[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 041805
SWOMCD
SPC MCD 041804 
IAZ000-NEZ000-SDZ000-050000-

MESOSCALE DISCUSSION 0023
NWS STORM PREDICTION CENTER NORMAN OK
1204 PM CST TUE JAN 04 2005

AREAS AFFECTED...SERN SD...NRN AND ERN NEB...WRN IA

CONCERNING...HEAVY SNOW 

VALID 041804Z - 050000Z

FIRST ROUND OF HEAVY SNOW IN AN EXTENDED WINTER STORM EVENT WILL
SPREAD EAST ACROSS MUCH OF NERN NEB...SERN SD...AND WRN IA THROUGH
THIS AFTERNOON. SNOWFALL RATES ACROSS THESE AREAS WILL LOCALLY REACH
1 INCH PER HOUR INTO THE EARLY EVENING.

LARGE SCALE SPLIT FLOW REGIME WITH STRONG MID LEVEL CONFLUENCE
ACROSS NRN PLAINS AND DEEP UPPER TROUGH OVER CA WILL CONTINUE TO
SUPPORT WIDESPREAD WINTER WEATHER FROM THE ROCKIES EAST ACROSS THE
CNTRL PLAINS THROUGH TONIGHT. OVER THE NEXT FEW HOURS...A SHORT WAVE
IMPULSE ROTATING OUT OF STRONG WRN TROUGH WILL ACT TO ENHANCE MID
LEVEL FRONTOGENESIS AND DEEP LAYER ASCENT IN A WEST-EAST SWATH
ACROSS NEB/SD. THIS LIFT MAY TEND TO WEAKEN GRADUALLY WITH TIME AS
SHORT WAVE MOVES EWD TOWARD DOWNSTREAM CONFLUENCE. NONETHELESS...
HEAVY SNOW...POSSIBLY OCCURRING IN ONE OR MORE MESOSCALE BANDS...
WILL OCCUR WHERE STRONGEST SLOPED ASCENT WITHIN MID/UPPER JET
ENTRANCE REGION COINCIDES WITH THERMODYNAMIC PROFILE FAVORABLE FOR
DENDRITIC SNOW CRYSTAL GROWTH. FORECAST SOUNDINGS SUGGEST A DEEP
SATURATED AIRMASS WITH ISOTHERMAL PROFILES IN THE -12C TO -17C RANGE
WILL EXIST ALONG THE NEB/SD BORDER THROUGH THIS AFTERNOON. GIVEN
VERY COLD BOUNDARY LAYER AIRMASS ACROSS MUCH OF THE AREA...HIGH SNOW
TO LIQUID RATIOS MAY RESULT IN GREATER SNOWFALL RATES DESPITE
LIMITED MOISTURE.

SLEET/ICE PELLETS MAY INITIALLY OCCUR ACROSS PARTS OF SERN NEB AND
WRN IA EARLY IN THE PERIOD. HOWEVER...COOLING IN THE 850-700MB LAYER
SHOULD RESULT IN A GRADUAL CHANGEOVER TO ALL SNOW IN THESE AREAS BY
LATE AFTERNOON/EARLY EVENING. HEAVIER SNOW WILL SPREAD ACROSS THE MO
RIVER AND INTO WRN/SWRN IA AFTER 20Z.

..CARBIN.. 01/04/2005

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A 
SCHEDULED BASIS...FOUR TIMES A DAY...BETWEEN 00-01 UTC...
06-07 UTC...12-13 UTC...AND 18-19 UTC AS SIGNIFICANT SHORT
RANGE WINTER WEATHER EVENTS UNFOLD.  THIS SCHEDULE WILL BE
USED FROM DECEMBER 1 THROUGH FEBRUARY 28.

ATTN...WFO...DMX...FSD...OAX...ABR...GID...LBF...UNR...

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