Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 221424 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1024 AM EDT TUE JUL 22 2014 .SYNOPSIS... AS A HIGH PRESSURE SYSTEM MOVES SLOWLY EAST OF THE AREA TODAY...A COLD FRONT WILL APPROACH FROM THE WEST ON WEDNESDAY. THE COLD FRONT CROSSES THE AREA FROM WEDNESDAY NIGHT INTO THURSDAY MORNING...FOLLOWED BY HIGH PRESSURE BUILDING TO THE SOUTH OF LONG ISLAND INTO SATURDAY. A STORM SYSTEM THEN IMPACTS THE AREA INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... FORECAST REMAINS ON TRACK. WITH HIGH PRES OVER THE REGION...SKIES WILL BE SUNNY WITH TEMPS A FEW DEGREES ABOVE NORMAL...TOPPING OFF IN THE MID TO UPPER 80S...POSSIBLY AROUND 90 WEST OF THE HUDSON RIVER. ATLANTIC OCEAN AND LONG ISLAND SOUND SEA BREEZES WILL DEVELOP BY NOON. WIND SPEEDS WILL BE 10 KT OR LESS. WILL ALSO CONTINUE A LOW CHANCE FOR POPS...30 PERCENT OR LESS...FOR SHOWERS/TSTMS THIS AFTERNOON FOR AREAS NW OF NYC. BRIEF...HEAVY DOWNPOURS ARE POSSIBLE. THERE IS A MODERATE RISK OF RIP CURRENTS...MAINLY THIS AFTERNOON THROUGH EVENING WITH ENHANCED SEA BREEZE DEVELOPMENT AND LONG PERIOD SE SWELLS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... TONIGHT...SW WINDS WILL CONTINUE TRANSPORTING HIGHER DEW POINTS ACROSS THE REGION MAKING IT FEEL UNCOMFORTABLE. WEDNESDAY...SUMMER HEAT AND HUMIDITY RETURNS WITH DAY TIME HIGH TEMPS REACHING AROUND 90 ACROSS NYC AND URBAN NORTHEAST NJ AND WITH HEAT INDEX VALUES RISING INTO THE MID AND UPPER 90S. NO EXTENDED HEAT WAVE IS FORECAST AS THE NEXT COLD FRONT APPROACHES. A WARM MOIST UNSTABLE MARITIME TROPICAL AIR MASS WILL SET THE STAGE FOR THE DEVELOPMENT OF MORE NUMEROUS SHOWERS AND TSTMS BY WED AFTERNOON MAINLY WEST AND NORTH OF NYC. INCREASED POPS TO LIKELY CATEGORY BY 6 PM. PRIMARY POTENTIAL HAZARD IS HEAVY RAIN WHICH COULD CAUSE ISOLATED FLASH FLOODING MAINLY OF LOW LYING POOR DRAINAGE AREAS. CAN NOT RULE OUT THE POTENTIAL FOR A STRONG TO POSSIBLY SEVERE TSTM WITH DAMAGING WINDS BEING THE PRIMARY THREAT. BECAUSE MORE WIDESPREAD FLASH FLOODING OR SEVERE STORMS ARE NOT FORECAST...A HAZARDOUS WEATHER OUTLOOK WILL NOT BE ISSUED AT THIS TIME FOR THESE POTENTIAL HAZARDS. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... HAVE THE POTENTIAL FOR SIGNIFICANT CONVECTION WEDNESDAY NIGHT...WITH THE PASSAGE OF A SURFACE COLD FRONT THROUGH A RATHER WARM AND HUMID AIR MASS. THERE ARE SOME INDICATIONS THAT CAPES OF 1000-1500 J/KG COULD PERSIST AT LEAST THROUGH WEDNESDAY EVENING...AND SHOWALTER INDICES OF 0 TO -2 PERSIST THROUGH THE NIGHT...ESPECIALLY OVER EASTERN PORTIONS. THIS COUPLED WITH THE REGION AT THE MINIMUM INT HE RIGHT REAR QUADRANT OF A 80+ KT UPPER LEVEL JET...AND POSSIBLY IN A COUPLED UPPER JET REGION - DEPENDING ON THE EXACT LOCATION OF THE SUBTROPICAL JET. MODELS DUE VARY ON THE LOCATION/STRENGTH OF THE LATTER. 0-6 KM BULK SHEAR IS FORECAST TO INCREASE TO 25-35 KT DURING THE EVENING SO THERE COULD BE SUFFICIENT SHEAR/CAPE FOR ISOLATED SUPER CELLS DURING THE EVENING MAINLY ACROSS NYC/NE NJ/S CT/LOWER HUDSON VALLEY ZONES. AS SUCH THERE IS THE POTENTIAL FOR STRONG TO POSSIBLY SEVERE STORMS WEDNESDAY NIGHT...MAINLY PRIOR TO 6Z. MODELS DO DIFFER ON AMOUNT/EXTENT OF PRECIPITATION ON THURSDAY DUE TO DIFFERENCES IN TIMING OF 850 HPA COLD FRONT. NAM/SREF ARE THE SLOWEST WITH THIS FEATURE. GIVEN THE PROPENSITY FOR COLD FRONTS TO HANG UP CROSSING THE MOUNTAINS...SLOWER PROGRESSION OF THE 850 COLD FRONT MAKES SOME SENSE...SO DID WEIGH POPS AND CONVECTIVE PROBABILITIES MORE TOWARDS THIS LINE OF THINKING. HOWEVER...THERE SHOULD NOT BE ENOUGH INSTABILITY FOR ANY STRONG OR SEVERE STORMS ON THURSDAY. HAVE LINGERED SLIGHT CHANCE POPS INTO THURSDAY EVENING ACROSS FAR SE ZONES...THIS MIGHT BE A TAD TOO LONG ULTIMATELY...BUT WITH OVERALL TREND WITH FRONTAL TIMING A TAD SLOWER THAN PREVIOUS FORECAST...CANNOT RULE OUT PRECIPITATION LASTING A TAD LONGER THAN CURRENTLY EXPECTED. SEE THE HYDROLOGY SECTION OF THE AFD FOR RAINFALL AMOUNTS AND POTENTIAL IMPACTS FROM TONIGHT INTO THURSDAY. FOR LOWS WEDNESDAY NIGHT USED A BLEND OF MAV/MET GUIDANCE WITH NAM 2-METER TEMPERATURES THEN ADDED A DEGREE TO WEIGH TOWARDS WARMER SOLUTIONS - WITH VALUES FORECAST TO BE A FEW DEGREES ABOVE NORMAL. FOR HIGHS THURSDAY USED A BLEND OF MIXING DOWN FROM 950-875 HPA PER BUFKIT SOUNDINGS...WITH NAM 2-METER TEMPERATURES AND A BLEND OF MAV/MET GUIDANCE...THEN ADDED 2 DEGREES TO WEIGH TOWARDS WARMER SOLUTIONS. EXPECT HIGHS TO BE AROUND A FEW DEGREES BELOW NORMAL. FOR LOWS THURSDAY NIGHT USED A BLEND OF MEX/EKD/ECE/ECM/WPC GUIDANCE WITH NAM 2-METER TEMPERATURES - WITH VALUES A FEW DEGREES BELOW NORMAL. THE REGIONS WEATHER FRIDAY-MONDAY WILL LARGELY BE DETERMINED BY THE EXACT POSITION/STRENGTH OF A RATHER LARGE CUTOFF LOW OVER EASTERN CANADA...AND WHEN SPOKES OF ENERGY ROTATING AROUND ITS BASE PASS THROUGH THE REGION. FOR NOW...IT APPEARS THE REGION SHOULD BE BETWEEN SPOKES FRIDAY AND FRIDAY NIGHT AND POSSIBLY INTO SATURDAY. SO FOR NOW HAVE GONE WITH A DRY FORECAST FROM FRIDAY-SATURDAY NIGHT. HOWEVER...THERE ARE SOME INDICATIONS THAT A SMALL SHORTWAVE COULD PASS THE AREA ON SATURDAY...POSSIBLY TRIGGERING SOME -SHRA ON SATURDAY. CONFIDENCE IN THIS IS TOO LOW TO REFLECT IN THE FORECAST AT THIS TIME. BASED ON MODEL CONSENSUS...AM MORE CONFIDENT IN A PERIOD OF UNSETTLED WEATHER SUNDAY...SUNDAY NIGHT AND MONDAY. IT WILL NOT RAIN THE ENTIRE TIME...IN FACT MOST AREAS WILL BE DRY FOR MORE TIME DURING THIS TIME FRAME THAN IT WILL RAIN AT ANY GIVEN LOCATION. GIVEN DIFFICULTY IN TIMING OF SHORTWAVE ROTATING AROUND A CUTOFF LOW THIS FAR OUT...YET ALONE INHERENT UNCERTAINTY IN MODELS HANDLING OF A CUTOFF LOW THIS FAR OUT...DO NOT WANT TO EVEN ATTEMPT ANY SORT OF TIMING - SO HAVE CHANCE POPS SUNDAY-MONDAY. FOR TEMPERATURES FRIDAY-MONDAY USED A BLEND OF MEX/EKD/ECE/ECM/WPC GUIDANCE WITH HIGHS RUNNING BELOW NORMAL...AND LOWS STARTING OUT BELOW NORMAL AND TRENDING TO NEAR NORMAL. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... HIGH PRESSURE WILL SLOWLY MOVE OFFSHORE TODAY. VFR WITH LIGHT W/SW FLOW THIS MORNING. SEA BREEZE LATE THIS MORNING INTO AFTERNOON. TIMING COULD BE OFF +/- 1-2 HOURS FROM TAF. MEDIUM CONFIDENCE SEA BREEZE MAKES IT TO KEWR/KTEB...RESULTING IN WIND DIR AROUND 170-180 TRUE BY LATE AFTERNOON. A SHRA POSSIBLE ACROSS INTERIOR LATE AFTERNOON INTO EARLY EVENING. CONFIDENCE FAIRLY LOW THOUGH...SO ONLY VCSH AT KSWF. ...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: TIMING OF SEA BREEZE MAY BE OFF +/- 1 HOUR. KLGA FCSTER COMMENTS: TIMING OF SEA BREEZE MAY BE OFF +/- 2 HOURS. GUSTS INDICATED IN TAF MAY BE MORE OCCASIONAL IN FREQUENCY. KEWR FCSTER COMMENTS: MEDIUM CONFIDENCE IN SEA BREEZE REACHING TERMINAL THIS AFTERNOON. IF IT DOES NOT...WIND DIR WILL STAY CLOSER TO 220 TRUE. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: MEDIUM CONFIDENCE IN SEA BREEZE REACHING TERMINAL THIS AFTERNOON. IF IT DOES NOT...WIND DIR WILL STAY CLOSER TO 220 TRUE. KHPN FCSTER COMMENTS: TIMING OF SEA BREEZE MAY BE OFF +/- 2 HOURS. KISP FCSTER COMMENTS: TIMING OF SEA BREEZE MAY BE OFF +/- 1 HOUR. .OUTLOOK FOR 12Z WED THROUGH SAT... .WED...PRIMARILY VFR. BRIEF MVFR VSBY POSSIBLE EARLY WED...ESP INTERIOR AND EASTERN TERMINALS. ISOLATED SHRA/TSTM NW OF THE NY METRO LATE. .WED NIGHT-THU...SLOW MOVING COLD FROPA. MVFR OR LOWER CONDS IN SCT-NUMEROUS SHOWERS/TSTMS. .THU NIGHT-SAT...VFR. && .MARINE... MADE MINOR CHANGES THIS UPDATE TO REFLECT THE LATEST TRENDS IN OBSERVATIONS AND GUIDANCE. FORECAST APPEARS ON TRACK. WINDS AND SEAS ARE FORECAST TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS OF 25 KT AND 5 FT THROUGH WEDNESDAY MORNING. OCCASIONAL GUSTS TO 25 KT ARE POSSIBLE ON MAINLY THE OCEAN WATERS WEDNESDAY AFTERNOON. SUSTAINED WINDS UP TO 15 KT ARE LIKELY WEDNESDAY NIGHT AHEAD OF A COLD FRONT. FOR NOW APPEARS GUSTS AND SEAS SHOULD STAY BELOW SMALL CRAFT THRESHOLDS. THE PRESSURE GRADIENT THEN RELAXES OVER THE REGION THURSDAY AND REMAINS LIGHT INTO SATURDAY. AS A RESULT EXPECT WINDS OF 10 KT OR LESS FROM THURSDAY THROUGH SATURDAY...WITH SEAS 4 FT OR LESS ON THE COASTAL OCEAN WATERS AND 1 FT OR LESS ELSEWHERE. && .HYDROLOGY... MAINLY DRY THROUGH WEDNESDAY MORNING...THOUGH A BRIEF LOCALLY HEAVY DOWNPOUR IS POSSIBLE IN ANY STRONGER CONVECTION THIS AFTERNOON. THIS BEST CHANCE FOR THIS IS TO THE N/W OF NYC. THERE IS THE POTENTIAL FOR AROUND 1/2 INCH OF RAINFALL FROM LATE WEDNESDAY THROUGH THURSDAY WITH LOCALLY HIGHER AMOUNTS POSSIBLE. PRECIPITABLE WATERS ARE FORECAST TO BE AROUND 2 INCHES ON WEDNESDAY NIGHT...SO LOCALLY HEAVY RAINFALL IS POSSIBLE IN ANY STRONGER CONVECTION. AREAS EXPERIENCING LOCALLY HEAVY RAINFALL COULD EXPERIENCE AT LEAST MINOR FLOODING OF URBAN/POOR DRAINAGE AREA...AND POSSIBLY LOCALIZED FLASH FLOODING. THE CONFIDENCE IN THE LATTER IS CURRENTLY LESS THAN 30 PERCENT SO WILL NOT HIGHLIGHT IN THE HAZARDOUS WEATHER OUTLOOK. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...GC/MALOIT NEAR TERM...GC/MALOIT/MPS SHORT TERM...GC LONG TERM...MALOIT AVIATION...BC/PICCA MARINE...GC/MALOIT HYDROLOGY...GC/MALOIT

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