


Area Forecast Discussion
Issued by NWS Upton, NY
Issued by NWS Upton, NY
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995 FXUS61 KOKX 122355 AFDOKX Area Forecast Discussion National Weather Service New York NY 755 PM EDT Mon May 12 2025 .SYNOPSIS... A weak backdoor cold front moves across the region tonight as high pressure builds southward off the New England coast. Meanwhile, an area of low pressure slowly approaches from the Mid-Atlantic Tuesday and Wednesday and passes nearby during Thursday. A warm front then moves through during Friday, followed by a cold front on Saturday into Saturday night. Weak high pressure will then be in place for Sunday and Monday with a few weak cold fronts or troughs possibly passing through. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... The forecast remains mainly on track. Minor adjustments were made to some of the hourly forecast elements with this update. Clouds gradually increase as a broad area of low pressure approaches from the south. Meanwhile, high pressure well north of the region gradually builds southeastward, forcing a back door cold front to approach from the northeast. With the low pressure system approaching from the south, some rain showers may develop after midnight, mainly across NE NJ and NYC. Will introduce some chance or slight chance POPs. Any showers should remain light in intensity. The eastward progression of this band of scattered showers remains a bit uncertain as the showers will be running into the drier airmass from the high pressure offshore. With increasing cloud cover, temperatures should remain somewhat mild, with lows only falling into the 50s to lower 60s in the NYC metro area. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... A backdoor cold front continues to move into the area Tuesday morning and either moves through the entire area or stalls over the area as a stationary boundary. Meanwhile, the broad area of low pressure continues to spread precipitation into portions of the CWA. the best chances will be across the western half of the CWA,. There remains some uncertainty with just how far east the precipitation reaches. Some eastern areas may remain mostly dry during this timeframe. Cloudy skies should prevent temperatures from rising too much Tuesday with highs in the upper 60s to middle 70s for the northeasternmost areas. Tuesday night lows only fall into the middle and upper 50s. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Models in good agreement with a closed h5 low opening up as it heads NE into the Great Lakes Region Wednesday into Wednesday night. Associated trough axis shifts through the forecast area during Thursday night. At the surface, weakening low pressure over the Mid- Atlantic on Wednesday slowly approaches and passes over or nearby us at some point in the Thursday to Thursday night period. Rain will be possible at any given time during this period, however it appears that it will be most likely during the daytime Wednesday. This is when the strongest h8 theta-e advection and isentropic lift with the help of llj upward forcing interact with the deepest moisture. The magnitude of the moisture doesn`t appear to be significantly anomalous, so hydrologic impacts are not anticipated at this time. Even the NBM probabilities of 6-hour rainfall being greater than a half inch through the period are very low. Even with the strongest forcing and deepest moisture shifting away, rainfall is still likely during Wednesday night as the aforementioned weak low approaches. Indications are that the low weakens into a trough by the time of its closest approach, so PoPs are capped at chance (40-50% most locations) for Thursday, but went above NBM guidance considering the proximity of the trough as well as a shortwave and trough axis aloft shifting through. A warm front then shifts through during Friday with with ridging aloft mitigating shower chances. A cold front follows for Saturday into Saturday night with additional showers and maybe a thunderstorm. Uncertainty then increases for Sunday and Monday, stemming from global model disagreement on the placement of an upper low. There`s general agreement that it remains to our north, but still cannot rule out a diurnally-driven shower both days as a surface trough and cyclonic flow aloft are potentially in the area. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... During the TAF period, a weak cold front moves into the area from the north. High pressure will continue moving offshore. Large area of low pressure approaches slowly from the southwest. VFR conditions expected through early Tuesday afternoon. MVFR chances increase from west to east thereafter for the rest of the TAF period. Some light rain is possible early Tuesday for NYC and Lower Hudson Valley terminals. There are higher chances of rain moving into NYC and Lower Hudson Valley terminals Tuesday afternoon into start of Tuesday evening with MVFR chances also increasing. To the east, expecting mainly dry conditions and VFR conditions expected to prevail through much of the afternoon. Winds through the TAF period around 10 kts or less. Wind direction southerly this evening, with some variability overnight, becomes generally more easterly Tuesday. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... MVFR and IFR timing could be a few hours off from TAF. .OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY... Tuesday night through Wednesday night: Low stratus/fog with IFR conditions at times. Periods of rain. Slight chance of thunderstorms Wednesday afternoon into Wednesday night. E-SE winds G20kt possible on Wednesday, day into early evening. Thursday: MVFR possible with a chance of showers. Friday and Saturday: Mainly VFR, chance of MVFR and showers. Slight chance of thunderstorms afternoon into early evening. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 && .MARINE... Sub-SCA conditions are expected on all waters through Tuesday night. Onshore flow will help build seas to 5-6 ft on the ocean waters during Wednesday along with gusts around 25 kt. Winds weaken Wednesday night, however a residual swell should keep seas at advisory levels through the night and into a portion of Thursday. Sub-advisory conditions then follow for Thursday nigh through Saturday with winds remaining at around 10kt or less. && .HYDROLOGY... Rainfall from Tuesday afternoon through Wednesday night is expected to average around a half of an inch across the area. No hydrologic impacts are expected with this event, and no impacts are expected thereafter through Monday. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...BC/JC NEAR TERM...BC SHORT TERM...BC LONG TERM...JC AVIATION...JM MARINE...BC/JC HYDROLOGY...BC/JC