Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 271557
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1157 AM EDT FRI MAR 27 2015

.SYNOPSIS...
A COLD FRONT WILL PUSH FARTHER OFFSHORE TODAY. 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/...
MOST OF THE SHOWERS HAVE TAPERED OFF OVER THE AREA...BUT SEVERAL
SHORTWAVES CONTINUE TO PASS THROUGH THE REGION THROUGH THIS
AFTERNOON. THERE ARE SOME RADAR RETURNS MOVING TOWARDS THE
NORTHEAST...BUT THERE ARE NOT MANY SFC OBS CONFIRMING PRECIP
REACHING THE GROUND. WILL LOWER POPS TO SLIGHT CHANCE FOR THE
AFTERNOON...AS SHOWERS WILL BE SPOTTY.

NORTHERLY WINDS WILL SLOWLY ADVECT COLDER AIR INTO THE
REGION...NOT ALLOWING TEMPS TO RISE MUCH FROM MORNING LOWS. 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 TONIGHT 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 ECMWF...DO SPREAD WESTERN EDGE OF LIGHT PRECIP SHIELD
INTO 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 LI/CT.

AT THE SAME TIME...SEVERAL MODELS HAVE BEEN SIGNALING A WEAK
INVERTED TROUGH HANGING BACK OVER THE REGION TONIGHT 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 NIGHT. 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...INSPIRING LITTLE CONFIDENCE ON WHERE THIS FEATURE SETS UP.
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.
WITH THE ABOVE MENTIONED UNCERTAINTY AND PRECIP POTENTIAL HAVE
MAINTAINED AN W TO E GRADIENT OF CHANCE POPS TONIGHT INTO SAT
NIGHT.

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

IN TERMS OF P-TYPE...CAA TONIGHT INTO SAT SHOULD ALLOW PRECIP TO
MIX WITH/CHANGE TO WET SNOW LATE TONIGHT. IF PRECIP IS
STEADY/HEAVY 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
INABILITY TO COOL BOUNDARY LAYER SUFFICIENTLY.

MOST LIKELY SCENARIO AT THIS POINT IS 1-2 INCHES OR LESS OF WET
SNOW FRI NIGHT INTO SAT NIGHT 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 ACROSS MAINLY
LI/CT...WITH A LIGHT COATING TO INCH FARTHER WEST. THIS LATTER
SCENARIO IS A LOW PROBABILITY AT THIS TIME.

TEMPS ON SAT/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 /16Z FRIDAY THROUGH TUESDAY/...
WEAK HIGH PRESSURE WILL GRADUALLY BUILD IN TODAY. WILL SEE MAINLY
VFR CONDS...BUT COULD SEE ON-OFF MVFR CONDITIONS/LIGHT RAIN
SHOWERS THROUGH THE DAY.

WINDS N-NNW AROUND 10 KT...BACKING NW AND 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: BRIEF MVFR CIGS POSSIBLE AT ANY TIME BEFORE
20Z.

KLGA FCSTER COMMENTS: BRIEF MVFR CIGS POSSIBLE AT ANY TIME BEFORE
20Z.

KEWR FCSTER COMMENTS: BRIEF MVFR CIGS POSSIBLE AT ANY TIME BEFORE
20Z.

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

KTEB FCSTER COMMENTS: BRIEF MVFR CIGS POSSIBLE AT ANY TIME BEFORE
20Z.

KHPN FCSTER COMMENTS: NO UNSCHEDULED AMD.

KISP FCSTER COMMENTS: BRIEF MVFR CIGS POSSIBLE AT ANY TIME BEFORE
21Z.

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

&&

.MARINE...
MARGINAL SCA WINDS THIS MORNING WITH SCA OCEAN SEAS TODAY AS HIGH
SOUTHERLY SWELLS ONLY SLOWLY SUBSIDE. MARGINAL SCA CONDS EXPECTED
ON OCEAN TONIGHT INTO SAT MORNING WITH GUSTY NW FLOW...CAA...AND
RESIDUAL SOUTHERLY SWELLS. BETTER CHANCE OF SCA CONDS ON OCEAN AND
POSSIBLY ALL WATERS WILL BE SAT NIGHT IN WAKE OF DEPARTING
OFFSHORE LOW AND AS HIGH PRESSURE BUILDS 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 TENTH OF AN INCH OR SO OF 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 ACROSS THE LOWER HUDSON VALLEY AND
SOUTHERN CONNECTICUT 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...MPS
SHORT TERM...NV
LONG TERM...JP
AVIATION...JC/GOODMAN
MARINE...JP/NV
HYDROLOGY...JP/NV


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