[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 171238
SWOMCD
SPC MCD 171237 
WAZ000-171630-

MESOSCALE DISCUSSION 0107
NWS STORM PREDICTION CENTER NORMAN OK
0637 AM CST MON JAN 17 2005

AREAS AFFECTED...INTERIOR WA

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 171237Z - 171630Z

FREEZING RAIN IS EXPECTED TO INCREASE IN COVERAGE ACROSS THE MTN
PASSES OF THE WA CASCADES WITH THE DEVELOPMENT OF SLEET/FREEZING
RAIN EWD INTO CENTRAL WA THROUGH 18Z. FREEZING RAIN RATES OF
0.05"/HR ARE EXPECTED...PARTICULARLY IN THE CASCADE MT. PASSES BY
MID-LATE MORNING.

LOW-LEVEL ARCTIC AIR MASS REMAINS FIRMLY ENTRENCHED EAST OF CASCADES
AS EVIDENCED BY 1036MB SURFACE HIGH OVER THE COLUMBIA BASIN AT
17/12Z. SURFACE TEMPERATURES WERE GENERALLY IN THE TEENS TO AROUND
20 IN THE MTN PASSES EWD ACROSS CENTRAL WA...WITH ONLY SMALL
DEWPOINT DEPRESSIONS OF 3-5F.

MEANWHILE...THE 700MB SHORTWAVE RIDGE CURRENTLY IN PLACE OVER
CENTRAL WA WILL TRANSLATE EWD IN RESPONSE TO STRENGTHENING SWLY FLOW
ALONG THE COAST. VAD WIND PROFILE FROM NWRN WA INDICATES STRONG
VEERING WINDS FROM THE SFC THROUGH 6KM WITH WIND SPEEDS OF 50-55KT
THROUGH MUCH OF THE LAYER. IR IMAGERY REVEALS AN IMPRESSIVE WARM
CONVEYOR BELT FROM THE CENTRAL PACIFIC INTO VANCOUVER ISLAND AND
NWRN WA...THAT SHOULD GRADUALLY BUILD SEWD ACROSS WA STATE BY THIS
AFTERNOON. UVV WILL BE DRIVEN BY 850-700MB WARM ADVECTION WHICH
SHIFTS INTO CENTRAL WA BY 18Z...WITH LOCALLY STRONG ISENTROPIC LIFT
OWING TO EXISTING SHALLOW ARCTIC AIR. LIFT WILL BE AUGMENTED BY
OROGRAPHIC INFLUENCES...AND MAY DELAY ONSET OF PRECIPITATION IN SOME
DOWNSLOPE AREAS EAST OF THE CASCADES. HOWEVER...STRONG SYNOPTIC
SUPPORT AND HIGH MOISTURE VALUES /PW 1-1.25 IN ALONG THE WA COAST BY
THIS AFTERNOON/ SUGGEST PRECIPITATION WILL GRADUALLY INCREASE IN
COVERAGE ACROSS CENTRAL WA. THERMODYNAMIC PROFILES BASED ON 09Z RUC
GENERALLY SUPPORT FREEZING RAIN IN THE MT. PASSES AND SLEET
INITIALLY ACROSS CENTRAL WA. TENDENCY WILL BE FOR SLEET TO BECOME
FREEZING RAIN DURING THE AFTERNOON HOURS AS CONSIDERABLE WARMING IS
FORECAST TO OCCUR IN 850-700MB LAYER ACROSS CENTRAL WA.

..BANACOS.. 01/17/2005

...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...OTX...PDT...SEW...

48342143 47392150 46952151 46662150 46332139 46072070
46141950 46571885 47181869 47911866 48521884 48771925
48971960 48952053 48912106 

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