SWOMCD
SPC MCD 070510
MAZ000-RIZ000-NHZ000-CTZ000-VTZ000-NYZ000-NJZ000-PAZ000-MDZ000-070915-
MESOSCALE DISCUSSION 0023
NWS STORM PREDICTION CENTER NORMAN OK
1110 PM CST TUE JAN 06 2009
AREAS AFFECTED...NORTHEAST/SRN NEW ENGLAND
CONCERNING...FREEZING RAIN
VALID 070510Z - 070915Z
ONGOING ICE STORM WILL GRADUALLY EXPAND NEWD OVERNIGHT. BY 12Z...THE
TRANSITION BETWEEN SLEET AND FREEZING LINE SHOULD LIE ROUGHLY ALONG
THE SRN SHORES OF LK ONTARIO TO NEAR THE ALB AND BOS METRO AREAS.
WIDESPREAD FREEZING RAIN RATES OF 0.02 TO 0.10 IN/HR WILL
CONTINUE...WITH THE MORE INTENSE RATES AND SIGNIFICANT ICE
ACCUMULATIONS EXPECTED ACROSS ERN PA/NRN NJ/SERN NY/CT/RI.
RADAR/SATELLITE IMAGERY DEPICTS A LONG PLUME OF PRECIPITATION AND
BAROCLINIC LEAF STRUCTURE EXTENDING FROM THE NORTHEAST TO CNTRL GULF
COAST DOWNSTREAM OF POTENT SHORT WAVE TROUGH APPROACHING THE
MID/LOWER MS RIVER VALLEY. AS CYCLOGENESIS ENSUES INVOF LK ERIE...A
STRONG LLJ /60 KT AT 850 MB ALONG THE PIEDMONT AS SAMPLED BY 00Z FFC
RAOB/...WILL LIKELY STRENGTHEN TO AROUND 75 KT BY 12Z AS IT SHIFTS
NEWD. THIS WILL MAINTAIN/ENHANCE THE ALREADY ROBUST LOWER-LEVEL
WARM/MOIST ADVECTION REGIME ACROSS THE NORTHEAST. LATEST NAM/NAMKF
WERE TOO SLOW WITH THE LEADING EDGE OF MEASURABLE PRECIPITATION
THROUGH 03Z...WITH THE GFS QPF APPEARING TO FIT CLOSER TO
OBSERVATIONS. GIVEN THE EXPECTED STRENGTHENING OF LARGE-SCALE ASCENT
AND RECENT RADAR TRENDS...THE GFS APPEARS CONSISTENT WITH INCREASING
QPF VALUES TO AOA 0.25 IN BETWEEN 09-12Z FROM ERN PA TO CT/RI.
WITH SURFACE WINDS ORIENTED NEARLY PARALLEL TO THE WET-BULB FREEZING
LINE...ONLY A SLOW NWD MOVEMENT OF THIS LINE IS EXPECTED GIVEN
DOWNWARD SENSIBLE HEAT FLUX VIA PRECIPITATION FALLING FROM WARMER
LAYER JUST ABOVE SURFACE. MODEL FORECASTS ADVECT THE WARM NOSE OF
ABOVE-FREEZING TEMPERATURES ALOFT MUCH FARTHER NORTH. THIS SUGGESTS
THAT THE AREAL COVERAGE OF FREEZING RAIN/SLEET WILL EXPAND NEWD WITH
LITTLE CONTRACTION ALONG THE SRN EDGE.
..GRAMS.. 01/07/2009
...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...BOX...OKX...ALY...PHI...BGM...BUF...CTP...LWX...
PBZ...
LAT...LON 42327111 42727140 42897331 43087484 43387662 43467823
43357898 42777891 42347946 41557951 41047889 40277794
39587709 39917593 40347490 40647420 40867368 41207303
41387208 41527155 41757118 42327111
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