MO...CNTRL IL...FAR SERN KS...FAR NWRN
AR...FAR NERN OK

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 130033Z - 130530Z

A SIGNIFICANT ICE STORM WILL CONTINUE THROUGH MUCH OF THE EVENING
HOURS NW OF A QUASI-STATIONARY ARCTIC FRONT. ICE ACCUMULATIONS OF
.05 TO .10 IN/HR WILL REMAIN LIKELY. LOCALIZED RATES UP TO .25 IN/HR
WILL ALSO OCCUR AT TIMES.

A NEARLY STEADY-STATE MIXED PRECIPITATION EVENT IS EXPECTED TO OCCUR
OVER THE NEXT SEVERAL HOURS ACROSS THE MCD AREA...AS A WARM/MOIST
CONVEYOR BELT HAS BECOME WELL-ESTABLISHED FROM THE LOWER RIO GRANDE
N/NEWD TOWARDS THE MID-MS RIVER VALLEY. LOW-LEVEL WARM THETA-E
ADVECTION/ISENTROPIC LIFT ATOP A NEAR-SURFACE BASED COLD DOME WILL
AID IN THE CONTINUED PRODUCTION OF MIXED PRECIPITATION. 18Z NAM/GFS
AND 21Z RUC GUIDANCE ARE CONSISTENT WITH STRENGTHENING THE LLJ THIS
EVENING FROM NERN TX INTO SRN MO AND SRN IL...WITH CORRESPONDING
INCREASES IN QPF AS WELL.

AT 00Z...THE SURFACE FREEZING LINE WAS LOCATED FROM AROUND FYV TO
STL TO BMI. THIS BOUNDARY SHOULD PROGRESS VERY SLOWLY SWD IN THE
OZARKS REGION...WITH MORE SUBSTANTIAL PROGRESS SEWD IN SRN IL WITH
GREATER PRESSURE RISES. 00Z SGF AND ILX OBSERVED SOUNDINGS INDICATE
FREEZING RAIN WILL REMAIN THE PREDOMINANT PTYPE CENTERED ALONG THE
I-44 CORRIDOR ACROSS MO /INCLUDING THE STL METRO AREA/ NEWD INTO
CNTRL IL. FURTHER NWWD...THE PTYPE WILL REMAIN MOSTLY SLEET FROM
AROUND CNU NEWD TO SZL AND UIN. HERE...A LARGER NEAR-SURFACE COLD
LAYER WILL REMAIN BENEATH A SMALLER ABOVE-FREEZING LAYER COMPARED TO
LOCALES FURTHER SE.

..GRAMS.. 01/13/2007

...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...LOT...ILX...LSX...DVN...LZK...SGF...EAX...TSA...TOP...ICT...

37359570 38079547 38859468 39769337 40439202 41039013
41298912 41048824 40438813 39428871 38778950 38099064
37029257 35839394 36069497 