Area Forecast Discussion
Issued by NWS Upton, NY

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991 FXUS61 KOKX 221924 AFDOKX Area Forecast Discussion National Weather Service New York NY 324 PM EDT Wed May 22 2024 .SYNOPSIS...
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High pressure remains in control the rest of today. A cold front approaches late tonight and slowly moves through the area on Thursday, moving offshore sometime early Friday morning. Weak high pressure builds on Friday. A weak low passes through the area late Saturday into early Sunday. A deep low pressure system tracks through the Great Lakes and into Canada late Sunday through Tuesday with the system`s warm front passing north Monday and its associated cold front moving through Tuesday into Wednesday.
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&& .NEAR TERM /THROUGH THURSDAY/...
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A mid-level low, embedded in the broader upper level trough over the western US, lifts north of the Great Lakes tonight. The associated surface low will also pass well to our north and west, but will send a cold front towards our area. Ahead of the front, a S/SW flow has brought in a hot and humid airmass with 850mb temps around 16 to 18C and surface dewpoints in the low to mid 60s for most. Moisture will continue to increase ahead of the front tonight, with guidance showing pwats peaking around 1.60 inches tonight into early Thursday. These pwat values are over the 90% moving average for the 12z 05/23 sounding at OKX per the SPC Sounding Climatology Page. Some showers and thunderstorms have fired up west of the area along and ahead of a pre frontal trough. Some of this activity could make it into western portions of the area overnight, mainly north and west of NYC, but is not expected to be severe with a lack of shear. The better chances for showers and thunderstorms for our area will be as the cold front starts to slowly move through the area Thursday morning. PoPs have trended earlier in the day with a shift in timing in the 12z CAMs. Given the environment, with MLCAPE values around 1000-1500 J/kg and 0-6 km shear increasing to around 35-40 kt, some storms could become strong to severe. The SPC continues to outline the area in a "marginal" risk of severe weather, with large hail and damaging winds being the main threat. Given the high pwats, any thunderstorms could also produce heavy downpours. At this time, there are no flooding concerns. Given the activity in the morning, it will be difficult to destabilize again for the afternoon and we will likely see just lingering showers as the front continues to sag through the area. However, if we end up seeing less or no activity in the morning, the stronger showers/thunderstorms could be in the afternoon. For this reason, have left chance of thunder through the day Thursday.
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&& .SHORT TERM /THURSDAY NIGHT/...
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With the front slowly sagging south, a chance of showers and thunderstorms continue through Thursday night, mainly for the southern half of the area. The front likely finally passes south early Friday morning. With plenty of clouds around, above normal low temperatures are expected. If the front moves through northern locations a bit quicker and they get under some clearing, some of these locations could drop lower than the upper 50s.
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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A cold front exits Friday morning with any lingering precip quickly exiting with the front. The cold front will not help cool things down much, with afternoon temperatures still expected to reach the mid-80s to mid-70s. The front will, however, help dry us out, reducing any chances for showers or thunderstorms. Sunny to mostly sunny conditions are expected on Friday. Zonal flow will remain aloft through the weekend with above normal temperatures and occasional shortwaves. Moisture will increase late Saturday with a returning southerly flow. Shower chances will increase with it late Saturday into Saturday night with slighter better chances for a few thunderstorms in the western interior developing along a passing warm front. Rain chances increase early Monday into Monday night then linger in the forecast through Wednesday. A Great Lakes low will lead to a stalled boundary that will pass as a warm front on Monday, then bring a cold front Tuesday or Wednesday as it tracks into Canada and/or New England. The warm front will bring us into the warm sector of the system and bring a chance for thunderstorms across the area late Monday into early Tuesday. The pressure gradient front the low passing to the north may lead to breezy conditions late Monday into early Tuesday. Guidance varies somewhat on the timing and location of this system so have kept chance POPs throughout Tuesday and Wednesday. Temperatures will be closer to seasonal Monday through mid-week aided by an approaching and deepening trough.
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&& .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... Weak surface high pressure will remain just offshore tonight, then drift farther out to seas late tonight into Thursday as a cold front approaches. VFR with sea breezes now in at all coastal/metro terminals. Winds sustained up to 15 kt at KJFK/KLGA, and a few gusts 15-20 kt possible at KEWR/KTEB/KLGA/KHPN. Winds diminish to under 10 kt tonight. Weakening convection moving in from the west could impact KSWF late this evening with thunder possible there or nearby, then some passing showers farther east overnight. Main shower/tstm impact from the NYC metros north/west now looks to be in the morning from about 12Z-16Z give/take an hour, reaching KBDR/KISP from 13Z-17Z. MVFR cond likely and brief IFR vsby possible with this activity, and gusty winds and some hail also possible with the stronger cells. Before that, some low stratus and fog with IFR cond expected at KBDR/KISP/KGON late tonight into Thu morning. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... No unscheduled AMD expected. OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY... Thursday afternoon: Showers/tstms with IFR cond and gusty winds possible especially for KSWF/KHPN. Thursday night: Chance of showers and possibly a tstm, with MVFR cond possible. Friday: VFR. Saturday: Chance of afternoon/evening showers and possibly a tstm, with VFR cond possible. Sunday: Mainly VFR. Monday: Chance of showers and possibly a tstm, with MVFR cond possible. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 && .MARINE...
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Winds and waves will generally remain below SCA criteria through Thursday night, with wind gusts potentially briefly reaching 25 kt this evening. A cold front approaches late tonight and slowly moves through the area on Thursday. Some showers and thunderstorms ahead and along the front are possible tonight through Thursday night, with the highest chances being Thursday morning/early afternoon. Sub-SCA conditions are then expected through Monday night.
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&& .HYDROLOGY...
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Thunderstorms are possible tonight through Thursday, with potential for heavy downpours mainly during Thursday morning/early afternoon. At this time, no hydrologic impacts are expected through the middle of next week.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...None.
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&& $$ SYNOPSIS...BR/JT NEAR TERM...JT SHORT TERM...JT LONG TERM...BR AVIATION...BG MARINE...BR/JT HYDROLOGY...BR/JT