Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 172145 AFDOKX Area Forecast Discussion National Weather Service New York NY 545 PM EDT Fri Aug 17 2018 .SYNOPSIS... A cold front approaches tonight and then moves across the area waters Saturday into Saturday night. A series of lows along the cold front south of Long Island will keep the frontal boundary not too far away for the close of the weekend into early next week. Meanwhile, high pressure from the Canadian Maritimes will begin building down along the Northeastern Seaboard. High pressure gets closer to the local region Monday into Tuesday next week. A frontal system from the west moves across Wednesday into Wednesday night with high pressure returning thereafter. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... **A Severe Thunderstorm Watch is in effect for portions of northeast New Jersey, Lower Hudson Valley and Southern Connecticut through 11 PM.** Cold front continues to move towards the area this evening. Meanwhile showers and thunderstorms have developed across areas northwest of NYC. Showers and thunderstorms will become more widespread this evening and into tonight. A few storms will likely become strong to severe with the potential for some gusty winds. With the very moist airmass and precipitable water values between 1.5 and 2.0 inches, some storms have also the potential to produce torrential downpours resulting in flash flooding. As the front continues to move southeast near the region additional scattered showers with thunderstorms are possible overnight. Temperatures tonight will be in the low to mid 70s. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... The cold front will be very slow to push southward across the area. Some additional showers and thunderstorms are possible Saturday. Although, instability looks limited lowering the potential for severe thunderstorms development, precipitable waters will remain above normal and as a result any thunderstorm that do development have the potential for heavy downpours. Temperatures on Saturday will be in the mid to upper 80s with heat indices remaining below heat advisory criteria. There is a moderate rip risk at the ocean. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Cooler and a little less humid conditions expected to start out Sunday through Monday with more rain in the forecast Sunday and Sunday night as the region gets more NE flow. Airmass warms up for mid to late in the week, near normal levels with winds having more westerly and southerly components. Upper level trough will be slow to exist for the close of the weekend. Trough axis will be west of the region Sunday and Sunday night with jet streak across the region. The trough axis moves across Monday. The steering flow will not promote the front to move farther south of Long Island and with weak low pressure areas forming along it, essentially keeping some rain showers in the forecast for the region, highest chances along the coast. More drying takes place Monday when more ridging aloft and high pressure at the surface will settle more southwestward along the Northeastern Seaboard. Dry conditions remain until midweek when the next frontal system approaches from the west. Aloft, a large amplitude trough will be approaching with a stronger southerly jet ahead of it. This jet moves in Wednesday night into early Thursday. Chances for showers return Tuesday afternoon and Tuesday night with highest chances N/W of NYC. The chances for showers continues Wednesday with thunderstorms possible as well as instability is forecast to increase again with the airmass getting warmer and more humid. Dry conditions return Thursday into Friday next week with high pressure returning. && .AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
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Thunderstorms will move northwest of the metro terminals, but may be close enough to the terminals to warrant a VCTS through 23Z. KTEB is closest to these thunderstorms, so TSRA between 22Z-23Z is more likely here. No mention of VCTS for KJFK as they are farthest from the thunderstorms and will likely not see VCTS. Otherwise, A weak cold front will slowly approach from the west tonight, and cross through the region Saturday. VFR through the afternoon. A pre-frontal trough arriving this evening, may have a weakening line of showers and sparse thunderstorms affect the NYC/NJ and NW terminals between 00z and 03z. Additional scattered showers and thunderstorms possible overnight through Sat morning, with MVFR cigs/vsby. S winds gradually strengthen this afternoon, with gusts to 20-25 kt possible for KLGA/KJFK after 20-21z. SE seabreezes possible at KEWR/KTEB btwn 19z and 21z. S/SW winds subside to 5-10 kt this evening. Winds veer SW/W late Sat morning into afternoon. 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: Sparse convection potential, mainly after 00z. Southerly gusts of 20-25 kt possible after 21z. KLGA TAF Comments: VCTS through 23Z. Sparse convection potential, mainly after 00z. Southerly gusts of 20-25 kt possible after 21z. KEWR TAF Comments: VCTS through 23Z. Sparse convection potential, mainly after 00z. KTEB TAF Comments: TSRA may affect terminal through 23Z. Gusts greater than 20kt possible with TSRA. Sparse convection potential, mainly after 00z. KHPN TAF Comments: Sparse convection potential, mainly after 00z. TSRA may affect terminal between 23Z-24Z. Southwesterly gusts greater than 20 kt possible in TSRA. KISP TAF Comments: Southerly gusts to 20 kt possible this afternoon. .OUTLOOK FOR 18Z SATURDAY THROUGH TUESDAY... .Sat Aft...Scattered showers/tstms. W flow becoming NE Sat eve. .Sun...Potential for MVFR conditions in shra and ne winds of 8-12kt. .Mon-Tue..VFR. .Tue Night-Wed...Chance of shower/tstm with MVFR conds.
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&& .MARINE... SCA level conditions expected across western ocean waters through tonight. Elsewhere, winds and seas are expected to remain below SCA conditions. SCA conditions likely remain for the second half of the weekend on the ocean. Some marginal SCA wind gusts are possible for non-ocean waters with otherwise sub SCA conditions expected for all non-ocean waters. Then, sub-SCA conditions are expected for all the forecast waters early into the middle of next week but there is a possibility the SCA seas could linger into Monday for the ocean. Ocean seas could reach SCA criteria again Wednesday night into Thursday. && .HYDROLOGY... Heavy thunderstorms tonight and through Saturday could result in minor urban flooding. There is also an isolated flash flood threat with the strongest thunderstorms. No significant widespread rainfall expected during the long term. && .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...
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CT...None. NY...Heat Advisory until 6 PM EDT this evening for NYZ071>075- 176>179. NJ...Heat Advisory until 6 PM EDT this evening for NJZ006-104- 106>108. MARINE...None.
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&& $$ SYNOPSIS...Fig/JM NEAR TERM...Fig SHORT TERM...Fig LONG TERM...JM AVIATION...JP/NV MARINE...Fig/JM HYDROLOGY...Fig/JM EQUIPMENT...

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