Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 270236 AFDOKX Area Forecast Discussion National Weather Service New York NY 1036 PM EDT Fri May 26 2017 .SYNOPSIS... Low pressure departs the New England Coast tonight as weak high pressure settles over the region. A weak wave of low pressure passes to the south Saturday into Saturday night. A series a weak waves of low pressure or troughs will move through the northeast Sunday through Thursday. A cold front is expected to move through the region Friday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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Forecast is on track. Minor adjustments made to winds/T/Td based on latest obs/trends. Heights aloft will continue to rise tonight as low pressure continues to depart the New England coast. Clouds will dissipate somewhat, but there is enough low level moisture for at least partly cloudy skies overnight. Lows will range from the lower 50s inland to the middle and upper 50s near the coast.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Main concern for Saturday is with a convectively induced shortwave that is currently located over the Upper Mississippi river valley. Models have not been handling this energy very well as depicted with Dprog/Dt at H5. However, it appears they are beginning to handle this feature better with just some timing differences overall. The shortwave is forecast to quickly traverse through the Ohio Valley tonight and then towards the region on Saturday. Prefer to follow a blend of the NAM, 3-km NAM and ECMWF, which brings the shortwave offshore late afternoon and early evening. The GFS, GEFS, and CMC are a bit slower and do not bring it offshore until overnight Saturday. Have elected to go with slight chance PoPs, mainly for the western half of the area, as better lift and moisture appears to pass to the south of the region. Otherwise, mostly cloudy skies are expected with high temperatures around 70 in NYC and middle and upper 60s elsewhere. Clouds gradually decrease Saturday night as ridging builds aloft. Lows will be near normal. && .LONG TERM /SUNDAY THROUGH FRIDAY/... With a delay in the timing of the northern stream longwave trough and the shortwave rotating through the base of the trough have delayed the probabilities of showers until late in the day Sunday; and mainly across the far west and southwest zones. Aloft, an upper ridge axis will still be west of the region at 12Z Sunday with heights rising until the afternoon. At the surface a weak high will be moving off the coast. Then as the shortwave moves into the region probabilities increase Sunday night into Monday. At the surface the will be weak forcing as a weak cold front moves into the region. A thermal ridge also moves into the area Monday afternoon. Monday may be one of the warmer days of next week. With weak surface based instability, and increasing aloft along with increasing CAPE will have thunderstorms Monday afternoon into the evening. There is still some uncertainty with the timing of the upper trough and shortwave for Sunday and Monday. The closed upper low and longwave trough will be slow to move east through the week as a series of shortwaves rotate through the trough, while at the surface weak lows, or troughs move through the area. There remains a lot of uncertainty with the timing and placement of the systems through the upcoming week. And, there will be a prolonged period of unsettled weather. Will carry slight chance to low chance probabilities through the week, although there may be periods of dry weather. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
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Low pressure near Nova Scotia will move slowly east tonight through Saturday. Weak high pressure builds into the terminals Saturday. VFR. A few isolated showers are possible Saturday afternoon from the NYC terminals and west and south, with VFR conditions. NW wind diminish late tonight and remain less than 10 KT into Saturday morning. Sea breezes develop Saturday afternoon. .OUTLOOK FOR 00Z SUNDAY THROUGH WEDNESDAY... .Saturday Night...MVFR to IFR in stratus and fog. .Sunday...Improving to VFR. .Sunday Night-Monday...MVFR/IFR likely in showers. Thunderstorms possible Monday afternoon. .Tuesday-Wednesday...VFR. Slight chance of showers and thunderstorms.
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&& .MARINE... Southerly swell continues on the ocean waters through tonight. Seas will subside overnight as the swell diminishes. 5 ft seas could linger east of Moriches inlet through Saturday morning, so have extended the SCA to account for this. Otherwise, Sub-SCA conditions are forecast on the waters through Saturday night. A weak surface pressure gradient force will be across the forecast waters Sunday through Wednesday as a series of weak lows or troughs move through the waters with low pressure remaining north of the Great Lakes into Tuesday night. The lows then moves slowly east through Friday. Winds and seas will remain below small craft advisory levels Sunday through Wednesday. && .HYDROLOGY... No hydrologic impacts into early next week. && .TIDES/COASTAL FLOODING... The combination of high astronomical tides and a southerly swell will keep water levels within striking distance of minor coastal flood benchmarks for potentially several high tide cycles through this weekend into early next week for the more vulnerable locations. The new moon was yesterday and tide levels will gradually begin to lower this weekend. However, the swell will likely inhibit water levels from receding much in the south shore back bays of western Long Island today with a minor coastal food episode likely during the higher of the two tide cycles this evening. Thus, a coastal flood advisory has been issued for Southern Queens and Southern Nassau counties. A statement is also in effect for isolated minor coastal flooding across lower New York Harbor. Elsewhere, the coastlines adjacent to western Long Island Sound could also come close tonight, but confidence is low at this time. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Coastal Flood Advisory from midnight Saturday night to 3 AM EDT Sunday for CTZ009. NY...Coastal Flood Advisory from midnight Saturday night to 3 AM EDT Sunday for NYZ071. Coastal Flood Advisory until 1 AM EDT Saturday for NYZ178-179. Coastal Flood Advisory from 9 PM Saturday to 2 AM EDT Sunday for NYZ075-178-179. NJ...None. MARINE...Small Craft Advisory for hazardous seas until 6 AM EDT Saturday for ANZ353-355. Small Craft Advisory for hazardous seas until 11 AM EDT Saturday for ANZ350.
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