Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 230233
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1033 PM EDT TUE JUL 22 2014

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO MOVE OFFSHORE AS A COLD FRONT
APPROACHES FROM THE WEST. THE FRONT WILL MOVE ACROSS FROM
WEDNESDAY NIGHT INTO THURSDAY...FOLLOWED BY BUILDING HIGH PRESSURE
ON FRIDAY. THE HIGH WILL WEAKEN ON SATURDAY...THEN LOW PRESSURE
PASSING TO THE SOUTHEAST WILL IMPACT THE AREA SUNDAY INTO MONDAY.
AN ASSOCIATED COLD FRONT WILL APPROACH LATE DAY MONDAY...AND MOVE
ACROSS MONDAY NIGHT INTO TUESDAY.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
DRY CONDITIONS EXPECTED OVERNIGHT WITH WEAK SHORTWAVE ENERGY
SLIDING SOUTH OF THE REGION.

WARM AND HUMID NIGHT ON TAP WITH LOWS IN THE 60S TO LOW 70S. THE
WARMEST TEMPS WILL OCCUR IN/AROUND NYC DUE TO THE URBAN HEAT
ISLAND EFFECT. SFC DEW POINTS WILL CLIMB THROUGH THE MID 60S AND
INTO THE UPPER 60S. CAN EXPECT PATCHY FOG TO DEVELOP AWAY FROM THE
CITY.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
HOT AND INCREASINGLY HUMID AIR MASS REMAINS OVER THE AREA
WEDNESDAY. WITH HIGH PRES DEPARTING AND COLD FRONT APPROACHING
FROM THE WEST...SW FLOW INCREASES THROUGHOUT THE DAY...AND SFC
DEWPOINTS WILL RISE THROUGH THE 60S AND INTO THE LOWER 70S. MAX
TEMPS ON WEDNESDAY WILL TOP OFF IN THE LOWER 90S ACROSS NYC AND NE
NJ...AND WILL BE IN THE UPPER 80S TO NEAR 90 ELSEWHERE. TEMPS WILL
BE SIGHTLY COOLER NEAR THE SOUTH COASTS. THE HEAT INDEX ON
WEDNESDAY WILL GENERALLY TOP OFF IN THE LOW TO MID 90S...EXPECT
FOR NYC/NE NJ...WHERE THE HEAT INDEX WILL BE IN THE MID TO UPPER
90S. SINCE THE HEAT INDEX IN NYC WILL NOT REACH 95 FOR 2
CONSECUTIVE DAYS...AND SINCE THE HEAT INDEX WILL REMAIN BELOW 100
ACROSS THE CWA...WILL NOT ISSUE A HEAT ADVISORY.

AS COLD FRONT APPROACHES...SHOWERS AND THUNDERSTORMS WILL DEVELOP
NORTH AND WEST OF NYC IN THE AFTERNOON ALONG A PRE-FRONTAL TROUGH.
SHOWERS AND THUNDERSTORMS SPREAD EAST WEDNESDAY EVENING AND
WEDNESDAY NIGHT...AND THE BULK OF THE ACTIVITY SHOULD HOLD OFF
UNTIL WEDNESDAY NIGHT AS THE COLD FRONT PASSES THROUGH THE REGION.

WITH THE HEAT AND HUMIDITY...ML MUCAPE VALUES WILL RANGE FROM
1000-1500 J/KG DURING THE DAY...AND THEN WILL DROP TO AROUND 400
J/KG AT NIGHT WITH THE LOSS OF THE HEATING. 0-6 KM BULK SHEAR WILL
BE WEAK DURING THE DAY...AND THEN WILL RISE TO 25-35 KT AFTER 00Z
THURSDAY. CANNOT RULE OUT STRONG WINDS WITH ANY THUNDERSTORMS...
BUT PRIMARY THREAT WILL BE HEAVY RAIN DUE TO PWATS AROUND 2".
FLASH FLOODING OF LOW LYING AND POOR DRAINAGE AREAS IS POSSIBLE.
WILL NOT ISSUE A HAZARDOUS WEATHER OUTLOOK AS THE THREAT WILL NOT
BE WIDESPREAD.

SHOWERS AND THUNDERSTORMS TAPER OFF FROM WEST TO EAST WEDNESDAY
NIGHT AS THE COLD FRONT WORKS ITS WAY ACROSS THE REGION.

THERE IS A MODERATE RISK OF RIP CURRENTS...MAINLY WEDNESDAY
AFT/EVE WITH ENHANCED SEA BREEZE DEVELOPMENT.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
THE SFC COLD FRONT SHOULD BE TO THE EAST THU MORNING...BUT WITH THE
H8 FRONT STILL YET TO MOVE ACROSS...A MID LEVEL TROUGH STILL WELL TO
THE WEST AND POTENTIAL FOR A WEAK SFC WAVE ALONG THE FRONT TO SLOW
ITS PROGRESS EVEN FURTHER...WILL HAVE LIKELY POP TO START ACROSS SE
CT AND ERN LONG ISLAND AND CHANCE ELSEWHERE...WITH CHANCES GRADUALLY
RAMPING DOWN DURING THE AFTERNOON AND EARLY EVENING. CONDS LOOK
MAINLY DRY FOR LATER THU NIGHT AND MORE SO INTO FRI AS HIGH PRESSURE
BUILDS FROM THE WEST.

THE HIGH SHOULD WEAKEN ON SAT AS FLOW ALOFT BECOMES MORE ZONAL.
AS LOW TO MID LEVEL MOISTURE RETURN COMMENCES...WITH PRECIP
EFFICIENCY INCREASING BACK TO OVER 1 INCH BY LATE DAY...AND AS MID
LEVEL SHORTWAVES APPROACH IN ZONAL FLOW...SHOULD START TO SEE
INCREASING CHANCES FOR SHOWERS/TSTMS BEGINNING LATE DAY SAT INTO
SAT NIGHT.

THE FLOW ALOFT SHOULD UNDERGO SIGNIFICANT AMPLIFICATION EARLY NEXT
WEEK AS AN UPPER RIDGE BUILDS IN THE WESTERN STATES AND A POTENT
SHORTWAVE TROUGH DIVING OUT OF CENTRAL CANADA MERGES WITH AN UPPER
LOW OVER QUEBEC...CARVING OUT A DEEP LONGWAVE TROUGH OVER THE
EASTERN STATES. THERE WILL BE GOOD CHANCES FOR SHOWERS/TSTMS...
ESPECIALLY SUNDAY NIGHT INTO MON MORNING AS AN ASSOCIATED WAVE OF
LOW PRESSURE PASSES JUST OFF TO THE SE...THEN LATE DAY MON INTO MON
NIGHT WITH THE APPROACH OF A COLD FRONT FROM THE WEST.

COULD SEE SOME LEFTOVER SHOWERS/TSTMS ON TUE MAINLY IN THE MORNING
AS THE COLD FRONT MOVES TO THE EAST...THEN DRIER AND SLIGHTLY COOLER
AIR ARRIVING THROUGH THE REST OF TUE INTO TUE NIGHT.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
HIGH PRESSURE MOVES EAST AS A COLD FRONT APPROACHES WEDNESDAY.

GENERALLY VFR THROUGH THE TAF PERIOD. PATCHY FOG COULD RESULT IN
MVFR VSBYS OUTSIDE OF NYC TERMINALS LATE TONIGHT. OTHERWISE...VFR
WITH POSSIBLE LATE DAY SHOWERS/TSTMS FROM NYC WEST. ANY STORM COULD
PRODUCE SUB VFR CONDITIONS BRIEFLY LATE IN THE DAY WEDNESDAY.

SOUTH WINDS DIMINISH AND REMAIN LIGHT OVERNIGHT. SEA BREEZES ARE
EXPECTED AGAIN WEDNESDAY...WITH SPEEDS INCREASING DURING THE
AFTERNOON ONCE AGAIN.

.OUTLOOK FOR 00Z THU THROUGH SUN...
.WED NIGHT-THU MORNING...SLOW MOVING COLD FROPA. MVFR OR LOWER CONDITIONS
IN SCT-NUMEROUS SHOWERS/TSTMS.
.THU AFTERNOON-SAT...VFR.
.SUN...CHANCE OF SHOWERS OR THUNDERSTORMS. SUB-VFR POSSIBLE.

&&

.MARINE...
WINDS WILL GRADUALLY SUBSIDE THROUGH 06Z...WITH SUB-SCA CONDS
EXPECTED OVERNIGHT. LOW PROBABILITY OF FOG ON THE WATERS BASED ON
FORECAST DEWPOINTS NEAR OR SLIGHTLY BELOW WATER TEMPS...SO HAVE
REMOVED FROM FORECAST.

WINDS WILL INCREASE TO 15-20 KT ONCE AGAIN ON THE OCEAN WATERS
WEDNESDAY AFTERNOON AND TO 10-15 KT WITH 15-20 KT GUSTS ON THE
REST OF THE WATERS AHEAD OF AN APPROACHING COLD FRONT. CONVECTION
LIKELY WEDNESDAY NIGHT. SEAS WILL AVERAGE 2-4 FT ON THE OCEAN AND
AROUND 1 FT ELSEWHERE.

OUTSIDE OF TSTMS THU AND LATE DAY SAT HAVE HIGH CONFIDENCE IN
QUIET CONDS THU THROUGH SAT...THEN FCST UNCERTAINTY CREEPS IN
BEGINNING ON SUNDAY. HAVE FCST CONTINUED QUIET CONDS...BUT IF AN
APPROACHING WAVE OF LOW PRESSURE AND/OR FRONTAL SYSTEM ARE
STRONGER THAN FCST...HAZARDOUS OCEAN SEAS COULD DEVELOP IF
CORRESPONDING S-SW FLOW IS STRONGER THAN FCST.

&&

.HYDROLOGY...
THERE IS THE POTENTIAL FOR AROUND 1/2 INCH OF RAINFALL FROM LATE
WEDNESDAY THROUGH THURSDAY WITH LOCALLY HIGHER AMOUNTS POSSIBLE.
PRECIPITABLE WATERS ARE FORECAST TO BE AROUND 2 INCHES ON
WEDNESDAY NIGHT...SO LOCALLY HEAVY RAINFALL IS POSSIBLE IN ANY
STRONGER CONVECTION. AREAS EXPERIENCING LOCALLY HEAVY RAINFALL
COULD EXPERIENCE AT LEAST MINOR FLOODING OF URBAN/POOR DRAINAGE
AREA...AND POSSIBLY LOCALIZED FLASH FLOODING. THE CONFIDENCE IN
THE LATTER IS CURRENTLY LESS THAN 30 PERCENT SO WILL NOT HIGHLIGHT
IN THE HAZARDOUS WEATHER OUTLOOK.

LOW PRESSURE PASSING JUST OFF TO THE SE SUNDAY NIGHT INTO MON
MORNING...FOLLOWED BY A COLD FRONTAL PASSAGE LATER MON...HAVE SOME
POTENTIAL TO PRODUCE HEAVY RAIN...AS PRECIP EFFICIENCY INCREASES
TO OVER 1.5 INCHES. THIS WILL DEPEND FIRST ON THE LOW TRACK...THEN
ON POTENTIAL FOR TRAINING OF CELLS AHEAD OF THE COLD FRONT...AS
WELL AS OTHER MESOSCALE/THERMODYNAMIC FACTORS. GIVEN THESE
UNCERTAINTIES IT IS TOO EARLY TO OUTLOOK THIS IN THE HWO.

&&

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

&&

$$
SYNOPSIS...GOODMAN/MPS
NEAR TERM...MPS
SHORT TERM...MPS
LONG TERM...GOODMAN
AVIATION...BC/PW
MARINE...GOODMAN/MPS
HYDROLOGY...GOODMAN/MPS





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