MESOSCALE DISCUSSION 2169
   NWS STORM PREDICTION CENTER NORMAN OK
   1205 AM CST SAT DEC 01 2007
   
   AREAS AFFECTED...NRN KS...SRN NEB...NWRN MO...FAR SWRN IA
   
   CONCERNING...FREEZING RAIN 
   
   VALID 010605Z - 011000Z
   
   SIGNIFICANT ICE ACCUMULATIONS APPEAR LIKELY TOWARDS 12Z AS RAPID
   INFLUX OF WARM/MOIST AIR OVERRIDES AN INITIALLY COLD/DRY AIR MASS
   NEAR THE SURFACE. ICE ACCUMULATION RATES AOA 0.05 IN/HR APPEAR
   PROBABLE FROM S-CNTRL NEB/N-CNTRL KS...EXPANDING EWD TOWARDS THE
   LOWER MO RIVER VALLEY. A BAND OF MODERATE FREEZING RAIN SHOULD
   DEVELOP WITHIN A ZONE OF STRONG FORCED ASCENT...WITH LOCALIZED ICE
   ACCUMULATION RATES NEAR 0.15 IN/HR.
   
   DOWNSTREAM OF LARGE-SCALE UPPER-LEVEL TROUGH OVER THE WRN
   CONUS...LEE CYCLOGENESIS WILL INTENSIFY ALONG THE CO HIGH PLAINS
   WITH A STRENGTHENING LLJ OVERNIGHT CENTERED ACROSS THE CNTRL/SRN
   PLAINS. THIS IN TURN WILL LEAD TO INTENSE LOW-LEVEL WARM THETA-E
   ADVECTION GIVEN SEASONABLY MOIST AIR MASS OVER THE SRN PLAINS /REF
   850 TD AROUND 6C IN 00Z OUN RAOB/. 00Z MODEL GUIDANCE FORECASTS ARE
   CONSISTENT WITH BLOSSOMING PRECIPITATION OVER THE CNTRL PLAINS BY
   12Z. ALTHOUGH THERE IS SOME DISCREPANCY WITH EXACTLY WHERE THE
   HEAVIEST QPF LIES...THE STRONGEST ASCENT JUXTAPOSED WITH SATURATED
   PROFILES SHOULD LIE ACROSS SERN NEB/NERN KS/NWRN MO BY 12Z. 05Z
   OBSERVED SURFACE AND PAVEMENT TEMPERATURES INDICATED THE FREEZING
   LINE ARCING ROUGHLY W TO E FROM 30 S RSL TO JEF. DESPITE VEERING
   SURFACE WINDS WITH TIME...AN INITIALLY COLD/DRY AIR MASS BENEATH A
   STRONG INVERSION COMMENCING AROUND 900 TO 950 MB /REF 00Z TOP AND
   OAX RAOBS/...WILL MAINTAIN BELOW FREEZING SURFACE TEMPERATURES FROM
   FAR NRN KS/MO NWD THROUGH 12Z.
   
   ..GRAMS.. 12/01/2007
   
   
   ...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...DMX...EAX...OAX...TOP...ICT...GID...DDC...GLD...
   
   39149357 39229520 39129713 39029792 38999922 39619973
   40429975 40989930 41299782 41329658 41279558 40979446
   40169341