[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 080644
SWOMCD
SPC MCD 080644 
RIZ000-MAZ000-CTZ000-NYZ000-NJZ000-PAZ000-081245-

MESOSCALE DISCUSSION 0047
NWS STORM PREDICTION CENTER NORMAN OK
1244 AM CST SAT JAN 08 2005

AREAS AFFECTED...NRN PA/NRN NJ...SRN NY...CT/RI AND WRN MA

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 080644Z - 081245Z

A MIX OF SLEET/FREEZING RAIN AND SNOW WILL DEVELOP NEWD ACROSS THE
REGION THROUGH 12Z. THE HEAVIEST RATES ARE ANTICIPATED TO OCCUR
ACROSS PORTIONS OF NRN PA/SRN NY THROUGH 12Z...WHERE HRLY
ACCUMULATION RATES FROM 0.05-0.15 INCH WILL BE POSSIBLE.

LATEST RADAR IMAGERY SHOWS AN EXPANDING AREA OF MODERATE 
PRECIPITATION OVER THE CENTRAL APPALACHIANS/UPPER OHIO VALLEY WHERE
A DEEP LAYER OF DIFFERENTIAL DIVERGENCE WAS OCCURRING. 06Z SURFACE
ANALYSIS INDICATES THE SFC FREEZING ISOTHERM EXTENDS FROM NWRN PA
EWD INTO ECENTRAL PA...THEN BACK NEWD TO THE NYC METRO AREA/FAR SRN
CT. LOW LEVEL WAA WILL CONTINUE TO SUPPORT A SLOW NWD PROGRESSION OF
THIS LINE THROUGH THE OVERNIGHT HOURS...ESPECIALLY OVER NRN PA.
INITIAL MID LEVEL WAA WILL AID IN LIGHT SLEET/FREEZING RAIN
DEVELOPMENT AS FAR NORTH AS ERN CT/RI AND WRN MA THROUGH 12Z.
HOWEVER...PRESENCE OF A DRY AIR IN THE LOWEST 150 MB AS EVIDENT BY
THE 00Z OKX SOUNDING/RECENT SFC OBS...AND LIMITED LOW LEVEL
CONVERGENCE/MOISTURE ADVECTION WILL PRECLUDE HRLY AMOUNTS IN THESE
AREAS FROM EXCEEDING 0.05 INCH. THE TRACK OF THE LOW LEVEL CYCLONE
PER RECENT PRESSURE TENDENCY ANALYSES INDICATES THAT THE STRONGEST
LOW LEVEL WAA WILL OVERSPREAD NRN PA/FAR SRN NY AND NRN NJ BETWEEN
09-12Z. FORECAST SOUNDINGS OVER THIS REGION INDICATE THE EXISTENCE
OF AN ELEVATED WARM LAYER CENTERED AROUND 850 MB THAT WILL SUPPORT
FREEZING RAIN AS THE PREDOMINANT PTYPE OVER SCENTRAL NY...NRN PA AND
INLAND AREAS OF NRN NJ/SERN NY. 

FARTHER NE ACROSS THE REST OF SRN NY/WRN MA...CT AND RI...RELATIVE
DRYNESS OF THE LOW LEVELS INDICATES THAT AS SATURATION
OCCURS...PTYPE WILL CHANGE FROM A MIX OF FREEZING RAIN/SLEET OVER TO
LIGHT TO MODERATE SNOW. DESPITE INITIAL WET-BULB EFFECTS...COASTAL
ARAS OF NRN NJ/SERN NY...LONG ISLAND WILL SEE A GRADUALLY CHANGEOVER
FROM LIGHT SLEET/FREEZING RAIN TO RAIN AS LOW LEVEL FLOW CONTINUES
TO VEER IN RESPONSE TO SFC LOW MOVEMENT INTO THE CENTRAL
APPALACHIANS.

..CROSBIE.. 01/08/2005

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

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A 
SCHEDULED BASIS...FOUR TIMES A DAY...BETWEEN 00-01 UTC...
06-07 UTC...12-13 UTC...AND 18-19 UTC AS SIGNIFICANT SHORT
RANGE WINTER WEATHER EVENTS UNFOLD.  THIS SCHEDULE WILL BE
USED FROM DECEMBER 1 THROUGH FEBRUARY 28.

ATTN...WFO...BOX...OKX...ALY...PHI...BGM...BUF...CTP...PBZ...CLE...

42767590 42637792 42467905 42007987 41337947 40997799
40937593 40787526 40727408 40907287 41457181 41937147
42667292 

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