Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 270810
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
410 AM EDT MON JUL 27 2015

.SYNOPSIS...
A WEAK TROUGH WILL REMAIN ACROSS THE AREA THROUGH TUESDAY. HIGH
PRESSURE WILL BUILD IN FOR THE MID WEEK. A COLD FRONT APPROACHES
FROM THE WEST LATE WEDNESDAY NIGHT AND THURSDAY MORNING...THEN
CROSSES THE TRI-STATE THURSDAY AFTERNOON AND EVENING. WEAK HIGH
PRESSURE THEN BUILDS IN TO CLOSE THE WEEK...THEN GIVES WAY TO AN
EASTWARD EXTENSION OF THE BERMUDA HIGH BY SUNDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WEAK SHORTWAVE ENERGY OVER WESTERN NY THIS MORNING WILL GRADUALLY
AMPLIFY AS IT PIVOTS THROUGH THE REGION TODAY. AT THE SURFACE...A
WEAK COLD FRONT WILL DISSIPATE AS IT APPROACHES THE REGION THIS
MORNING.

MOST WIDESPREAD SHOWER/THUNDERSTORMS ACTIVITY CONTINUES ACROSS
EASTERN PA AND WESTERN NJ EARLY THIS MORNING...WITH MOISTURE POOLING
AHEAD OF WEAK FRONT. EXPECT ACTIVITY TO INCREASE INTO NYC/NJ METRO
EARLY THIS MORNING AS SHORTWAVE APPROACHES.

TOUGH TO DISCERN THE FRONTAL BOUNDARY...BUT MODELS APPEAR TO BE
SIGNALING THIS WEAK TROUGHING LAYING ACROSS THE NYC/NJ METRO INTO
SW CT THIS MORNING. AREAS ALONG AND TO THE EAST OF FRONT SHOULD BE
FOCUS FOR SCT CONVECTION THIS MORNING AS SHORTWAVE
APPROACHES...AS WELL AS ALONG ANY OUTFLOW BOUNDARIES.

INSTABILITY SHOULD BUILD TO NEAR MODERATE LEVELS LATE THIS MORNING
INTO AFTERNOON TO THE INTERIOR OF DEVELOPING SEABREEZE BOUNDARIES.
WOULD EXPECT SEABREEZE BOUNDARIES TO BE POTENTIAL FOCUS FOR ISO-
SCT CONVECTION UNDER THE MEAN TROUGH LATE THIS MORNING THROUGH
AFTERNOON. LIMITING FACTOR IS THAT REGION WILL BE ON BACKSIDE OF
BEST LIFT AHEAD OF TROUGH AXIS. WOULD EXPECT CONVECTIVE POTENTIAL TO
CONTINUE TO STEADILY SHIFT NORTH AND WEST AWAY FROM THE COAST THIS
AFTERNOON...TO MAINLY NE NJ AND LOWER HUDSON VALLEY BY LATE IN THE
AFTERNOON AS AREAS TO THE SOUTH AND EAST STABILIZE. THIS TYPE OF
EVOLUTION APPEARS TO BEAR OUT IN NCAR AND SPC SSEO ENSEMBLES.

MAIN THREAT WITH CONVECTION WILL BE HEAVY DOWNPOURS AND LOCALIZED
URBAN FLOODING DUE TO SLOW STORM MOTION. AN ISOLATED PULSE STRONG TO
SEVERE STORM IS NOT OUR OF THE QUESTION...WITH MODEST INSTABILITY
BUT RATHER WEAK WIND FIELDS.

CONVECTION SHOULD DECREASE IN COVERAGE AND INTENSITY THIS EVENING AS
SHORTWAVE AXIS MOVES EAST AND INSTABILITY WANES.

HIGHS TODAY GENERALLY IN THE LOWER TO MID 80S DUE TO ABUNDANT CLOUD
COVER.

THERE IS A MODERATE RISK FOR RIP CURRENT DEVELOPMENT AT ATLANTIC
BEACHES TODAY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
SHORTWAVE AXIS SLIDES EAST THIS EVENING...WITH ANOTHER SHORTWAVE
DIGGING THROUGH NEW ENGLAND LATE TONIGHT INTO TUE MORNING.

WITH SURFACE TROUGH LINGERING OVER THE REGION TONIGHT....WEAK
INSTABILITY AND NEXT APPROACHING SHORTWAVE...CANT RULE OUT ISOLATED
CONVECTION LATE TONIGHT INTO TUE MORNING. APPEARS NYC METRO/SW CT
AND POINTS EAST WOULD BE MOST FAVORABLE BASED ON TROUGH POSITION.
WARM AND MUGGY CONDITIONS TONIGHT.

SHORTWAVE AXIS PIVOTS EAST IN THE AFTERNOON. CONVECTIVE POTENTIAL
APPEARS TO WANE IN THE AFTERNOON AS MID-LEVELS WARM AND IN WAKE OF
SHORTWAVE AXIS.

INCREASING SUNSHINE FOR MUCH OF THE REGION AND RISING HEIGHTS SHOULD
ALLOW FOR TEMPS TO WARM TO ABOVE NORMAL LEVEL ON TUESDAY...GENERALLY
MID TO UPPER 80S AWAY FROM IMMEDIATE SOUTH COASTS. AFTERNOON
SEABREEZE DEVELOPMENT SHOULD KEEP SOUTH COASTAL AREAS IN THE LOWER
TO MID 80S.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
THE MAIN ISSUE IN THE LONG TERM WILL BE THE HEAT AND HUMIDITY
THROUGH THURSDAY.

DEEP LAYERED RIDGING BUILDS IN TUESDAY NIGHT-WEDNESDAY NIGHT...THIS
SHOULD KEEP THINGS DRY THROUGH THEN...EXCEPT FOR MAYBE A SLIGHT
CHANCE OF A LINGERING SHOWER AND/OR THUNDERSTORM OVER SE CT EARLY
TUESDAY EVENING...IN RESPONSE TO A SHORTWAVE PASSING TO THE NE.

THE RIDGE AXIS SLIDES OFFSHORE ON THURSDAY...EXACTLY HOW FAST WILL
DETERMINE HOW QUICKLY AND HOW FAR E SHOWERS AND THUNDERSTORMS AHEAD
OF A NORTHERN STREAM TROUGH MOVE INTO THE CWA. FOR NOW INCREASE POPS
TO CHANCE OVER THE NW 2/3 OF THE CWA BY AFTERNOON AND SLIGHT CHANCE
OVER THE SE 1/3. MODELS ARE STILL FORECASTING A MID LEVEL CAP FROM
AROUND 675 TO 600 HPA AND THIS WILL SERVE AS LIMITING FACTOR FOR
ANY STORMS BECOMING STRONG TO SEVERE.

LOWS TUESDAY NIGHT SHOULD RUN AROUND 5 DEGREES OR SO ABOVE NORMAL
BASED ON A BLEND OF ECS/MET/MAV GUIDANCE AND NAM 2-METER
TEMPERATURES.

HIGHS WEDNESDAY ARE FORECAST TO BE A FEW DEGREES HIGHER THAN
PREVIOUSLY IN RESPONSE TO LOW LEVEL TEMPERATURES BEING FORECAST TO
BE SLIGHTLY HIGHER THAN PREVIOUSLY. HIGHS SHOULD RUN MAINLY FROM THE
LOWER TO MIDDLE 90S...WITH A FEW UPPER 90S POSSIBLE IN URBAN NE NJ
AND POSSIBLY N/NW PORTIONS OF NYC...WITH UPPER 80S TO AROUND 90
ACROSS THE TWIN FORKS OF LONG ISLAND AND COASTAL SE CT. THIS IS
BASED ON A BLEND OF MAV/MET/ECS GUIDANCE WITH NAM 2-METER
TEMPERATURES AND A MIX DOWN FROM850-800 HPA PER BUFKIT SOUNDINGS.
NEAR RECORD HIGHS ARE POSSIBLE ON WEDNESDAY AS A RESULT. REFER TO
THE CLIMATE SECTION OF THE AFD FOR DETAILS.

HEAT INDICES ON WEDNESDAY SHOULD GENERALLY BE IN THE LOWER TO MID
90S...WITH UPPER 90S LIKELY ACROSS NYC/URBAN NE NJ...WITH VALUES OF
100 POSSIBLE THERE. LIMITING FACTOR ON THE HEAT INDEX WILL BE THE
AFTERNOON DEWPOINTS...AND WITH POTENTIAL FOR MIXING TO AT LEAST 850
HPA...SHOULD SEE THE DEWPOINTS LOWER AS THE TEMPERATURE RISES. THE
EXTENT OF THIS FALL OF IS UNCERTAIN AT THIS TIME...BUT AM CONFIDENT
ENOUGH IN SOME FALL OFF THAT DEWPOINTS IN THE AFTERNOON OVER URBAN
AREAS SHOULD REMAIN BELOW 70 DEGREES. FOR THIS REASON...BELIEVE THE
RISK OF HEAT INDICES REACHING 105 IS VERY LOW...SOMETHING LESS THAN
10 PERCENT.

TEMPERATURES WEDNESDAY NIGHT-THURSDAY ARE BASED ON A BLEND OF
MEX/MEN/EKD/ECE/ECM/WPC GUIDANCE WITH NAM 2-METER TEMPERATURES
BLENDED IN AS WELL WEDNESDAY NIGHT. LOWS WEDNESDAY NIGHT SHOULD BE 5-
10 DEGREES ABOVE NORMAL AND HIGHS ON THURSDAY 5-10 DEGREES ABOVE
NORMAL...BUT A FEW DEGREES COOLER THAN ON WEDNESDAY. HEAT INDICES IN
URBAN AREAS ON THURSDAY SHOULD GENERALLY BE IN THE MIDDLE TO UPPER
90S.

A NORTHERN STREAM SHORTWAVE PASSES TO THE NORTH THURSDAY
EVENING...BRINGING WITH IT A CHANCE OF SHOWERS AND THUNDERSTORMS. IT
SHOULD THEN BE DRY LATE THURSDAY NIGHT AND FRIDAY UNDER WSW FLOW
ALOFT WITH NO SHORTWAVES FORECAST OVER THE AREA.

A NORTHERN STREAM TROUGH BUILDS IN FRIDAY NIGHT AND SATURDAY...BUT
THE LOW LEVELS APPEAR TO BE TO DRY TO SUPPORT ANY PRECIPITATION...SO
ONLY AM FORECASTING SOME PASSING CLOUDS FOR NOW.

ZONAL FLOW IS EXPECTED SATURDAY NIGHT...WITH WEAK RIDGING BUILDING
IN ON SUNDAY...SO BOTH PERIODS SHOULD BE DRY AS WELL.

TEMPERATURES THURSDAY NIGHT-SUNDAY SHOULD CONTINUE TO RUN ABOVE
NORMAL...AND ARE BASED ON A BLEND OF MEX/MEN/EKD/ECE/ECM/WPC
GUIDANCE.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
DECAYING COLD FRONT MOVES IN THIS MORNING AND DISSIPATES
THEREAFTER. PRIMARILY VFR CONDITIONS DURING THE TAF PERIOD EXCEPT
FOR TERMINALS THAT EXPERIENCE ANY SHRA/TSRA OR HAZE IN WHICH CASE
MVFR WILL BE POSSIBLE. TIMING OF ACTIVITY COULD BE 1-3 HRS OFF
FROM FORECAST. AMENDMENTS WILL BE LIKELY ESPECIALLY WITH REGARDS
TO TIMING OF TSRA.

SW-S FLOW 5-10 KT THROUGH MUCH OF THE PERIOD WITH SLIGHTLY HIGHER
WINDS MON AFTN FOR KJFK/KLGA.

.OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY...
.MONDAY NIGHT...VFR.
.TUESDAY-THURSDAY...MAINLY VFR. 5-6SM HAZE DEVELOPMENT POSSIBLE.
SW WINDS WITH AFTERNOON SEABREEZE DEVELOPMENT AT COASTAL
TERMINALS. THUNDER IS POSSIBLE THURSDAY AFTERNOON.
.FRIDAY...VFR.

&&

.MARINE...
WIND AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT LEVELS
THROUGH TUESDAY WITH A FAIRLY WEAK PRESSURE GRADIENT.

A RELATIVELY RELAXED PRESSURE GRADIENT OVER THE WATERS TUESDAY NIGHT
THROUGH FRIDAY SHOULD KEEP WINDS 10 KT OR LESS IN THIS TIME FRAME. A
POSSIBLE EXCEPTION IS OVER THE COASTAL OCEAN WATERS WEDNESDAY NIGHT
AND THURSDAY WHERE WINDS COULD REACH 15 KT AHEAD OF A COLD FRONT.

BASED ON THESE WINDS...AND NO EXPECTED SIGNIFICANT
SWELL...SEAS/WAVES SHOULD REMAIN BELOW SMALL CRAFT LEVELS TUESDAY
NIGHT THROUGH FRIDAY.

&&

.HYDROLOGY...
ANY THUNDERSTORMS TODAY WILL BE VERY SLOW TO MOVE...WITH STORM
MOTION FORECAST TO BE 10 KT OR LESS. AS A RESULT...THERE IS THE
POTENTIAL FOR LOCALIZED URBAN/POOR DRAINAGE FLOODING. IN MOST
CASES ANY FLOODING SHOULD BE MINOR DUE TO PULSEY STORM
NATURE...BUT THERE IS POTENTIAL FOR FLASH FLOODING WITH ANY
TRAINING.

IT SHOULD BE MAINLY DRY TUESDAY NIGHT-THURSDAY MORNING.

WHILE WIDESPREAD SIGNIFICANT RAINFALL IS NOT EXPECTED WITH ANY
SHOWERS/THUNDERSTORMS THURSDAY AFTERNOON/EVENING...THERE IS THE
POTENTIAL FOR LOCALLY HEAVY RAINFALL WITH ANY STRONGER CONVECTION.
IF THIS WERE TO OCCUR...THAN LOCALIZED MINOR URBAN/POOR DRAINAGE
FLOODING WOULD BE POSSIBLE.

IT SHOULD THEN BE DRY FROM LATE THURSDAY NIGHT THROUGH THE END OF
THE WEEK.

&&

.CLIMATE...
RECORD HIGHS FOR WEDNESDAY JULY 29 2015...

LOCATION..........RECORD HIGH/YEAR.........FORECAST HIGH
NEWARK....................100/1949.................97
BRIDGEPORT.................96/2002.................91
CENTRAL PARK...............99/1949.................95
LA GUARDIA.................97/1949.................97
J F KENNEDY................99/2002.................92
ISLIP......................96/2002.................93

&&

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

&&

$$
SYNOPSIS...MALOIT/NV
NEAR TERM...NV
SHORT TERM...NV
LONG TERM...MALOIT
AVIATION...JM
MARINE...MALOIT/NV
HYDROLOGY...MALOIT/NV
CLIMATE...MALOIT



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