Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 051114
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
714 AM EDT THU MAY 5 2016

.SYNOPSIS...
A COASTAL LOW TRACKS FROM OFF THE MID ATLANTIC COAST TO NOVA
SCOTIA THROUGH TONIGHT. ANOTHER COASTAL LOW MEANDERS NORTH UP THE
MID ATLANTIC COAST FRIDAY AND FRIDAY NIGHT...THEN WEAKENS NEARBY
ON SATURDAY. A COLD FRONT APPROACHES FROM THE WEST SATURDAY
NIGHT...THEN CROSSES THE AREA SUNDAY. HIGH PRESSURE BUILDS INTO
THE REGION EARLY NEXT WEEK...WITH A WARM FRONTAL BOUNDARY POSSIBLY
STALLING THROUGH THE REGION MIDWEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
FORECAST MAINLY ON TRACK. NO SIGN OF ANY DZ AROUND...SO HAVE
REMOVED THIS FROM THE FORECAST. OTHERWISE...ONLY MINOR ADJUSTMENTS
TO TEMPS AND DEWS BASED ON LATEST OBS AND TRENDS.

ALL MODELS EXCEPT THE NAM TAKE A 700-500 HPA SHORTWAVE AND
ASSOCIATED SURFACE LOW FAR ENOUGH TO THE EAST TODAY...THAT THE
REGION SHOULD EXPERIENCE MINIMAL FORCING. AS A RESULT FORECASTING
A SLIGHT CHANCE OF LIGHT RAIN FOR MOST OF THE DAY. DO INCREASE
POPS TO CHANCE THIS AFTERNOON AS APPEARS THE REGION WILL BE UNDER
A COUPLED UPPER JET STRUCTURE.

FOR HIGHS TODAY A BLEND OF ECS/MET/MAV GUIDANCE...NAM 2-METER
TEMPERATURES AND A MIX DOWN FROM 950-925 HPA PER BUFKIT SOUNDINGS
WAS USED. HIGHS SHOULD BE AROUND 10-15 DEGREES BELOW NORMAL.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
LOW CHANCE POPS THIS EVENING AS COUPLED JET STRUCTURE EXITS TO
THE NE. INCREASE POPS OVERNIGHT...BUT STILL IN CHANCE CATEGORY...
AS 700-500 HPA DIFFERENTIAL POSITIVE VORTICITY ADVECTION
INCREASES...AS WELL AS THE FLOW ALOFT BECOMES DIFFLUENT.

THIS GENERAL SET UP CONTINUES ON FRIDAY...WITH 500 HPA COLD POOL
BUILDING IN ALOFT...AND SHOWALTER INDICES FALLING TO -2 TO 2. AS
A RESULT...MAINTAINED LIKELY POPS FOR RAIN AND ADDED A SLIGHT
CHANCE OF THUNDER (ELEVATED IN NATURE) FRIDAY AFTERNOON.

FOR LOWS TONIGHT A BLEND OF MAV/ECS/MET GUIDANCE AND NAM 2-METER
TEMPERATURES WAS USED...WITH VALUES PROGGED TO BE NEAR TO SLIGHTLY
BELOW NORMAL. HIGHS ON FRIDAY WERE BASED ON A BLEND OF MET/MAV/ECS
GUIDANCE...NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 950 HPA
PER BUFKIT SOUNDINGS. HIGHS SHOULD BE A FEW DEGREES WARMER THAN
TODAY...BUT STILL AROUND 10-15 DEGREES BELOW NORMAL.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE GENERAL H5 FLOW ACROSS
NORTH AMERICA THROUGH THE MIDDLE OF NEXT WEEK. AS USUAL...THERE
ARE SOME TIMING AND AMPLITUDE DIFFERENCES THAT START TO DEVELOP
OVER THE WEEKEND...ALTHOUGH THE GENERAL IDEA IS THAT THE
PERSISTENT BLOCKED UPPER PATTERN ACROSS THE CONUS WILL FINALLY
LOSE ITS GRIP NEXT WEEK.

CUTOFF LOW PRES NEAR THE MID ATLANTIC COAST FRI NIGHT WILL
GRADUALLY WEAKEN WHILE SLOWLY MOVING E THROUGH SAT NIGHT.
MEANWHILE...A SHORTWAVE TROUGH DIVING OUT OF CENTRAL CANADA CUTS
OFF OVER ONTARIO WITH THE TWO SYSTEMS CONSOLIDATING INTO A BROAD
VORTEX OVER SE CANADA. THIS SYSTEM WILL GRADUALLY LIFT NE INTO THE
MARITIMES EARLY NEXT WEEK AS RIDGING OVER THE UPPER MIDWEST
FLATTENS WITH A SW UPPER FLOW DEVELOPING BY THE MIDDLE OF NEXT
WEEK.

AT THE SFC...WEAK SFC LOW PRES NEAR THE DELAWARE/NJ COAST
GRADUALLY WEAKENS S OF THE AREA THROUGH THE DAY SAT. WIDESPREAD
RAIN WILL GRADUALLY DRY OUT ACROSS THE AREA WITH DRY WEATHER
RETURNING BY SAT NIGHT. THE STRENGTH AND EXACT TRACK OF THIS LOW
STILL REMAIN IN QUESTION WHICH WILL IMPACT WIND STRENGTH/DIRECTION
AND ULTIMATELY ANY CONTINUED COASTAL FLOOD IMPACTS ON SAT. SEE
COASTAL FLOOD SECTION BELOW FOR MORE INFORMATION.

A COLD FRONT APPROACHES FROM THE WEST SAT NIGHT AND TRACKS THROUGH
ON SUN...BRINGING ANOTHER ROUND OF SHOWERS TO THE AREA. THERE ARE
TIMING DISCREPANCIES WITH THIS...WITH THE EC BEING SLIGHTLY FASTER
THAN THE GFS. THE BIGGER ISSUE THAT NEEDS TO BE RESOLVED IS THAT
THE GFS IS INDICATING MAINLY POST-FRONTAL PRECIPITATION AND
REALLY WRAPS THE SYSTEM UP ONCE IT PUSHES THROUGH RESULTING TO A
MUCH STRONGER PRESSURE PATTERN ACROSS THE AREA. RIDGING THEN
RETURNS THROUGH EARLY NEXT WEEK WITH TEMPERATURES GRADUALLY
RETURNING TO NEAR TO ABOVE NORMAL LEVELS.

A WARM FRONT APPROACHING FOR THE MIDDLE OF THE WEAK HAS THE
POTENTIAL TO STALL OVER OR NEAR THE AREA WITH WAVES OF LOW PRES
TRACKING ALONG IT. THERE IS HIGH BUST POTENTIAL IN THE TEMP
FORECAST ON WED DUE TO THIS.

&&

.AVIATION /11Z THURSDAY THROUGH MONDAY/...
LOW PRESSURE ALONG WITH A NEARLY STATIONARY FRONT WILL REMAIN SOUTH
OF LONG ISLAND THROUGH TONIGHT.

GENERALLY LOOKING AT IFR/MVFR CONDITIONS IN STRATUS THROUGH THE TAF
PERIOD. SOME OF THE 00Z FORECAST GUIDANCE IS HINTING AT THE
POSSIBILITY OF SOME VFR CONDITIONS DURING THE LATE AFTERNOON HOURS.
CONFIDENCE NOT HIGH ENOUGH TO PUT IN THE TAF QUITE YET...BUT WILL
CONTINUE TO MONITOR. VISIBILITIES ARE EXPECTED TO REMAIN
VFR...HOWEVER SOME LOWER POCKETS OF MVFR OR EVEN IFR CAN NOT BE
RULED OUT EARLY THIS MORNING.

NORTHEAST FLOW IS EXPECTED THROUGH THE TAF PERIOD. SPEEDS WILL
GENERALLY RANGE BETWEEN 10 AND 15 KT THROUGH THE TAF PERIOD..WITH
GUSTS BETWEEN 20-25 KT. SOME LOCALLY HIGHER GUSTS WILL BE
POSSIBLE. WIND GUSTS MAY BE OCCASIONAL THROUGH 12Z.

MODERATE CONFIDENCE WITH WIND FORECAST. LOW CONFIDENCE WITH
CATEGORY FORECAST MAINLY DUE TO UNCERTAINTY OF TIMING BETWEEN MVFR
AND IFR CEILINGS...WHICH COULD BE SEVERAL HOURS OFF...ALONG WITH
THE POSSIBILITY OF VFR CONDITIONS LATE THIS AFTERNOON.

...NY METRO ENHANCED AVIATION WEATHER SUPPORT...

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

KJFK FCSTER COMMENTS: GUSTS MAY BE OCCASIONAL THIS MORNING. LOW
CHANCE CONDITIONS IMPROVE TO VFR LATE THIS AFTERNOON OR EVENING FOR
A FEW HOURS.

KLGA FCSTER COMMENTS: GUSTS MAY BE OCCASIONAL THIS MORNING. LOW
CHANCE CONDITIONS IMPROVE TO VFR LATE THIS AFTERNOON OR EVENING FOR
A FEW HOURS.

KEWR FCSTER COMMENTS: GUSTS MAY BE OCCASIONAL THIS MORNING. LOW
CHANCE CONDITIONS IMPROVE TO VFR LATE THIS AFTERNOON OR EVENING FOR
A FEW HOURS.

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

KTEB FCSTER COMMENTS: GUSTS MAY BE OCCASIONAL THIS MORNING. LOW
CHANCE CONDITIONS IMPROVE TO VFR LATE THIS AFTERNOON OR EVENING FOR
A FEW HOURS.

KHPN FCSTER COMMENTS: GUSTS MAY BE OCCASIONAL THIS MORNING. LOW
CHANCE CONDITIONS IMPROVE TO VFR LATE THIS AFTERNOON OR EVENING FOR
A FEW HOURS.

KISP FCSTER COMMENTS: GUSTS MAY BE OCCASIONAL THIS MORNING.

.OUTLOOK FOR 12Z FRI THROUGH MON...
.FRIDAY THROUGH SUNDAY MORNING...PERIODS OF RAIN/FOG/LOW CLOUDS WITH
MVFR OR LOWER CONDITIONS. NE WINDS G15-20 KT FRI.
.SUNDAY AFTERNOON/NIGHT...COLD FRONTAL PASSAGE SHOULD FINALLY
BRING AN END TO DISMAL CONDITIONS...WITH CONDITIONS IMPROVING TO
VFR AND NW WINDS G20KT.
.MON...VFR. W WINDS G25KT POSSIBLE.

&&

.MARINE...
A TIGHTENING PRESSURE GRADIENT TODAY WILL PRODUCE 25-30KT GUSTS ON
ALL WATERS BY MID-LATE MORNING THROUGH THE AFTERNOON. FOR THE
OCEAN WATERS GUSTS OF 25-30 KT ARE EXPECTED THROUGH FRIDAY WITH
SEAS OF 4-8 FT AS WELL. FOR THE NON-OCEAN WATERS...WIND GUSTS TO
25 KT MIGHT CONTINUE TONIGHT...BUT CONFIDENCE IN THIS IS ONLY
MODERATE. GUSTS ON ON FRIDAY SHOULD BE AROUND 20 KT.

AS A RESULT...HAVE MADE NO CHANGES TO THE SCA FOR THE COASTAL
OCEAN WATERS THROUGH FRIDAY AND HAVE ISSUED AN SCA FOR THE NON-
OCEAN WATERS FROM 12Z- 22Z TODAY.

THE SCA HAS BEEN EXTENDED THROUGH FRI NIGHT ON THE OCEAN
WATERS...MAINLY FOR SEAS. WHILE THE CURRENT FORECAST KEEPS
MARGINAL SEAS ON THE OCEAN THROUGH SAT...THERE IS UNCERTAINTY THAT
THIS WILL OCCUR. THE PRES GRADIENT WEAKENS...BUT WAVEWATCH IS
INDICATING A SE-S SWELL CONTINUES THROUGH THIS TIME. A SLY FLOW
INCREASES SAT NIGHT AHEAD OF AN APPROACHING COLD FRONT...WITH THE
POTENTIAL FOR SCA CONDITIONS ON ALL WATERS BEHIND THE FRONT
SUN...BEFORE SUBSIDING SUN EVE. 5 FT SEAS MAY LINGER ON THE
EASTERN OCEAN WATERS INTO MON.

&&

.HYDROLOGY...
GENERALLY LESS THAN 1/10 OF AN INCH OF RAIN IS EXPECTED THROUGH
TONIGHT.

AROUND 1/2 TO 2/3 OF AN INCH OF RAIN IS EXPECTED FROM
FRIDAY INTO SATURDAY...WITH LOCALLY HIGHER AMOUNTS POSSIBLE.
PONDING OF WATER IS POSSIBLE IN AREAS RECEIVING LOCALLY HEAVY
RAINFALL.

UP TO 1/4 INCH IS POSSIBLE SATURDAY NIGHT INTO SUNDAY WITH A COLD
FRONTAL PASSAGE. NO HYDROLOGIC ISSUES ARE EXPECTED.

&&

.TIDES/COASTAL FLOODING...
THE HIGHEST SPRING TIDE OF THE YEAR IS APPROACHING WITH THE NEW MOON
ON FRIDAY. THE THREAT FOR MINOR TO LOCALLY MODERATE COASTAL
FLOODING WILL INCREASE DURING THE EVENING HIGH TIDES THROUGH
FRIDAY...AND LIKELY CONTINUE INTO THIS WEEKEND.

WATER LEVELS MAY BRIEFLY TOUCH MINOR COASTAL FLOOD LEVELS IN A
FEW SOUTH SHORE BAY LOCALES ON SOUTHWESTERN LONG ISLAND WITH THIS
MORNINGS AND FRIDAY MORNINGS HIGH TIDES.

FOR TONIGHTS HIGH TIDE...ASTRONOMICAL TIDES WILL BE AROUND
1/4-1/2 FT HIGHER THAN LAST NIGHT...WHILE TIDAL DEPARTURES SHOULD
BE NEAR TO MAYBE A 1/4 FT HIGHER THAN LAST NIGHT. THIS WILL RESULT
IN MORE WIDESPREAD MINOR COASTAL FLOODING ACROSS THE VULNERABLE
LOCALES ALONG THE SOUTH SHORE BAYS OF WESTERN LONG ISLAND/NYC AND
WESTERN LONG ISLAND SOUND AND NY HARBOR. AN ADVISORY HAS BEEN
ISSUED FOR THESE AREAS. THERE IS POTENTIAL FOR THE MOST VULNERABLE
SOUTH SHORE BAY LOCALES OF WESTERN GREAT SOUTH BAY TO HIT MODERATE
FLOOD THRESHOLDS THIS EVENING...BUT THE PROBABILITY REMAINS TOO
LOW FOR A WARNING AT THIS TIME. MINOR FLOOD LEVELS WILL BE
APPROACHED AND POSSIBLY LOCALLY TOUCHED ACROSS THE REMAINING
EASTERN COASTAL AREAS.

FOR FRIDAY NIGHTS HIGH TIDES...WIDESPREAD MINOR COASTAL FLOODING
IS EXPECTED ONCE AGAIN AS ASTRONOMICAL TIDES PEAK AND SURGE LIKELY
REMAINS STEADY. THE POTENTIAL EXISTS FOR MODERATE COASTAL FLOODING
IN VULNERABLE SOUTH SHORE BAYS LOCALES OF WESTERN LONG ISLAND AND
QUEENS AT THAT TIME WITH ONLY 1 TO 1 1/4 FT SURGE NEEDED IN SPOTS.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...COASTAL FLOOD ADVISORY FROM 9 PM THIS EVENING TO MIDNIGHT EDT
     TONIGHT FOR CTZ009-010.
NY...COASTAL FLOOD ADVISORY FROM 9 PM THIS EVENING TO MIDNIGHT EDT
     TONIGHT FOR NYZ071-078-177.
     COASTAL FLOOD ADVISORY FROM 7 PM TO 10 PM EDT THIS EVENING FOR
     NYZ074-075-080-178-179.
NJ...COASTAL FLOOD ADVISORY FROM 7 PM TO 10 PM EDT THIS EVENING FOR
     NJZ006-106-108.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ330-
     335-338-340-345.
     SMALL CRAFT ADVISORY UNTIL 6 AM EDT SATURDAY FOR ANZ350-353-
     355.

&&

$$


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