[MCD] SWOMCD

Sun Jan 7 19:58:38 UTC 2007

ACUS11 KWNS 072002
SWOMCD
SPC MCD 072001 
IDZ000-MTZ000-080130-

MESOSCALE DISCUSSION 0031
NWS STORM PREDICTION CENTER NORMAN OK
0201 PM CST SUN JAN 07 2007

AREAS AFFECTED...THE BITTERROOT AND CLEARWATER MTNS OF NRN ID AND
FAR WRN MT ABOVE 3500 FT

CONCERNING...HEAVY SNOW 

VALID 072001Z - 080130Z

HEAVY SNOW WITH HOURLY RATES IN EXCESS OF 1 INCH IS ANTICIPATED TO
DEVELOP SWD OVER THE BITTERROOT AND CLEARWATER MTNS THROUGH 01Z.
COMBINED WITH THE HVY SNOW...STRONG WINDS (GUSTING AT TIMES OVER 50
MPH) WILL LEAD TO NEAR BLIZZARD CONDITIONS IN THE HIGHER WEST FACING
SLOPES INTO THE EARLY EVENING.

A VERY STRONG MID/UPPER LEVEL JET MAX (100 KTS OBSERVED BY THE
MISSOULA VWP AT 6KM) WILL CONTINUE TO PROGRESS SEWD. AS A
RESULT...WSWLY LOW LEVEL FLOW WILL CONTINUE TO STRENGTHEN OVER ERN
WA/NRN ID AND NERN ORE IN AGEOSTROPHIC RESPONSE TO THE RIGHT REAR
QUAD OF THIS MID/UPPER LEVEL JET. IN ADDITION TO THE INCREASING
WINDS...MODERATE MID LEVEL FRONTOGENESIS WILL AID IN INCREASING MID
LEVEL VERTICAL MOTION. THIS WILL SUPPORT MID LEVEL
SATURATION...WHICH HAS BEEN SLOW TO OCCUR THROUGH THE MORNING GIVEN
THE STRONG DOWNSLOPE FLOW EAST OF THE CASCADES. THE COMBINATION OF
STRONG MID LEVEL VERTICAL MOTION (COINCIDENT WITH A DEEP LAYER OF
FAVORABLE TEMPERATURES FOR DENDRITIC SNOW GROWTH) AND STRONG (50-70
KTS) UPSLOPE FLOW WILL SUPPORT HVY SNOW DEVELOPMENT OVER THE WRN
SLOPES OF THE BITTERROOT AND CLEARWATER MTNS THIS AFTERNOON. GIVEN
THE DEGREE OF FORCING...AND MODEST PRECIPITABLE WATER VALUES (OVER
1/2 OF AN INCH PER GOES SOUNDER DATA) SNOWFALL RATES IN EXCESS OF 1
INCH/HR ARE EXPECTED FOR AT LEAST A 3-6 HR PERIOD INTO THE EARLY
EVENING.

..CROSBIE.. 01/07/2007

...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...MSO...OTX...

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