Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 260220 AFDOKX Area Forecast Discussion National Weather Service New York NY 1020 PM EDT Sun Sep 25 2016 .SYNOPSIS... High pressure over the Northeast will slowly drift off the coast on Monday. A frontal system moves through on Tuesday. The front will likely linger near or just offshore through the end of the week...resulting in an unsettled weather. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Very little change to the forecast with this update as it is mostly on track. Clear skies tonight with the high pressure ridge building over the forecast area. Good radiational cooling conditions overnight with temps dropping through the 50 and 40s. Some patchy frost possible for portions of the Long Island Pine Barrens and the interior valley with reading likely falling into the mid 30s and possibly the lower 30s. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... After a sunny start to the day, high clouds will overspread the area from the west as a 500 millibar trough over the Northern Plains advances towards the area. Southerly winds will increase, especially along the south shore of Long Island, as the center of the high sets up over the Atlantic. The models progress the associated front eastward at around 20 kt, so the front will supposedly not delay its arrival. Based on this speed and timing, rain chances begin after dark, with the best chance for rain coming during the overnight period. The ribbon of moisture ahead of the front is progged to translate into about 1.8 inches of precipitable water, so max rainfall with the steadily moving system is expected to be capped at around an inch and a half at this time. There is a low risk for rip current development Monday morning from a 2 ft long period se swell; expected to increase to moderate in the afternoon as southerly wind waves increase. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Models in good agreement with a deep closed low sitting over the Great Lakes/Southern Ontario on Tuesday. Then models coming into better agreement with the upper low slowly sinking se into the Ohio/Tennessee River Valley through the end of the week...and possibly meandering around through the weekend. This setup is pointing towards a more unsettled weather pattern for the mid to late week period. At the surface...a cold front associated with the stacked Great Lakes low approaches the region Monday Night...and crosses the region Tuesday. Continued good agreement in deep layered lift interacting with southern moisture (1 to 2 std PWAT) bringing a soaking rain during the late Monday night to Tuesday morning period. An isolated tstm is not out of the question Tue morning with some weak elevated instability and strong lift ahead of the cold front...but prob is quite low. Appears the cold front pushes far enough east late Tue/Tue eve for rain to taper off. Confidence is increasing in an unsettled mid to late week period based on ensemble/operational trend towards a less progressive and cutoff upper level scenario as described earlier. This will result in potential for additional waves of low pressure to develop along the cold front just offshore as well as broad low pressure to sit sw of the region...affecting the region with periods of rain mid to late week. Forecast has been further weighted towards the unsettled scenario. Temps on Tuesday will likely be above seasonable with offshore flow in wake of cold front and with any partial clearing. Thereafter...temps should be nears seasonable under a maritime airmass. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... VFR as high pressure builds across the area overnight, then offshore on Monday. Light NE flow tonight veers around to the SE by late Monday morning. .Outlook for 00Z Tuesday through Friday... .MON NIGHT...VFR...then MVFR w/areas of IFR in showers late at night. .TUE...MVFR w/areas of IFR in the morning. Becoming VFR from West to East midday. .WED...VFR. .THU and FRI...Potential IFR/MVFR CIGS with RA. NE Wind 15-20 KT. && .MARINE... Sub sca conds overnight. Southerly winds will increase Monday ahead of a cold front, but speeds will not reach 25 kt until Monday night. A small craft advisory will likely be required on the ocean as a result, and possible elsewhere. SCA conditions likely Tuesday morning on ocean waters...and possibly eastern nearshore waters...ahead of an approaching frontal system. Winds will fall below sca behind the front Tue afternoon...with ocean seas gradually following suit. Sub sca conditions likely return for Tues night into Wed...then potential for sca seas to develop once again with persistent easterly flow for remainder of the week. There is still a great deal of uncertainty regarding the specifics of the forecast during this time period. && .HYDROLOGY... Around an inch of rain is possible Monday night into Tuesday. Some locally higher amounts are possible. Additional bouts of rain are possible during the mid to late week. No significant hydrologic impacts are expected at this time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JMC NEAR TERM...JMC/NV SHORT TERM...JMC LONG TERM...NV AVIATION...JC/DW MARINE...JMC/NV HYDROLOGY...JMC/NV is the U.S. government's official web portal to all federal, state and local government web resources and services.