Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 012145 AFDOKX Area Forecast Discussion National Weather Service New York NY 545 PM EDT Thu Jun 1 2023 .SYNOPSIS... High pressure weakens tonight. Back door cold front moves in Friday. This front moves south of Long Island Friday night. High pressure will begin to approach from the north Saturday. An area of low pressure will begin to exit Saturday night with weak high pressure Sunday into Monday. A cold front is expected Tuesday. Low pressure lingers in the area Tuesday through Thursday. This area of low pressure may linger nearby through the middle of next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Mostly clear sky conditions expected tonight for all locations except Long Island and Southeast Connecticut. This will be where some lower level clouds will move in. There will be potential for fog along the coast as well. Onshore flow will be light along the coast, with otherwise very light to calm winds. Models overestimated the amount of low moisture and low clouds and fog previous night and even into today. Kept the mention of fog to patchy coverage. Used a blend of NBM, MAV, MET and CONSRaw for forecast lows, mid 50s to mid 60s range. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/... Light winds initially Friday with mostly sunny conditions to start. Any morning fog and low clouds along the coast are expected to burn off with diurnal heating. Ahead of an approaching back door cold front, a pre-frontal trough develops and moves in for the afternoon. Clouds and eventually some showers and thunderstorms develop in the afternoon. Temperatures about the same as previous day at 850mb, about 16-17 degrees C. However the vertical mixing is shown to be deeper, allowing for more adiabatic warming. Also, dewpoints trend several degrees higher. This will allow for more low level CAPE. The sea breeze will keep coastal locations cooler compared to farther inland. Coastal locations have forecast high temperatures in the mid 70s to near 80 while NYC will be more in the mid to upper 80s. Interior areas forecast to have high temperatures more in the mid 80s to near 90. As the back door cold front approaches from the north, showers and thunderstorms pop up and develop in the afternoon from north to south. This will be from the increased low level instability and convergence along the pre-frontal trough. The showers become more likely going into Friday night along with a continued chance of thunderstorms as the back door cold front itself moves in from the north. Higher chances will be across Southern Connecticut and Long Island compared to farther west. Bulk shear 0-6 km limited by models to near 20 kt, but elevated instability remains into the night. Also, with mid level height falls, could have some small hail with some thunderstorms. Expecting most convective activity to stay sub-severe. The back door cold front moves across Friday night and will be south of Long Island on Saturday. Winds become NE late Friday night and increase on Saturday, becoming gusty. A more stable airmass develops in the area, allowing for thunderstorm chances to decrease with showers lingering around going into early Saturday. The weather becomes drier Saturday afternoon with high pressure building down from Southeast Canada. Temperatures are expected to be below normal with highs mostly in the 60s. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
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Minor adjustments made to temperatures and dewpoints in just a few spots to account for latest trend in observations. Otherwise, forecast is on track. Low pressure to our east begins to push out further east Saturday night into Sunday with a weak ridge of high pressure nosing in from the west in between the exiting low and a new low to the north SUnday in to Monday. Most deterministic models and ensembles have agreed with this solution for the 6Z and 12Z runs. Have lowered chances for showers Sunday into Monday to account for weak conditions for lift and slightly drier air. Did not run completely with the NBM on this as it had POPs too high for that period, contradicting recent deterministic and model guidance. Temperatures will also remain cooler during Sunday to Monday time frame as heights remain generally low with north winds and cooler 850 mb temps aloft. Its important to note that while I refrained from using NBM guidance for temperatures, opting to use CONSALL instead, a different in-house model consensus, there is a 20+ degree spread in high temperatures for Sunday and Monday between NBM`s 10th and 90th percentiles. This means confidence is not great and is still subject to change given the track of the first low, which has been changing position from model run to model run. A cold front will likely move through Tuesday from a deepening upper- low dropping south from Canada into New England. This upper-low will build down to the surface as it continues to retrograde south and to the west of us. This system is supposed to bring better rain chances Wednesday and Thursday with general cyclonic flow over the area and rain chances on Tuesday also along a cold front.
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&& .AVIATION /22Z THURSDAY THROUGH TUESDAY/... High pressure remains in control into Friday. A backdoor cold front approaches during Friday afternoon. VFR. There is a chance of MVFR to IFR stratus late tonight at KJFK, however with low confidence only have scattered 010. More likely IFR at KISP and KGON, and with increased confidence included a TEMPO for IFR ceilings. Patchy MVFR fog is possible, however, with low confidence and patchy fog, have not included fog in any of the terminals. A light southerly flow continues at the terminals, except for NE to E winds at KLGA that becomes SE to S late in the afternoon, with timing uncertain. Winds become light and variable this evening and overnight. Winds then become southerly Friday morning, with timing uncertain as light and variable winds may continue longer than forecast. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Timing of the wind shift to SE to S at KLGA uncertain. There is a chance of MVFR to possibly IFR stratus at KJFK late tonight into Friday morning, 05Z to 12Z, and with uncertainty at this time will only have a TEMPO for scattered stratus. OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY... Friday afternoon: Mainly VFR. A chance of showers/thunderstorms, likely north and east, with MVFR during the afternoon and at night. Saturday: MVFR to IFR with showers in the morning, becoming a slight chance during the afternoon with improvement to VFR possible. NE winds 10-15kt with gusts 20-25kt, highest at the coastal terminals. Sunday: Mostly VFR, a chance of MVFR with showers east of the NYC metro terminals. N wind 15-20kt gusts 25-30kt east of the NYC metro terminals. Monday: VFR, a slight chance of showers. Tuesday: VFR, a chance of afternoon and evening showers and thunderstorms with MVFR. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/ && .MARINE... Sub-SCA conditions forecast until Saturday with weak pressure gradient in place, then SCA conditions likely for most waters for Saturday with 5-6 ft seas on the ocean with an increase in pressure gradient. This will be as high pressure starts to build in from Southeast Canada. SCA will be met for ocean waters Saturday night with 25 kt wind gusts and 5-6 ft waves. Only eastern ocean waters will meet SCA conditions through Sunday with 25-30 kt wind gusts and 5 ft waves. SCA may persist into early Monday with 5 ft waves for E ocean waters, wind gusts will be below 25 kt at that time. Sub-SCA conditions forecasted for the remainder of the period. && .HYDROLOGY... No hydrologic impacts expected through early next week. && .TIDES/COASTAL FLOODING...
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A moderate rip current risk is expected Friday and Saturday.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JM/BR NEAR TERM...JM/BR SHORT TERM...JM LONG TERM...BR AVIATION...MET MARINE...JM/BR HYDROLOGY...JM/BR TIDES/COASTAL FLOODING... is the U.S. government's official web portal to all federal, state and local government web resources and services.