[MCD] SWOMCD

Fri Nov 25 06:44:40 UTC 2005

ACUS11 KWNS 250642
SWOMCD
SPC MCD 250642 
IDZ000-WAZ000-ORZ000-251245-

MESOSCALE DISCUSSION 2465
NWS STORM PREDICTION CENTER NORMAN OK
1242 AM CST FRI NOV 25 2005

AREAS AFFECTED...NCNTRL ORE/ERN WA

CONCERNING...FREEZING RAIN 

VALID 250642Z - 251245Z

...A WINTRY MIX OF PRECIPITATION IS EXPECTED OVERNIGHT ACROSS THE
COLUMBIA BASIN WITH AREAS OF FZRA...

A PACIFIC STORM SYSTEM IS APPROACHING THE NORTHWEST...WITH A BROAD
AREA OF PRECIPITATION THAT HAS DEVELOPED AHEAD OF THE MAIN WAVE OR
SFC FRONT. INSPECTION OF THE 25/00Z SOUNDING FROM SPOKANE INDICATES
AN INVERSION...WITH A WARM LAYER ABOVE 850MB AND A SHALLOW COLD
LAYER NEAR THE SFC WHERE TEMPS ARE NEAR OR JUST BELOW FREEZING. WEAK
WARM ADVECTION WILL CONTINUE OVERNIGHT WHICH WILL MAINTAIN THE
INVERSION. LATEST RADAR LOOPS SHOW AN INITIAL BAND OF PRECIPITATION
FROM LINCOLN CO SWD TO UMATILLA CO IN NE ORE. THIS MAY BRING A SHORT
PERIOD OF FZRA TO AREAS NEAR AND S OF SPOKANE IN THE NEXT 1-3 HOURS.

WITH INCREASING LARGE SCALE ASCENT...ADDITIONAL PCPN IS LIKELY
OVERNIGHT. SFC WET BULB ZERO TEMPS ARE NEAR FREEZING ACROSS ERN WA
AND PORTIONS OF NCNTRL ORE...AND SFC TEMPS WILL FALL TO 32F OR BELOW
ONCE PCPN BEGINS. FORECAST SOUNDINGS FROM THE ETA/ETAKF SUGGEST FZRA
WILL BE POSSIBLE ONCE SATURATION OCCURS. SOME OF THE HIGHER
ELEVATIONS /ABOVE 2000 FEET/ WILL HAVE SNOW.

..TAYLOR.. 11/25/2005

...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...BETWEEN 00-01 UTC...06-07 UTC...12-13 UTC...
AND 18-19 UTC FOR SIGNIFICANT SHORT RANGE WINTER WEATHER EVENTS.

ATTN...WFO...OTX...PDT...

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