Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 040623
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
123 AM EST WED MAR 4 2015

.SYNOPSIS...
DEEPENING LOW PRESSURE TRACKS ACROSS EASTERN CANADA OVERNIGHT
INTO WEDNESDAY...PRECEDED BY A WARM FRONTAL PASSAGE BEFORE
DAYBREAK. 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 TODAY/...
WARM FRONT APPROACHING THE REGION...LOOKS TO HAVE CLEARED LONG
ISLAND AND NEW YORK AS TEMPS REMAIN EITHER STEADY OR SLOWLY RISE.
TEMPS THERE ARE GENERALLY IN THE MID 30S ON AVERAGE. ELSEWHERE TO
THE NORTH AND WEST...TEMPS ARE SLOWLY WARMING BUT THERE ARE SOME
LOCATIONS STILL A FEW DEGREES BELOW FREEZING. REMOVED EASTERN
BERGEN NJ AND SOUTHERN WESTCHESTER NY FROM WINTER WEATHER ADVISORY
AS TEMPS THERE HAVE RISEN ABOVE FREEZING.

MAIN REASON FOR KEEPING WINTER WEATHER ADVISORY FOR REST OF THE
REGION PARTICULARLY THE MORE NORTHERN AND INTERIOR LOCATIONS WAS
THE POTENTIAL FOR ADDITIONAL FREEZING RAIN AND SOME PATCHY
FREEZING DRIZZLE BEFORE 5 AM. OVERALL MUCH OF THE PRECIP WILL BE
SHIFTING EAST OF LONG ISLAND AND SOUTHEAST CT...LEAVING A MORE
SPOTTY AND SCATTERED AREAL COVERAGE BEHIND IT IN A GENERAL LULL IN
PRECIP ACTIVITY.

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 /TONIGHT 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 FARED 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 /06Z WEDNESDAY THROUGH SUNDAY/...
LOW PRESSURE TRACKS ACROSS EASTERN CANADA TODAY...PRECEDED BY A WARM
FRONT. THE TRAILING COLD FRONT CROSSES THE AREA TONIGHT.

LINGERING PRECIP TRANSITIONING TO PLAIN RAIN MOST TERMINALS...EXCEPT
LINGERING -FZRA AT KSWF AND KGON. ON AND OFF LIGHT RAIN IS EXPECTED
THIS MORNING AND THROUGH THE DAY.

IFR SHOULD PREVAIL TONIGHT...ALTHOUGH CONDITIONS MAY BOUNCE AROUND
TO LIFR AND MVFR AT TIMES.

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

SW WINDS 10 KTS OR LESS SHIFT TO THE SW-W. LLWS IS EXPECTED EARLY
THIS MORNING.

.OUTLOOK FOR 06Z THURSDAY THROUGH SUNDAY...
.TONIGHT-THURSDAY...BECOMING IFR WITH A TRANSITION BACK TO SNOW
AROUND 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 OVERNIGHT
INTO WEDNESDAY IN THE W/SW FLOW AHEAD OF AN APPROACHING FRONTAL
SYSTEM. THE STRONGEST WINDS AND HIGHEST SEAS WILL BE OVERNIGHT
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 STORM WATCH FROM THIS EVENING THROUGH THURSDAY EVENING
     FOR CTZ008>012.
     WINTER WEATHER ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR
     CTZ005>012.
NY...WINTER STORM WATCH FROM THIS EVENING THROUGH THURSDAY EVENING
     FOR NYZ071>075-078>081-176>179.
     WINTER WEATHER ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR
     NYZ067>070.
NJ...WINTER STORM WATCH FROM THIS EVENING THROUGH THURSDAY EVENING
     FOR NJZ002-004-006-103>108.
     WINTER WEATHER ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR
     NJZ002-004-103-105-107.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ350-
     353-355.

&&

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







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