Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 250247 AFDOKX Area Forecast Discussion National Weather Service New York NY 1047 PM EDT Wed Apr 24 2019 .SYNOPSIS... High pressure remains near the region through Thursday. A warm front approaches Thursday night, then low pressure and cold front pass Friday followed by brief high pressure. Another weak low passes Sunday, followed by high pressure briefly building across the region into the early week. Another frontal system will impact the area Tuesday into Thursday. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... High clouds were filtering in from the west ahead of the next system moving into the Ohio Valley . This will likely result in varying amounts of clouds during the overnight. Otherwise, just some minor adjustments to fit with the latest obs. High pressure building over the region will result diminishing north winds. Expect lows to fall to near 40 in the usually cooler spots. Otherwise, most locations will be in the lower to mid 40s, except around 50 NYC metro. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... A warm front approaches the area on Thursday, resulting in an increase in cloud cover through the day. Weak warm advection and a shortwave passing over the region could set off some light rain late in the day into the evening. The chance is low and will only go with a 20 POP for now. With little to no instability, will keep thunder out of the forecast. Highs on Thursday climb into the lower and middle 60s. If the timing of the clouds is a bit delayed, temperatures may have to be increased into the upper 60s, especially across NE NJ and NYC. Rain chances gradually increase overnight Thursday. Lows will fall into the 40s and lower 50s. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Warm advection precipitation will move through fairly quickly Friday morning. Although instability appears limited, height and temperature falls aloft may lead to at least marginal elevated instability which could locally enhance rainfall rates for a brief period in the morning. With the morning short wave and warm front generally passing to the north of the local area by afternoon, a short period of subsidence may limit more widespread coverage of showers into the day, with only intermittent showers until broader height falls occur with the approaching system. The intensity of the surface low will very much depend on the phasing aloft of two short waves, though regardless, conditions will become favorable for a line of heavy showers and thunderstorms along the cold front, as flow aloft will generally be parallel to the surface boundary. With strong southerly flow, PWATs will rapidly increase as Gulf moisture is advected northward. Current model forecasts project near record daily values when compared against sounding climatology. Exact hydrologic impacts will be difficult to pinpoint given the fast motion of any cells that develop, but more details are provided in the hydrology section below. As the system moves east, strong cold advection quickly follows, with winds becoming increasingly strong and gusty into Saturday. Depending on the intensity of the departing low pressure system, winds may approach advisory levels. Although most deterministic models suggest dry conditions, with the strong upper low not completely departing until evening, there is potential for at least isolated showers to develop into the afternoon. The flow aloft then becomes more zonal into the remainder of the extended, with a series of embedded short waves leading to the potential for showers most days. The next chance of rain will be for Sunday as a weak surface low passes through. Considerable uncertainty then exists into the mid week. There will be minor fluctuations in temperatures, but in general, temperatures should remain within a few degrees of climo through the period. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... High pressure builds over the northeast tonight then slides offshore on Thursday as a warm front approaches from the south. VFR expected through the TAF period. NW-N winds less than 10kt overnight, then become southerly Thursday afternoon around 10 kt. .OUTLOOK FOR 00Z THURSDAY THROUGH MONDAY... .Thursday night-Friday...MVFR conds and rain developing Thu night, continuing Friday with isolated thunder. IFR possible by Friday afternoon. .Saturday...VFR. W to NW gusts to 25 kt. .Sunday...A chance of showers with MVFR conditions. .Monday...VFR. && .MARINE... Northerly winds over generally less than 10 kt as high pressure builds in from the NW overnight. Winds on Thursday will veer around to the S by afternoon before becoming southeast Thursday night ahead of a warm front. Wind speeds increase Friday night into Saturday behind a cold front, with SCA conditions increasingly likely on all waters. Winds diminish Saturday night as high pressure briefly builds, though ocean seas will be slow to subside. Another low and frontal system are forecast to approach from the west Sunday, and winds increase as they back to the S/SW, allowing any ocean seas that have subsided below 5 ft to quickly build once again. These winds then shift once again to the W as the front passes Sunday night, with ocean seas remaining at SCA levels into Monday. && .HYDROLOGY... Next chance for significant rain of at least a half inch, to possibly over an inch in spots, will occur late Thursday night and Friday. Quick motion of the cells may limit a more widespread flooding threat, with nuisance urban/poor draining flooding the main concerns at this time. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO35 (162.55 MHz) remains off the air. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...BC/MD NEAR TERM...BC/DW SHORT TERM...BC/DW LONG TERM...MD AVIATION...24 MARINE...BC/MD/DW HYDROLOGY...BC/MD EQUIPMENT...// is the U.S. government's official web portal to all federal, state and local government web resources and services.