Area Forecast Discussion
Issued by NWS Upton, NY

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101 FXUS61 KOKX 271427 AFDOKX Area Forecast Discussion National Weather Service New York NY 1027 AM EDT Mon Mar 27 2017 .SYNOPSIS...
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A warm front will slowly lift into the 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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Issued dense fog advisory for Long Island until 12 noon. Vsby at all ASOS stations was 1/4 mile or less even at 14Z. Rain moving in from the west and warm front moving onshore may improve vsby but this remains to be seen. Also adjusted PoP based on trends of radar and in HRRR and GFS LAMP, with one band of rain moving across from late morning into the early afternoon, followed by scattered showers this afternoon. Adjusted high temps upward slightly across Long Island and southern CT, with a little more widespread lower 50s.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... 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. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... 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. && .AVIATION /14Z MONDAY THROUGH FRIDAY/...
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A warm from approaches from the south for late this morning. 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 this morning. expect widespread SUB-IFR at most terminals. 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 and final placement of the warm front. Confidence has lowered regarding improving visibilities and ceilings from 18z to 22z across most terminals. In any event ceilings and visibilities will be low again for Monday night into Tuesday morning with exact timing and magnitude in question. 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: Winds generally under 10kt but with low confidence in timing of wind direction change for the early afternoon. Amendments likely for changing flight categories. KLGA TAF Comments: Winds generally under 10kt but with low confidence in timing of wind direction change for the early afternoon. Amendments likely for changing flight categories. KEWR TAF Comments: Winds generally under 10kt but with low confidence in timing of wind direction change for the early afternoon. Amendments likely for changing flight categories. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Winds generally under 10kt but with low confidence in timing of wind direction change for the early afternoon. Amendments likely for changing flight categories. KHPN TAF Comments: Winds generally under 10kt but with low confidence in timing of wind direction change for the early afternoon. Amendments likely for changing flight categories. KISP TAF Comments: Winds generally under 10kt but with low confidence in timing of wind direction change for the early afternoon. Amendments likely for changing flight categories. .OUTLOOK FOR 12Z 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.
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&& .MARINE...
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Marine dense fog advy in effect for this morning and may have to be extended into this afternoon/tonight. SCA for hazardous seas remains in effect with max sea still 5 ft. Winds and seas will be below Small Craft Advisory levels late tonight into 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... 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. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...Dense Fog Advisory until noon EDT today for NYZ078>081-177-179. NJ...None. MARINE...Dense Fog Advisory until noon EDT today for ANZ330-335-338-340- 345-350-353-355. Small Craft Advisory for hazardous seas until 2 AM EDT Tuesday for ANZ350-353-355.
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&& $$ SYNOPSIS...12/MET NEAR TERM...Goodman SHORT TERM...12 LONG TERM...MET AVIATION...JE/DW MARINE...12/Goodman/MET HYDROLOGY...12/MET

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