Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 172017 AFDOKX Area Forecast Discussion National Weather Service New York NY 417 PM EDT Tue Jul 17 2018 .SYNOPSIS... A cold front will move across the area this evening. High pressure will then build across the region Wednesday through Thursday, sliding offshore Friday night into Saturday. A frontal system approaches Saturday night into Sunday with a prolonged period of unsettled weather possible into early next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Flood watch will be taken down shortly. A line of convection along a pre-frontal trough was just east of NYC and the Lower Hudson Valley. This area will work east across southern CT and Long Island through early this evening. Main impacts will be brief heavy rainfall and winds gusts up to 30 mph. Minor nuisance flooding is possible. Additionally, due to the convection winds will likely vary significantly with winds initially shifting to the NW behind the initial line and then reverting back to the south ahead of the approaching cold front. The actual cold front moves through this evening across western portions of the Lower Hudson Valley, and then far eastern areas by early morning. Some of the Hires models attempt to regenerate convection with the actual cold front and exit region of the upper jet. It may be difficult for the airmass to recover from the initial convection. Current thinking is for the activity to become more scattered in nature behind the main line. Skies clear late with drier air slowly filtering in as dew points drop into the lower 60s by morning. Lows will range from around 60 far NW zones to the around 70 NYC metro. This is slightly above normal. A high risk of rip currents exists for the ocean beaches into this evening. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Drier and less humid conditions are tap for Wednesday with a northerly flow and a highs in the 80s. Readings will be a few degree above normal but it will feel much more comfortable as dewpoints drop into the 50s. Lows Wednesday night will be near seasonable levels. Aloft, the upper trough axis swings across the area Wednesday into Wednesday night. Lack of moisture though will keep the region dry. && .LONG TERM /THURSDAY THROUGH TUESDAY/... The long term period will begin will tranquil conditions as middle and upper trough axis moves offshore. Ridging will build aloft Thursday into Friday along with surface high pressure. Near seasonable temperatures are expected on Thursday and Friday. There is good agreement among the models for the ridge to move offshore late Friday into the weekend as a shortwave digs and amplifies across the eastern states. This could potentially set the stage for an unsettled period into early next week. As the surface high moves offshore on Saturday, there will likely be enough surface ridging to keep the area dry. However, a frontal system associated with the shortwave/upper trough will approach the region on Saturday. The latest models show the warm front approaching Saturday night into Sunday morning. There continues to be indications of a wave forming on the warm front as a strong vort max moves up the coast. This will need to be watched for any early morning strong thunderstorms with the approaching warm front. Otherwise, showers and thunderstorm chances continue into early next week overall as the frontal system lingers nearby with a blocking ridge over the Atlantic. Temperatures this weekend and into early next week will ultimately be determined by how much clouds and precipitation occur, but should be near or slightly above normal. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... A line of showers and thunderstorms is moving through the airspace this afternoon, bringing brief reductions in ceilings/visibility, and an abrupt wind shift to NW with gusts up to 40 kt. The wind shift/increase is expected to last about an hour after the thunderstorms move through, before winds gradually shift back to the WSW-SW again. Convection will largely be east of the NYC terminals by 22Z, and east of KGON/KISP by 23Z. Thereafter, there will be a brief break in convective activity before a secondary, but weaker line moves through along the cold front. Any shower or perhaps isolated thunderstorm activity will move through from west to east from the 01-05Z time frame. Following the cold frontal passage, winds will shift to northwest and conditions will quickly improve to VFR. VFR and north flow persists into tomorrow. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: Winds may remain NW through about 20-21Z following the passage of the gust front. KLGA TAF Comments: Winds may remain NW through about 20-21Z following the passage of the gust front. KEWR TAF Comments: Winds may remain NW through about 20-21Z following the passage of the gust front. KTEB TAF Comments: Winds may remain NW through about 20-21Z following the passage of the gust front. KHPN TAF Comments: Winds may remain NW through about 20-21Z following the passage of the gust front. KISP TAF Comments: Stratus may be slow to lift. Winds may remain NW through about 21-22Z following the passage of the gust front. .OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY... .Wednesday-Saturday...VFR. .Sunday...MVFR or lower in showers and thunderstorms. && .MARINE... SCA conditions will likely end shortly after midnight with a an offshore flow. Seas will gradually diminish through Wednesday with a lingering southerly swell around 4 ft on the ocean waters. Sub SCA criteria through Saturday morning. Seas will build on a southerly flow on the ocean waters Saturday, with 5 ft waves by Saturday night. Wind gusts should remain below 25 kt for the weekend. With an approaching complex frontal system to affect the waters by Sunday and a prolonged southerly flow, expect SCA conditions to exist into early next week. && .HYDROLOGY... Lingering showers and thunderstorms this evening will briefly produce heavy rainfall. Minor nuisance flooding is possible with up to an additional inch of rainfall possible. The heaviest rain will be across eastern Long Island and southern CT. An extended period of unsettled weather is forecast starting Sunday into next week. Due to the uncertainty this far out, there is a low chance of any hydrologic impacts. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...Flash Flood Watch until 10 PM EDT this evening for CTZ005>007- 009-010. NY...Flash Flood Watch until 10 PM EDT this evening for NYZ069>075- 176>179. High Rip Current Risk until 9 PM EDT this evening for NYZ075- 080-081-178-179. NJ...Flash Flood Watch until 10 PM EDT this evening for NJZ002-004- 006-103>108. MARINE...Small Craft Advisory until midnight EDT tonight for ANZ350-353- 355. && $$ SYNOPSIS...CB/DW NEAR TERM...DW SHORT TERM...DW LONG TERM...CB AVIATION...MD MARINE...CB/DW HYDROLOGY...CB/DW EQUIPMENT...//

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