Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 251705 AFDOKX Area Forecast Discussion National Weather Service New York NY 105 PM EDT Sun Sep 25 2016 .SYNOPSIS... High pressure settles over the area through tonight. The high slides offshore on Monday followed by a frontal system moving through on Tuesday. The front may linger near or just offshore through the end of the week. && .NEAR TERM /THROUGH TONIGHT/... The forecast was on track this afternoon with no major changes made. Deep upper trough continues to track SE across far eastern Canada today with high pressure settling over the area at the surface. Northerly flow will continue to usher in an autumn airmass with dew points in the 30s today under clear skies. These dew points will combine with temperatures in the middle and upper 60s for most locations. A few readings near 70 are likely in the NYC metro and Urban NE NJ. There is a moderate risk of rip current development at ocean beaches today. Excellent radiational cooling conditions tonight with high pressure overhead, nearly calm winds, and mostly clear skies. Coldest locations across the interior and Long Island Pine Barrens fall into the upper 30s. Elsewhere, lows will generally be in the lower and middle 40s with readings in the upper 40s and lower 50s closer to the NYC metro. && .SHORT TERM /MONDAY THROUGH TUESDAY/... Deep layered ridge axis moves over the region on Monday as the surface high begins to slide offshore. This will set the stage for another seasonable autumn day with temperatures in the upper 60s and lower 70s. Models continue to come into better agreement with the evolution of a deep upper low settling over the Great Lakes/Southern Ontario late Monday into Monday night. A frontal system associated with the upper low approaches Monday night with increasing warm advection and moisture. Overall, deterministic and ensembles agree on the front moving across on Tuesday morning/early afternoon. However, there are some members that are a bit slower. Have increased PoPs to categorical Tuesday morning, decreasing to chance in the afternoon. This system already has shown signs of a deep plume of moisture across the central states where it is currently located. PWATs are forecast to range between 1.5 and 2 SD above normal ahead of the front with moderate to heavy rain possible. A low amount of elevated CAPE is noted on NAM BUFKIT profiles, with more stable profiles on the GFS. An isolated rumble of thunder cannot be ruled out, but the chance appears very low at this time to include in the forecast. Some clearing is expected Tuesday afternoon as much drier air begins to work in behind the front. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... There remains a general agreement on the upper low sitting near or over the Great Lakes/Ohio Valley region through midweek...before models diverge in evolution and opening on the low for the late week period. With this in mind, forecast uncertainty continues for the mid to late week on evolution of the closed low and how quickly it opens up and move through the east coast. A more progressive scenario would allow high pressure to return for the late week with mainly dry and seasonable conditions. Meanwhile a less progressive or cutoff scenario would result in potential for additional waves of low pressure to develop along the cold front and affect the region mid to late week. The forecast continues to be weighted towards a dry solution, but have noted the 00z models have indicated the more unsettled solution may hold a little more weight. Rainfall chances may need to be increased in subsequent forecasts as confidence increases in the outcome. && .AVIATION /17Z SUNDAY THROUGH THURSDAY/... VFR. Northerly winds around 10 kt this morning will gradually veer around to the NW this afternoon. For the NYC terminals, winds have been varying 10-40 degrees to the right of true north. This should be short lived. KEWR wind direction this AFTN will vary either side of 310 Magnetic, but gusts do not appear likely to occur with the speed averaging below 10 KT. KJFK wind direction may back more to W for or during the INTL Departure Bank. .Outlook for 12Z Monday through Thursday... .MON...VFR. .TUE...MVFR w/areas of IFR in the morning. Becoming VFR from West to East midday. .WED...VFR. .THU...Potential IFR/MVFR CIGS with RA. NE Wind 15-20 KT. && .MARINE... Northerly winds will continue across the waters through tonight with wind gusts around 20 kt still possible, mainly on the ocean this morning. Long period SE swells from distant tropical cyclone Karl will continue to impact the ocean waters with seas right around 4-5 ft. The SCA has been replaced with a small craft advisory for hazardous seas as wind criteria is not expected to be met. Sub-SCA conditions are likely on Monday with SCA conditions Monday Night into Tuesday on ocean waters ahead of a frontal system. The possibility also exists for SCA winds on near shore waters. Sub sca conditions likely return for Wednesday and Thursday as the pressure gradient weakens although there is a great deal of uncertainty regarding the forecast during this time period. && .HYDROLOGY... A frontal system moves through Tuesday with a general 1/2 to 1 inch of rain likely...with locally higher amounts possible. Any hydrologic impacts will be minor as the system will move through quickly. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory for hazardous seas until 6 PM EDT this evening for ANZ350-353-355. && $$ SYNOPSIS...DS NEAR TERM...JMC/DS SHORT TERM...DS LONG TERM...DS/NV AVIATION...Tongue/DW MARINE...JMC/DS/NV HYDROLOGY...DS/NV

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