Area Forecast Discussion
Issued by NWS Upton, NY

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720 FXUS61 KOKX 291623 AFDOKX Area Forecast Discussion National Weather Service New York NY 1223 PM EDT FRI JUL 29 2016 .SYNOPSIS... Low pressure passes to the south and east of Long Island through this afternoon. High pressure will then briefly build into the region tonight into the first half of Saturday, giving way to low pressure approaching from the Ohio Valley later in the day. This low will pass to the north as a few waves of low pressure pass along a frontal boundary to the south into early next week. High pressure then returns for the middle of the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Back edge of the rain is moving across eastern Long Island and southeastern Connecticut. The rain should end at these locations by 18z. The heaviest rain is generally south and east of the coast, although a few pockets of moderate rain are still possible until the rain ends. Clouds are clearing west of the Hudson River with the back edge of the clouds moving eastward. Expect this clearing to continue eastward through the afternoon. Have bumped highs up a few more degrees from the city north and west and across the interior. Temperatures are already in the upper 70s and lower 80s, and middle 80s appear attainable here. Further east, the slower clearing should prevent highs from getting above the upper 70s and lower 80s. Some instability is noted on high resolution models this afternoon/early evening west of the city so have continued with a slight chance of showers. Have left out mention of thunder as it appears instability will be marginal if any showers develop.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Weak ridging builds behind the shortwave tonight with surface high pressure building from the northwest. Lows will be near seasonable levels, but remaining muggy. Weak high pressure will remain over the region Saturday morning, resulting in a dry Saturday morning. Models have trended quicker with the next approaching shortwave, which may trigger scattered showers and thunderstorms as early as Saturday afternoon. Eastern LI and SE CT may be able to remain dry most of the day. Highs also will be near seasonable levels. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Latest NWP guidance in fair agreement with the H5 pattern across North America consisting of strong high pressure over the southwest US...a Bermuda high over the western Atlantic and a mean trough extending from west of the Rockies to the east coast this weekend. Early next week the high out west expands back into the southern Plains sharpening the trough east of the Mississippi. The trough moves east of the area on Tue with upper level ridging building in for the middle of the week. Model trends over the past 24 hours have sped up the weekend system with pcpn moving in during the day Sat. The shortwave is lagging behind the RRQ of a 65kt upper jet...but could have decent warm rain processes with PW`s around 2 inches. However...the GFS looks suspicious aloft between 00z and 12z developing a coupled vort max/min in the mid levels thus enhancing pcpn total at the sfc. So...while there will likely be overrunning Sat night with a frontal boundary to our south...the best dynamics associated with the shortwave appear to pass to the N on Sun with the majority of the rainfall likely remaining to our N with areas N and W of NYC having the best chance to see pcpn. A few weak waves of low pres does develop along the boundary Sun and Sun night...but they look to pass too far S to have any real impact on the region. Have remained with chc pops for most of the area during this time except NW zones which will be closest to the upper jet and shortwave energy. There is also uncertainty with the location of the frontal boundary. EC is further N with it on Sun tracking the waves directly over the local area. Upper trough axis approaches Mon and moves through Mon night with sct showers/thunderstorms expected during this time. An isolated shower is possible on Tue although there may not be enough moisture and we could be capped as upper level ridging begins to build in. The remainder of the week looks dry with increasing heat and humidity. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/...
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Rain beginning to taper off over western portions of the NY airspace, and conditions should lift to VFR through 15Z. It will take some time for rain to end over eastern portions of the airspace, probably through 17-18Z. VFR conditions expected from this afternoon and through the remainder of the TAF period. NE winds become LGT/VRB tonight. ...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: MVFR cigs could persist another hour after rain ends. KLGA TAF Comments: MVFR cigs could persist another hour after rain ends. KEWR TAF Comments: MVFR cigs could persist another hour after rain ends. The afternoon KEWR haze potential forecast is yellow, which implies slant range visibility 4-6SM outside of cloud. KTEB TAF Comments: MVFR cigs could persist another hour after rain ends. KHPN TAF Comments: No unscheduled AMD. KISP TAF Comments: MVFR cigs could persist another hour after rain ends. .OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY... .Saturday morning...VFR. .Saturday afternoon into Sunday...Chance of showers and possibly a tstm. MVFR or lower conditions possible. .Sunday night-Monday night...Chance of showers. MVFR conditions possible. .Tuesday...Mainly VFR.
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&& .MARINE...
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As the low moves south and east of the waters this afternoon, occasional gusts on the eastern ocean waters up to 25 kt are possible. These winds should weaken after 18z as the pressure gradient relaxes. Winds and seas are then expected to remain below small craft advisory levels through Saturday. Low pressure is forecast to track south of the waters today with strengthening E/NE winds through this afternoon. Winds and seas are forecast to remain below SCA, but could gusts up to around 20 kt, especially on the ocean waters east of Moriches Inlet. Winds diminish tonight as high pressure builds across the waters. Sub-advsy conds are then expected through the rest of the forecast period.
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&& .HYDROLOGY...
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The next chance for organized rainfall Saturday into Sunday. Less than an inch is expected.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...24/DW NEAR TERM...DS SHORT TERM...DW LONG TERM...24 AVIATION...Goodman/MPS MARINE...24/DW/DS HYDROLOGY...24/DW/DS

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