Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 211756 AFDOKX Area Forecast Discussion National Weather Service New York NY 156 PM EDT Wed Oct 21 2020 .SYNOPSIS... The front that stalled northwest of the region will move farther north as a warm front today. A cold front will be approaching from the west tonight and move through the region early Thursday. High pressure builds in thereafter but the center of it will stay to the north through Thursday night. High pressure will be sliding across New England Thursday night into Friday. Another cold front will approach on Saturday, and push through Sunday. High pressure briefly moves through on Sunday, before a slow moving frontal system affects the region for early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A stalled front will move farther northeast today, which may provide some weak lift for showers that will move across eastern Long Island and southeastern Connecticut. However, coverage will be sparse, so only a slight chance for showers is expected through early to mid afternoon. The local region will be in the warm sector with another developing frontal system in Quebec. 850mb temperatures increase by about a degree C compared to the previous day. More southerly flow will keep coastal locations across Southern Connecticut and Long Island a few degrees cooler. Max temperatures are mainly in the lower 70s. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... There will be a cold front approaching the region tonight and eventually moving into and through the region by early Thursday. There will be some extra clouds tonight from this feature but weather is expected to remain dry. Low levels are expected to become saturated again so another round of fog could very well be in store for the area. Lows were a blend of MOS consensus and NBM, ranging from the mid 50s to mid 60s. For Thursday, the front will move across early in the day, with a switch to more westerly low level flow. The pressure gradient is weak so the wind speed will be light. High pressure will start building in from the north. More of a northwest flow stays across the interior while the coast will have more variability in the wind direction. Drier conditions and more sunshine will lead to a warmer day. Highs forecast are in the low to upper 70s. For Thursday night, high pressure moves to more northeast of the region, with the center of high pressure moving from Northern New England into the Canadian Maritimes. More of a southeast flow will develop across the region. Some weak convergence is indicated by multiple numerical weather prediction models, so a slight chance of showers was added to the forecast. Once again, low levels look to become nearly saturated so patchy fog and patchy drizzle was added to the Thursday night forecast. Lows forecast are in the mid 50s to lower 60s. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Models continue good agreement with the region remaining under the influence of western Atlantic ridging for late week, as longwave troughing dominates the northern half of the western and central US. The ridging gets suppressed this weekend as an energetic shortwave slides through southern Ontario and Quebec Friday Night into Saturday night allowing the eastern flank of the upper trough to slide a bit farther east, with a fast cross-CONUS SW flow developing aloft. This upper flow will help deflect Hurricane Epsilon NE away from the coast heading into this weekend, eventually shearing into this flow east of the Canadian Maritimes. A transition to a maritime airmass expected Thu Night into Friday, with gusty E flow between high pressure sliding off the Canadian maritimes and Epsilon making its closest approach. Long period energetic swells from Epsilon will be building to the shoreline as well Thu night into Friday, lingering through the weekend. The next chance of a few showers looks to be late Saturday into Sat Night as a somewhat stronger cold front sags into the region. The front may briefly clear the region Sunday, before returning as a warm front Sunday Night into Monday. Then increasing potential for an extended period of unsettled weather Mon into Wed as the longwave trough amplifies across the western US, and northern and southern stream phase heading into early/mid next week, orientating a fast upper flow over the area. This will have an approaching cold front only slowly sliding through the area Mon into Wed, with several waves of low pressure and resultant periods of showers (and even some embedded thunder) tracking along it. Low predictability on rainfall amounts this far out, but overall an unseasonably mild and very moist airmass will be in place for late October early next week. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... A cold front passes late tngt, then stalls near the region on Thu. Gradual improvement will continue this aftn. VFR is still expected by 19-20Z for most areas. MVFR and lower is likely to develop again tngt. LIFR is possible especially E of the NYC arpts. Improvement to VFR is expected on Thu, however, if the front stalls too close to the area MVFR or lower will linger thru the day. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Exact timing of improvement today uncertain. There is the potential that 1/4sm FG develops at some of the arpts tngt, including JFK. Confidence was too low to included in the TAFs attm. There is the potential for MVFR or lower to linger thru much of Thu if the front does not pass far enough S of the area. .OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY... .Rest of Thu...Mainly VFR in the aftn. MVFR or lower possible Thu ngt, especially E of NYC terminals. .Fri...MVFR or lower possible. Lgt S flow. .Sat...Becoming VFR. Winds becoming NW less than 25kt. .Sun...VFR with lgt N flow. .Mon...MVFR or lower possible. Strong SW flow possible. Detailed information, including hourly TAF wind component forecasts, can be found at: http:/www.weather.gov/zny/n90 && .MARINE... Visibilities have improved across the coastal waters and the Dense Fog Advisory that was in effect has been cancelled. Visibilities may become patchy dense at times, through early afternoon. Otherwise, sub-SCA conditions will continue across all waters through early Thursday morning. Then, long period swell from distant Hurricane Epsilon will build ocean seas to 5 ft Thursday afternoon. Long period energetic ocean swells from Hurricane Epsilon are likely to reach 5-8 ft Thursday night into Friday and likely continue into the weekend. Please refer to National Hurricane Center products for further details on Epsilon. SCA in effect for the ocean from 11AM Thursday through Friday. SCA seas on the ocean could very well extend into the weekend. Winds will remain below SCA in a weak flow regime. && .HYDROLOGY... No hydrologic concerns anticipated through next week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from 11 AM Thursday to 6 PM EDT Friday for ANZ350-353-355. && $$ SYNOPSIS...JM/NV NEAR TERM...JM/JP SHORT TERM...JM LONG TERM...NV AVIATION...JMC MARINE...JM/NV HYDROLOGY...JM/NV

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