[MCD] SWOMCD

Mon Dec 19 19:59:01 UTC 2005

ACUS11 KWNS 191956
SWOMCD
SPC MCD 191956 
IDZ000-ORZ000-WAZ000-200100-

MESOSCALE DISCUSSION 2583
NWS STORM PREDICTION CENTER NORMAN OK
0156 PM CST MON DEC 19 2005

AREAS AFFECTED...NRN/ERN ORE...SWRN ID AND SRN WA-

CONCERNING...PRECIPITATION TRENDS...WINTER PRECIPITATION 

VALID 191956Z - 200100Z

MODERATE SNOW OVER THE TREASURE VALLEY MAY CHANGEOVER TO LIGHT
FREEZING RAIN THROUGH 21Z...BEFORE WEAKENING TOWARDS 00Z. FURTHER
NORTH MIXED PRECIP OVER NERN ORE/SERN WA...INCLUDING MUCH OF THE
COLUMBIA RIVER BASIN...WILL CONTINUE TO DIMINISH THROUGH THE
AFTERNOON. HOWEVER...A NEW AREA OF FREEZING RAIN WILL REDEVELOP 
AFTER 22Z IN THE DESCHUTES RIVER VALLEY OF NRN ORE AND OVER THE WRN
COLUMBIA RIVER BASIN/GORGE AFTER 00Z.

LATEST RADAR IMAGERY INDICATES A LARGE AREA OF PRECIPITATION OVER
ERN ORE...ASSOCIATED WITH MODERATE-STRONG MID LEVEL WAA/ISENTROPIC
LIFT. AS OF YET...THE WAA HAS BEEN INSUFFICIENT TO ALLOW FOR A
CHANGEOVER TO FREEZING RAIN IN THE TREASURE VALLEY WITH MODERATE
SNOWFALL THE PRIMARY P-TYPE. GIVEN RECENT TRENDS IN OBSERVATIONS AT
BURNS /ELEV 4000 FT/ INDICATING ABOVE FREEZING TEMPERATURES
DEVELOPING ...THERE IS STILL SOME POTENTIAL THAT SNOW WILL
CHANGEOVER TO FREEZING RAIN BEFORE PRECIPITATION DIMINISHES BY LATE
THIS AFTERNOON.

FURTHER NW...RADAR IMAGERY AND SURFACE OBSERVATIONS INDICATE THAT
WEAKENING MIXED PRECIP RATES WILL CONTINUE OVER MUCH OF THE COLUMBIA
RIVER BASIN REGION THROUGH THE REMAINDER OF THE AFTERNOON AS MID
LEVEL ISENTROPIC LIFT SHIFTS EWD AWAY FROM THE AREA. UPSTREAM OF
THIS AREA...ANOTHER SURGE OF STRONG MID LEVEL WAA WAS BEGINNING
AHEAD OF DEEP SYSTEM WELL OFF THE ORE COAST. THE ASSOCIATED
PRECIPITATION WAS ALREADY ADVANCING NWD ALONG THE CENTRAL ORE COAST
AND WILLAMETTE VALLEY. AS THIS PRECIPITATION ADVANCES
NEWD...SUBFREEZING AIR WILL REMAIN IN PLACE OVER THE WRN COLUMBIA
RIVER BASIN...COLUMBIA GORGE AND DESCHUTES VALLEY. THUS ANOTHER
ROUND OF LIGHT TO MODERATE FREEZING RAIN WILL DEVELOP BETWEEN
22-01Z.

..CROSBIE.. 12/19/2005

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

ATTN...WFO...MSO...BOI...OTX...PDT...SEW...PQR...

46911830 46751993 46592117 46392195 46222219 45492219
45042202 44252169 44302124 44962022 45081900 44701828
42881643 42671594 43311556 44691617 46701708 

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