MESO: Mesoscale Discussion 0005

ACUS11 KWNS 041131
SWOMCD
SPC MCD 041131
CAZ000-ORZ000-041500-

MESOSCALE DISCUSSION 0005
NWS STORM PREDICTION CENTER NORMAN OK
0531 AM CST FRI JAN 04 2008

AREAS AFFECTED...THE KLAMATH MOUNTAINS/SRN OREGON CASCADES SWD THRU
THE NRN SIERRA NEVADA

CONCERNING...HEAVY SNOW

VALID 041131Z - 041500Z

HEAVY SNOW IS EXPECTED TO DEVELOP THIS MORNING...AT RATES INCREASING
TO AROUND 2-4 INCHES PER HOUR.

A VIGOROUS COLD UPPER TROUGH/CLOSED LOW NEARING NORTHERN PACIFIC
COASTAL AREAS IS PROGGED TO CONTINUE INLAND THIS MORNING...
ACCOMPANIED BY AN OCCLUDING SURFACE FRONT TRAILING FROM A DEEP
NORTHEASTERN PACIFIC SURFACE CYCLONE ON THE ORDER OF 960 MB. AN
INTENSE...70-90 KT...SOUTHWESTERLY LOWER/MID TROPOSPHERIC JET STREAK
ON THE SOUTHEASTERN PERIPHERY OF THIS CIRCULATION IS NOW IN THE
PROCESS OF SHIFTING INLAND ACROSS NORTHERN CALIFORNIA/WESTERN
OREGON. AND...THIS FEATURE WILL CONTRIBUTE TO AN INTENSIFYING
UPWARD VERTICAL MOTION FIELD ON THE WINDWARD SLOPES OF THE HIGHER
TERRAIN...NOW THROUGH THE 15-18Z TIME.

STRONGEST LIFT IS GENERALLY PROGGED ACROSS THE KLAMATH
MOUNTAINS...SOUTH SOUTHEASTWARD ALONG THE NORTHERN SIERRA
NEVADA...TOWARD THE LAKE TAHOE AREA. THIS IS WHERE MODELS SUGGEST
STRONGEST UPPER DIVERGENCE WILL BECOME FOCUSED...ABOVE A STRONG
LOW/MID-LEVEL WARM ADVECTION REGIME...FROM THE FRONTAL OCCLUSION
SOUTHEASTWARD ALONG A SURFACE WARM FRONT. GIVEN THE RELATIVELY HIGH
MOISTURE CONTENT OF THE AIR...WITH PRECIPITABLE WATER ON THE ORDER
OF 1 INCH...ADVECTING INTO THIS AREA...A SUSTAINED PERIOD OF HEAVY
SNOW APPEARS LIKELY AT 5000-6000+ FT ELEVATIONS. LATEST NAM/NCEP
SREF...GFS...AND RUC ARE ALL SUGGESTIVE THAT SNOW RATES IN EXCESS OF
3 INCHES PER HOUR ARE PROBABLE BY 15Z...CONTINUING INTO MIDDAY AND
BEYOND.

.KERR.. 01/04/2008

..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...AROUND 00 UTC...06 UTC...12 UTC...AND 18 UTC
FOR SIGNIFICANT SHORT RANGE WINTER WEATHER EVENTS.

ATTN...WFO...REV...MFR...STO...EKA...

41212368 41602375 42142337 42172252 41472124 40492059
39692014 39172010 38702067 39402118 40262179 40812204
40862256 40692287 40802341 40972358

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@PO.UIUC.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.