[MCD] SWOMCD

Wed Dec 20 18:48:56 UTC 2006

ACUS11 KWNS 201849
SWOMCD
SPC MCD 201849 
NEZ000-SDZ000-COZ000-WYZ000-210045-

MESOSCALE DISCUSSION 2287
NWS STORM PREDICTION CENTER NORMAN OK
1249 PM CST WED DEC 20 2006

AREAS AFFECTED...SERN WY...WRN AND NCENTRAL NEB...SCENTRAL SD

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 201849Z - 210045Z

HEAVY SNOW WITH HRLY RATES OVER 1 INCH COMBINED WITH STRONG NLY
WINDS /SUPPORTING BLIZZARD CONDITIONS/ WILL CONTINUE TO DEVELOP NWD
OVER SERN WY AND THE NEB PANHANDLE THROUGH 21Z. ACROSS NCENTRAL
NEB/SCENTRAL SD...FREEZING RAIN WILL INITIALLY BE THE PRIMARY P-TYPE
THROUGH 21Z. A CHANGEOVER TO SLEET AND/OR HEAVY SNOW IS ANTICIPATED
TO DEVELOP EWD ACROSS WRN/NCENTRAL NEB AND SCENTRAL SD IN THE 21-00Z
PERIOD.

RECENT MBW AND MRR PROFILERS INDICATE INCREASING WIND FIELDS IN THE
2-4 KM LAYER. MID LEVEL WINDS HAVE ALSO RECENTLY BACKED AT THE MRR
PROFILER FURTHER INDICATING A RESPONSE TO STRONG FRONTOGENESIS
OCCURRING OVER SERN WY AND THE NEB PANHANDLE. AS THE MID LEVEL LOW
OVER NERN NM CONTINUES TO LIFT SLOWLY NEWD INTO WRN KS THROUGH THE
AFTERNOON...THE MID LEVEL DRYSLOT WILL CONTINUE TO MOVE INTO NERN
CO. THIS WILL FURTHER AID IN MAINTAINING STRONG FRONTOGENETIC
FORCING SUPPORTING HEAVY SNOWFALL DEVELOPMENT. MODERATE SFC PRESSURE
FALLS WILL CONTINUE TO OCCUR OVER NWRN KS AND SWRN NEB IN ADVANCE OF
THE UPPER LOW ASSOCIATED WITH STRONG UPPER TROPOSPHERIC WARM
ADVECTION. THIS WILL SUPPORT AN INCREASE IN SFC WINDS OVER MUCH OF
WRN/CENTRAL NEB...SERN WY AND EVENTUALLY SCENTRAL SD TOWARD 00Z.

SHALLOW SUBFREEZING AIR WILL CONTINUE TO EXIST OVER PORTIONS OF
NCENTRAL NEB AND SCENTRAL SD...SUPPORTED BY LOW LEVEL DRY AIR
ADVECTION. AS MODERATE LOW LEVEL WARM ADVECTION CONTINUES...
FREEZING RAIN WILL BE THE PRIMARY PTYPE IN THIS AREA FOR THE NEXT
SEVERAL HRS BEFORE A CHANGEOVER TO SLEET OCCURS AFTER 21Z AS THE MID
LEVEL SYSTEM GRADUALLY SHIFTS NEWD AND LOW LEVEL COOLING OCCURS. IN
ADDITION..MODERATE RAINFALL FALLING ACROSS PORTIONS OF WRN NEB
SHOULD CHANGEOVER TO HVY SNOW AFTER 21Z. THE ANTICIPATED HVY
SNOW/RAIN LINE SHOULD EXTEND FROM ANW TO LBF TO MCK BY 00Z.

..CROSBIE.. 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...ABR...LBF...UNR...BOU...CYS...

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