[MCD] SWOMCD

Fri Dec 30 05:40:11 UTC 2005

ACUS11 KWNS 300541
SWOMCD
SPC MCD 300540 
IDZ000-ORZ000-301145-

MESOSCALE DISCUSSION 2602
NWS STORM PREDICTION CENTER NORMAN OK
1140 PM CST THU DEC 29 2005

AREAS AFFECTED...NERN OREGON INTO EXTREME SWRN ID

CONCERNING...HEAVY SNOW 

VALID 300540Z - 301145Z

MDT TO HVY SNOW IS EXPECTED TO DEVELOP BY AROUND 09Z MAINLY OVER
NERN OREGON...WITH 1.50-2.00 IN/HR SNOW RATES POSSIBLE IN UPSLOPE
REGION AND 1.00 IN/HR POSSIBLE LOWER ELEVATIONS. SNOW WILL THEN
SHIFT EWD TOWARD 12Z INTO SWRN ID WHERE A MIXTURE OF RAIN AND HEAVY
WET SNOW APPEAR LIKELY INTO THE LOWER TREASURE VALLEY.

PRECIPITATION SHIELD IS EXPECTED TO GRADUALLY FILL IN ACROSS ERN
OREGON AS SWLY FLOW BRINGS IN HIGHER PRECIPITABLE WATER CONTENT.
UPWARD VERTICAL MOTIONS FIELDS WILL INCREASE AS ZONE OF
FRONTOGENETICAL FORCING MATERIALIZES NEAR LEADING EDGE OF WARM/MOIST
ADVECTION ALOFT. LIFTING ZONE IS EXPECTED TO LIE ALONG A NW-SE AXIS
FROM THE MTNS OF NERN OREGON INTO FAR SWRN ID BY 12Z. RUC AND NAM
FORECAST SOUNDINGS INDICATE STRONG VERTICAL MOTION CENTERED AROUND
550-500 MB LAYER WHICH IS COINCIDENT WITH FAVORABLE TEMPERATURE
LAYER FOR DENDRITIC GROWTH. THIS...COMBINED WITH SATURATED AND
SUB-ZERO PROFILES IN THE SFC-700 MB LAYER AND SURFACE WET BULB ZERO
TEMPERATURES NEAR FREEZING SHOULD RESULT IN LOCALLY HEAVY SNOWFALL
RATES...ESPECIALLY IN THE HIGHER TERRAIN WHERE SLY FLOW WILL ENHANCE
UPSLOPE. PRECIPITATION MAY BEGIN AS RAIN IN THE LOWER TREASURE
VALLEY...BUT COULD CHANGE TO HVY WET SNOW DURING HEAVIEST
PRECIPITATION RATE PERIOD...WHICH WILL GENERALLY OCCUR AFTER 12Z.

..JEWELL.. 12/30/2005

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

ATTN...WFO...BOI...PDT...

44081904 44981929 45581858 45641758 45581746 45201696
44941673 44301665 43871676 43321698 43291819 43641860 

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