Area Forecast Discussion
Issued by NWS Upton, NY

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475 FXUS61 KOKX 221940 AFDOKX Area Forecast Discussion National Weather Service New York NY 340 PM EDT Mon Jul 22 2019 .SYNOPSIS... A frontal boundary remains stalled over the area into Tuesday, with waves of low pressure developing along it. High pressure then builds from the west, allowing the boundary to move east of the area by Wednesday. High pressure remains over the area into the weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... An approaching cold front is triggering a few thunderstorms across northwest parts of the area. These thunderstorms are forecast to expand in intensity and coverage through the afternoon and evening. With any thunderstorm development there is the potential of strong gusty winds and frequent lighting and the potential for urban flash flooding, especially across northeastern New Jersey, the Lower Hudson Valley, NYC, Nassau County, NY and southeastern Connecticut where storms may back build and train across the same area. A flood watch remains in effect and has been expanded into Fairfield and New Haven counties in Connecticut. The threat for severe weather is expected to diminish overnight but expect rainfall to continue through Tuesday morning. See the hydrology section for more information. Additionally, veering winds with height in the vicinity of the frontal boundary may support weak rotation, and the potential for a weak/brief tornado. Temperatures tonight will be in the mid to upper 60s to near 70. There is a low rip current risk for Atlantic Ocean beaches today. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... The frontal system will remain over the area, with the threat for heavy rainfall and locally gusty winds continuing at least into Tuesday morning, before building high pressure from the west gradually allows the system to move offshore. With light winds and recent moisture, fog may develop into Tuesday night. Expect temperatures to be well below climatological normals on Tuesday, then closer to normal overnight. There is a moderate rip current risk for Atlantic Ocean beaches on Tuesday morning, possibly becoming high in the afternoon. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Strong polar upper low drops into Hudson Bay during the mid to late week, gradually shearing the closed low currently over Northern Quebec towards Greenland. The associated deep Eastern US troughing will slowly weaken through the week as a result, with weak upper ridging signaled for the weekend ahead of the next closed shearing eastward just north of the Great lakes. At the surface, generally tranquil conditions expected, with weak and elongated high pressure sprawled across the Eastern US in wake of the offshore cold front slowly drifting eastward. A gradual moderation in temps expected through the period, starting a seasonable levels with comfortable humidity mid week and rising to above seasonal with increasing humidity late week into the weekend. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... A front will remain near the terminals today as a wave of low pressure develops and moves along the front into tonight. Showers and thunderstorms have developed across northern NJ and the Lower Hudson Valley. As these storms approach, expect MVFR conditions to develop. Some storms may become severe and produce gusty winds and heavy rainfall, mainly in the 20-00Z time frame. The MVFR or lower conditions and the threat of Showers and isolated thunder will continue into the overnight hours and Tuesday morning. VFR conditions will return during the mid to late part of Tuesday. Winds are generally light or out of the south-southeast, however the forecast becomes tricky through the afternoon as a wave of low pressure moves along the front. Winds should favor a SE direction before veering to the W/NW later in the day and tonight. 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: Low confidence wind forecast, amendments likely. KLGA TAF Comments: Low confidence wind forecast, amendments likely. KEWR TAF Comments: Low confidence wind forecast, amendments likely. KTEB TAF Comments: Low confidence wind forecast, amendments likely. KHPN TAF Comments: Low confidence wind forecast, amendments likely. KISP TAF Comments: Low confidence wind forecast, amendments likely. .OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY... .Tuesday afternoon...Scattered showers, with MVFR or lower conditions expected. .Wednesday though Saturday...VFR. && .MARINE... A front will remain stalled over the waters at least into Tuesday, with waves of low pressure passing along it. Any showers and thunderstorms that develop along or near the boundary will likely have locally heavy downpours with visibility restrictions, and the potential for gusty winds. Winds will remain light outside of any thunderstorms. A Small Craft Advisory is in effect for ocean seas to build near 5 ft and persist through Tuesday night. In general seas will continue to gradually subside into mid week as the system moves east and high pressure begins to build. Winds and seas will then remain tranquil into the weekend with high pressure over the area. && .HYDROLOGY... 1.5 to 2 inches of average basin rainfall is expected into Tuesday with locally higher amounts. The highest amounts are forecast to be across parts of NYC and to the north and west. Urban and low-lying flooding will be most likely. The flash flood watch remains in effect for northeastern New Jersey and New Jersey and Lower Hudson Valley, and has been expanded into Fairfield and New Haven counties in Connecticut. No hydrologic impacts are then expected through the remainder of the week. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO35 (162.55 MHz) remains off the air. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...Flash Flood Watch through Tuesday morning for CTZ005-006-009- 010. NY...Flash Flood Watch through Tuesday morning for NYZ067>075- 176>179. NJ...Flash Flood Watch through Tuesday morning for NJZ002-004-006- 103>108. MARINE...Small Craft Advisory for hazardous seas from midnight tonight to 6 PM EDT Tuesday for ANZ350-353-355. && $$ SYNOPSIS...Fig/NV NEAR TERM...Fig SHORT TERM...Fig LONG TERM...NV AVIATION...BC MARINE...Fig/NV HYDROLOGY...Fig/NV EQUIPMENT...

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