Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 032351
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
651 PM EST TUE MAR 3 2015

.SYNOPSIS...
DEEPENING LOW PRESSURE TRACKS ACROSS EASTERN CANADA TONIGHT INTO
WEDNESDAY...PRECEDED BY A WARM FRONTAL PASSAGE LATE TONIGHT. THE
TRAILING COLD FRONT CROSSES THE AREA WEDNESDAY NIGHT...WITH WEAK
WAVES OF LOW PRESSURE RIDING ALONG IT INTO THURSDAY. HIGH PRESSURE
THEN BUILDS IN FROM THE WEST INTO FRIDAY. A SERIES OF WEAK COLD
FRONTS CROSS THE REGION THIS WEEKEND INTO EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
PRECIP CONTINUES TO SPREAD INTO THE REGION FROM THE WEST...WITH
MAINLY SNOW ACROSS MOST OF THE AREA...BUT SNOW IS CHANGING TO
SLEET AND FREEZING RAIN ACROSS PARTS OF NE NJ...NYC...AND THE
SNOW/FREEZING RAIN LINE IS CREEPING INTO THE LOWER HUDSON VALLEY.
PRECIP WILL GRADUALLY TRANSITION TO PLAIN RAIN LATER THIS
EVENING...BUT NOT BEFORE 1-3 INCHES OF SNOW WITH LIGHT ICE
ACCRETIONS.

TEMPS WILL GRADUALLY RISE THROUGH THE OVERNIGHT WITH ACTUAL HIGH
TEMPS EARLY THIS EVENING RIGHT AROUND OR JUST BELOW FREEZING. BY
DAYBREAK...MOST LOCATIONS WILL BE 35 TO 40. USED A BLEND OF THE
MET MOS WITH 2M HIGH RES WRF NMM TEMPS.

THERE WILL BE A CHANCE OF LIGHT RAIN ON WED...WITH THE BEST CHANCE
RIGHT ALONG THE COAST. TEMPS WILL REMAIN NEARLY STEADY IN THE MID
TO UPPER 30S.

RAINFALL AMOUNTS WILL GENERALLY BE AROUND ONE-HALF INCH DURING
THIS TIME PERIOD.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
THREAT CONTINUES FOR AROUND 6 INCHES OF SNOW ACROSS NYC/LONG
ISLAND/NE NJ/N COAST OF LONG ISLAND SOUND...AND ALL OF FAR SE CT.

MODELS CONTINUE TO ADVERTISE ANAFRONTAL NATURE OF A COLD FRONT
PASSING WEDNESDAY NIGHT...IN RESPONSE TO REGION BEING IN THE RIGHT
REAR QUADRANT OF A 180-200KT 250 HPA JET AND PASSING OF NORTHERN
STREAM SHORTWAVES AT 700 HPA...THEN APPROACH OF 500 HPA SHORTWAVE
LATER THURSDAY.

MODELS ALSO AGREE IN SHIFTING PRIMARY AXIS OF QPF JUST TO THE S OF
LONG ISLAND...THIS SERVERS TO LIMIT THE THREAT TO N INTERIOR
ZONES...WITH THE EXCEPTION OF N NEW LONDON COUNTY...GIVEN FORECAST
WSW TO ENE ORIENTATION OF THE QPF AXIS.

MODELS ALSO HAVE COME INTO BETTER AGREEMENT WITH THE TIMING OF THE
CHANGE OVER FROM RAIN TO SNOW WEDNESDAY EVENING...WITH A PERIOD OF
SLEET MIXED IN DURING THE TRANSITION. THE CMC AND NAM REMAIN THE
SLOWEST TO COOL THE LOW LEVELS...BUT NOW ARE ONLY A FEW HOURS SLOWER
THAN A GFS/ECMWF/SREF BLEND. GIVEN TREND IN LOW LEVEL THERMAL
FIELDS...USED A GFS/ECMWF/SREF BLEND TO DETERMINE CHANGE OVER
TIMING. BASICALLY EXPECT THE TRANSITION TO OCCUR FAIRLY QUICKLY IN
THE EVENING OVER N INTERIOR ZONES...AND CLOSER TO AROUND
MIDNIGHT/SHORTLY THEREAFTER ACROSS SOUTHERN ZONES.

THERE IS STILL QUITE A BIT OF UNCERTAINTY ON 1) HOW FAR N/W OF NYC
SIGNIFICANT PRECIPITATION WILL FALL...AND 2) WHETHER OR NOT THE QPF
AXIS WILL CONTINUE TO SHIFT FARTHER TO THE S. THERE IS STILL SOME
UNCERTAINTY ON 1) THE EXACT TIMING OF CHANGE OVER 2) HOW MUCH SLEET
IN THE TRANSITION WILL LIMIT SNOW AMOUNTS 3) THE EXACT END TIME OF
PRECIPITATION - MODELS HAVE EXTENDED THE DURATION FOR THE MOST PART
INTO THURSDAY AFTERNOON WHILE THE CMC CONTINUES INTO THURSDAY
EVENING. HAVE DISCOUNTED CMC AS OUTLIER SOLUTION ON THIS FOR
NOW...BUT DO NOTE IT HAS BEEN ADVERTISING A LONGER DURATION SINCE
YESTERDAY.

FOR NOW HAVE ISSUED A WINTER STORM WATCH FROM 7PM WEDNESDAY THROUGH
7PM THURSDAY FOR NYC/LONG ISLAND/NE NJ/S WESTCHESTER COUNTY/ALL OF
COASTAL CT PLUS N NEW LONDON COUNTY AS WELL...FOR THE POTENTIAL FOR
4 TO 8 INCHES OF SNOW. OUTSIDE OF THE WATCH AREA THERE IS THE
POTENTIAL FOR 3 TO 6 INCHES OF SNOW.

500 HPA TROUGH AXIS EXITS TO THE EAST THURSDAY NIGHT...FOLLOWED BY
NORTHERN STREAM SHORTWAVE RIDGING BUILDING INTO FRIDAY
MORNING...THEN PUSHING OFFSHORE FRIDAY AFTERNOON. WITH NO
SIGNIFICANT FORCING EXPECTED HAVE GONE DRY THURSDAY NIGHT AND
FRIDAY...EXCEPT FOR A LINGERING CHANCE OF SNOW MAINLY OVER THE SE
1/2 OF THE CWA EARLY THURSDAY EVENING.

TEMPERATURES IN THE SHORT TERM WERE BASED ON A BLEND OF AVAILABLE
GUIDANCE WITH NAM 2-METER TEMPERATURES. GFS 2-METER TEMPERATURES
WERE BLENDED IN AS WELL THURSDAY NIGHT...AS THEY HAVE FAIRED WELL
THIS YEAR SO FAR DURING COLD ADVECTION PATTERNS. TEMPERATURES ARE
FORECAST TO REMAIN BELOW NORMAL WEDNESDAY NIGHT-FRIDAY. LOWS SHOULD
RUN AROUND 5 DEGREES BELOW NORMAL WEDNESDAY NIGHT AND HIGHS 15-20
DEGREES BELOW NORMAL THURSDAY. LOWS THURSDAY NIGHT SHOULD BE MAINLY
IN THE POSITIVE SINGLE DIGITS...AROUND 20-25 DEGREES BELOW NORMAL.
WIND CHILLS THURSDAY NIGHT SHOULD GENERALLY BE IN
THE NEGATIVE SINGLE DIGITS. HIGHS FRIDAY SHOULD BE AROUND 15 DEGREES
BELOW NORMAL.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
RATHER TRANQUIL IN THE LONG TERM DESPITE THE FACT THAT AN UPPER
LEVEL LOW TO THE NORTHWEST OF HUDSON BAY WILL SEND A COUPLE OF
FRONTS THROUGH THE REGION...ONE SATURDAY NIGHT INTO SUNDAY
MORNING...AND ANOTHER MONDAY NIGHT. THESE FRONTS WILL BE WEAK...WITH
LITTLE MOISTURE TO WORK WITH. IN FACT...AS OF RIGHT NOW...THE COLD
FRONT FOR SATURDAY NIGHT LOOKS TO COME THROUGH THE AREA DRY...WHILE
THE COLD FRONT ON MONDAY NIGHT WILL ALLOW FOR JUST A SLIGHT CHANCE
FOR SNOW SHOWERS. HIGH PRESSURE BUILDS IN FOR TUESDAY WITH DRY
CONDITIONS.

TEMPERATURES ON SATURDAY AND SUNDAY WILL BE IN THE 30S REGION-WIDE.
TEMPERATURES WARM INTO THE LOWER 40S FOR THE BEGINNING OF THE WORK
WEEK. WITH NORMAL HIGHS THIS TIME OF YEAR IN THE MIDDLE TO UPPER
40S...THESE TEMPERATURES WILL STILL BE BELOW NORMAL.

&&

.AVIATION /23Z TUESDAY THROUGH SUNDAY/...
A WARM FRONT APPROACHES TONIGHT AND MOVES THROUGH LATE. A COLD
FRONT MOVES THROUGH DURING THE DAY WEDNESDAY.

ANY SNOW QUICKLY CHANGES TO FREEZING RAIN...SLEET...THEN PLAIN
RAIN. PRIMARILY IFR OR LOWER CONDITIONS EXPECTED OVERNIGHT IN ON
AND OFF RAIN.

IFR OR MVFR LIKELY CONTINUES THROUGH THE DAY WEDNESDAY...ALTHOUGH
STRATUS MAY SCATTER...ESPECIALLY ACROSS THE INTERIOR. IF THAT DOES
OCCUR...VFR CONDITIONS ARE POSSIBLE.

S WINDS SHIFT SW-W OVERNIGHT. LLWS DURING THE LATE NIGHT HOURS.

W WINDS WEDNESDAY.

   ..NY METRO ENHANCED AVIATION WEATHER SUPPORT...

DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT:  HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)

KJFK FCSTER COMMENTS: PLAIN RAIN IS EXPECTED BY 2Z. ANY ICE
ACCRETION WILL BE VERY LIGHT. RUNWAY ACCUMULATION OF SNOW/SLEET OF
1 OR 2 INCHES BEFORE CHANGEOVER TO RAIN.

KLGA FCSTER COMMENTS: PLAIN RAIN IS EXPECTED BY 2Z. ANY ICE
ACCRETION WILL BE VERY LIGHT. RUNWAY ACCUMULATION OF SNOW/SLEET OF
1 OR 2 INCHES BEFORE CHANGEOVER TO RAIN.

KEWR FCSTER COMMENTS: PLAIN RAIN IS EXPECTED BY 1 OR 2Z. ANY ICE
ACCRETION WILL BE VERY LIGHT. RUNWAY ACCUMULATION OF SNOW/SLEET OF
1 OR 2 INCHES BEFORE CHANGEOVER TO RAIN.

KTEB FCSTER COMMENTS: PLAIN RAIN IS EXPECTED BY 2Z. ANY ICE
ACCRETION WILL BE VERY LIGHT. RUNWAY ACCUMULATION OF SNOW/SLEET OF
1 OR 2 INCHES BEFORE CHANGEOVER TO RAIN.

KHPN FCSTER COMMENTS: PLAIN RAIN IS EXPECTED BY 3Z. ICE ACCRETION
OF A TRACE TO A FEW HUNDREDTHS OF AN INCH EXPECTED. RUNWAY
ACCUMULATION OF SNOW/SLEET OF 2 INCHES BEFORE CHANGEOVER TO RAIN.

KISP FCSTER COMMENTS: PLAIN RAIN IS EXPECTED BY 2 OR 3Z. ANY ICE
ACCRETION WILL BE VERY LIGHT. RUNWAY ACCUMULATION OF SNOW/SLEET OF
1 OR 2 INCHES BEFORE CHANGEOVER TO RAIN.

.OUTLOOK FOR 00Z THURSDAY THROUGH SUNDAY...
.WEDNESDAY NIGHT-THURSDAY...BECOMING IFR WITH A TRANSITION BACK
TO SNOW LATE EVENING/NEAR MIDNIGHT. CHC N GUSTS TO 20 KT ON
THURSDAY.
.THURSDAY NIGHT-FRIDAY...IMPROVING TO VFR THURS NIGHT. NW GUSTS
15-20KT POSSIBLE THURSDAY NIGHT.
.SAT/SUN...VFR.

&&

.MARINE...
MARGINAL SCA CONDITIONS FORECAST ON THE OCEAN WATERS TONIGHT INTO
WEDNESDAY IN THE W/SW FLOW AHEAD OF AN APPROACHING FRONTAL SYSTEM.
THE STRONGEST WINDS AND HIGHEST SEAS WILL BE LATE TONIGHT INTO WED
MORNING. WAVEWATCH COULD BE UNDERDONE HERE BY A FOOT.

SMALL CRAFT CONDITIONS ARE POSSIBLE ON THE COASTAL OCEAN WATERS EAST
OF MORICHES INLET ON WEDNESDAY NIGHT...THEN ON ALL COASTAL OCEAN
WATERS THURSDAY AND THURSDAY NIGHT...AND POSSIBLY INTO FRIDAY AS
WELL.

A SERIES OF WEAK COLD FRONTS WILL MOVE THROUGH THE WATERS...ONE
SATURDAY NIGHT INTO SUNDAY MORNING AND ANOTHER MONDAY NIGHT. THESE
FRONTS WILL BE WEAK...WITH JUST A SLIGHT CHANCE OF SNOW SHOWERS
FOR MONDAY AND MONDAY NIGHT. WINDS APPROACH SCA CRITERIA SATURDAY
INTO SATURDAY NIGHT AND THEN AGAIN MONDAY NIGHT INTO TUESDAY ON
THE OCEAN WATERS...BUT AS OF RIGHT NOW...THEY SHOULD REMAIN BELOW.
WAVES REMAIN BELOW SCA CRITERIA THROUGH THE PERIOD.

&&

.HYDROLOGY...
AROUND A TOTAL 1/2 TO 3/4 INCH OF LIQUID EXPECTED THROUGH WEDNESDAY.
A LITTLE LESS THAN HALF OF IT BEING IN FORM OF WINTRY PRECIP. SOME
PONDING OF WATER IS EXPECTED WITH STEADY MODERATE RAIN THAT FALLS
DUE TO EXCESS RUNOFF FROM MELTING SNOWPACK.

FROM AROUND .4 TO .9 INCHES OF QPF IS CURRENTLY FORECAST FROM
WEDNESDAY NIGHT INTO THURSDAY EVENING...WITH MOST OF THIS FALLING IN
THE FORM OF FROZEN PRECIPITATION. THERE IS STILL SOME UNCERTAINTY IN
AMOUNTS...WITH LOWER AMOUNTS MORE LIKELY THAN HIGHER AMOUNTS. THERE
IS ALSO SOME UNCERTAINTY IN HOW FAST THE RAIN CHANGES TO FROZEN
PRECIPITATION WEDNESDAY NIGHT OVER NYC METRO/LONG ISLAND. THE LONGER
THIS TAKES...IT INCREASES THE RISK OF POSSIBLE PONDING OF WATER.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
     CTZ009>012.
     WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
     EVENING FOR CTZ008>012.
     WINTER WEATHER ADVISORY UNTIL 5 AM EST WEDNESDAY FOR
     CTZ005>008.
NY...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
     NYZ071>075-078>081-176>179.
     WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
     EVENING FOR NYZ071>075-078>081-176>179.
     WINTER WEATHER ADVISORY UNTIL 5 AM EST WEDNESDAY FOR
     NYZ067>070.
NJ...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NJZ004-
     006-103>108.
     WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
     EVENING FOR NJZ002-004-006-103>108.
     WINTER WEATHER ADVISORY UNTIL 5 AM EST WEDNESDAY FOR NJZ002.
MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST
     WEDNESDAY FOR ANZ353-355.
     SMALL CRAFT ADVISORY UNTIL 6 PM EST WEDNESDAY FOR ANZ350.

&&

$$
SYNOPSIS...MALOIT/JP/DW
NEAR TERM...MPS/DW
SHORT TERM...MALOIT
LONG TERM...JP
AVIATION...PW
MARINE...MALOIT/JP/DW
HYDROLOGY...MALOIT/DW









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