[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 310615
SWOMCD
SPC MCD 310615 
CAZ000-NVZ000-311015-

MESOSCALE DISCUSSION 2596
NWS STORM PREDICTION CENTER NORMAN OK
1215 AM CST FRI DEC 31 2004

AREAS AFFECTED...SIERRA MTNS OF CA AND ADJACENT AREAS OF FAR WRN NV
ABOVE 4000FT

CONCERNING...HEAVY SNOW AND NEAR BLIZZARD CONDITIONS 

VALID 310615Z - 311015Z

CONDITIONS WILL REMAIN FAVORABLE FOR EXTREMELY HEAVY SNOW RATES OF
2-3"/HR ACROSS THE CENTRAL SIERRA MTNS...INCLUDING THE I-80 CORRIDOR
AND ADJACENT AREAS OF FAR WRN NV THROUGH 12Z. A SLOW SWD SHIFT OF
THE HEAVY SNOW AXIS SHOULD BEGIN BETWEEN 09-12Z. GUSTY WINDS WILL
CREATE NEAR BLIZZARD CONDITIONS AT TIMES THROUGH THE REMAINDER OF
THE OVERNIGHT PERIOD.

PERSISTENT LONG WAVE TROUGHING WITH CLOSED 500MB LOW OFF THE ORE
COAST REMAINS IN PLACE LATE THIS EVENING...WITH STRONG SHORTWAVE
TROUGH NEAR 37N 128W EXPECTED TO APPROACH THE CENTRAL CA COAST
AROUND 12Z. THE QUASI-STATIONARY 850MB-700MB BAROCLINIC ZONE
EXTENDING FROM ROUGHLY SFO-RNO IS EXPECTED TO TRANSLATE SLOWLY SWD
THROUGH 12Z IN RESPONSE TO APPROACHING/DIGGING SHORTWAVE TROUGH.
AXIS OF HEAVIEST PRECIPITATION WITH EMBEDDED CONVECTIVE ELEMENTS HAS
BEEN COINCIDENT WITH THIS BAROCLINIC ZONE THROUGH THE PAST
12-18HRS...SO A GRADUAL SWD SHIFT OF THE BAND INTO THE CENTRAL/SRN
SIERRAS SHOULD OCCUR...PARTICULARLY AS TROUGH APPROACHES THE COAST
AFTER 09Z.

OTHERWISE...LITTLE SHORT-TERM CHANGE IN FORECAST IN VERY FAVORABLE
HEAVY SNOW PATTERN. SWLY 3KM FLOW OF 60KT WITHIN MAIN PRECIPITATION
BAND WILL RESULT IN CONTINUATION OF STRONG UPSLOPE FLOW COMPONENT
INTO THE CENTRAL SIERRAS. SMALL-SCALE VORTICITY MAX MOVING INLAND
ACROSS FAR NWRN CA HAS ENHANCED UPPER DIFFLUENT FLOW AND VERTICAL
MOTION ALONG AND NORTH OF 140KT 300MB JET AXIS ACROSS CENTRAL CA.
DEEP LAYER SATURATION WITH PW VALUES AROUND 0.75" AND EMBEDDED
CONVECTION SHOULD SUPPORT 2-3"/HR SNOW RATES...WITH HIGHEST RATES
LIKELY ALONG WEST FACING SLOPES.

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

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