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Mesoscale Discussion 81 |
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MESOSCALE DISCUSSION 0081
NWS STORM PREDICTION CENTER NORMAN OK
0623 AM CST TUE FEB 10 2009
AREAS AFFECTED...OLYMPIC PENINSULA
CONCERNING...HEAVY SNOW
VALID 101223Z - 101630Z
PERIODS OF HEAVY SNOW WILL DEVELOP ACROSS THE REGION THIS MORNING
WITH HOURLY RATES OF ONE INCH LIKELY. LOCAL RATES APPROACHING TWO
INCHES ARE POSSIBLE...PRIMARILY ALONG THE OLYMPIC RANGE.
INTENSE...DEEP-LAYER LOW CENTERED NEAR 49N/136W AS OF 1130Z WILL
TRANSLATE SEWD TOWARD THE BRITISH COLUMBIA/WA COASTS BY THIS
EVENING...IN CONCERT WITH OCCLUDED...FILLING SURFACE LOW. LATEST
SHORT TERM MODEL GUIDANCE SUGGESTS THAT A NW-SE ORIENTED BAND OF
PRECIPITATION WILL GRADUALLY MOVE ONSHORE THIS MORNING IN ADVANCE OF
THIS SYNOPTIC SYSTEM...FOCUSED ALONG AND E OF SURFACE-850 MB WARM
FRONTS. HERE...FORECAST SOUNDINGS INDICATE THAT STRONG WAA THROUGH
THE LOWEST 2-3 KM AGL WILL BE THE PRIMARY MECHANISM FORCING THIS
PRECIPITATION.
THERMODYNAMIC ENVIRONMENT WILL BE QUITE SUPPORTIVE OF HEAVY SNOW
WITH A DEEP...SATURATED PROFILE UPWARD THROUGH TEMPERATURES FAVORING
DENDRITIC GROWTH...AND THE DEVELOPMENT OF AN ISOTHERMAL LAYER
BETWEEN 800-700 MB. THESE CONDITIONS SHOULD YIELD HOURLY SNOW RATES
OF ONE INCH WITH LOCAL BURSTS APPROACHING TWO INCHES PER HOUR. THE
MORE INTENSE AND CONTINUOUS SNOWFALL WILL LIKELY BE FOCUSED ALONG
THE OLYMPIC RANGE WHERE BROADER-SCALE ASCENT WILL BE AUGMENTED BY
OROGRAPHIC FORCING.
..MEAD.. 02/10/2009
...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...SEW...PQR...
LAT...LON 46702369 47242425 48092455 48222424 48152358 47842303
47332272 46882264 46592290 46472327 46702369
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