Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 301449 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1049 AM EDT THU JUL 30 2015 .SYNOPSIS... A COLD FRONT APPROACHES THE REGION TODAY AND MOVES ACROSS TONIGHT. WEAK HIGH PRESSURE FOLLOWS FOR FRIDAY. MULTIPLE WEAK COLD FRONTS OR TROUGHS WILL MOVE ACROSS THE AREA STARTING SATURDAY NIGHT AND CONTINUING INTO THE MIDDLE OF NEXT WEEK. THE STRONGEST COLD FRONTAL PASSAGE LOOKS TO BE ON TUESDAY AFTERNOON. IN BETWEEN....WEAK HIGH PRESSURE WILL PREVAIL ACROSS THE AREA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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WEAK WAVE OF SHOWERS DEVELOPED AHEAD OF THE MAIN LINE OF STORMS ACROSS NYC AND IS TRACKING INTO LONG ISLAND. NO LIGHTNING HAS BEEN DETECTED WITH THESE SHOWERS...BUT AS INSTABILITY INCREASES...WOULD EXPECT STORMS TO DEVELOP. GOING THROUGH THE AFTERNOON...THE COLD FRONT AT THE SURFACE CONTINUES TO APPROACH WITH A CONTINUED SOUTHWEST FLOW AHEAD OF IT. THIS WILL CONTINUE THE WARM AND MOIST AIR ADVECTION. PWATS GROW UP TO NEAR 2-2.2 INCHES...ALLOWING FOR HEAVY RAIN POTENTIAL WITH ANY SHOWER OR THUNDERSTORM THAT FORMS. THE CONVECTION WILL FURTHER DEVELOP AND EXPAND IN THE AFTERNOON WITH THE CLOSER PROXIMITY OF THE FRONT AND COLDER AIR ALOFT. MORE OF A CYCLONIC FLOW ALOFT ARRIVES WITH A DIGGING TROUGH INTO THE NORTHEAST. IN TERMS OF HAZARDS...HEAT ADVISORY REMAINS IN EFFECT. HEAT INDICES CAME CLOSE TO 100 DEGREES ELSEWHERE ALONG THE URBAN CORRIDORS OF NORTHEAST NEW JERSEY...SOUTHERN LOWER HUDSON VALLEY AS WELL AS SOUTHWEST CONNECTICUT. HOWEVER...WITH EXPECTATION OF INCREASING CLOUDS AND INCREASING LIKELIHOOD OF SHOWERS AND THUNDERSTORMS...KEPT TEMPS AND HEAT INDICES SLIGHTLY LOWER THAN OTHERWISE. OVERALL THOUGH A HOT AND HUMID DAY AGAIN IN STORE. THIS WILL FUEL THE CAPE WHICH WILL BE PRETTY SUBSTANTIAL...UP TO NEAR 2000 J/KG MAINLY N/W OF NYC. MODELS ALSO SHOW 0-6 KM BULK SHEAR OF 20-25 KT. MODELS ARE SHOWING EXPANSIVE CLOUDS ACROSS THE REGION WHICH WILL LIMIT THE HEATING AND INSTABILITY. HOWEVER...IF THERE IS MORE SUNSHINE THAN FORECAST...MORE AREAS COULD POTENTIALLY REACH HEAT INDEX OF 100 DEGREES. USED THE WARMER MET GUIDANCE FOR HIGHS. THERE IS A HIGH RISK OF RIP CURRENTS AT OCEAN BEACHES TODAY.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... CONVECTION ONGOING ACROSS LONG ISLAND EARLY THIS EVENING AS THE COLD FRONT MOVES ACROSS. THIS WILL DISSIPATE LATE IN THE EVENING INTO THE OVERNIGHT AS THE BULK OF CONVECTION MOVES SOUTHEAST OF LONG ISLAND WITH THE FRONT. A SHORTWAVE IN THE MID LEVELS PIVOTS AROUND THE LONGWAVE TROUGH AS MOVES NORTH OF THE REGION THROUGH THE NIGHT. THE WEATHER WILL BE DRY FRIDAY AS WEAK HIGH PRESSURE BUILDS IN FROM THE SOUTH AND WEST. THE SOURCE REGION OF THE NEXT AIRMASS WILL BE ACROSS THE SOUTH CENTRAL U.S. A CONTINUED VERY WARM BUT NOW DRIER AIRMASS WILL BUILD IN. DEWPOINTS LOWER TO UPPER 50S TO LOWER 60S FOR MUCH OF THE REGION WITH MORE OF A WEST TO NORTHWEST FLOW. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... A RATHER BENIGN PERIOD WITH A BROAD UPPER TROUGH ACROSS EASTERN CANADA AND THE NE QUARTER OF THE NATION. POLAR VORTEX DURING THIS TIME DESCENDS FROM HUDSON BAY ON SAT SE INTO ONTARIO PROVINCE BY MID WEEK. A SERIES OF DISTURBANCES IN THE UPPER FLOW WILL SEND WEAK COLD FRONTS OR TROFS ACROSS THE AREA WITH THE POTENTIAL FOR SCT CONVECTION. MDT INSTABILITY...DECENT MID LEVEL LAPSE RATES...AND SOME WIND SHEAR SUPPORTS ISOLATED STRONG CONVECTION. THE LIMITING FACTOR WILL BE MOISTURE WITH A DEEP-LAYERED W/SW FLOW. TEMPS DURING THE PERIOD WILL BE SEVERAL DEGREES ABOVE NORMAL...BUT OVERALL THE AIRMASS WILL BE DRIER THAN RECENT DAYS...SO A LITTLE LESS HUMID. TEMPS ON WED MAY BE OVERDONE A BIT AS THE GFS IS SIGNIFICANTLY COOLER WITH A SHARPER TROF AND COLD FRONT PASSING THROUGH LATE TUE. ECMWF/GGEM ARE CONSIDERABLY FLATTER AND WARMER. SUBSEQUENT TENDS IN GLOBAL MODEL RUNS WILL BE WATCHED. GEFS SUPPORTS WARMER SOLUTIONS. && .AVIATION /15Z THURSDAY THROUGH MONDAY/...
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A SOUTHERLY FLOW CONTINUES AROUND HIGH PRESSURE OFF THE MID ATLANTIC COAST AS A COLD FRONT THROUGH THE ERN GREAT LAKES AND WRN PA SLOWLY APPROACHES. VFR STILL EXPECTED TO BREAK OUT IN THE 16-17Z PERIOD. THEREAFTER...MAINLY VFR EXPECTED INTO MID AFTN. THE COLD FRONT AND A WEAK PRE-FRONTAL TROUGH WILL BE MOVING INTO THE TERMINALS AROUND 19-21Z TODAY AND MOVE THROUGH THIS EVENING. THUNDERSTORMS WILL ACCOMPANY THE FRONT WITH MVFR OR LOWER CONDITIONS. THERE IS A HIGHER CHANCE OF CONVECTION FROM THE NYC TERMINALS AND AREAS WEST. TEMPO GROUPS FOR THE 2-3 HOUR PERIOD WITH HIGHEST LIKELIHOOD OF TSTMS. ADJUSTMENTS POSSIBLE AS THE SYSTEM DRAWS CLOSER. A PERIOD OF MVFR POSSIBLE OVERNIGHT TIL THE FRONT CLEARS OUT THE LLVL MOISTURE. VARIABILITY IN WIND SPEED AND DIRECTION LIKELY INVOF SHWRS AND TSTMS. OTHERWISE...MODERATE TO HIGH CONFIDENCE IN WIND FORECAST. ...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: MVFR MAY LINGER BEYOND 16Z. KLGA FCSTER COMMENTS: MVFR MAY LINGER BEYOND 16Z. KEWR FCSTER COMMENTS: MVFR MAY LINGER BEYOND 16Z. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: MVFR MAY LINGER BEYOND 16Z. KHPN FCSTER COMMENTS: MVFR MAY LINGER BEYOND 16Z. KISP FCSTER COMMENTS: MVFR MAY REMAIN ALL DAY. .OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY... .FRIDAY-MONDAY...VFR.
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&& .MARINE... BUFKIT EXHIBITS PRETTY GOOD AGREEMENT WITH GUSTY WINDS ACROSS MUCH OF THE WATERS THIS AFTERNOON INTO EARLY THIS EVENING WITH 25 KT GUSTS ACROSS MOST WATERS. WAVEWATCH CURRENTLY VERIFYING WITHIN A FOOT OF BUOY OBS. THE OCEAN SEAS INCREASE TO 5 FEET THIS AFTERNOON IN RESPONSE TO CONTINUED SOUTHERLY FETCH AND SOUTH TO SOUTHEAST SWELL. THE SCA SEAS LAST THROUGH TONIGHT. A RETURN TO SUB SCA CONDITIONS WILL BE IN PLACE FOR FRIDAY INTO SATURDAY AS WEAK HIGH PRESSURE MOVES IN. OCEAN SEAS COULD BUILD TO AROUND 5 FT SAT NIGHT...AND THEN AGAIN LATE MON INTO TUE AHEAD OF AN APPROACHING COLD FRONT. PREVAILING FLOW WILL BE S/SW DURING THIS TIME. && .HYDROLOGY... BASIN AVG QPF OF APPROXIMATELY 1/2 INCH POSSIBLE THROUGH TONIGHT...LIKELY ACROSS INTERIOR AREAS AND LOCATIONS NEAR NYC AND TO THE NORTH AND WEST. WITH PW OVER 2 INCHES...LOCALLY HEAVY RAINFALL IS POSSIBLE WITH ANY STRONGER CONVECTION. MINOR URBAN/POOR DRAINAGE FLOODING IS THE MOST LIKELY OUTCOME. THERE WILL ALSO THOUGH BE A POSSIBILITY OF FLASH FLOODING BUT EXPECT THIS TO BE MORE ISOLATED. OTHERWISE...NO SIGNIFICANT WIDESPREAD RAIN EXPECTED. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. NY...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NYZ072>075-176- 178. HIGH RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR NYZ075- 080-081-178-179. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 8 PM EDT THIS EVENING FOR ANZ330-340-345. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ355. SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ350-353.
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&& $$ SYNOPSIS...JM/DW NEAR TERM...JM/MPS SHORT TERM...JM LONG TERM...DW AVIATION...24/JMC MARINE...JM/DW HYDROLOGY...JM/DW

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