Area Forecast Discussion
Issued by NWS Upton, NY

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011 FXUS61 KOKX 211357 AFDOKX Area Forecast Discussion National Weather Service New York NY 957 AM EDT Fri Apr 21 2017 .SYNOPSIS...
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While one weak low passes well to the north today, a stationary front will remain to the south, with another weak low moving east along it this afternoon and evening. A weak cold front will pass through tonight, followed by high pressure building east from the Great Lakes on Saturday and remaining into Sunday. A wave of low pressure will move off the Southeast coast Sunday night and Monday, and track slowly north through Wednesday. High pressure will build back across on Thursday.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Showers continue to move off to the east this morning. Along with the showers, patchy fog is possible for the next few hours across eastern Suffolk County. Otherwise the forecast remains on track. As a weak closed low aloft moves from the upper Great Lakes into Ontario, the associated primary sfc low will move into Ontario and occlude. Another weak low developing in the lee of the Appalachians this afternoon should move east with the flow aloft, passing south along a stationary front south of Long Island. Showers and a few tstms with the primary low will move across from west to east this morning. Thunder now unlikely as layers aloft have stabilized. After precip passes, skies should remain overcast. Pulled mention of late afternoon showers as hi-res guidance has backed off on areal extent, keeping them more to the south and west. Backed of slightly on high temps, now from the lower 50s out east, to near 60 in NE NJ and in the valleys well NW of NYC.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Should see some patchy fog development mainly along the coast this evening as winds diminish after passage of the weak low to the south. Otherwise tonight should be mostly dry, with only an isolated shower expected two inland with the weak cool frontal passage. Saturday should start off mostly cloudy, then become mostly sunny in the afternoon as remaining mid level clouds move off to the east, allowing temps to reach seasonal norms in the lower 60s. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A near zonal flow will remain across the lower 48 into early next week with weak shortwaves moving through the flow. One shortwave will be exiting the northeast coast Saturday night with weak flow aloft and surface high pressure building to the northwest and north. Some upper level energy will get cutoff from the flow and remain over the mid Mississippi Valley and into the southeastern states, The northern high will then influence the movement of a surface low that will remain over the southeastern states, and then emerge off the coast and slowly deepen. There is a lot of uncertainty with the timing of when the upper closed and cutoff low will reach the southeast coast and then track to the north. Leaned toward a slower and weaker low with the GFS solution rather than the deeper and faster ECMWF as the flow remains weak. Start to bring in chances of precipitation Sunday night and will keep chances into Wednesday. The upper low does get picked up by a northern stream shortwave Wednesday and lifted to the northeast. A surface frontal boundary may remain in the vicinity of the region Wednesday night into Thursday, however, height will be rising across the area as a deep western trough developing into the southeastern states Thursday into Friday. A strong ridge is expected to develop along the east coast late next week and into the weekend with temperatures rising well above seasonal normals. && .AVIATION /13Z FRIDAY THROUGH TUESDAY/...
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A warm front remains SW of the area. A weak wave of low pressure is forecast to develop on this boundary and pass S of the area this aftn/eve. IFR/MVFR expected through this afternoon...likely coming down to IFR evening. LIFR possible for eastern terminals. Light rain pushes east of eastern terminals this morning...with isolated rain showers late this afternoon. Winds will be E-NE around 10 KT, diminishing this evening. 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: Prevailing IFR cigs...with occasional MVFR cigs through this afternoon. Brief MVFR vsby in any -shra. KLGA TAF Comments: Prevailing IFR cigs...with occasional MVFR cigs through this afternoon. Brief MVFR vsby in any -shra. KEWR TAF Comments: Prevailing IFR cigs...with occasional MVFR cigs through this afternoon. Brief MVFR vsby in any -shra. The afternoon KEWR haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KTEB TAF Comments: Prevailing IFR cigs...with occasional MVFR cigs through this afternoon. Brief MVFR vsby in any -shra. KHPN TAF Comments: Prevailing IFR cigs through this afternoon. Brief MVFR vsby in any -shra. KISP TAF Comments: Prevailing IFR cigs through this afternoon. Brief MVFR vsby in any -shra. .OUTLOOK FOR 12z SATURDAY THROUGH TUESDAY... .Saturday...CHC sub-VFR early, otherwise VFR. .Sunday...VFR. .Monday...CHC MVFR/rain. .Tuesday...CHC IFR/rain. CHC East gusts 20-25 KT.
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&& .MARINE...
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Dense Fog Advisory issued this morning for the eastern Long Island Sound, Bays, and the eastern ocean waters with beach cameras showing low visibilities in fog. Expect this to continue through at least early afternoon on the eastern Sound and bays, and into tonight on the eastern ocean waters. E winds still gusting to 20 kt. Seas at 44017 reached 5 ft for a couple of hours overnight, and if they do not subside early this AM s a short fused SCA for hazardous seas may be needed for this morning out east. Minimal SCA criteria may again be possible on the ocean out east for a time late today into tonight, as seas generated by stronger winds to the east could move in and reach 5 ft during that time. A weak pressure gradient force will be across the forecast waters Saturday night into early Monday with high pressure building into the area and then remaining to the north. A low pressure system will be developing along the southeastern coast Sunday night into Monday and then track to the north through midweek. A prolonged and increasing easterly flow will set up from Monday night into Wednesday. There may be a period of gusts approaching small craft levels on the ocean waters Tuesday and Tuesday night. However, with the easterly flow, ocean seas are expected to build to small craft levels by late Monday night and remain into Wednesday. As the low tracks through the forecast waters and weakens Wednesday winds will remain below small craft levels and seas will subside below small craft. Then winds and seas remain below advisory Wednesday night into Thursday.
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&& .HYDROLOGY... Rainfall today will be mostly under a half inch. Locally heavier rainfall amounts are possible with any heavier showers or tstms. Rainfall in the extended period will have no hydrologic impacts across the hydrologic service area. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Dense Fog Advisory until 2 AM EDT Saturday for ANZ350-353. Dense Fog Advisory until 2 PM EDT this afternoon for ANZ330- 340-345.
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&& $$ SYNOPSIS...Goodman/MET NEAR TERM...FEB/Goodman SHORT TERM...Goodman LONG TERM...MET AVIATION...JC MARINE...FEB/Goodman/MET HYDROLOGY...Goodman/MET

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