Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 080150
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
950 PM EDT TUE JUL 7 2015

.SYNOPSIS...
A COLD FRONT APPROACHES FROM THE NORTHWEST TONIGHT...AND THEN
CROSSES THE AREA ON WEDNESDAY. THE FRONT STALLS TO OUR SOUTH
WEDNESDAY NIGHT INTO THURSDAY. WAVES OF LOW PRESSURE RIDING ALONG
THE FRONT THROUGH THURSDAY NIGHT. WEAK HIGH PRESSURE BUILDS IN
FRIDAY THROUGH SATURDAY...THEN SLOWLY SLIDES OFFSHORE SUNDAY. A
WARM FRONT SLOWLY APPROACHES FROM THE WEST SUNDAY NIGHT AND
MONDAY. A COLD FRONT APPROACHES MONDAY NIGHT INTO TUESDAY.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
REMNANT SHWRS WERE RAPIDLY DISSIPATING ACROSS CT AT 130Z.
REDEVELOPMENT IS NOT EXPECTED OVER THE NEXT FEW HRS AS CIN
INCREASES AND THE SHRTWV TRACKS E OF THE REGION. RADAR COMPOSITE
PLACES THE UPSTREAM PCPN ASSOCIATED WITH FALLING HEIGHTS AND THE
APPROACH OF THE SFC FRONT OVER WRN PA AND UPSTATE NY TRACKING EWD
AT AROUND 33KT. THIS TAKES THE LEADING EDGE INTO THE CWA AROUND
6Z. EXPECT SOME EROSION ALONG THE LEADING EDGE AS THE CONVECTION
OUT RUNS THE FORCING A BIT INTO A MORE STABLE AIRMASS...SO
DELAYED THE ONSET OF POPS FURTHER. OTHERWISE...PATCHY FOG IS
POSSIBLE OVERNIGHT IN MOISTURE RICH LOW LEVEL AIR MASS. DENSE FOG
IS POSSIBLE IN SOME LOCATIONS ACROSS LONG ISLAND AND SE CT...BUT
NOT ENOUGH CONFIDENCE FOR ANY ADVISORY AT THIS POINT.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
A COLD FRONT APPROACHES FROM THE NORTHWEST WEDNESDAY MORNING.
CLOUDS WILL BE ON THE INCREASE AS WELL AS CHANCES FOR SHOWERS AND
THUNDERSTORMS THROUGHOUT THE DAY. SEVERAL FACTORS BRING
UNCERTAINTY TO THE FORECAST FOR COVERAGE OF SHOWERS/STORMS DURING
THE DAY ON WEDNESDAY. A SHORTWAVE IS FORECAST BY THE MODELS TO
MOVE ACROSS DURING THE MORNING HOURS...AND THIS COULD LEAD TO LESS
IN THE WAY OF SUPPORT FOR WIDESPREAD CONVECTION WITH NEGATIVE
VORTICITY ADVECTION BEHIND IT. ANOTHER POTENTIALLY LIMITING FACTOR
IS HOW MUCH WE DESTABILIZE. WITH THE FRONT NEARBY...CLOUDS MAY
LIMIT THE OVERALL AMOUNT OF HEATING. WITH THIS IN MIND...HAVE
CAPPED POPS OFF AT 50 PERCENT. THERE SHOULD BE ENOUGH LOW LEVEL
CONVERGENCE FOR SCT SHOWERS/STORMS TO DEVELOP ALONG AND NEAR THE
FRONT IN THE AFTERNOON AND EVENING. ANY OF THESE SHOWERS/STORMS
HAS THE POTENTIAL TO PRODUCE TORRENTIAL RAIN WITH PWATS AROUND 2
INCHES. SEVERE WEATHER THREAT APPEARS LIMITED DUE TO OVERALL WEAK
SHEAR AS 0-6 KM BULK SHEAR IS AROUND 20 KTS.

THE FRONT SHOULD STALL NEAR OR JUST SOUTH OF THE REGION WEDNESDAY
NIGHT. ANOTHER SHORTWAVE IS FORECAST TO APPROACH FROM THE WEST
WEDNESDAY NIGHT...AND THIS COULD ACT ON THE FRONT TO ENHANCE
COVERAGE OF CONVECTION. HAVE CONTINUED WITH HIGH CHANCE DURING THE
FIRST PART OF THE EVENING...TAPERING TO LOW CHANCE LATE IN THE
NIGHT. THE MAIN THREAT FROM ANY STORMS THAT LINGER INTO THE NIGHT
CONTINUES TO BE LOCALLY HEAVY RAINFALL.

HIGHS ON WEDNESDAY ARE A BIT UNCERTAIN DUE TO AMOUNT OF CLOUD COVER
AND PRECIPITATION...BUT TEMPS IN THE LOW TO MID 80S LOOK LIKELY.
HEAT INDEX VALUES WILL REACH THE UPPER 80S TO NEAR 90
DEGREES...ESPECIALLY IN THE NYC METRO. LOWS WED NIGHT WILL BE IN THE
MID TO UPPER 60S.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
GENERALLY GOOD AGREEMENT IN THE MODELS WITH THE OVERALL SET UP
EARLY IN THIS PERIOD. ZONAL FLOW ALOFT WITH A STALLED FRONTAL
BOUNDARY IN THE VICINITY FOR THURSDAY INTO THURSDAY NIGHT. A
COUPLE OF DISTURBANCE WILL DEVELOP ALONG THE FRONTAL
BOUNDARY...ONE IN THE EARLY MORNING TO EARLY AFTERNOON HOURS...AND
ANOTHER IN THE EVENING TO OVERNIGHT TIME PERIOD. THE 12Z GFS...12Z
CANADIAN...AND 00Z ECMWF ALL SHOW THESE DISTURBANCES MOVING
THROUGH THE REGION...ALONG WITH LOW SPREAD IN THE NAEFS AND GEFS.
ZONAL FLOW WILL MEAN THESE DISTURBANCES WILL MOVE THROUGH RATHER
QUICKLY. HOWEVER...UNCERTAINTY LIES IN THE AMOUNT OF QPF.
STABILITY DURING THIS TIME PERIOD IS NOT IMPRESSIVE WITH
LITTLE...IF ANY CAPE PRESENT OVER THE AREA AND SHOWALTER INDICES
GENERALLY GREATER THAN 0.

HIGH PRESSURE BUILDS IN FOR FRIDAY...BRINGING WITH IT DRY CONDITIONS
THROUGH SATURDAY NIGHT. THE HIGH WILL PUSH OFFSHORE
SUNDAY...ALLOWING FOR A WARM FRONT TO APPROACH LATE SUNDAY INTO
MONDAY MORNING. A COLD FRONT APPROACHES THE REGION LATE MONDAY INTO
TUESDAY. THIS FRONT MAY STALL IN THE VICINITY THROUGH THE MID-WEEK
PERIOD AS AN OMEGA BLOCK LOOKS TO DEVELOP ACROSS NORTH AMERICA EARLY
TO LATE NEXT WEEK.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
A COLD FRONT OVER THE OH VALLEY APPROACHES TNGT AND PASSES SLOWLY
DURING THE DAY WED.

VFR MOST AREAS TNGT. KGON WILL LIKELY HAVE IFR MOST OF THE NGT.
REDEVELOPMENT OF IFR IS POSSIBLE AT KISP IF SW FLOW DOES NOT
DEVELOP.

SHWRS AND TSTMS LIKELY DEVELOP AFT 13Z WED FROM NW TO SE. WITH
THE SLOW MOVEMENT OF THE FRONT...ACTIVITY MAY IMPACT THE AREA FOR
MOST OF THE DAY. VCTS INCLUDED IN THE TAFS FOR THIS. MVFR OR EVEN
LWR POSSIBLE INVOF THE TSTMS WED.

FLOW WEAKENS TNGT WITH A GENERAL WLY FLOW ON WED. WINDS SHIFT TO
THE NW BEHIND THE FRONT LATE WED AFTN INTO WED EVE.

 ...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: SOME VARIABILITY BETWEEN 180-220 TRUE THRU
3Z.

KLGA FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.

KEWR FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.

KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.

KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.

KISP FCSTER COMMENTS: LOW PROB OF IFR TNGT.

.OUTLOOK FOR 00Z THU THROUGH SUN...
.WED NGT-THU EVENING...SHRA/TSTMS POSSIBLE WITH MVFR OR LOWER
CONDITIONS AT TIMES.
.LATE THU NIGHT-SUN...VFR.

&&

.MARINE...
VISIBILITIES ACROSS THE WATERS HAVE RISEN TO ABOVE 1 NM. WHILE
DENSE FOG MAY BE POSSIBLE AGAIN TONIGHT...AT THIS TIME IT LOOKS
TO BE PATCHY RATHER THAN WIDESPREAD.

OTHERWISE...SEAS WILL BE AROUND 2-3 FT THROUGH THE FIRST PORTION OF
TONIGHT AND THEN COULD BUILD FURTHER TO 4 FT INTO WEDNESDAY...BUT
ARE EXPECTED REMAIN BELOW 5 FT. WINDS COULD GUST TO AROUND 20 KT
THIS EVENING ON THE OCEAN...BUT WILL ALSO REMAIN BELOW SCA LEVELS
THROUGH WEDNESDAY NIGHT.

LACK OF A STRONG PRESSURE GRADIENT IN THE LONG TERM WILL MEAN WINDS
AND WAVE BELOW SCA CRITERIA.

&&

.HYDROLOGY...
LOCALIZED URBAN AND POOR DRAINAGE FLOODING IS POSSIBLE
IN HEAVIER SHOWERS THROUGH THIS EVENING AND THEN AGAIN ON WEDNESDAY
INTO WEDNESDAY NIGHT. TRAINING OF STORMS IS ALSO POSSIBLE...WITH A
LOW PROBABILITY OF FLASH FLOODING.

THERE IS THE POTENTIAL FOR A HEAVY RAINFALL EVENT THURSDAY INTO
THURSDAY NIGHT. HOWEVER...THERE IS LARGE UNCERTAINTY IN WHERE THE
AXIS OF HEAVY RAINFALL WILL OCCUR AS TWO DISTURBANCES MOVE
THROUGH.

&&

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

&&

$$
SYNOPSIS...JP/DS
NEAR TERM...JMC/JP
SHORT TERM...DS
LONG TERM...JP
AVIATION...JMC/NV
MARINE...JP/DS
HYDROLOGY...JP/DS



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