Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 270607 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 207 AM EDT WED MAY 27 2015 .SYNOPSIS... BERMUDA HIGH REMAINS ANCHORED WELL OFF THE EAST COAST THROUGH THURSDAY. A WEAK COLD FRONT WILL APPROACH THE AREA FROM THE WEST WEDNESDAY NIGHT...AND DISSIPATE ACROSS THE AREA ON THURSDAY. A STRONGER COLD FRONT WILL THEN IMPACT THE AREA SUNDAY INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... FORECAST IS GENERALLY ON TRACK. REMOVED POPS OVERNIGHT AS FORCING LOOKS VERY WEAK. FOG HAS DEVELOPED IN NORTHERN PORTIONS OF ORANGE COUNTY WHERE DEWPOINTS SPIKED INTO THE 70S AFTER THE SHOWERS EXITED. WINDS ARE CALM AND SHOULD REMAIN THIS WAY...SO ADDED FOG TO THE FORECAST UP THERE THROUGH THE NIGHT. IT COULD BECOME LOCALLY DENSE AT TIMES. PATCHY FOG IS POSSIBLE ELSEWHERE TOWARDS MORNING. THERE IS A LOW CHANCE THAT FOG BECOMES LOCALLY DENSE NEAR THE COAST...BUT IT REMAINS UNCERTAIN HOW WIDESPREAD THIS WOULD END UP BEING. THERE IS A GREATER LIKELIHOOD FOR STRATUS TO DEVELOP WITH PERSISTENT ONSHORE FLOW...ESPECIALLY NEAR THE COAST. SKY CONDITIONS SHOULD REMAIN MOSTLY CLEAR TO PARTLY CLOUDY UNTIL THEN. LOW TEMPERATURES WILL BE IN THE MIDDLE AND UPPER 60S. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/... POTENTIAL FOR CONVECTION INCREASES ON WEDNESDAY AS THE UPPER LEVEL RIDGE BEGINS TO MOVE FURTHER OFFSHORE. THE DEVELOPMENT OF A PRE- FRONTAL/THERMAL TROUGH WILL PROVIDE A SOURCE FOR LIFT IN THE AFTERNOON...MAINLY NORTH AND WEST OF THE CITY. CAPE VALUES IN THE MODELS DIFFER IN THE AFTERNOON AND THIS IS DUE TO HOW MUCH HEATING THEY FORECAST. THE NAM HAS MUCH HIGHER SURFACE BASED CAPE WITH ITS WARMER SURFACE TEMPERATURES IN COMBINATION WITH DEW POINTS IN THE MID 60S. FEEL CAPE VALUES MAY BE A BIT TOO HIGH IN THE NAM...BUT IT HAS THE RIGHT IDEA WITH ITS WARMER TEMPERATURES LEADING TO HIGHER AMOUNTS OF INSTABILITY. ANY MORNING CLOUDS WILL BREAK LATE MORNING AND EARLY AFTERNOON TO ALLOW FOR ENOUGH SUNSHINE TO REALIZE THIS HIGHER INSTABILITY. SHOWERS AND STORMS SHOULD DEVELOP IN THE AFTERNOON AND LINGER INTO THE AFTERNOON WITH THE ABOVE IN MIND. SPC HAS THE INTERIOR OF NE NJ AND THE LOWER HUDSON VALLEY IN A MARGINAL RISK FOR SEVERE THUNDERSTORMS. AN ISOLATED SEVERE WIND GUST CANNOT BE RULED OUT HERE...BUT FEEL STORMS SHOULD REMAIN BELOW SEVERE LIMITS. LOCALLY HEAVY RAINFALL IS POSSIBLE IN ANY STORM WITH URBANIZED MINOR FLOODING A POSSIBILITY. CHANCE POPS CONTINUE FOR MAINLY WEST OF THE HUDSON RIVER. THE QUESTION FOR WEDNESDAY EVENING IS HOW FAR EAST THE CONVECTION GETS. THE MARINE INFLUENCE AND PROXIMITY OF THE UPPER RIDGE WILL MOST LIKELY WEAKEN THE STORMS CONSIDERABLY AS THEY MOVE NEAR THE HUDSON RIVER. NO HIGHER THAN SLIGHT CHANCE POPS FORECAST IN THE EVENING EAST OF THE HUDSON. POPS DO INCREASE TO LOW CHANCE FOR EASTERN ZONES OVERNIGHT AS THE PRE-FRONTAL TROUGH REMAINS NEARBY AND ELEVATED INSTABILITY COULD PROMOTE DEVELOPMENT OF A FEW SHOWERS/STORMS. HIGH TEMPERATURES ON WEDNESDAY WILL BE IN THE MID AND UPPER 80S FROM NYC NORTH AND WEST AND MAINLY MIDDLE AND UPPER 70S ACROSS SOUTHERN CT AND LONG ISLAND. LOWS WEDNESDAY NIGHT WILL BE IN THE 60S. THERE IS A MODERATE RISK FOR THE DEVELOPMENT OF RIP CURRENTS AT ATLANTIC OCEAN BEACHES ON WEDNESDAY. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... A HIGH AMPLITUDE RIDGE ALONG THE EASTERN SEABOARD WILL EXPAND WESTWARD BACK INTO THE MS RIVER VALLEY AS SHORT WAVE ENERGY OVER THE GREAT LAKES DAMPENS AND LIFTS TO THE NE THU. THIS WILL ALLOW THE SUB TROPICAL RIDGE TO REMAIN IN PLACE THROUGH NEXT WEEKEND...PUMPING IN WARM...HUMID AIR ACROSS THE REGION. A WEAK COLD FRONT WILL MOVE ACROSS THE AREA ON THU BEFORE DISSIPATING OFFSHORE ON FRI. THERE MAY BE A FEW SHOWERS OR THUNDERSTORMS THROUGH THU EVE...BUT DRY AIR LOOKS TO BE A LIMITING FACTOR. HEIGHTS BUILD ALOFT FRI INTO SAT WITH STRONG SUBSIDENCE CAPPING THE AIRMASS. ANY CONVECTION WILL BE ISOLATED...DIURNAL IN NATURE...AND LIKELY WELL INLAND. FORECAST DILEMMA REMAINS THE TIMING OF A STRONGER COLD FRONT SAT NIGHT INTO SUN. THE 12Z OPERATIONAL GFS STILL REMAINS THE FASTER...AND MORE AGGRESSIVE SOLUTION. HOWEVER...DEFERRED TO THE SLOWER ECMWF WHICH HAS MAINTAINED THE BEST RUN-TO-RUN CONTINUITY. THE ECMWF DOES NOT BRING THE FRONT THROUGH UNTIL SUN AFT AND THEN KEEPS IT IN CLOSE PROXIMITY THROUGH EARLY NEXT WEEK. THERE IS THE POTENTIAL FOR AN ORGANIZED RAINFALL EVENT LATE IN THE WEEKEND INTO EARLY NEXT WEEK AS THE COLD FRONT MOVES INTO THE AREA. CONDITIONS WILL REMAIN UNSEASONABLY WARM THROUGH SAT...THEN COOLS DOWN SUN INTO MON BEHIND THE COLD FRONT. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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A WEAK COLD FRONT WILL APPROACH THE REGION TODAY...AND DISSIPATE OVER THE AREA THU. MAINLY VFR THIS MRNG...HOWEVER THERE IS THE POTENTIAL FOR SOME POCKETS OF STRATUS AND BR WHICH COULD BRING MVFR. ANY MVFR BURNS OFF BY 13-15Z EXCEPT KGON WHERE THERE IS THE POTENTIAL THAT IT COULD LINGER MOST IF NOT ALL OF THE DAY. OTHERWISE...AFTN TSTMS LIKELY TO DEVELOP ACROSS THE LOWER HUDSON VALLEY AFT 18Z. THE ACTIVITY MAY HOLD TOGETHER TO IMPACT AREAS ROUGHLY ALONG AND W OF A KHPN-KEWR LINE. MVFR OR LOWER AT TIMES TNGT WITH STRATUS AND POSSIBLY FOG. SW FLOW THRU THE TAF PERIOD. HIGHEST SPEEDS THIS AFTN INTO EARLY EVE...ESPECIALLY INVOF KJFK WHERE SUSTAINED AROUND 20KT EXPECTED. .OUTLOOK FOR 06Z THURSDAY THROUGH SUNDAY... .LATE WED NGT...MVFR OR LOWER AT TIMES WITH SW FLOW. .THU...MRNG MVFR OR LOWER. SCT TSTMS POSSIBLE INVOF A WEAKENING COLD FRONT. SW FLOW DIMINISHING AND POSSIBLY BECOMING NW OR VRB. .FRI...VFR WITH LGT NE WINDS VEERING THRU THE DAY. .SAT...MRNG MVFR OR LOWER POSSIBLE. CHC SHWRS AND TSTMS IN THE AFTN AND OVERNIGHT WITH MVFR OR LOWER. STRONG SLY FLOW. .SUN...POSSIBLE IMPROVEMENT TO VFR. NE WINDS.
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&& .MARINE... LOOKING AT OBSERVATIONS AROUND THE GREAT SOUTH BAY...FREQUENT WIND GUSTS TO 25 KT HAVE COME TO AN END...SO WILL ALLOW THE SMALL CRAFT ADVISORY FOR THE SOUTH SHORE BAYS OF LONG ISLAND TO EXPIRE AS SCHEDULED. OTHERWISE...THE SCA ON THE OCEAN WATERS CONTINUES THROUGH WEDNESDAY NIGHT. WIND GUSTS AROUND 25 KT AT 44065 WILL DECREASE OVER THE NEXT FEW HOURS AND THEN INCREASE AGAIN ON WEDNESDAY AND WEDNESDAY EVENING WITH PROLONGED SOUTHERLY FLOW. SEAS WILL ALSO BUILD TO 5 FT TONIGHT AND REMAIN NEAR 5 FT THROUGH WEDNESDAY NIGHT. WINDS MAY ALSO APPROACH SCA LEVELS ON THE NY HARBOR AND SOUTH SHORE BAYS AGAIN ON WEDNESDAY AFTERNOON. THERE IS ALSO THE POTENTIAL FOR AREAS OF DENSE FOG TO FORM ON THE WATERS LATE TONIGHT INTO WEDNESDAY MORNING. CONFIDENCE REMAINS LOW ON THIS AND FOR NOW HAVE CONTINUED TO FORECAST PATCHY FOG. MARGINAL SCA CONDITIONS ON THE OCEAN WATERS POSSIBLE THU-SUN WITH A MODERATE SLY FLOW. THERE WILL BE A BRIEF PERIOD OF OFFSHORE WINDS THU NIGHT BEHIND A DISSIPATING COLD FRONT. && .HYDROLOGY... GENERALLY LESS THAN TWO TENTHS OF AN INCH OF BASIN AVERAGE RAINFALL IS EXPECTED THROUGH WEDNESDAY. HOWEVER ANY STRONGER CONVECTION THAT FORMS...ESPECIALLY IF THERE IS ANY TRAINING OF STORMS...COULD LEAD TO MINOR FLOODING OF URBAN AND/OR POOR DRAINAGE AREAS. THERE IS THE POTENTIAL FOR AN ORGANIZED RAINFALL EVENT LATE IN THE WEEKEND INTO EARLY NEXT WEEK AS COLD FRONT MOVES INTO THE AREA. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ350-353- 355. && $$ SYNOPSIS...DS/DW NEAR TERM...DS SHORT TERM...DS LONG TERM...DS/DW AVIATION...JMC MARINE...DS/DW HYDROLOGY...DS/DW

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