Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 281752 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 152 PM EDT THU APR 28 2016 .SYNOPSIS... HIGH PRESSURE DRIFTS OFF THE NORTHEAST COAST THIS AFTERNOON AS LOW PRESSURE APPROACHES FROM THE OHIO VALLEY. THE LOW WILL PASS TO THE SOUTH TONIGHT INTO FRIDAY. ANOTHER WAVE OF LOW PRESSURE WILL PASS THROUGH THE REGION LATE FRIDAY INTO FRIDAY NIGHT. CANADIAN HIGH PRESSURE ACROSS THE REGION SATURDAY GIVES WAY TO AN APPROACHING LOW FOR THE REST OF THE WEEKEND. THE LOW PASSES NEAR OR JUST SOUTH OF LONG ISLAND MONDAY AND THEN EAST OF THE REGION TOWARDS NOVA SCOTIA MONDAY NIGHT. THE FRONT ASSOCIATED WITH LOW SLOWLY MOVES OFFSHORE INTO MIDWEEK AS WEAK HIGH PRESSURE BUILDS IN. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATED TEMPERATURES AND DEWPOINTS TO BETTER MATCH OBSERVED TRENDS. ALSO...LATEST OBS AND HI-RES GUIDANCE SUGGEST THAT CLOUDS WILL LOWER/THICKEN AND PRECIP ARRIVE IN MOST PLACES A LITTLE LATER THAN ORIGINALLY EXPECTED...SO CUT BACK TO CHANCE POP BY LATE AFTERNOON WEST OF NYC AND SLIGHT CHANCE FOR NYC AND IMMEDIATE BURBS. WEAK UPPER RIDGE OVER THE AREA BETWEEN A LARGE CLOSED LOW ROTATING THROUGH EASTERN CANADA AND WEAKENING LOW PRESSURE OVER NORTHERN PLAINS WILL FLATTEN THROUGH THE DAY AS THE PLAINS LOW SHEARS OUT AND MOVES INTO THE RIDGE. LIFT WILL BE WEAK AS WILL THE SURFACE LOW THAT WILL MOVE INTO THE CENTRAL APPALACHIANS BY 00Z FRIDAY. WILL CONTINUE WITH THE SLIGHT CHANCE AND CHANCE POPS...MAINLY FOR THE WESTERN ZONES LATE THIS AFTERNOON. MAY BE A PERIOD OF LIGHT RAIN OR SPRINKLES. FORECAST HIGH TEMPS TODAY ARE ABOUT 6-8 DEGREES BELOW AVG. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... WEAK UPPER TROUGH APPROACHES TONIGHT. HI-RES GUIDANCE ALSO AGREES ON ENHANCED LIFT FROM COMBO OF THE RIGHT REAR QUAD OF AN UPPER JET STREAK AHEAD OF THIS TROUGH AND H7 FRONTOGENESIS IMPACTING MAINLY INLAND SECTIONS THIS EVENING...SO RAISED POP TO LIKELY THERE. MODELS ARE RELATIVELY DRY ACROSS LONG ISLAND DURING THIS TIME...BUT STILL HELD ONTO LOW CHANCE POP THERE TO ACCOUNT FOR SOME UNCERTAINTY IN THE EXACT POSITION OF THE ABOVE MESOSCALE FEATURES...AND ALSO WITH MID LEVEL SHORTWAVE PASSING THROUGH THIS EVENING. OTHERWISE...THE UPPER FLOW SHOULD REMAINS FLAT AND NEARLY ZONAL INTO FRIDAY NIGHT. A SECOND WAVE WILL BE A LITTLE DEEPER AND SOUTH OF THE AREA. MEANWHILE AT THE SURFACE LOW PRESSURE REDEVELOPS OFF THE CAROLINA AND MID ATLANTIC COASTS TONIGHT AS THE SECOND LOW MOVES INTO THE OHIO VALLEY AND IS MERGED WITH THE COASTAL LOW FRIDAY INTO FRIDAY NIGHT. THERE MAY BE A PROLONGED DRY PERIOD FRIDAY INTO FRIDAY AFTERNOON BETWEEN THE WAVES. HOWEVER WITH THE UNCERTAINTY WILL CARRY SLIGHT CHANCE POPS AT THAT TIME. THEN POPS INCREASE...STILL CHANCE...LATE FRIDAY INTO FRIDAY NIGHT. AGAIN WILL HAVE LIGHT RAIN MENTIONED. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... UPPER LEVEL ZONAL JET STREAK WILL BE MOVING NORTH OF THE REGION SATURDAY. AN UPPER LEVEL JET STREAK REDEVELOPS AHEAD OF AN APPROACHING TROUGH SATURDAY NIGHT AND SUNDAY. THIS JET PUSHES SOUTH OF THE REGION SUNDAY NIGHT BUT REMAINS WITHIN THE VICINITY OF THE REGION GOING INTO NEXT WEEK. AT THE SURFACE...HIGH PRESSURE FROM ONTARIO BUILDS SATURDAY AND WEAKENS SATURDAY NIGHT. THIS WILL BE GIVING WAY TO AN APPROACHING AREA OF LOW PRESSURE. THE LOW AND ITS ASSOCIATED WARM FRONT LOOK TO STAY SOUTH OF THE REGION...WITH THEREFORE A PROLONGED PERIOD OF EASTERLY FLOW. RAIN RETURNS SATURDAY NIGHT AND CONTINUES THROUGH MONDAY WITH THE HIGHEST CHANCES SUNDAY AFTERNOON THROUGH MONDAY MORNING. THE NATURE OF THE RAIN LOOKS TO BE STEADY...LIGHT AND OCCASIONALLY MODERATE. THE LAYER PW VALUES ONLY REACH UP TO A LITTLE OVER AN INCH WITH THE 1.5 INCH VALUES STAYING WELL SOUTH OF THE REGION. THE RAIN TAPERS OFF MONDAY NIGHT AS THE LOW MOVES EAST OF THE REGION AND NEAR NOVA SCOTIA. MAINLY DRY CONDITIONS ARE FORECAST THEREAFTER BUT WITH THE JET STREAK ALOFT AND THE REGION STILL ON THE EASTERN SIDE OF A LONGWAVE TROUGH...SURFACE FRONT ASSOCIATED WITH THE LOW WILL NOT BE TOO FAR SOUTHEAST OF THE REGION. THEREFORE LEFT A LINGERING SLIGHT CHANCE OF SHOWERS GOING INTO THE MIDWEEK PERIOD. CONCERNING TEMPERATURES...THEY WILL AVERAGE BELOW FOR HIGHS THROUGH THE WEEKEND AND MONDAY...WITH A TREND CLOSER TO AVG FOR TUESDAY AND WEDNESDAY NEXT WEEK. THE LOWS AT NIGHT MUCH OF THE TIME PERIOD WILL STAY ABOVE AVG. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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THE REGION WILL BE BETWEEN HIGH PRES TO THE N AND A STATIONARY FRONT TO THE S THRU THE TAF PERIOD. VFR THRU THE TAF PERIOD. SOME LIGHT RAIN IS POSSIBLE BEGINNING THIS AFTERNOON AND CONTINUING TONIGHT. THE BEST CHANCES FOR STEADIER RAIN ARE NEAR THE CITY TERMINALS AND ALONG THE CONNECTICUT COAST. INCLUDED -RA IN TAFS WHERE BEST CHANCES OF THIS STEADY RAIN ARE AND -SHRA ELSEWHERE. SEA BREEZES ARE WORKING NORTH ACROSS LONG ISLAND AND SOUTHERN CONNECTICUT THIS AFTERNOON. WINDS GENERALLY FROM THE SE AT 10KT OR LESS THIS AFTERNOON...BECOMING NELY AGAIN TONIGHT. EAST WINDS DURING THE DAY ON FRIDAY. ...NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.WEATHER.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: START TIME OF LIGHT RAIN LATE THIS AFTERNOON COULD BE OFF BY 1-2 HOURS. KLGA FCSTER COMMENTS: START TIME OF LIGHT RAIN LATE THIS AFTERNOON COULD BE OFF BY 1-2 HOURS. KEWR FCSTER COMMENTS: START TIME OF LIGHT RAIN LATE THIS AFTERNOON COULD BE OFF BY 1-2 HOURS. KTEB FCSTER COMMENTS: START TIME OF LIGHT RAIN LATE THIS AFTERNOON COULD BE OFF BY 1-2 HOURS. KHPN FCSTER COMMENTS: START TIME OF LIGHT RAIN LATE THIS AFTERNOON COULD BE OFF BY 1-2 HOURS. KISP FCSTER COMMENTS: START TIME OF LIGHT RAIN LATE THIS AFTERNOON COULD BE OFF BY 1-2 HOURS. .OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY... .FRI NIGHT...VFR. CHANCE OF ADDITIONAL LIGHT RAIN LATE FRIDAY AFTERNOON OR EARLY FRIDAY EVENING. .SAT...VFR. .SUN THROUGH MON...MVFR OR LOWER POSSIBLE IN RAIN. .TUE...VFR.
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&& .MARINE... SUB-SCA CONDITIONS ARE EXPECTED TODAY WITH A WEAK PRESSURE GRADIENT IN PLACE. WITH A PERSISTENT AND INCREASING NORTHEAST TO EAST FLOW TONIGHT INTO FRIDAY NIGHT SEAS ON THE OCEAN WATERS MAY BUILD TO MINIMUM SMALL CRAFT LEVELS BY LATE FRIDAY AFTERNOON AND INTO FRIDAY NIGHT. OTHERWISE SUB SMALL CRAFT CONDITIONS ARE EXPECTED. THE WEEKEND STARTS WITH CONDITIONS STAYING BELOW SCA WITH A WEAK PRESSURE GRADIENT WITH CANADIAN HIGH PRESSURE IN PLACE. THEN A LOW APPROACHES FROM THE SOUTH AND WEST...WITH INCREASING EASTERLY FLOW SATURDAY NIGHT AND SUNDAY. THE FLOW BECOMES MORE NORTHEASTERLY INTO MONDAY. WHILE WIND GUSTS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA...THE EASTERLY FETCH WILL CAUSE OCEAN SEAS TO EVENTUALLY BUILD TO SCA LEVELS OF 5 TO 6 FT LATE SUNDAY AFTERNOON THROUGH MONDAY. && .HYDROLOGY... A TENTH TO A QUARTER INCH OF RAINFALL IS POSSIBLE FROM THIS AFTERNOON THROUGH FRIDAY NIGHT WITH THE LOWEST ACROSS SOUTHEASTERN CONNECTICUT AND THE HIGHEST ACROSS NORTHEASTERN NEW JERSEY. DRY CONDITIONS ARE EXPECTED SATURDAY. NEXT RAIN EVENT MOVES IN SATURDAY NIGHT AND CONTINUES THROUGH MONDAY...TAPERING OFF MONDAY NIGHT. RAIN AMOUNTS CARRY UNCERTAINTY BUT MODELS ARE SHOWING A GENERAL RANGE OF 0.75 TO 1.5 INCHES OF RAIN. CHANCES FOR RAIN WILL BE MINIMAL THEREAFTER. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...JM/MET NEAR TERM...GOODMAN/JM/MET SHORT TERM...MET LONG TERM...JM AVIATION...FEB MARINE...GOODMAN/JM/MET HYDROLOGY...JM/MET

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