Area Forecast Discussion
Issued by NWS Upton, NY

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364 FXUS61 KOKX 260811 AFDOKX Area Forecast Discussion National Weather Service New York NY 411 AM EDT Sun Mar 26 2017 .SYNOPSIS...
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High pressure centered over eastern Canada and extending into New England and the northeast will gradually slide east today. A stationary front well to the southwest will approach as a warm front tonight and move north Monday. Another frontal system affects the region Tuesday and Tuesday night. High pressure builds to the west Wednesday and Thursday. Another low pressure system approaches Friday.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Surface high pressure was extending into the region from southeastern Canada with a northeast to east flow, with a cold air damming situation as a stationary front remains from Ohio across West Virginia and through northern Virginia. Convergence and weak thermal forcing has resulted in a band of light rain from western upstate New York, and across northeastern New Jersey to western Long Island. Temperatures were above freezing across the interior and do not expected freezing rain Possible that some higher elevations of western Orange county New York briefly have freezing rain with mesonet stations reporting temperatures just above freezing. Otherwise with the surface and upper ridge into much of the area keeping the eastern CWA dry until late this morning with just slight chance probabilities and then by late this afternoon, as the ridge weakens, will have low chance probabilities across the CWA.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
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The closed and nearly cut off low that was over Missouri will continue to open and weaken as the shortwave gets picked up by a weak southern stream flow, and the wave moves into the eastern ridge. There remains some timing difference with the movement of the warm front and low tonight into Monday. Also, with weak forcing unsure how much precipitation will occur. So have lowered probabilities into the likely category, with the higher chance west and north late tonight into Monday.
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&& .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
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With the wave continuing to dampen late Monday into Monday night with weak ridging ahead of the next shortwave, there may be a break in the precipitation. However, with the uncertainty, and to keep continuity have continued with slight chance probabilities Monday night. Yet another shortwave approaches in the weak southern stream as this wave also dampens as wave approaches the mid Atlantic. There are timing differences and whether or not the shortwave will phase with a digging northern stream shortwave Tuesday. With uncertainties will keep probabilities at low chance Tuesday into Tuesday night. Wednesday and Thursday look to be dry with high pressure building in. Cold air advection appears to be delayed enough to the point where highs on Wednesday end up above normal, then near-normal for Thursday. Friday could be completely dry as well, but perhaps some rainfall sneaks into the western zones by the end of the day. High temps again near normal. Global models then disagree with the track of an area of low pressure that could bring rainfall on Saturday. Have capped PoPs at 40% for now.
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&& .AVIATION /08Z SUNDAY THROUGH THURSDAY/...
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As a cold front settles south across the Mid Atlantic states overnight, high pressure will build southward across the area with a push of drier air. Much of the area will experience MVFR conditions for a time overnight with VFR conditions working in from the NE. Amendments area likely for the timing of the improvement. If conditions can clear overnight there is low potential for a brief period of fog from 09-12Z. Flight cat Sunday morning uncertain. Started off VFR, then lowered to MVFR after about 13Z-14Z with light rain moving in well in advance of the warm front. Dry air through may win out, delaying the onset of the MVFR cigs and light rain until the afternoon/evening, especially east of the NYC terminals. N-NE winds around 10 kt will gradually pick up overnight, then the direction becomes more easterly after daybreak, with a few gusts G15- 20KT possible in the afternoon at the coastal/NYC metro terminals. .OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY... .Sunday night...Lowering to IFR/LIFR with light rain/drizzle/fog ahead of an approaching warm front. .Monday...IFR/LIFR to start. Conds could improve to MVFR or VFR by late morning or afternoon if the warm front moves through. .Monday night-Tue night...IFR likely, LIFR possible with low clouds/fog. .Wednesday...VFR. NW winds G20-25KT, possibly stronger. .Thursday...VFR.
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&& .MARINE...
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Northeast flow strengthens today between high pressure to the north and the cold front to the south/low pressure to the west. Marginal SCA gusts are possible on the ocean waters through tonight. The resultant easterly fetch should allow for ocean seas to build to 4 to 6 ft. Winds are expected to weaken and veer se on Monday as a warm front works into the waters...but e/se swells will likely keep seas at SCA levels through the evening. Otherwise, sub-sca conditions are expected across all waters briefly on Tuesday before gradually building through the evening in strengthening southerly flow ahead of a low pressure approaching from the west. Strong west-northwesterly flow with gusts to 25 kt will develop on Wednesday as a cold front passes which will initially allow seas to stay elevated at SCA levels before gradually shifting east of the ocean waters. Stronger winds may persist into Thursday before weakening by late week as high pressure briefly builds over the area.
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&& .HYDROLOGY...
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One quarter of an inch to one half an inch of rainfall is possible today through Tuesday night. No hydrologic issues are anticipated through Tuesday.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 7 PM EDT Monday for ANZ350-353-355.
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&& $$ SYNOPSIS...MET NEAR TERM...MET SHORT TERM...MET LONG TERM...JC/MET AVIATION...MD MARINE...MD HYDROLOGY...MET

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