Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 310145 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 945 PM EDT SUN AUG 30 2015 .SYNOPSIS... A SURFACE TROUGH WILL MOVE INTO THE REGION OVERNIGHT AND MOVE SOUTH OF LONG ISLAND MONDAY. A BACK DOOR COLD FRONT MOVES ACROSS LATE MONDAY NIGHT. HIGH PRESSURE WILL KEEP HOT AND HUMID CONDITIONS ACROSS THE REGION THROUGH MUCH OF THE WEEK. A WEAK COLD FRONT WILL MOVE THROUGH THURSDAY NIGHT...BUT IT WILL STILL BE WARM AND MAINLY DRY THROUGH NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... FORECAST IS GENERALLY ON TRACK. ADJUSTED POPS A BIT BASED ON LATEST SHOWER DEVELOPMENT AND ALSO MADE MINOR ADJUSTMENTS TO T/TD/WIND AND SKY GRIDS TO BETTER REFLECT CURRENT CONDS AND TRENDS. MID LEVEL SHORTWAVE AND ASSOCIATED HIGHER PVA MOVE MOSTLY SOUTH OF THE REGION WITH A STRONGER ONE TRACKING ACROSS SOUTHEAST CANADA. AT THE SURFACE...THERE WILL BE A WEAK SURFACE TROUGH MOVING TOWARDS THE REGION. THIS WILL KEEP AN ABUNDANCE OF CLOUDS OVERHEAD FOR THE NIGHT. THE LOWS WERE TAKEN FROM THE RELATIVELY WARMER SIDE OF GUIDANCE OF THE MAV MOS...WITH VALUES EXPECTED TO BE WARMER THAN THE PREVIOUS NIGHT WITH SOUTHWEST FLOW. COOLING TEMPERATURES WITH COVERAGE OF ANY CONVECTION REMAINING DECREASING INTO THIS EVENING. HOWEVER...THE ENVIRONMENT WILL STILL BE SOMEWHAT UNSTABLE WITH SOME ELEVATED INSTABILITY AHEAD OF THE SURFACE TROUGH. WITH THESE AFOREMENTIONED FACTORS...THERE WILL BE A SLIGHT CHANCE FOR SHOWERS AND THUNDERSTORMS FOR TONIGHT ACROSS ALL LOCATIONS. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... THE SHORTWAVE WEAKENS SOUTH OF THE REGION MONDAY. A HIGH AMPLITUDE RIDGE FROM THE WEST WILL BEGIN TO BUILD IN. HOWEVER...AT THE SURFACE...THE TROUGH WILL REMAIN AND THE DAYTIME SHOULD ENHANCE IT WITH THE SEA BREEZE GIVING SOME INCREASE IN THE TEMPERATURE GRADIENT WITHIN THE REGION ACROSS THE COAST. THE COOLER TEMPS WILL BE ADVECTED INTO THE REGION FROM THE MORE SOUTHERLY FLOW. THIS WILL CONVERGE AGAINST PLACES THAT HAVE SOUTHWEST FLOW. THE POPS OVERALL WILL NOT BE HIGH...JUST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS CLOSE TO THE COAST...BUT WITH THE AIRMASS BECOMING INCREASINGLY WARM AND HUMID...INSTABILITY WILL BE LARGER AS CAPE INCREASES TO APPROXIMATELY 500-1000 J/KG. INLAND...DRIER CONDITIONS SHOULD PREVAIL. AN OVERALL VERY WARM DAY EXPECTED. A MAV/MET BLEND WAS USED FOR HIGHS...YIELDING VALUES FROM THE MID 80S TO LOWER 90S ACROSS A MAJORITY OF THE REGION. ONCE THE HEATING WANES DOWN FOR MONDAY EVENING...THE ENVIRONMENT WILL BECOME MORE STABLE AND THE HIGH AMPLITUDE RIDGE FROM THE WEST WILL CONTINUE TO BUILD IN. THE SURFACE TROUGH WILL HAVE PUSHED SOUTH OF LONG ISLAND. THERE WILL BE A WEAK BACK DOOR COLD FRONT MOVING ACROSS LATE. OVERALL...THE GREATER INFLUENCE WILL BE FROM THE RIDGE AND THE SUBSIDENCE FROM THE RIDGING WILL LEAD TO LESSENING CLOUDS. HOWEVER...DESPITE LIGHT WINDS...LOWS WILL NOT CHANGE TOO MUCH COMPARED TO THE PREVIOUS NIGHT. THE RELATIVELY WARM AND HUMID AIRMASS WILL REMAIN THOUGH AS WARM AIR ADVECTION INCREASES AT THE 850MB LEVEL. THERE IS A MODERATE RISK FOR THE DEVELOPMENT OF RIP CURRENTS ON MONDAY. && .LONG TERM /TUESDAY THROUGH SUNDAY/... THE MAIN THEME OF THE LONG TERM PERIOD WILL BE THE CONTINUATION OF HEAT AND HUMIDITY ACROSS THE REGION. MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE H5 PATTERN ACROSS NOAM THROUGH THE PERIOD. A LATE SEASON HEAT WAVE IS EXPECTED FOR PARTS OF THE TRI-STATE AREA THIS WEEK AS A DEEP LAYERED RIDGE ENCOMPASSES THE EASTERN US. A SLY FLOW FOR MUCH OF THE WEEK WILL KEEP HUMIDITY LEVELS HIGH AS WELL. THE HOTTEST DAY...HEAT AND HUMIDITY COMBINED LOOKS TO BE THURSDAY WITH MOISTURE POOLING AHEAD OF A WEAK COLD FRONT. NOT EXPECTING HEAT ADVSY CRITERIA TO BE MET...ALTHOUGH HEAT INDICES WILL RANGE BETWEEN THE UPPER 80S TO LOWER 90S EACH AFTERNOON THROUGH WED WITH 90 TO 95 ON THU. ALTHOUGH PARTS OF NYC MAY REACH A 95 DEGREE HEAT INDEX THU...NOT EXPECTING IT FOR 2 CONSECUTIVE DAYS. THEREFORE...NO ADVSY IS ANTICIPATED FOR THE CITY EITHER. IT WILL BE A FAIRLY DRY WEEK WITH ONLY A FEW SHOWERS/TSTMS WITH THE WEAK BOUNDARY THU/THU EVE AND AGAIN FRI/FRI EVE AS ANOTHER WEAK BOUNDARY APPROACHES FROM THE N...THIS TIME WITH WEAK SHORTWAVE ENERGY. THE FLOW BECOMES ELY FRI...BUT THE COMBINATION OF THE UPPER ENERGY...LOW LEVEL CONVERGENCE AND THE OROGRAPHIC INFLUENCE COULD TRIGGER A FEW SHOWERS/TSTMS. THE ONSHORE FLOW WILL ALSO PROVIDE SOME RELIEF FROM THE HEAT ESPECIALLY AT THE COAST FRI THROUGH SUN. TEMPS WILL STILL BE 5 TO 10 DEGREES ABOVE NORMAL THOUGH. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... A WEAK TROUGH OF LOW PRESSURE WILL CROSS THE TRI-STATE THIS EVENING...THEN STALL OUT SOUTH OF LONG ISLAND INTO MONDAY. VFR CONDITIONS ARE ANTICIPATED THROUGH THE TAF PERIOD. AN ISOLATED SHOWER OR THUNDERSTORM CANNOT BE RULED OUT...BUT CONFIDENCE VERY LOW FOR ANY ACTIVITY TO IMPACT ANY PARTICULAR AIRPORT. WILL AMEND AS NECESSARY. LIGHT SW OR VARIABLE WINDS ARE FORECAST FOR TONIGHT. WSW-WNW WINDS AT AROUND 10 KT DEVELOP BY MID TO LATE MONDAY MORNING AND INTO EARLY MONDAY AFTERNOON. WIND SPEEDS SHOULD INCREASE DURING THE AFTERNOON...10 TO 15 KT. OCCASIONAL GUSTS TO 20 KTS POSSIBLE...ESPECIALLY AT KJFK. .OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY... .MONDAY NIGHT-WEDNESDAY NIGHT...VFR. AFTERNOON SEABREEZES PROBABLE EACH AFTERNOON. .THURSDAY...MOST LIKELY VFR. ISOLATED SHOWERS/THUNDERSTORMS POSSIBLE. AFTERNOON SEABREEZES PROBABLE. .THURSDAY NIGHT...VFR. .FRIDAY...MOST LIKELY VFR. E WINDS G15-20KT POSSIBLE. ISOLATED- SCATTERED SHOWERS/THUNDERSTORMS POSSIBLE. && .MARINE... PRIMARILY A WEAK PRESSURE GRADIENT THROUGH MON NIGHT. THE WINDS WILL BE MAINLY LESS THAN 15 KT OUT OF THE SOUTHWEST TO SOUTH. THERE COULD BE A ROUND OF GUSTS MONDAY AFTERNOON BUT THESE ARE EXPECTED TO BE UP TO 20 KT. SEAS ON THE OCEAN MAY GET TO 5 FT MONDAY NIGHT. HOWEVER...WITH THE WEAK PRESSURE GRADIENT...DID NOT THINK WINDS WOULD SUPPLY A STRONG ENOUGH FETCH TO INCREASE SEAS TO 5 FT. THEREFORE CAPPED THE OCEAN SEAS AT 4 FT MONDAY NIGHT. SUB-ADVSY CONDS ARE EXPECTED ON ALL WATERS THROUGH THE REMAINDER OF THE PERIOD. && .HYDROLOGY... ANY SHOWER OR THUNDERSTORM THROUGH MONDAY COULD RESULT IN A BRIEF HEAVY DOWNPOUR...WITH PERHAPS A QUICK QUARTER OF AN INCH IN RAINFALL AMOUNTS. THERE COULD BE SOME LOCALLY MINOR FLOODING BUT CONFIDENCE IN THIS IS LOW WITH COVERAGE OF CONVECTION FORECAST BEING LOW. OVERALL...NO WIDESPREAD SIGNIFICANT RAINFALL IS FORECAST THROUGH NEXT WEEKEND. && .TIDES/COASTAL FLOODING... WITH A RECENT FULL MOON...BRIEF MINOR INUNDATION IS POSSIBLE DURING THE TIMES OF HIGH TIDE ACROSS THE TYPICALLY VULNERABLE COASTAL LOCALES FOR THE START OF THE WORK WEEK. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$

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