Tuesday, January 12, 2010

MESO: Mesoscale Discussion 0004

ACUS11 KWNS 130035
SWOMCD
SPC MCD 130034
CAZ000-NVZ000-130430-

MESOSCALE DISCUSSION 0004
NWS STORM PREDICTION CENTER NORMAN OK
0634 PM CST TUE JAN 12 2010

AREAS AFFECTED...NRN/CNTRL SIERRA MOUNTAINS IN CA

CONCERNING...HEAVY SNOW

VALID 130034Z - 130430Z

LIGHT SNOW COMMENCING IN HIGHER ELEVATIONS FROM 03-06Z WILL
TRANSITION TO HEAVY SNOW AFTER 09Z WHILE SNOW LEVELS GRADUALLY LOWER
TO NEAR 5000 FT BY TOMORROW MORNING. STRONG WINDS WILL CREATE
BLIZZARD-LIKE CONDITIONS IN BLOWING SNOW AS THIS OCCURS.

WV IMAGERY SHOWS A LEADING IMPULSE NOW MOVING INTO THE INTERMOUNTAIN
WEST...WHILE A SECOND STRONGER WAVE IS QUICKLY FOLLOWING...NOW
CENTERED ROUGHLY 275 MI W OF THE NRN CA COAST. ALTHOUGH GOES PWAT
IMAGERY REFLECTS A RELATIVE LULL IN MOISTURE OVER CA AT THE
MOMENT...MORE THAN ADEQUATE MOISTURE / PWAT VALUES AOA 1 INCH...OR
GREATER THAN 200 PERCENT OF NORMAL/ WILL QUICKLY MOVE INLAND WITH
THE APPROACHING WAVE. INITIALLY HIGH SNOW LEVELS GREATER THAN 7000
FT PER RECENT OBS WILL FALL TONIGHT AS TEMPERATURES COOL ALOFT AND
HEAVY SNOWFALL BEGINS TO OCCUR. LOOPING WV IMAGERY SUGGESTS THE WAVE
SHOULD BE OVER NRN CA BY 09-12Z...WITH THE INCREASINGLY NEGATIVELY
TILTED UPPER WAVE PROVIDING UPPER DIVERGENCE AND WLY FLOW AIDING IN
UPSLOPE...CONTRIBUTING TO HEAVY SNOWFALL THEREAFTER. LIGHTNING
OBSERVED OFFSHORE SUGGESTS THAT INSTABILITY/CONVECTIVE SNOWFALL WITH
INTENSE RATES NEAR 2-4 INCHES PER HOUR WILL BE POSSIBLE AT TIMES.

..HURLBUT.. 01/13/2010

...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...VEF...REV...HNX...STO...

LAT...LON 37931871 37081867 37121935 37852012 38722060 39422104
40382166 40782107 39662012 38971984 37931871

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