Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 072334 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 734 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/... SHOWERS HAVE DEVELOPED ALONG SEA BREEZE CONVERGENCE INVOF OF THE NYC METRO ON NORTHWARD ALONG THE HUDSON RIVER. A BAND OF SHOWERS IS ALSO MOVING INTO WESTERN ZONES ASSOCIATED WITH A PRE-FRONTAL TROUGH. LAST SEVERAL HOURS OF H5 ANALYSIS AND WATER VAPOR IMAGERY ILLUSTRATE A SHORTWAVE TROUGH APPROACHING FROM THE SW...BRINGING SOME ENHANCEMENT LIFT. THERE HAVE ONLY BEEN A FEW LIGHTNING STRIKES WITH THIS ACTIVITY AS MOST CELLS HAVE BEEN RELATIVELY SHALLOW AND NOT GETTING DEEP ENOUGH FOR GOOD CHARGE GENERATION. WARM RAIN PROCESSES SEEM TO BE DOMINATING. WILL LEAVE THUNDER WORDING IN THE FORECAST...BUT FEEL MOST ACTIVITY WILL BE SHOWERS WITH THE BIGGEST THREAT LOCALLY HEAVY RAINFALL WITH PWATS 1.6 TO 1.8 INCHES. NO SEVERE WEATHER EXPECTED THIS EVENING. THE SHORTWAVE IS FORECAST TO SWING THROUGH THE REGION THIS EVENING...WHICH IN TURN WILL LIMIT OVERALL LIFT ONCE IT PASSES AS WELL AS LOSS OF DAYTIME HEATING. POPS FALL TO SLIGHT CHANCE AROUND 00Z AND THEN A DRY CONDITIONS ARE EXPECTED OVERNIGHT. 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. THERE IS A MODERATE RISK OF THE METEOROLOGICAL ENHANCEMENT OF RIP CURRENT DEVELOPMENT AT AREA ATLANTIC BEACHES TODAY.. && .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 /00Z WEDNESDAY THROUGH SUNDAY/... A COLD FRONT OVER THE OH VALLEY APPROACHES TNGT AND PASSES SLOWLY DURING THE DAY WED. LAST OF THE TSTMS NOW IN CT SHOULD NOT IMPACT ANY TAF SITES THIS EVE. KGON COULD BE IMPACTED IF THERE IS ADDITIONAL DEVELOPMENT AHEAD OF THE COMPLEX. 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: WINDS MAY SHIFT TO AROUND 230 TRUE WITH GUSTS UP TO AROUND 20KT THRU 2Z. KLGA FCSTER COMMENTS: OCNL GUSTS POSSIBLE AFT 01Z. KEWR FCSTER COMMENTS: OCNL GUSTS POSSIBLE AFT 01Z. KTEB FCSTER COMMENTS: GUSTS MAY ONLY BE OCNL THIS EVE. KHPN FCSTER COMMENTS: WINDS MAY SHIFT TO AROUND 230 TRUE BEFORE BECOMING VRB TNGT. 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... DENSE FOG ADVISORY CONTINUES UNTIL 00Z FOR CENTRAL AND EASTERN OCEAN...PECONIC AND GARDINER BAYS...AND EASTERN SOUND. 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...DENSE FOG ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ330-340- 350-353. && $$ SYNOPSIS...JP/DS NEAR TERM...JP/DS SHORT TERM...DS LONG TERM...JP AVIATION...JMC/NV MARINE...JP/DS HYDROLOGY...JP/DS

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