[MCD] SWOMCD

Sat Jan 28 11:45:57 UTC 2006

ACUS11 KWNS 281146
SWOMCD
SPC MCD 281145 
ORZ000-WAZ000-CAZ000-281745-

MESOSCALE DISCUSSION 0084
NWS STORM PREDICTION CENTER NORMAN OK
0545 AM CST SAT JAN 28 2006

AREAS AFFECTED...THE CASCADE RANGE OF SRN WA / ORE INTO NRN CA

CONCERNING...HEAVY SNOW 

VALID 281145Z - 281745Z

HEAVY SNOW WITH HOURLY RATES APPROACHING TWO INCHES IS EXPECTED TO
DEVELOP ABOVE 3000-3500 FT MSL THIS MORNING.  THIS HEAVY SNOW WILL
BEGIN TO DECREASE AROUND MIDDAY ACROSS THE HIGHER ELEVATIONS OF SRN
WA/NRN ORE AND LATER THIS AFTERNOON OVER SRN ORE/NRN CA.

EARLY MORNING WATER VAPOR IMAGERY SHOWS A POTENT MID-LEVEL TROUGH
APPROACHING THE WA AND ORE COASTS WITH A RECENT BURST OF LIGHTNING
ACTIVITY OBSERVED WITHIN THE PAST HOUR ALONG THE ORE COAST.  INTENSE
LARGE-SCALE FORCING FOR ASCENT AND RESULTANT STEEPENING MID-LEVEL
LAPSE RATES ARE LIKELY CONTRIBUTING TO THIS CONVECTIVE
DEVELOPMENT...WHICH IS NEARLY COINCIDENT WITH SURFACE FRONT WHICH
HAS MOVED ONSHORE AND EXTENDS FROM E OF UIL TO E OF AST TO JUST E OF
ONP AS OF 11Z.

EXPECT THE ZONE OF STRONGEST LARGE-SCALE FORCING AND
MID-TROPOSPHERIC DESTABILIZATION TO SPREAD INLAND BETWEEN
12-15Z...SUPPORTING AN INCREASE IN SNOW INTENSITY ABOVE 3000-3500 FT
MSL.  SNOW RATES WILL APPROACH TWO INCHES PER HOUR AT THIS
TIME...THOUGH EMBEDDED CONVECTIVE ELEMENT MAY SUPPORT LOCALIZED
RATES UPWARDS OF TWO AND A HALF TO THREE INCHES PER HOUR.  GIVEN
GENERAL SEWD MOTION OF THE MID-LEVEL TROUGH...THE STRONGEST DYNAMIC
FORCING FOR ASCENT SHOULD TEND TO WEAKEN BY LATE MORNING ACROSS THE
HIGHER ELEVATIONS OF SRN WA AND NRN ORE...WHILE THE HEAVY SNOW MAY
WELL CONTINUE INTO THE AFTERNOON FROM THE CNTRL/SRN ORE CASCADES
INTO NRN CA.

..MEAD.. 01/28/2006

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

ATTN...WFO...PDT...MFR...STO...SEW...PQR...EKA...

41462348 43972285 46332246 47002221 47432155 46482075
43622111 41572189 40682211 40562309 

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