Area Forecast Discussion
Issued by NWS Upton, NY

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536 FXUS61 KOKX 291423 AFDOKX Area Forecast Discussion National Weather Service New York NY 1023 AM EDT Sat Jun 29 2024 .SYNOPSIS... A warm front moves north of the area this afternoon and evening. A cold front then approaches tonight and moves across Sunday afternoon and evening. High pressure then follows Monday and lasts into Wednesday. A weakening cold front may impact the area Wednesday night. A more robust frontal system may impact the area from late day Thursday into Friday. && .NEAR TERM /THROUGH TONIGHT/... Updated to add in slight chance of showers for Long Island and coastal CT early this morning. Warm advection has developed some mainly light showers. Otherwise, clouds have lowered and thickened and anticipate this trend to continue this morning as a warm front approaches. Some showers may also glance Orange county, but the morning hours should largely remain dry. Chances for showers slowly increase into the afternoon north and west of the NYC metro as the warm front begins to lift through the area. Forcing is generally weak and there is limited instability aloft. A consensus of the latest CAMS indicates a line of showers with embedded thunderstorms should approach from the west this evening. Some of the CAMs actually dissipate the line as it enters the area while others slowly weaken it. The forcing remains weak and instability is elevated. The warm front should continue lifting north through the rest of tonight, but a pre-frontal trough settles nearby early Sunday morning. Some weak energy aloft may be enough to regenerate showers and a few thunderstorms early in the morning, with the higher probability across the eastern two thirds of the region. Not anticipating a severe thunderstorm threat through early Sunday morning given the weak forcing and little to no surface based instability. However, deep subtropical moisture will be in place with PWATs approaching 2-2.25 inches on average. This will lead to the potential of locally heavy downpours. Minor flooding is the main threat as the activity should have enough forward speed, but cannot completely rule out a localized flash flood occurrence tonight. Strengthening onshore flow will lead to wind gusts 20-25 mph, especially near the coast this afternoon. There will also be a good deal of cloud cover so temperatures will not rise much above the upper 70s for most with lower 80s in NE NJ. It will become increasingly more humid as dew points rise into the upper 60s by this afternoon and evening and then into the lower 70s tonight. && .SHORT TERM /SUNDAY THROUGH MONDAY/... Main concern for Sunday will be the potential for severe thunderstorms and locally heavy downpours, mainly in the afternoon and evening. There remains potential for some showers and a few thunderstorms to be ongoing to start the day along and ahead of the pre- frontal trough. This looks to align itself closest to the coast. Some of the guidance pushes any of this activity to our east shortly after 12z. The uncertainty with how any morning convection evolves may ultimately impact the environment in the afternoon and evening, especially if lingering clouds are slow to clear. The pre-frontal trough does look to remain near Long Island/Southern CT with the actual cold front to the northwest into the early afternoon. The cold front should then make its way from northwest to southeast across the area in the evening. Deep subtropical moisture should remain in place ahead of the cold front, although there may be a slight decrease behind the pre- frontal trough. Overall, PWATs look to average around 2-2.25 inches, so the threat for locally heavy downpours continues. The flow aloft will be strengthening through the day as the middle and upper level shortwave moves over New England. These increasing winds bring bulk shear values to 40-45 kt. MLCAPEs may range from around 1500 J/kg near the coast and upwards of 2500-3000 J/kg inland. The flow is mainly unidirectional, but there may be some backing of the low level flow immediately ahead of the cold front. SPC has continued to place the entire region in a slight risk for severe thunderstorms Sunday afternoon and evening. The main severe thunderstorm threat appears to be from damaging wind gusts. Some hail is possible, especially if the higher CAPE values aloft materialize. There is also a risk for an isolated tornado. The threat for flash flooding remains low and localized, with minor urban/poor drainage flooding the main concern. The other story for Sunday will be brief heat and humidity. Despite varying levels of cloud cover, there should be enough warming to push temperatures into the upper 80s to around 90 for the NYC metro and NE NJ with middle to upper 80s most elsewhere. These temperatures combined with dew points in the lower 70s will yield heat indices in the low 90s for much of the area, with NYC metro and NE NJ in the middle to upper 90s. The cold front pushes offshore Sunday evening bringing an end to the severe thunderstorm threat. Drier and cooler air will work in behind the front and skies will clear through the night. The upper trough axis moves across Monday morning with high pressure at the surface and aloft beginning to build in from the west Monday afternoon. Highs will be near seasonable levels in the upper 70s and lower 80s. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
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High pressure sfc and aloft will be mostly in control through mid week, with a warm front passing to the north Tue night into Wed. A weakening cold front may touch off a shower or tstm Wed night, but a more important frontal system as heights fall aloft and shortwave energy streams eastward from the Plains states, with chances for more widespread showers/tstms during that time. Temps will be near to slightly above normal during of of that time, with highs mostly in the 80s. Thu should be warmer, with highers in the lower 90s in the NYC metro area and NE NJ, and heat index values in the mid/upper 90s in those areas and parts of the Hudson Valley and nearby SW CT.
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&& .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
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A warm front approaches this afternoon and moves through this evening. A pre-frontal trough approaches tonight and settles nearby on Sunday. MVFR cigs across a good portion of the area lifts for the early afternoon. VFR returns for much of the remainder of the day. Cigs lower to MVFR this evening towards 22 to 00z, and then to IFR at some terminals (mainly outlying terminals) tonight. IFR conds with tstms possible mainly after midnight. Winds will be SE and S this afternoon, with most terminals S for this evening. Winds at most coastal terminals gust to 20 to 25 kt this afternoon, with a few gusts closer to 30 kt possible at KLGA/KJFK. The winds likely become more SW Sunday morning. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Timing of sub VFR conditions returning this evening may be off by a couple of hours. Amendments may be needed with changing flight cats this evening / tonight. OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY... Showers/tstms tapering off early, then becoming likely again in the afternoon with MVFR/IFR cond and gusty winds. Monday through Wednesday: VFR. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90
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&& .MARINE... S-SE winds increase today as a warm front lists north of the waters. Near shore gusts to around 25 kt are likely this afternoon and will be followed by ocean seas building to 5-6 ft this evening into tonight. Have left the start of the SCA for the ocean and South Shore Bays to 2 pm this afternoon. The most widespread wind gusts 25- 30 kt looks to occur tonight into Sunday morning with winds diminishing below SCA levels Sunday afternoon and evening. There is a threat for severe thunderstorms which could locally increase winds Sunday afternoon and evening. Elevated seas continue into Sunday evening. The passage of the cold front Sunday evening will bring weakening winds and subsiding seas into Monday morning. Conditions will then remain below SCA levels Monday through Wednesday. Late day winds in the NY Bight area just E of Sandy Hook could gust close to 25 kt both Wed and Thu afternoons. && .HYDROLOGY... A round of showers and thunderstorms are expected tonight into early Sunday morning with potential of locally heavy downpours. Another round of showers and thunderstorms will accompany a cold front passage Sunday afternoon and evening with a continued chance for locally heavy downpours. The most likely threat will be from minor urban and poor drainage flooding. The risk for flash flooding is low and localized. Locally heavy rainfall may be possible Thu night into Fri with a passing frontal system. && .TIDES/COASTAL FLOODING... The rip current risk this morning is moderate, but quickly increases to high this afternoon and evening with strengthening SE winds and building seas. The high risk continues into Sunday with swells of 5-6 ft and 7 second period. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...High Risk for Rip Currents through Sunday evening for NYZ075-080- 081-178-179. NJ...None. MARINE...Small Craft Advisory from 2 PM this afternoon to 8 PM EDT Sunday for ANZ345-350-353-355. && $$ SYNOPSIS...BG/DS NEAR TERM...DS SHORT TERM...DS LONG TERM...BG AVIATION...JE MARINE...BG/DS HYDROLOGY...BG/DS TIDES/COASTAL FLOODING...