Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 210237 AFDOKX Area Forecast Discussion National Weather Service New York NY 937 PM EST Mon Nov 20 2017 .SYNOPSIS... High pressure over the Carolinas moves east over the Atlantic tonight into Tuesday. A cold front passes through early Wednesday followed by high pressure. A warm front moves north Saturday followed by a cold front Saturday night. High pressure builds to the west Sunday and Monday. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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Temperatures, dewpoints, and cloud coverage were adjusted to better match observed trends. Temperatures were holding nearly steady along the coast this evening with the westerly breeze continuing. The region will be in between the polar jet and subtropical jet with some slight mid level ridging taking place. At the surface, high pressure will be moving off the Carolina Coastline and into the Western Atlantic Ocean. Clouds are more abundant across Southern CT this evening but expect those to move east, and with surface high pressure, this will yield mostly clear conditions for all locations. Winds are becoming lighter as well, making for more radiational cooling, more for the inland locations. The coast will have more of a breeze, making for less radiational cooling there. MAV/MET guidance in fairly good agreement for overnight lows. This combination was used for lows overnight but with some slight manual adjustments. Min temperatures along coast were made slightly higher. Temperatures fall into upper 20s and 30s, for much of the region. NYC will remain in the upper 30s to lower 40s.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Gusty SSW flow returns on Tuesday as the cold front approaches from the west. Gusts to around 25 mph will be likely across the coastal locations. It will be a mostly sunny day, with temperatures climbing into the middle and upper 50s. Southerly flow across the area Tuesday night will result temperatures remaining nearly steady overnight. Low pressure will develop over the SE coast and gradually lift up the eastern seaboard as a cold front approaches from the west. Rain expected to move in late Tue night although there is some uncertainty in the westward extent of the precipitation shield. For now, will keep just chance pops in for the eastern half of the CWA. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Good agreement with most of the guidance and the previous forecast as regards the passage of a cold front early Wednesday, as a southern stream wave of low pressure passes to the east of Long Island. The northern stream wave passes well to the north as a weakening cold front moves through. There is a chance that the northwestern zones of the forecast area remain dry, and have only slight chance probabilities there. The ECMWF is a little slower with the frontal passage and low, keeping precipitation into later in the afternoon. Have sided with continuity and end precipitation early Wednesday afternoon, keeping probabilities in the likely category east. Also, the ECMWF was more than double with the QPF and again stayed with continuity. A very active flow will remain across the region as a full latitude trough remains across the eastern United States into the beginning of next week. Surface high pressure will remain late Wednesday into Friday. However, another shortwave moves through the trough Thursday night into Friday, and at this time passes to the north. There is a chance that the wave digs farther to the south, weakening the mid and low level ridge, with the possibility of precipitation inland. Again, kept with continuity and will remain dry into Friday night. Yet another shortwave rotates through the eastern trough Saturday, with a surface low, a clipper type system, passing through the Great Lakes region. A weak warm front develops Friday night and passes through Saturday, followed quickly by the cold front. At this time only the well inland areas may see a period of light snow, slight chance, as the cold air moves in behind the front Saturday night. Otherwise all rain is expected. Will leave Sunday and Monday dry, however, a weak tough or re- enforcing cold front, moves through Sunday with maybe a few flurries. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/...
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High pressure remains in control through Tuesday. VFR. WSW-SW winds diminish tonight then increase after daybreak, becoming gusty by late Tuesday morning. Winds become more SW on Tuesday as well. .OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY... .Tuesday evening...VFR. SW winds G20-25KT possible. Strongest gusts at eastern terminals. .Late Tuesday night-Wednesday...MVFR possible with showers. NW-N winds G20-25KT possible in the afternoon. .Wednesday night-Friday...VFR. NW-N winds G15-25KT possible Wednesday night. .Saturday...MVFR possible in showers. SW G15-25KT, highest at the coast.
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&& .MARINE...
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Winds briefly subside tonight, but increase again on Tuesday from the SSW as a cold front approaches for the west. SCA remains in effect for all waters tonight through Tuesday evening, except for the ocean waters which continues through Tuesday night. Much of the timeframe from tonight into Tuesday night is expected to meet SCA criteria on the waters in terms of wind gusts. A few gusts may approach gale force, however, thinking that gusts remain just below criteria. Ocean seas build to 5-8 ft during the day on Tuesday, and start to subside late Tuesday night. A cold front will be moving east of the forecast waters early Wednesday as high pressure builds to the west, and then over the waters Thursday into Friday. Winds are expected to remain below small craft advisory levels across all the forecast waters Wednesday into Friday. However, ocean seas likely remain at small craft levels into Friday. As a warm front approaches from the south Friday night and moves north Saturday, as a cold front approaches Saturday, southwesterly winds will increase and ocean gusts may be around small craft levels Friday night and Saturday. Also, ocean seas likely build to small craft levels. Winds and gusts may fall below small craft levels for several hours late Saturday into Saturday night, then Sunday increase again in the cold air behind the cold front. Ocean seas remain at small craft levels into Sunday night.
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&& .HYDROLOGY... No hydrologic problems are anticipated the next 7 days. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until midnight EST Tuesday night for ANZ330-335-338-340-345. Small Craft Advisory until 6 AM EST Wednesday for ANZ350-353- 355. && $$ SYNOPSIS...BC/19 NEAR TERM...BC/JM SHORT TERM...BC LONG TERM...19 AVIATION...JC MARINE...BC/JM/19 HYDROLOGY...BC/19

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