Issued by NWS Upton, NY
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997 FXUS61 KOKX 221418 AFDOKX Area Forecast Discussion National Weather Service New York NY 918 AM EST Sun Dec 22 2024 .SYNOPSIS... High pressure will be in control through Monday. A weak frontal system approaches Monday night and moves through Tuesday. High pressure builds into the area Wednesday and remains in control through the end of the week. A frontal system may approach the area by the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Arctic air mass in place over the Tri-State today with high pressure building across the northeast. Forecast remains on track. Breezy NW flow continues this morning with gusts 20-25 mph. The pressure gradient begins to weaken from west to east into the afternoon with gusts subsiding through sunset. Temperatures will only rise slowly through the afternoon with continued cold advection, topping out around 20 inland to the mid 20s near the coast. Wind chills will be in the single digits this morning and teens this afternoon. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... The center of the high pressure will be moving over the region by late tonight and with clear skies ideal radiational cooling will take place, especially across the interior with snow covered ground. Inland overnight lows will be near 5 degrees lower than Saturday night`s lows, and along the coast temperatures will be only a degree or two lower. Once again, no record lows are expected, with lows 10 to 15 degrees below normal. The high begins to move offshore late Monday into Monday night. The airmass begins to modify, and highs Monday will be 5 to 10 degrees higher than Sunday`s, but still below normal. With a light return flow Monday night and clouds increasing in advance of a clipper system, temperatures will fall after sunset, then become nearly steady, and even begin to rise, especially along the coastal areas. The low will be passing to the north Monday night and light snow will be possible mainly after midnight. With the system weakening as it approaches, and little moisture, any snowfall will be light, with just a tenth or two. The low passes across the region Tuesday, and precipitation ends during the afternoon. Total snow accumulations are most likely to be under 1 inch. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Large-scale upper level ridging moves in Tuesday night and into Christmas Day with surface high pressure building in from the north. This surface high pressure remains fairly stationary over Southeast Canada filtering air down into the Northeast through much of the next week under a persistent NE flow. Some weak transient pockets of energy attempt to approach the area over the crest of the ridge through the middle of the week, but with the stationary high pressure holding steady, this should result in some occasional cloud cover at most through the end of the week. By the end of the week and into the weekend, a digging trough over the Central US approaches the area, but global guidance differs in timing and orientation of the approach of a surface low. As of now, kept a slight chance to chance of precipitation in the forecast for the weekend, but it`s possible that the frontal system holds off impacts to the area until the beginning of the following week. Given the persistent NE flow under a high pressure system through much of the long term, temperatures will begin slightly below average and gradually moderate through the week. High temperatures Wednesday will be in the middle to upper 30s with moderating temperatures through the week so that by the weekend, highs will be in the low to middle 40s. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... High pressure builds across the terminals through Monday. VFR through the TAF period. NW/NNW winds 10-15 kt with gusts to 20-25 kt this morning, ending just after midday. Light NW or VRB flow tonight as high pressure builds in. Winds gradually shift out of the SSW Monday afternoon. ...NY Metro (KEWR/KLGA/KJFK/KTEB)TAF Uncertainty... Gusts may be occasional at times through midday, before gusts drop. OUTLOOK FOR 15Z MONDAY THROUGH THURSDAY... Monday: VFR. Monday night-Tuesday: Chance of MVFR in light snow/light rain mix, mainly into Tuesday morning. Wednesday-Thursday: VFR. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 && .MARINE... Light freezing spray is possible this morning across portions of the Long Island Sound, and along the south shore of Long Island as gusty northwest winds continue and air temperatures remain in the teens. With gusty northwest winds around 25 kt, and ocean seas near 5 feet, a SCA remains on the ocean waters until 100 PM EST. With high pressure building toward the waters, wind gusts and ocean seas are expected to fall below advisory levels by then. Winds and seas then remain below advisory levels across all the waters tonight through Tuesday. And sub-SCA conditions are expected Wednesday through Friday with high pressure in place and a weak pressure gradient over the area. && .HYDROLOGY... There are no hydrologic concerns through next weekend. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 1 PM EST this afternoon for ANZ350- 353-355. && $$ SYNOPSIS...MET/MW NEAR TERM...MET/DS SHORT TERM...MET LONG TERM...MW AVIATION...BR/MW MARINE...MET/MW HYDROLOGY...MET/MW