[MCD] SWOMCD

Wed Dec 20 12:08:57 UTC 2006

ACUS11 KWNS 201209
SWOMCD
SPC MCD 201209 
NEZ000-KSZ000-COZ000-WYZ000-201615-

MESOSCALE DISCUSSION 2284
NWS STORM PREDICTION CENTER NORMAN OK
0609 AM CST WED DEC 20 2006

AREAS AFFECTED...ERN CO PLAINS...URBAN CORRIDOR...SWRN NEB AND NWRN
KS

CONCERNING...HEAVY SNOW 

VALID 201209Z - 201615Z

SNOW WILL CONTINUE TO SPREAD/DEVELOP NWWD FROM THE ECNTRL/SERN CO
PLAINS AND WRN KS TO THE DEN URBAN CORRIDOR...NERN CO AND SWRN NEB
THROUGH 18Z.  HOURLY SNOWFALL RATES OF 1-2 INCHES CAN BE EXPECTED
WITH A BLIZZARD LIKELY DEVELOPING LATER THIS MORNING.

WATER VAPOR IMAGERY SHOWS THE CENTER OF UPPER LOW IN CNTRL NM.  H7
LOW WAS FORMING OVER NERN NM WITH INCREASING NLY FLOW NOTED ON
VWP/PROFILERS OVER ERN CO.  THE H7 LOW WILL INTENSIFY AND MOVE VERY
SLOWLY INTO SERN CO BY THIS AFTN.  STRONG H5-H3 QVEC CONVERGENCE
WILL SPREAD NWD ACROSS ERN CO...WRN KS AND SWRN NEB BY
MID-MORNING...WITH STRONGEST UNDERLYING H7-H6 FRONTOGENESIS SHIFTING
TO THE DEN URBAN CORRIDOR/PALMER DIVIDE AND NERN CO PLAINS BY 18Z. 
INCREASING QG ASCENT SHOULD BEGIN TO OVERWHELM THE DRY
AIR/DOWNSLOPING OFF THE CHEYENNE RIDGE AND HEAVY SNOWFALL RATES
SHOULD ENSUE AS THE MORNING PROGRESSES FARTHER NORTH AND WEST.

POTENTIAL EXISTS FOR INTENSE MESOSCALE BANDING AS NEGATIVE
MPVG/POTENTIAL SLANTWISE CONVECTION BECOMES COINCIDENT WITH THE
FRONTOGENESIS BETWEEN 15-18Z.  MOREOVER...AS THE SYSTEM BECOMES MORE
VERTICALLY STACKED OVER SERN CO...EVIDENCE OF A TROWAL DEVELOPS INTO
NERN CO BY 18Z...FURTHER LENDING CONFIDENCE OF VERY HEAVY SNOWFALL. 
BEST COMBINATION OF LARGE SCALE SUPPORT AND POTENTIAL MESOSCALE
BANDING VCNTY MOST INTENSE UPSLOPE COMPONENT WILL OCCUR ALONG THE
PALMER DIVIDE.

FINALLY...INCREASING PRESSURE GRADIENTS WILL CONTRIBUTE TO
ACCELERATING WINDS WITH H7 SPEEDS FORECAST TO 55 KTS ALONG THE
PALMER DIVIDE AT 18Z.  GIVEN VERY HEAVY SNOWFALL RATES AND THE DRY
NATURE OF THE SNOW...EVOLUTION INTO A BLIZZARD IS LIKELY BY AFTN AND
ESPECIALLY ALONG THE PALMER DIVIDE.

..RACY.. 12/20/2006

...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...LBF...GLD...PUB...BOU...CYS...

38480412 38910433 39120453 39210499 39330545 39720575
40330578 40640574 40750474 41090382 41440295 41440245
41390209 41230164 41010126 40670098 40100077 39670084
39410116 39330182 39310213 39060225 38750229 38590237
38510270 38470314 38470353 