Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 271827 AFDOKX Area Forecast Discussion National Weather Service New York NY 227 PM EDT FRI MAY 27 2016 .SYNOPSIS... Bermuda High pressure will remain across the region through the weekend. A cold front will pass through the area Monday into Tuesday. High pressure returns for the middle of the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Convection has fired well nw. Will need to keep an eye on western zones, west of the Hudson, for possible shower and thunderstorm development early. HRRR continues to develop convection, along the seabreeze boundary. Will seabreeze boundary be enough to break the cap. With increasing cape as the afternoon progresses, coverage increases warranting chance pops. The forecast remains on track. Shortwaves moving through today are progged to be weaker than they were 24 hours ago. No changes to temps at this time. 850 mb temps and sea breeze progress should be close to those of yesterday, but yesterday featured a mostly sunny sky for most of the day for most locations. Will forecast high temps lower than what occurred yesterday. Looks like clouds will be more numerous and more opaque this time around. Have gone above a guidance blend for high temps, especially across Long Island where guidance has been too low during the past couple of days. There is a moderate risk of rip current development at the Atlantic beaches Today into this evening. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... An evening shower/thunderstorm is possible northwest of the city, then with the loss of instability and only weak lift, dry overnight. For Saturday, still no significant source of lift outside of weak mid level shortwaves, but SBCAPEs will be building once again away from sea breezes. Again, will go with only slight chance to chance pops, focused more toward the afternoon and away from areas cooled by sea breezes. Highs on Saturday should be warmer than on Friday with warmer temps at the top of the mixed layer, and probably less cloud cover overall. Again, needed to adjust a guidance blend upward to account for the low bias as of late, especially over Long Island. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Deep middle and upper level ridging over the Tri-State will continue for the remainder of the weekend with Bermuda high pressure at the surface. Any isolated or scattered convection that develops Sat afternoon north and west of the city will quickly dissipate after sunset as there is not much support other than from daytime heating. A backdoor front may approach from the north Sunday morning, but models seem to have come more in line with the boundary staying north of the area. This makes sense given the strong ridging aloft and generally weak surface flow. The front likely retreats northward Sunday afternoon and may act as a focus for some scattered showers/storms, so will show low chance pops for the northern interior which will be closest to the boundary. Sundays high temperatures will be in the upper 80s to possibly near 90 in NE NJ. A stronger southerly flow closer to the coast should hold temperatures down a bit with highs closer to 80 degrees. The ridge breaks down and shifts into the western Atlantic Sunday night as a shortwave and its associated cold front approaches from the west. Increasing SW flow aloft will advect in much deeper moisture over the region. Models indicate precipitable waters approaching 2 inches by Monday morning as a plume of tropical moisture surges northward ahead of a tropical disturbance near the SE coast. These values are close to the maximum observed precipitable water for May 30 per SPC Sounding Climatology. The shortwave trough should push the deepest moisture and best lift east of the area by Monday evening. Have adjusted pops with this forecast package to show an increasing trend Sunday night with likely pop across the entire area on Monday morning. Pops trend down through the afternoon. Models on occasion can break down ridges too quickly, so it is possible that this timing will be adjusted in future forecasts. Instability looks marginal at this time so will only include slight chance thunder wording in the forecast. Locally heavy rainfall is possible with any shower/storm due to the high moisture content of this air mass. Temperatures will be much cooler on Monday and closer to seasonal norms due to clouds and precipitation. The cold front looks to be much slower and may not fully move through the area until Tuesday. With best moisture well offshore, have trended to a dry one overnight Monday into Tuesday. High pressure then builds into the region as ridging rebuilds aloft. There are differences between the GFS and ECMWF with its placement of the ridge axis and therefore its surface high. These differences also exist in their ensemble systems so have leaned close to model consensus for Wednesday and Thursday. Above normal temperatures forecast on Tuesday and the temperatures should return closer to seasonal norms Wednesday and Thursday. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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The area will remain on the western side of the Bermuda High into Saturday with a thermal trough across then interior each afternoon. Convection was developing along the NJ coast in the vicinity of the seabreeze front. This will likely have impacts to the gates to the west and southwest of the NYC terminals this afternoon into early this evening. Confidence remains low on thunderstorms at the NYC terminals as well as KISP and KBDR due to the airmass forecast to stabilize over the next few hours. However, based on latest radar imagery will mention VCSH. Highest confidence is at KSWF. VFR outside of any convection. MVFR fog/haze possible - probable outside of NYC/Long Island terminals tonight. South winds around 10 kt today with local seabreeze enhancements. Easterly winds across LI Sound will influence KBDR through part of this afternoon. There is some uncertainty with the timing of the winds veering back to the south. Winds become SW at under 10kt this evening and then gradually increase back to around 10 kt Sat morning. NY Metro Enhanced Aviation Weather Support... Detailed information...including hourly TAF wind component fcsts can be found at: http:/ KJFK TAF Comments: Occasional gusts 15-20kt possible with afternoon seabreeze. Low chance of afternoon/early evening shower/thunderstorm. KLGA TAF Comments: Occasional gusts 15-20kt possible with afternoon seabreeze. Low chance of afternoon/early evening shower/thunderstorm. KEWR TAF Comments: Occasional gusts around 15-20kt possible with afternoon seabreeze. Low chance of afternoon/early evening shower/thunderstorm. KTEB TAF Comments: Occasional gusts around 15-20kt possible with afternoon seabreeze. Low chance of afternoon/early evening shower/thunderstorm. KHPN TAF Comments: Low chance of afternoon/early evening shower/thunderstorm. KISP TAF Comments: Occasional gusts 15-20kt possible with afternoon seabreeze. .OUTLOOK FOR 18Z Saturday through Wednesday... .Saturday afternoon-Sunday...Mainly VFR with afternoon seabreezes. There is a chance of MVFR or lower in any isolated to scattered afternoon/evening showers/thunderstorms; mainly to the n/w of NYC. .Sunday night-Monday...MVFR or lower probable with showers and thunderstorms. .Monday night-Tuesday...Becoming VFR Monday night. Seabreezes likely Tuesday afternoon.
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&& .MARINE... The western periphery of Bermuda high pressure remains across the waters through Saturday. Winds and seas are expected to remain below small craft levels during this period, however, late this afternoon into early evening there could be occasional gusts to 25 kt over the ocean waters west of Fire Island Inlet. Will also be watching seas as they build close to 5 feet across the outer waters. A weak pressure gradient across the waters will keep winds and seas below sca levels Saturday night through Tuesday. && .HYDROLOGY... Isolated to scattered thunderstorms are possible mostly for the inland areas this afternoon, this evening, and Saturday afternoon. However, no significant widespread precipitation is expected through the weekend. Rainfall amounts around one half to three quarters of an inch are possible on Monday with locally higher amounts. Localized urban or poor drainage flooding is possible from the heaviest rain. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JC/DS NEAR TERM...JC/DS/PW SHORT TERM...JC LONG TERM...DS AVIATION...DW MARINE...JC/DS/PW HYDROLOGY...JC/DS is the U.S. government's official web portal to all federal, state and local government web resources and services.