[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 311220
SWOMCD
SPC MCD 311220 
CAZ000-NVZ000-311615-

MESOSCALE DISCUSSION 2597
NWS STORM PREDICTION CENTER NORMAN OK
0620 AM CST FRI DEC 31 2004

AREAS AFFECTED...CENTRAL AND SRN SIERRA MTNS OF CA ABOVE 4000 FT

CONCERNING...HEAVY SNOW 

VALID 311220Z - 311615Z

AXIS OF HEAVIEST SNOWFALL RATES WILL CONTINUE TO SHIFT SWD FROM THE
CENTRAL INTO THE SRN SIERRA MTNS THROUGH 31/18Z. EXTREMELY HEAVY
SNOW WITH RATES OF 2-3"/HR ARE EXPECTED ALONG WRN SLOPES WITH SNOW
LEVELS RANGING FROM 4000-5000 FT FROM NORTH TO SOUTH ACROSS THE
DISCUSSION AREA. 

AT 12Z...IR IMAGERY REVEALS WELL-DEFINED COMMA CLOUD ASSOCIATED WITH
STRONG MID-LEVEL VORT MAX CENTERED 100NM SW OF SFO. THIS FEATURE
WILL CONTINUE TO DIG SEWD AT 40KTS REACHING THE SAN JOAQUIN VALLEY
BY 18Z. PRE-EXISTING BAROCLINIC ZONE IN 850-700MB LAYER...WHICH HAS
BEEN COINCIDENT WITH LONG-LIVED BAND OF HEAVY PRECIPITATION FROM THE
CA COAST INLAND ACROSS THE SIERRA MTNS...HAS BEGUN TO SHIFT SWD IN
RESPONSE TO DIGGING SHORTWAVE TROUGH. HEAVY SNOW SHOULD TAPER OFF
NORTH OF I-80 AND BECOME INCREASINGLY FOCUSED ACROSS THE SRN SIERRA
MTNS DURING THE NEXT 6 HOURS OR SO. VAD WIND PROFILE AT HANFORD
INDICATES VERY STRONG SWLY FLOW OF 50-70KT BETWEEN 2 AND 6KM...WHICH
WILL FAVOR STRONG OROGRAPHIC LIFTING INTO THE SRN SIERRA MTNS DURING
THE REMAINDER OF THIS MORNING. ENHANCED UPPER DIVERGENCE WITH
APPROACHING VORT MAX IN ADDITION TO AMPLE DEEP-LAYER MOISTURE AND
EMBEDDED CONVECTIVE ELEMENTS SHOULD CONTINUE TO YIELD 2-3"/HR SNOW
RATES. SNOW SHOULD BEGIN TO TAPER OFF AREA WIDE WITH PASSAGE OF
SHORTWAVE TROUGH AFTER 18Z.

..BANACOS.. 12/31/2004

...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...VEF...REV...HNX...STO...

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37001840 36241803 36051838 36061875 36531898 37001926
37371965 37661992 37932014 38412045 

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