Areal Flood Advisory 113, NWS New York, NY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
454 PM EDT MON SEP 3 2012

.SYNOPSIS...
HIGH PRESSURE SLOWLY DRIFTS OFFSHORE TONIGHT AND TUESDAY.
MEANWHILE...A WARM FRONT SLOWLY APPROACHES THE AREA. A SLOW
MOVING FRONTAL SYSTEM PASSES EAST WEDNESDAY INTO THURSDAY...WITH
YET ANOTHER FRONTAL SYSTEM EXPECTED TO APPROACH AND IMPACT THE
AREA OVER THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
HIGH PRESSURE NOSING OVER THE EASTERN HALF OF THE CWA WILL GRADUALLY
DRIFT OFFSHORE TONIGHT. AS IT DOES...A WARM FRONT WILL APPROACH THE
REGION FROM THE SOUTH. AHEAD OF THIS FRONT...THERE WILL BE AN
INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS...FROM SW TO NE. ANY
THUNDERSTORM ACTIVITY WILL BE ISOLATED FROM LATE TONIGHT THROUGH
EARLY TUESDAY MORNING WITH MARGINAL INSTABILITY. THE AIRMASS WILL BE
TROPICAL AND THE MAIN THREAT AREA WIDE WILL BE TORRENTIAL DOWNPOURS
AS PWATS INCREASE OVER 2 INCHES.

WITH AN INCREASINGLY MOIST AIRMASS AND CLOUD COVER...EXPECT
OVERNIGHT LOWS TO ONLY FALL INTO THE MID TO UPPER 60S...EXCEPT
AROUND 70 ACROSS THE NYC/NJ METRO.

THERE IS A MODERATE RISK OF RIP CURRENTS FOR ATLANTIC OCEAN
BEACHES THROUGH THIS EVENING.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
UNSETTLED WEATHER WILL CONTINUE THROUGH THE SHORT TERM PERIOD AS A
WARM FRONT WILL REMAIN NEAR THE REGION. MEANWHILE...A LARGE UPPER
LEVEL LOW OVER CANADA WILL SLOWLY MOVE TOWARDS THE REGION SENDING A
SERIES OF SHORTWAVES TOWARDS THE REGION.

THE INCREASING SOUTHERLY FLOW AND MOIST AIRMASS...COMBINED WITH
APPROACHING SHORTWAVES AND A NEARBY FRONTAL BOUNDARY WILL BE THE
FOCUS FOR SHOWERS AND ISOLATED THUNDERSTORMS. PWATS REMAIN OVER 2
INCHES...SO ANY SHOWERS THAT DEVELOP WILL BE CAPABLE OF TORRENTIAL
DOWNPOURS.

A WARM AND VERY HUMID AIRMASS EXPECTED ON TUESDAY...WITH HIGHS RIGHT
AROUND OR SLIGHT BELOW SEASONABLE DUE TO CLOUD COVER AND SHOWER
ACTIVITY...GENERALLY UPPER 70S AND LOWER 80S.

TUESDAY NIGHT...MODELS ARE INDICATING THE REMNANT MOISTURE FROM
ISAAC MOVES OVER THE AREA. IT IS ALWAYS DIFFICULT WITH REMNANT
SYSTEMS TO DETERMINE THE EXACT PLACEMENT AND TIMING OF THE HEAVIEST
RAINFALL. THE POTENTIAL THOUGH IS THERE FOR SEVERAL INCHES OF
RAINFALL. THERE IS ALSO A CONCERN WITH THE CLOSE PROXIMITY OF THE
WARM FRONT AND MARGINAL INSTABILITY FOR ISOLATED SEVERE WEATHER.

OVERNIGHT LOWS ARE EXPECTED TO FALL INTO THE UPPER 60S AND LOWER 70S.

THERE IS A MODERATE RISK OF RIP CURRENTS FOR ATLANTIC OCEAN
BEACHES ON TUESDAY.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
LARGE CLOSED UPPER LOW OVER CENTRAL CANADA SLOWLY MOVES EAST IN
TIME...WITH SOUTHERN EDGE OF THE WESTERLIES SETTLING SOUTH. MODELS
ARE IN DECENT AGREEMENT HANDLING THIS FEATURE INITIALLY...BUT THEN
ENERGY TO THE WEST ROUNDS THE BASE OF THE LARGE TROUGH...WITH
DIFFERENCES IN THE MODELS NOTED BY THE WEEKEND. THE TROUGH DOES
AMPLIFY THIS WEEKEND TO OUR WEST...AND SOME GLOBAL MODELS INDICATE A
CUTOFF LOW DEVELOPING SOMEWHERE TO OUR WEST. THESE DIFFERENCES
OBVIOUSLY PRODUCE UNCERTAINTY IN THE MEDIUM RANGE FORECAST...HOWEVER
MY FEELING IS AN UNSETTLED PERIOD IS EXPECTED THROUGH MUCH OF THIS
TIME FRAME.

IN THE MEANTIME...WEAK LOW PRESSURE AND ASSOCIATED FRONTAL BOUNDARY
MOVES THROUGH WEDNESDAY...WITH THE BULK OF THE RAIN MOVING EAST BY
LATE WEDNESDAY AND WEDNESDAY NIGHT. KEPT LIKELY POPS EARLY PER
PREVIOUS FORECAST/MOS STATISTICAL NUMBERS WEDNESDAY...THEN SCALE
BACK ON PRECIPITATION PROBABILITIES THEREAFTER.

IN FACT...THURSDAY AND FRIDAY SHOULD BE MAINLY DRY...ALTHOUGH THE
PASSAGE OF A WEAK TROUGH AND FRONTAL BOUNDARY COULD PRODUCE SOME
DIURNALLY DRIVER SHOWERS/ISOLATED THUNDERSTORMS.

FOR THE WEEKEND...WILL INCLUDE CHANCE FOR SHOWERS/TSTMS DEPENDING ON
EVOLUTION OF THE DIGGING TROUGH/APPROACHING FRONTAL BOUNDARY.

TEMPS WILL BE SEASONABLY WARM THROUGH MUCH OF THE PERIOD...ALTHOUGH
SLIGHTLY COOLER TEMPS ARE ANTICIPATED THIS WEEKEND. FOLLOWED A BLEND
OF HPC TEMP FORECAST WITH 12Z MOSGUIDE DATA.

OF NOTE...AN EXTENDED PERIOD OF STRONG RIP CURRENTS IS LIKELY FROM
MID WEEK THROUGH THE WEEKEND AS SWELLS FROM FORMER HURRICANE KIRK
AND LESLIE...CURRENTLY A TROPICAL STORM...PROPAGATE LONG PERIOD
SWELLS TOWARDS THE COAST. FOR EXACT TRACK DETAILS ON THE
TROPICS...PLEASE STAY TUNED TO THE LATEST FORECASTS FROM THE
NATIONAL HURRICANE CENTER.

&&

.AVIATION /21Z MONDAY THROUGH SATURDAY/...
HIGH PRESSURE FROM THE NE OVER THE AREA THIS EVENING...THEN MOVES
FURTHER OFFSHORE OVERNIGHT WITH E TO SE WINDS BETWEEN 10 AND 15KT.
HIGH CONFIDENCE IN WIND FORECAST THROUGH THE PERIOD. OCCASIONAL
GUSTS POSSIBLE AT ALL TERMINALS...15-20KT...THROUGH 00Z. SHOWERS
CURRENTLY SW OF KEWR/KTEB MOVING SLOWLY N-NW AND WEAKENING WITH
VCSH TO INDICATE THEIR PRESENCE. HOWEVER...NOT ENOUGH CONFIDENCE
TO PUT THEM INTO A TEMPO GROUP FOR TIME BEING.

VFR EXPECTED THIS EVENING BUT GREATER UNCERTAINTY THEREAFTER IN
TERMS OF CIGS AND RAIN OVERNIGHT AND INTO TUE. TIMING WILL DEPEND
ON HOW QUICKLY HIGH LIFTS OUT WITH SHOWERS APPROACHING FROM THE W.
COULD BE TOO EARLY WITH SHOWERS IN THE TAFS. IFR OR LOWER ALSO
POSSIBLE ESPECIALLY LATE TONIGHT INTO TUE...BUT TIMING AGAIN HAS
HIGH DEGREE OF UNCERTAINTY.

     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: GUST END TIME MAY VARY BY AN HOUR OR TWO. A
BRIEF SHOWER WILL BE POSSIBLE BEFORE 00Z.

KLGA FCSTER COMMENTS: A BRIEF SHOWER WILL BE POSSIBLE BEFORE 00Z.

KEWR FCSTER COMMENTS: GUST END TIME MAY VARY BY AN HOUR OR TWO. A
BRIEF SHOWER WILL BE POSSIBLE BEFORE 00Z.

KTEB FCSTER COMMENTS: GUSTS MAY END AN HOUR EARLIER THAN FORECAST. A
BRIEF SHOWER WILL BE POSSIBLE BEFORE 00Z.

KHPN FCSTER COMMENTS: A BRIEF SHOWER WILL BE POSSIBLE BEFORE 00Z.

KISP FCSTER COMMENTS: A BRIEF SHOWER WILL BE POSSIBLE BY AROUND OR
SHORTLY AFTER 00Z.

OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY...
.TUE THROUGH WED...A SLOW MOVING FRONTAL SYSTEM WILL BRING AN
EXTENDED PERIOD OF SHOWERS WITH ISOLD TSTMS RESULTING IN MVFR TO
IFR CONDITIONS. LOCALLY LOWER CONDITIONS POSSIBLE AT TIMES.
.THU THROUGH SAT...MAINLY VFR...ALTHOUGH A SHOWER OR TWO IS
POSSIBLE.

&&

.MARINE...
SUB SCA WINDS EXPECTED THROUGH TUESDAY NIGHT WITH HIGH PRESSURE
EAST OF THE WATERS. A BUILDING SE SWELLS FROM LESLIE MAY BUILD
SEAS TO MARGINAL SCA LEVELS ON TUESDAY AND TUESDAY NIGHT. THERE IS
SOME UNCERTAINTY TO JUST HOW QUICKLY THE SEAS WILL RISE AND WILL
HOLD OFF ON ANY SCA FOR NOW.

GUSTY SOUTHERLY WINDS ARE EXPECTED WEDNESDAY AS LOW PRESSURE MOVES
TO THE NORTH/NORTHEAST OF THE WATERS. A FRONT THEN SETTLES JUST
SOUTH AND EAST OF THE WATERS THURSDAY AND FRIDAY.

WINDS THROUGH THE REMAINDER OF THE WEEK SHOULD REMAIN FAIRLY LIGHT
WITH A WEAK PRESSURE GRADIENT IN PLACE.

HOWEVER...ROUGH SEAS ON THE OCEAN WEDNESDAY DUE TO THE STRONGER
SOUTHERLY FLOW WILL NOT SUBSIDE MUCH PER WAVE WATCH III...N ATL
HURRICANE MODEL DUE PROLONGED SWELL FROM TROPICAL STORM LESLIE. 5 FT
SEAS LIKELY FOR MUCH OF THE PERIOD ACROSS THE OCEAN WATERS.

&&

.HYDROLOGY...
SCATTERED HEAVY DOWNPOURS ARE LIKELY LATE TONIGHT THROUGH TUESDAY
WITH WARM FRONTAL APPROACH. AREAL QPF OF 1/2 TO 1 INCH IS
EXPECTED...WITH THE HIGHEST AMOUNTS WEST. LOCALIZED HEAVIER AMOUNT
ARE QUITE POSSIBLE IN ANY CONVECTION...WITH RAINFALL RATES OF 1 TO
2 INCHES PER HOUR. THESE TYPE OF RAINFALL RATES WILL CAUSE MINOR
URBAN AND POOR DRAINAGE FLOODING ISSUES...WITH LOW END THREAT FOR
FLASH FLOODING WITH ANY TRAINING CELLS.

WIDESPREAD SIGNIFICANT RAINFALL WILL BE POSSIBLE TUESDAY NIGHT
THROUGH WEDNESDAY. ADDITIONAL RAINFALL AMOUNTS OF 1-2 INCHES WITH
LOCALLY HIGHER AMOUNTS POSSIBLE. THIS WILL PRESENT A MINOR URBAN AND
SMALL STREAM FLOODING THREAT...WITH LOCALIZED FLASH FLOODING
POSSIBLE WITH ANY HEAVY TRAINING ACTIVITY.

&&

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

&&

SYNOPSIS...BC/PW
NEAR TERM...BC
SHORT TERM...BC
LONG TERM...PW
AVIATION...JM/LN
MARINE...BC/PW
HYDROLOGY...BC/PW