Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 230842
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
442 AM EDT WED JUL 23 2014

.SYNOPSIS...
AS HIGH PRESSURE MOVES EAST OF THE AREA...A COLD FRONT WILL MOVE
SLOWLY EAST AND PASS EAST OF THE AREA ON THURSDAY. HIGH PRESSURE WILL
FOLLOW FRIDAY THROUGH SATURDAY. WAVES OF LOW PRESSURE THEN PASS NEAR
THE REGION SUNDAY INTO MONDAY FOLLOWED BY A COLD FRONT MONDAY NIGHT
INTO TUESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SOUTHWEST WINDS BETWEEN A DEPARTING OFFSHORE HIGH PRES SYSTEM AND AN
APPROACHING COLD FRONT WILL CONTINUE TO ADVECT WARM MOIST UNSTABLE MARITIME
TROPICAL AIR ACROSS THE AREA.

PREPARE FOR A HAZY...HOT AND HUMID SUMMER DAY FOLLOWED BY STRONG TO
POTENTIALLY SEVERE THUNDERSTORMS MAINLY AFTER 3 PM WEST AND NORTH
OF NYC.

HIGH TEMPS IN THE LOWER 90S COMBINED WITH DEW POINTS APPROACHING
70 DEGREES WILL PRODUCE HEAT INDEX VALUES IN THE MID 90S ACROSS URBAN
AREAS OF NYC AND NORTHEAST NJ THIS AFTERNOON. BECAUSE A COLD FRONT
IS FORECAST TO MOVE SOUTH OF THE AREA THU PRODUCING COOLER TEMPS...WE
WILL NOT MEET THE 2 DAY HEAT CRITERIA OF 95 DEGREES AND THEREFORE
WILL NOT ISSUE A HEAT ADVISORY FOR NYC.

BECAUSE BOTH SFC AND LOW LEVEL BASED INSTABILITY WILL BE INCREASING ALONG
AND AHEAD OF A DEVELOPING PRE FRONTAL TROUGH...THERE WILL BE AN INCREASING
POTENTIAL FOR SEVERE TSTMS...MAINLY WEST AND NORTH OF NY AFT 19Z.
WITH A FCST MEAN STORM MOTION OF 230 DEGREES AT 15 KTS...CAN NOT RULE
OUT TRAINING OF STORMS ACROSS THE SAME AREA WITH AN ADDED
POTENTIAL FOR ISOLATED FLASH FLOODING. STAY TUNED.

THERE IS A MODERATE RISK OF RIP CURRENTS...MAINLY THIS AFTERNOON
THROUGH EVENING WITH ENHANCED SEA BREEZE DEVELOPMENT.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
TONIGHT...SHOWERS AND TSTMS WILL GRADUALLY WEAKEN AS THEY MOVE
INTO A MORE STABLE MARINE ENVIRONMENT IN PLACE ACROSS LONG ISLAND
AND SOUTHERN CT.

THURSDAY...WITH MOST MODELS FORMING A WAVE OF LOW PRESSURE ALONG
THE SAGGING BOUNDARY...LOOK FOR THE REDEVELOPMENT OF A STRATIFORM
RAIN SHIELD WITH EMBEDDED CONVECTION FOCUSED ACROSS THE COASTAL
AREA THROUGH AT LEAST THE EARLY AFTERNOON HOURS. THE LATEST
RAINFALL AMOUNTS MIGHT BE UNDER ESTIMATED.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THE PERIOD BEGINS WITH THE COLD FRONT SLOWLY MAKING ITS WAY FARTHER
TO OUR E/SE. AS SUCH...POPS WILL CONTINUE DIMINISHING WITH ALL AREAS
DRY BY LATE THURSDAY NIGHT. HIGH PRESSURE BUILDS ACROSS THE AREA FOR
FRIDAY...YIELDING DRY WEATHER AND TEMPS NEAR TO A COUPLE DEGREES
BELOW SEASONAL NORMS.

SATURDAY WILL SEE SIMILAR TEMPERATURES WITH MOISTURE STARTING TO
INCREASE ACROSS THE AREA ONCE AGAIN. ZONAL FLOW WILL BE PRESENT
ALOFT...AND WITH A SUBTLE/WEAK SHORTWAVE PASSING NEAR THE
AREA...CONTINUED WITH SLIGHT CHANCE POPS ACROSS WESTERN PORTIONS OF THE
CWA. WEAK FORCING WILL LEAD TO MOST SPOTS STAYING DRY THOUGH.

THE UPPER-LEVEL PATTERN ACROSS THE CONUS REALLY STARTS TO AMPLIFY
SATURDAY NIGHT INTO SUNDAY...AS A STOUT SHORTWAVE DROPS OUT OF THE
SOUTHERN CANADIAN PRAIRIES AND INTO THE MIDWEST. AS IT PROPAGATES
AROUND THE UPPER LOW CENTERED ACROSS NORTHERN QUEBEC...A DEEP TROUGH
WILL BE CARVED OUT ACROSS THE EASTERN US. THIS WILL SET THE STAGE
FOR A PERIOD OF UNSETTLED WEATHER SUNDAY INTO MONDAY...AS
STRENGTHENING JET DYNAMICS ALOFT ALLOW FOR A COUPLE WAVES OF LOW
PRESSURE TO PASS NW OF THE AREA. WITH INCREASING SOUTHERLY
FLOW/MOISTURE ACROSS THE AREA...SHOWERS AND STORMS WILL BECOME MORE
LIKELY. STILL...SIGNIFICANT TIMING DIFFERENCES EXIST IN THE PASSAGE
OF SHORTWAVES/BETTER DYNAMICS ALOFT...WHICH LEADS TO CONTINUED
UNCERTAINTY IN THE TIMING OF MORE WIDESPREAD PRECIPITATION. WILL GO
WITH HIGHER-END CHANCE POPS SUNDAY THROUGH MONDAY AS A RESULT.

THE ATTENDANT SURFACE COLD FRONT THEN LOOKS TO PUSH THROUGH MONDAY
NIGHT INTO TUESDAY...WITH CONDITIONS SLOWLY DRYING OUT. THERE IS A
GOOD AMOUNT OF UNCERTAINTY WITH THE FRONTAL TIMING AS WELL...AS THE
23/00Z ECMWF SHOWS IT STALLING ACROSS THE AREA WITH PRECIP LINGERING
ACROSS EASTERN AREAS INTO TUESDAY NIGHT.

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
A COLD FRONT APPROACHES FROM THE WEST TODAY...THEN BEGINS TO CROSS
THE TRI-STATE THIS EVENING.

HIGH CONFIDENCE IN VFR INTO THIS AFTERNOON. FOR NOW ADDRESS
THUNDER POTENTIAL WITH PROB30 AT ALL TERMINALS EXCEPT KGON - FOR
NOW APPEARS THUNDER MOST LIKELY WILL NOT REACH KGON UNTIL
AROUND/JUST AFTER 6Z THURSDAY...SO NOT CONFIDENT ENOUGH THERE TO
REFLECT IN TAFS. FOR NOW WENT MVFR IN TEMPO GROUPS...HOWEVER WITH
LOCALLY HEAVY RAINFALL POSSIBLE IN STRONGER CONVECTION - WOULD NOT
BE SURPRISED IF THERE WERE BRIEF PERIODS OF IFR OR LOWER WITH ANY
STRONGER STORMS.

LIGHT SW FLOW GIVES WAY TO SEABREEZE AT ALL BUT KSWF THIS
AFTERNOON. FOR NOW CANNOT RULE OUT OCCASIONAL GUSTS 20-25 KT AT
CITY/LONG ISLAND TERMINALS WITH SEABREEZE THIS AFTERNOON. HOWEVER
CONFIDENCE IN OCCURRENCE/TIMING IS NOT HIGH ENOUGH TO INCLUDE IN
THE TAFS AT THIS TIME. WINDS DIMINISH TO UNDER 10 KT IN THE
EVENING...VEERING TO THE NW BEHIND THE FRONT THIS EVENING ACROSS
CITY AND NW.

...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: TIMING OF CHANGES IN WIND SPEED/DIRECTION
COULD BE OFF +/- 2-3 HOURS. MODERATE CHANCE OF OCCASIONAL GUSTS OF
20-25 KT WITH SEABREEZE THIS AFTERNOON. ISOLD SHRA/TSTM POSSIBLE 19-23Z.

KLGA FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION
COULD BE OFF +/- 2-3 HOURS. MODERATE CHANCE OF OCCASIONAL GUSTS OF
20-25 KT WITH SEABREEZE THIS AFTERNOON. SCT SHRA/TSTM POSSIBLE
19-23Z.

KEWR FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION
COULD BE OFF +/- 2-3 HOURS. MODERATE CHANCE OF OCCASIONAL GUSTS OF
15-20 KT WITH SEABREEZE THIS AFTERNOON. SCT SHRA/TSTM POSSIBLE
19-23Z.

THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS YELLOW...WHICH
IMPLIES  SLANT RANGE VISIBILITY 4-6SM OUTSIDE OF CLOUD.

KTEB FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION
COULD BE OFF +/- 2-3 HOURS. LOW CHANCE OF OCCASIONAL GUSTS OF
15-20 KT WITH SEABREEZE THIS AFTERNOON. SCT SHRA/TSTM POSSIBLE
19-23Z.

KHPN FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION
COULD BE OFF +/- 2-3 HOURS. LOW CHANCE OF OCCASIONAL GUSTS OF
15-20 KT WITH SEABREEZE THIS AFTERNOON. SCT SHRA/TSTM POSSIBLE
19-23Z.

KISP FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION
COULD BE OFF +/- 2-3 HOURS. MODERATE CHANCE OF OCCASIONAL GUSTS OF
20-25 KT WITH SEABREEZE THIS AFTERNOON.

.OUTLOOK FOR 06Z THURSDAY THROUGH SUNDAY...
.LATE WEDNESDAY NIGHT-THURSDAY MORNING...MVFR OR LOWER CONDITIONS
IN SCT-NUMEROUS SHRA/TSTMS AND POSSIBLE FOG.
.THURSDAY AFTERNOON-SATURDAY MORNING...VFR.
.SATURDAY AFTERNOON...MVFR OR LOWER POSSIBLE IN ISOLD SHRA/TSTM
MAINLY NW OF NYC.
.SATURDAY NIGHT-SUNDAY...CHANCE OF SHRA/TSTMS WITH MVFR OR LOWER
POSSIBLE.

&&

.MARINE...
THIS AFTERNOON THROUGH THIS EVENING...WINDS AND SEAS WILL APPROACH
SMALL CRAFT ADVISORY LEVELS OF 25 KNOTS AND 5 FEET AS A COLD FRONT
MOVES EAST TOWARD THE AREA. SOUTHWEST WINDS WILL INCREASE TO 10 TO 15
KNOTS WITH GUSTS TO 20 KNOTS DURING THIS TIME. ISOLATED WIND GUSTS
UP TO 25 KNOTS CAN NOT BE RULED OUT. GUSTY WINDS ARE ALSO POSSIBLE
IN AND AROUND TSTMS MAINLY FROM SANDY HOOK NJ EAST ACROSS THE
COASTAL WATERS DURING THIS TIME.

SATURDAY NIGHT THROUGH SUNDAY...INCREASING SOUTH WINDS AND BUILDING
SEAS WILL ONCE AGAIN APPROACH SMALL CRAFT ADVISORY LEVELS WITH THE
APPROACH OF LOW PRESSURE.

OTHERWISE...WINDS AND SEAS WILL REMAIN TRANQUIL.

&&

.HYDROLOGY...
THIS AFTERNOON THROUGH THURSDAY...1/4 TO 1/2 INCH OF RAIN IS
FORECAST WITH THE APPROACH OF A COLD FRONT. AS THE PRECIPITABLE
WATER CONTENT INCREASES TO AROUND 2 INCHES...BASED ON A SLOW MEAN
FLOW OF AROUND 15 KNOTS...A FEW STORMS MIGHT MOVE ACROSS TH SAME
AREA AND PRODUCE FLASH FLOODING WITH ISOLATED AMOUNTS OF 1.0 TO
1.5 INCHES.

WAVES OF LOW PRESSURE PASSING NEAR THE AREA SUNDAY INTO MONDAY
HAVE THE POTENTIAL TO PRODUCE SHOWERS AND STORMS CAPABLE OF HEAVY
RAIN. BECAUSE SIGNIFICANT UNCERTAINTY STILL EXISTS WITH THE TIMING
AND AMOUNTS...THIS HEAVY RAIN POTENTIAL WILL NOT BE INCLUDED IN
THE HAZARDOUS WEATHER OUTLOOK AT THIS TIME.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...GC/PICCA
NEAR TERM...GC
SHORT TERM...GC
LONG TERM...PICCA
AVIATION...MALOIT
MARINE...GC/PICCA
HYDROLOGY...GC/PICCA






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