Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 231748 AFDOKX Area Forecast Discussion National Weather Service New York NY 148 PM EDT MON MAY 23 2016 .SYNOPSIS... Low pressure off the Mid Atlantic coast moves slowly north through tonight, then drifts northeast Tuesday and Tuesday night, remaining offshore and passing south and east of the region. High pressure will then briefly follow for Wednesday through Thursday morning, then a cold front stalls in the vicinity Thursday afternoon and night. The front returns north as a warm front on Friday...followed by high pressure building in from the south through the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Currently only 100-300 J/kg of CAPE to the N/W of NYC. For now this is mainly to the N/W of a convergence line/weak surface trough stretching from SE CT into NYC. The trough should lift to the N/W later this afternoon, so given some additional daytime heating and with some marginal low level instability (showalter indices 0 to 4), there is the possibility for some isolated to scattered showers mainly to the N of Long Island Sound/W of NYC. Also cannot rule out isolated thunder across most of that area as well. For highs today...still running a tad warmer than forecast hourly bumped up highs a degree or so at most locations. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... The surface low continues to drift north and northeast tonight through Tuesday night, remaining offshore, as the mid and upper cutoff low also drifts along the coast. With the low a little closer to the coast tonight and additional energy rotating through, there will be a better, likely, chance of showers. There may be isolated thunder early, however, cape and instability will be decreasing. Not all areas will see precipitation, and will be dependent on where the low and upper low drift. Once again, Tuesday afternoon thunderstorms will be possible as a surface trough develops and the low drifts east of the region. Precipitation ends during Tuesday evening as the upper low begins to fill and open, moving farther to the east, and height will be rising at all levels after 03z Wednesday. Could be a rather sharp end to the precipitation. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Ridging aloft on Wednesday will help slow down a cold front sinking south across the Northeast. Insufficient moisture and lift should therefore keep the CWA dry. Mixing to 850 mb, where temps are forecast to rise to around 13C, along with a mostly sunny sky and SW winds will bring high temps about 10-15 degrees above normal across the entire area. The cold front weakens and stalls over us on Thursday as ridging aloft continues. Chance of afternoon tstms from around the city and points west where better instability will reside. Subsidence will limit mixing more than on Wednesday, so expecting high temps to be a couple of degrees cooler on average versus Wednesday. Friday and Saturday look to be similar days with ridging aloft and a weak SE-S wind flow. This will probably limit chances of showers/thunderstorms to inland sections both days, and chances don`t appear to be very high due to limited moisture and/or capping from ridging aloft. Models however hint at the possibility of an Mesoscale Convective System moving through late Thursday night into early Friday morning, so a more widespread rainfall is still a possibility. High temps both days still averaging above normals in spite of a limited mixing profile. It appears that Sunday could feature deeper mixing,and along with rising temps aloft, high temps could end up a few degrees warmer than currently forecast. Didn`t want to stray too far from WPC guidance this far out in time, which is warmer than Superblend. Highs well into the 80s for some inland spots. Once again, limited chances of showers/storms focused inland. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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Low pressure off the Delmarva moves slowly NNE through Tuesday. The sea breeze is advancing north and is currently located just south of LGA. Where it hasn`t already, flow should shift to the south over the next hour or two before becoming light and variable tonight as the sea breeze circulation weakens. NNW winds develop during the day on Tuesday before shifting to the WSW Tuesday evening. Mainly VFR thru this evening. Scattered showers have developed across the Hudson Valley and should remain north and west of NYC through the afternoon. An isolated thunderstorm cannot be ruled out, particularly from the city into the Hudson Valley and northeastern NJ. MVFR or lower in rain after 04Z, with MVFR ceilings lingering into Tuesday afternoon. ...NY Metro Enhanced Aviation Weather Support... Detailed information...including hourly TAF wind component fcsts can be found at: http:/ KJFK TAF Comments: Chance of an isolated shower or thunderstorm this afternoon. KLGA TAF Comments: Chance of an isolated shower or thunderstorm this afternoon. KEWR TAF Comments: Low prob of a thunderstorm this afternoon. KTEB TAF Comments: Low prob of a thunderstorm this afternoon. KHPN TAF Comments: A tempo may be needed for thunderstorms this afternoon. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 18Z Tuesday through Saturday... .Tuesday...periods of MVFR in -shra and/or tstms. .Wednesday-Thursday...VFR. .Thursday night...low chance of MVFR -shra. .Friday-Saturday...MVFR possible in tstms.
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&& .MARINE... Made minor changes this update to reflect the latest trends in observations and guidance. The forecast appears on track. A rather weak pressure gradient force will be across the waters through Tuesday night. Winds and seas will remain below small craft levels through Tuesday night as a result. Sub-sca conditions will prevail Wednesday through Friday as well, with the lack of a strong pressure gradient or significant swell. && .HYDROLOGY... A long period of generally light precipitation is expected today through Tuesday evening with 1/3 to 2/3 of an inch expected. Locally higher amounts are possible if any thunderstorms develop this afternoon and Tuesday afternoon. Widespread significant rainfall is not expected for the rest of the week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JC/Maloit/MET NEAR TERM...Maloit SHORT TERM...MET LONG TERM...JC AVIATION...FEB MARINE...JC/Maloit/MET HYDROLOGY...JC/Maloit/MET is the U.S. government's official web portal to all federal, state and local government web resources and services.