[MCD] SWOMCD

Fri Jan 12 18:32:01 UTC 2007

ACUS11 KWNS 121835
SWOMCD
SPC MCD 121834 
MOZ000-ILZ000-ARZ000-OKZ000-KSZ000-122330-

MESOSCALE DISCUSSION 0042
NWS STORM PREDICTION CENTER NORMAN OK
1234 PM CST FRI JAN 12 2007

AREAS AFFECTED...MUCH OF CNTRL MO...FAR SERN KS...EXTREME NERN OK

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 121834Z - 122330Z

FREEZING RAIN AND SLEET WILL INCREASE THIS AFTERNOON FROM SW TO NE.
ICE ACCUMULATIONS OF .05 TO .10 IN/HR WILL BE LIKELY...WITH LOCAL
RATES NEAR .15 IN/HR AT TIMES.

A LARGE AREA OF MIXED PRECIPITATION ACROSS MUCH OF SWRN INTO N-CNTRL
OK IS EXPECTED TO EXPAND NEWD INTO SERN KS/CNTRL MO DURING THE
AFTERNOON. THE PRECIPITATION HAS BEEN ASSOCIATED WITH STRONG
LOW-LEVEL FRONTOGENETICAL FORCING...AND WARM THETA-E ADVECTION ATOP
AN INCREASINGLY COLD DOME NEAR THE SURFACE. IN ADDITION...A SUBTLE
MID-LEVEL IMPULSE ENTERING WRN OK PER W/V SATELLITE IMAGERY...IS
FORECAST TO LIFT NEWD...FURTHER ENHANCING LARGE-SCALE ASCENT
DOWNSTREAM. AT 18Z...THE SURFACE FREEZING LINE WAS FROM AROUND GMJ
TO JEF TO 50 N STL. CONTINUED LOW-LEVEL CAA BEHIND AN ARCTIC COLD
FRONT SHOULD PUSH THE FREEZING LINE SEWD AT AROUND 10 KT THROUGH
00Z.

18Z SGF AND ILX OBSERVED SOUNDINGS INDICATE A RATHER LARGE WARM NOSE
PRESENT WITH A SATURATED 850-900 MB LAYER AROUND 10 DEGREES C. THE
LOW-LEVEL THERMAL STRUCTURE FROM BOTH THE 15Z RUC AND 12Z NAM MODEL
FORECAST SOUNDINGS WERE IN EXCELLENT AGREEMENT WITH THE OBSERVED SGF
SOUNDING. THEIR FORECAST SOUNDINGS INDICATE FREEZING RAIN WILL BE
THE MAIN PRECIPITATION TYPE IN A 50-75 KM BAND CENTERED ROUGHLY
ALONG THE 18Z SURFACE FREEZING LINE. FURTHER NW...FROM AROUND CNU TO
SZL TO UIN...INITIAL LIGHT FREEZING RAIN/DRIZZLE SHOULD TRANSITION
TO MAINLY SLEET. THIS SHOULD OCCUR AS THE DEPTH OF THE NEAR-SURFACE
COLD AIR SLOWLY INCREASES BENEATH THE ELEVATED ABOVE FREEZING LAYER.

..GRAMS.. 01/12/2007

...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...LSX...SGF...EAX...TSA...TOP...ICT...

37159586 37739574 38579481 39469341 39739218 39869124
39359038 38729055 37819194 37229279 36279444 36429510 