Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 270901
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
501 AM EDT FRI MAR 27 2015

.SYNOPSIS...
A COLD FRONT WILL PUSH WELL OFFSHORE THIS MORNING. LOW PRESSURE
WILL DEVELOP OFFSHORE TONIGHT...AND TRACK TOWARDS THE MARITIMES
SATURDAY. AN UPPER LEVEL DISTURBANCE MOVES ACROSS SATURDAY AND
MOVES EAST OF THE REGION SATURDAY NIGHT. HIGH PRESSURE BUILDS IN
THEREAFTER. FOR THE NEW WORK WEEK...A SERIES OF CLIPPER LOWS WILL
BE MOVING ACROSS.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A SLOW MOVING COLD FRONT HAS SLID EAST OF THE REGION EARLY THIS
MORNING...BUT LAGGING UPPER TROUGH AND UPPER JET ENERGIES...AND
WEAK INVERTED SURFACE TROUGHING...IS EXPECTED TO ALLOW FOR
LINGERING POST- FRONTAL RAIN BANDS TO ONLY GRADUALLY SLIDE EAST OF
NYC METRO AND POINTS WEST THIS MORNING AND LIKELY NOT UNTIL
AFTERNOON FOR E LI/SE CT.

NORTHERLY WINDS WILL GRADUALLY ADVECT COLDER AIR INTO THE REGION.
CLOUD COVER WILL KEEP TEMPS A FEW DEGREES BELOW SEASONABLE IN THE
MID TO UPPER 40S. AROUND 50 NYC/NJ METRO.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
DEEP UPPER TROUGH GRADUALLY PIVOTS TO THE EAST COAST TONIGHT INTO
SATURDAY NIGHT...WITH POTENTIAL CLOSED LOW TRACKING OVER THE TRI-
STATE TO MID-ATLANTIC VICINITY SATURDAY NIGHT.

AT THE SURFACE...LOW PRESSURE TRACKS NE ALONG THE COLD FRONT WELL SE
OF THE REGION FRIDAY NIGHT INTO SAT NIGHT. OPERATIONAL MODELS AND
RESPECTIVE ENSEMBLE ARE IN FAIRLY GOOD AGREEMENT WITH THE LOW
STAYING FAR ENOUGH OFFSHORE TO KEEP THE HEAVIEST PRECIP FROM THIS
LOW OFFSHORE. BUT THE MAJORITY OF SOLUTIONS...EXCEPT FOR OPERATIONAL
ECWMF...DO SPREAD WESTERN EDGE OF LIGHT PRECIP SHIELD INTO FAR
EASTERN LI/SE CT TONIGHT INTO SAT NIGHT. SUNYSB SENSITIVITY
ANALYSIS DEPICTS A SLIGHT SPREAD IN ENSEMBLE MEMBERS ON WEST SIDE
OF LOW TRACK...DEPICTING A LOW PROB OF SLIGHTLY FARTHER WEST
SOLUTION IF THE TROUGH DIGS A BIT DEEPER. THIS WOULD INCREASE
PRECIP POTENTIAL FOR MAINLY LI/CT.

AT THE SAME TIME...SEVERAL MODELS HAVE BEEN SIGNALING A WEAK
INVERTED TROUGH HANGING BACK OVER THE REGION FRI NIGHT INTO SAT AS
CLOSED MID-LEVEL LOW APPROACHES. THE TRACK/INTENSITY OF THE MID-
LEVEL CLOSED LOW AND ASSOCIATED SURFACE TROUGH LOCATION WILL BE
KEY TO POTENTIAL DEVELOPMENT OF ANY STEADIER AND MORE WIDESPREAD
PRECIP FRIDAY NIGHT INTO SAT. THE STRENGTH/POSITION OF THIS
FEATURE HAS WAVERED FROM MODEL RUN TO MODEL RUN FROM SOUTHERN NEW
ENGLAND TO NORTHERN MID ATLANTIC OVER THE LAST SEVERAL
DAYS...INSTILLING LOW CONFIDENCE ON WHERE THIS FEATURE SETS UP.
WITH THE ABOVE UNCERTAINTY AND POTENTIAL HAVE MAINTAINED AN W TO E
GRADIENT OF ONLY CHANCE POPS FRI NIGHT INTO SAT NIGHT.

FOR LOCATIONS THAT DO NOT FALL UNDER THE INVERTED TROUGH OR
WESTERN EDGE OF PRECIP SHIELD...THERE WILL BE AN ISO/SCT THREAT
FOR MAINLY DIURNAL SHOWER ACTIVITY ACROSS THE AREA ON SATURDAY
UNDER COMBO OF MID- LEVEL VORT ENERGY AND COLD POOL INSTABILITY.

THEREAFTER...MODELS IN GENERAL AGREEMENT WITH THE UPPER TROUGH
SLIDING EAST AND SURFACE HIGH BUILDING TOWARDS THE REGION SATURDAY
NIGHT WITH GRADUAL TAPERING OF PRECIP ACROSS EASTERN TRI-STATE.

IN TERMS OF P-TYPE OF POTENTIAL PRECIP...CAA TONIGHT INTO SAT SHOULD
ALLOW PRECIP TO MIX WITH/CHANGE TO WET SNOW LATE TONIGHT. IF PRECIP
IS STEADY ENOUGH A MAINLY WET SNOW WOULD BE EXPECTED ON SATURDAY
BASED ON THERMAL PROFILE ALOFT...BUT IF IT IS VERY LIGHT AND
SCATTERED IN NATURE A RAIN/SNOW MIX WOULD BE LIKELY DUE TO WARMER
BOUNDARY LAYER TEMPS.

MOST LIKELY SCENARIO AT THIS POINT IS 1-2 INCHES OR LESS OF WET
SNOW FRI NIGHT INTO SAT ACROSS EASTERN LI/SE CT...WITH A COATING
TO NOTHING FURTHER WEST. IF INVERTED TROUGH DEVELOPS OVER THE
REGION...OR OFFSHORE LOW TRACKS A BIT FARTHER WEST...AN ADVISORY
LEVEL WET SNOW WOULD BE POSSIBLE...PARTICULARLY LI/CT.

TEMPS ON SATURDAY/SAT NIGHT WILL LIKELY RUN ABOUT 10 TO 15
DEGREES BELOW SEASONABLE UNDER THE UPPER TROUGH AND COLD
POOL.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE BUILDS INTO THE AREA AT THE SURFACE ON SUNDAY...WITH
THE CENTER OF THE HIGH PASSING WELL TO THE SOUTH...WHILE AT THE SAME
TIME THERE WILL BE RIDGING ALOFT. THICKNESSES QUICKLY BUILD ON
SUNDAY AS THE HIGH PUSHES OFF THE SOUTHEAST COAST LATE IN THE
DAY...WHICH MEANS WARMER TEMPERATURES AS COMPARED TO
SATURDAY...MAINLY FOR NYC...NORTHEAST NJ...AND LOWER HUDSON VALLEY.
LONG ISLAND AND SOUTHERN CT MAY SEE ONLY SLIGHTLY WARMER
TEMPERATURES AS WINDS SHIFT TO MORE OF A SOUTHERLY DIRECTION DURING
THE DAY. THIS ONSHORE FLOW OFF THE COLD OCEAN WATERS WILL KEEP
TEMPERATURES COOLER THAN INLAND AREAS.

A COLD FRONT THEN APPROACHES THE AREA SUNDAY NIGHT...AND MOVES
THROUGH LATE MONDAY INTO MONDAY NIGHT. SOME LIGHT PRECIPITATION IS
POSSIBLE OUT AHEAD OF THE FRONT SUNDAY NIGHT. THERE IS LIMITED
MOISTURE TO WORK WITH HOWEVER...SO ONLY SLIGHT CHANCE POPS. WARM AIR
ADVECTION AHEAD OF THE FRONT WILL MEAN PRECIPITATION IN THE FORM OF
RAIN SHOWERS FOR MUCH OF THE AREA. HOWEVER...THERE MAY BE SOME SNOW
SHOWERS WELL INLAND. ANY SNOW WILL CHANGE TO RAIN DURING THE MORNING
ON MONDAY.

PATTERN BECOMES RATHER PROGRESSIVE AS THE UPPER LEVEL
FLOW IS PRETTY ZONAL. AT THE SURFACE...WEAK HIGH PRESSURE BUILDS
IN FOR TUESDAY. A QUICK MOVING CLIPPER SYSTEM MOVES THROUGH ON
TUESDAY NIGHT...DEPARTING THE AREA ON WEDNESDAY. AGAIN...MUCH OF
THE AREA SHOULD BE WARM ENOUGH FOR RAIN...WITH THE POSSIBILITY OF
SOME FLAKES MIXING IN TUESDAY NIGHT ACROSS SOUTHERN CT AS COLDER
AIR MOVES IN BEHIND THE LOW.

A WARM FRONT APPROACHES THE AREA ON WEDNESDAY NIGHT...MOVING THROUGH
ON THURSDAY...FOLLOWED QUICKLY BY THE ASSOCIATED COLD FRONT.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
WEAK HIGH PRESSURE BUILDS IN TODAY.

RAIN/SHRA CONTINUES INTO THE MORNING PUSH WITH PRIMARILY MVFR
CONDS...ALTHOUGH TEMPO VFR CONDS ARE POSSIBLE BEFORE 13-15Z. VFR
OTHERWISE PREVAILS THEREAFTER.

WINDS N-NNW AROUND 10 KT...DIMINISHING SLIGHTLY THIS AFTERNOON.

...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: GUSTS THRU 13Z MIGHT BE ONLY OCCASIONAL. VFR
CIGS COULD TEMPO OR PREVAIL NOW THRU 13Z.

KLGA FCSTER COMMENTS: OCCASIONAL GUSTS UP TO AROUND 20 KT UNTIL 13Z.
VFR CIGS COULD TEMPO OR PREVAIL NOW THRU 13Z.

KEWR FCSTER COMMENTS: GUSTS THRU 13Z MIGHT BE ONLY OCCASIONAL. VFR
CIGS COULD TEMPO OR PREVAIL NOW THRU 13Z.

THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.

KTEB FCSTER COMMENTS: TEMPO OR PREVAILING VFR CIGS POSSIBLE NOW
THRU 13Z.

KHPN FCSTER COMMENTS: MVFR/VFR CIGS POSSIBLY TEMPO OR PREVAILING
THRU 13Z.

KISP FCSTER COMMENTS: TEMPO VFR CIGS POSSIBLE BEFORE 14Z.

.OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY...
.SAT...CHANCE OF MVFR CONDS WITH ANY RAIN OR SNOW SHOWERS. NW G20-
25KT.
.SAT NIGHT. VFR. NW G25KT.
.SUN...VFR.
.MON...VFR. W G25KT.
.TUE...VFR. NW G20KT.

&&

.MARINE...
SMALL CRAFT OCEAN SEAS EXPECTED TODAY WITH A GRADUAL SUBSIDE OF HIGH
SOUTHERLY SWELLS. MARGINAL SCA CONDS POSSIBLE ON OCEAN TONIGHT WITH
GUSTY NW FLOW...CAA...AND RESIDUAL SOUTHERLY SWELLS...WITH BETTER
CHANCE OF SCA CONDS SAT NIGHT IN WAKE OF DEPARTING OFFSHORE LOW AND
AS HIGH PRESSURE IN FROM THE WEST.

WAVES DIMINISH TO SUB SCA ON SUNDAY...BUT BUILD TO ABOVE SCA
CRITERIA ON A SOUTHERLY FLOW LATE SUNDAY NIGHT INTO MONDAY AHEAD OF
AN APPROACHING WARM FRONT. WINDS MAINLY OVER THE OCEAN WATERS WILL
GUST TO 25 KT LATE SUNDAY NIGHT INTO MONDAY NIGHT. WINDS AND WAVES
WILL DIMINISH ON TUESDAY AS THE PRESSURE GRADIENT RELAXES WITH WEAK
HIGH PRESSURE BUILDING IN. WAVES QUICKLY BUILD AGAIN TO ABOVE SCA
CRITERIA TUESDAY NIGHT IN RESPONSE TO SOUTHERLY FLOW AHEAD OF AN
APPROACHING CLIPPER SYSTEM...THEN DIMINISH ON WEDNESDAY AS THE
SYSTEM DEPARTS THE REGION.

&&

.HYDROLOGY...
AN ADDITIONAL 1 TO 2 TENTHS QPF THROUGH THIS AFTERNOON.

NO SIGNIFICANT WIDESPREAD PRECIPITATION EXPECTED THROUGH THIS
WEEKEND INTO NEXT WEEK.

RIVERS AND STREAMS ARE EXPECTED TO REMAIN BELOW BANK FULL...BUT
INCREASED RIVER/STREAM FLOW WILL CONTINUE ICE BREAKUP AND
MOVEMENT INTO THIS WEEKEND. ISOLATED ICE JAMS ARE
POSSIBLE...WHICH IF THEY OCCUR...COULD RESULT IN LOCALIZED
FLOODING. SINCE ICE JAM FLOODING IS UNPREDICTABLE AND
SUDDEN...INTERESTS ALONG ICE COVERED RIVERS SHOULD MONITOR NWS
FORECASTS FOR THE LATEST INFORMATION.

FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING
OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE
VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON
OUR WEB SITE.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT SATURDAY FOR ANZ350-353-
     355.

&&

$$
SYNOPSIS...JP/NV
NEAR TERM...NV
SHORT TERM...NV
LONG TERM...JP
AVIATION...JC
MARINE...JP/NV
HYDROLOGY...JP/NV


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