Area Forecast Discussion
Issued by NWS Upton, NY

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393 FXUS61 KOKX 270252 AFDOKX Area Forecast Discussion National Weather Service New York NY 1052 PM EDT Thu Apr 26 2018 .SYNOPSIS... High pressure builds in briefly tonight, before a quick moving low pressure system moves through on Friday. A cold front will approach on Saturday and pass through late Saturday into Saturday night, followed by a series of upper level disturbances Sunday into Monday. High pressure will return for the middle of next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... The forecast is mainly on track with only minor adjustments made to some hourly forecast elements this evening. An upper low slides slides NE from Northern New England into the Canadian Maritimes tonight, while a southern upper low lifts towards the region. At the surface, high pressure briefly builds in overnight, only to give way to the approaching southern low. Mild night tonight, (50s in the NYC/NJ metro and 40`s elsewhere) with increasing and thickening high and mid cloud cover ahead of approaching low pressure overnight, although rain is expected to hold off till after daybreak. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Models in good agreement with the southern upper low opening up and lifting up the E US coastal plain tonight, and through the region Friday. At the surface, associated low pressure lifts northeast towards the region on Friday, and then to the northeast Friday Night. This is a progressive system, with a quick hit of moderate rain (1/4 to 1/2 inch, locally 3/4-1 inch) Friday morning into early afternoon, coincident with shortwave/llj lift. Still some uncertainty on where the axis of the heaviest rain will be, dependent of placement of warm front. In addition, some weak instability may allow for isolated convection and heavy downpours, particularly across LI/SE CT. Best lift/moisture axis pushes NE through the afternoon, but lingering stratus/drizzle and a few showers are likely into the evening with deep SW flow aloft ahead of northern stream trough digging into the Great Lakes. In fact, stratus/fog could maintain/develop in the evening and linger through the overnight with moist low-levels and weak flow. Temps on Friday will be a few degrees below seasonable due to the rain and cloud cover, and near seasonable Friday night. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Fog will gradually burn off Sat morning as weak sfc ridging briefly moves across. Then as a digging upper trough carves out a closed low over the Great Lakes region, a leading cold front will move across from late day into the evening, bringing scattered showers. The upper low will move slowly across New England Sunday into Monday, with a cooler air mass in place and chances for isolated/scattered showers as a cold pool aloft swings across, and cyclonic flow/transient shortwaves rotating around the upper low provide lift. Isolated thunder and/or small hail might not be out of the question given the forecast strength of the cold pool (H5 temps as low as -28C to -30C). Temps on Sunday should get no higher than the 50s, and while forecast highs on Mon are in the upper 50s/lower 60s, temps could very well remain in the 50s on Mon as well if the upper low pulls out more slowly than forecast. A warming trend does appear certain for mid to late week as the upper low pulls out and is replaced by deep layer ridging that should eventually park off the Mid Atlantic and Southeast coasts Wed into Thu. Temps on Tue are a little uncertain, and will depend on how quickly the upper low pulls out--if slower they may remain in the 60s across the board, for now will forecast 70-75 away from south facing coasts. But then as the high becomes established off the coast and transports warmer air northward, late week looks warm, with highs in the lower 80s on Wed and mid 80s on Thu per warmer MOS guidance. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/...
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High pressure tonight will be followed by a fast moving low moving across on Friday. VFR conditions are expected tonight along with winds near 5 kt or less while becoming more variable in direction. Mid and high level clouds will increase overnight. Clouds continue to increase, lower in height and thicken Friday morning. Winds will become SE 5-10 kt with rain moving in starting in the morning. Conditions are expected to drop to MVFR and eventually IFR during the day. An isolated thunderstorm will be possible. Rain showers eventually move east of the region late day into Friday night, but low level moisture and drizzle as well as fog will remain as winds will become very light. Expecting mainly IFR continuing going into Friday night. .OUTLOOK FOR 00Z SATURDAY THROUGH MONDAY... .Friday night...Mostly IFR and potentially lower in lingering light rain showers or drizzle as well as fog. .Saturday...SW winds G15-20KT afternoon into early evening. Patchy fog early with MVFR/IFR possible. MVFR remains possible during the day and at night with a chance of showers. .Sunday...MVFR possible in showers mainly in the morning, then mostly VFR thereafter with WNW-W winds G15-20KT by afternoon and into early evening. .Monday-Tuesday...Mainly VFR. W-NW winds G15-20KT Monday, SW winds G15KT Tuesday afternoon.
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&& .MARINE... Diminishing winds tonight as high pressure briefly builds, however seas remain elevated and a SCA remains posted on the ocean waters. Marginal SE SCA winds are possible Friday with a quick moving low pressure system, mainly eastern waters Friday aft/eve on the eastern flank of low pressure. Lingering 5-ft ocean swells should last into Sat and possibly Sat evening. SCA conds may also be possible on the ocean waters Sunday nigh/Monday morning in NW flow behind a departing cold front. && .HYDROLOGY... 1/4 to 1/2 inch of rain likely, with locally 3/4 to 1 inch possible, Friday with a quick moving low. No hydrologic issues anticipated. No hydrologic impacts are anticipated Sat-Wed. && .TIDES/COASTAL FLOODING... Water levels will approach minor flood thresholds along vulnerable Western Great South Bay and Western LI Sound waters with the Fri Night high tidal cycle. This in response to SE swells and SE winds ahead of low pressure during the day Friday. Water levels will get close once again in spots Saturday Night as well. Tidal departures as low as 1 to 1 1/2 ft are need for minor flooding, but at this time, water levels are expected to stay below just below minor flood thresholds. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off the air. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 PM EDT Saturday for ANZ350-353- 355. && $$ SYNOPSIS...Goodman/NV NEAR TERM...JC/NV SHORT TERM...NV LONG TERM...Goodman AVIATION...JM MARINE...Goodman/NV HYDROLOGY...Goodman/NV TIDES/COASTAL FLOODING... EQUIPMENT...

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