Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 270800 AFDOKX Area Forecast Discussion National Weather Service New York NY 400 AM EDT Mon Mar 27 2017 .SYNOPSIS...
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A warm front will slowly lift through the Tri-State Region today. A cold front with a wave of low pressure passes through the region Tuesday night. High pressure builds in for Wednesday and Thursday, and shifts offshore Thursday night. A low pressure system approaches from the central United States Thursday night and impacts the region Friday and Saturday. High pressure returns for Sunday.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Drizzle will continue this morning, with increasing lift allowing for areas of steady rain to develop. Radar returns are already showing this rain west of the Hudson River. It will be difficult to clear out this afternoon behind the front, with significant moisture at or below 4000 ft depicted by the models. This will keep the area from warming up to max potential, and therefore limiting instability. Regardless, there could be enough support from the upper jet to produce some showers this afternoon into the early evening after the frontal passage. A broad model consensus was used for temperatures today, with an emphasis given to the raw model output.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
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Convergence aloft in the dry layer does not seem conducive to much rainfall tonight. As a result, only low chances for rain were included in the forecast. If rain does develop, it may turn out to be mainly sprinkles or light drizzle. Surprisingly big differences exist between the NAM and GFS for Tuesday. The NAM holds off on the deep lift, and therefore the bulk of the rain, for the entire day. The GFS brings in rain by morning. The ECMWF supports the NAM, by keeping the bulk of the rain with the main shortwave. The GFS appears to be kicking off convection over Pennsylvania that brings residual energy in. The forecast sides with the drier solutions, although there may be some showers or pockets of light rain with weak vorticity advection and a moist airmass. A blend of the models was used for temperatures.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
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A southern stream shortwave over the Oklahoma and Kansas area this Monday morning will weaken and track to the Mid Atlantic coast Tuesday and offshore Tuesday night. Meanwhile, a northern stream longwave trough moving through south central Canada moves east and passes into northern New England Tuesday night. There is still some differences in whether or not the two systems will phase, with consensus for the south stream to be more progressive and remain separate, and farther south than other models, while dampening and exiting the Mid Atlantic. The southern movement will keep an associated warm front to the south. This southern and separate solution has been the trend the last several runs. With higher confidence in precipitation affecting the area, mainly the southern half of the CWA, will have likely probabilities Tuesday night. A northwest flow will persist across the region as surface high pressure builds to the north and the upper northern stream trough moves slowly off the northeast coast through Thursday night. The surface high weakens Thursday night as another southern stream shortwave approaches, however the upper ridge is holding with the axis shifting east of the area Friday. The southern stream system will also be weakening as the wave tracks east. Have brought in chances late Thursday night into Friday and this may be too quick if the ridge holds. The weakening low will re develop off the Mid Atlantic coast Saturday with chances of precipitation remaining into Saturday night. Cold air will be in place across the northern tier and some of the precipitation may fall as snow or a rain snow mix. Weak high pressure returns for Sunday into Monday.
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&& .AVIATION /07Z MONDAY THROUGH FRIDAY/... Low-level ridge gradually weakens overnight and gives way to an approaching warm front to the south. This front will lift slowly through during the late morning/early afternoon hours, possibly washing out across or just north of the area. Lower ceilings, drizzle, and fog continue to work in from the SW overnight. Conditions will continue to lower through the overnight with widespread LIFR before daybreak at most terminals based on current trends. IFR conditions could last through much of the period, especially to the north and east of the NYC terminals due to the uncertainty with the timing of the warm front. .OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY... .Monday night-Tue night...IFR likely, LIFR possible with rain/low clouds/fog. .Wednesday...VFR. NW winds G15-20KT. .Thursday...VFR. .Friday...Chance of rain with MVFR or lower conditions, especially late in the day and at night. E winds G20KT along the coast. && .MARINE...
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Waves were running about 1-2 feet above Wavewatch this morning. With winds below 25 kt, the Small Craft Advisory has been converted to one for hazardous seas into tonight. Winds and seas will be below Small Craft Advisory levels on Tuesday. A wave of low pressure passes to the south of the forecast waters Tuesday night along with a cold front. Winds and seas are expected to be below small craft levels across the forecast waters. Northwesterly winds will develop behind the cold front and then increase into Wednesday and Wednesday night as high pressure builds to the north. Minimal small craft conditions will be possible across the ocean waters Wednesday night into Thursday in the northwest flow. Then as high pressure builds over the waters Thursday winds and seas will fall below advisory levels. A southeasterly flow develops Friday and increases as low pressure approaches the Mid Atlantic region. Marginal small craft advisory wind gusts will be possible Friday night into Sunday, mainly across the ocean waters. In additions ocean seas will build to small craft levels late Friday and remain into Sunday.
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&& .HYDROLOGY...
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Around a half inch of rain is possible today. Additional rain of a quarter inch or less is forecast for Tuesday. One to two tenths of an inch of rainfall is likely Tuesday night. Then dry conditions expected Wednesday and Thursday. No hydrologic concerns are anticipated.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory for hazardous seas until 2 AM EDT Tuesday for ANZ350-353-355.
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&& $$ SYNOPSIS...12/MET NEAR TERM...12 SHORT TERM...12 LONG TERM...MET AVIATION...JE/DW MARINE...12/MET HYDROLOGY...12/MET

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