Area Forecast Discussion
Issued by NWS Upton, NY

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913 FXUS61 KOKX 021350 AFDOKX Area Forecast Discussion National Weather Service New York NY 950 AM EDT Tue Jul 2 2024 .SYNOPSIS... High pressure builds across the area today, and offshore on Wednesday. The high will then give way to an approaching weak frontal system Wednesday Night into Thursday, which lingers nearby into Friday. A warm front will approach Friday night and lift through Saturday morning, followed by a cold front Saturday afternoon and night. This front may linger nearby into early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Forecast is on track this morning with no significant changes to the forecast. Otherwise, building heights aloft as shortwave energy moves east. At the surface, overhead high pressure slides offshore late in the day. Seasonable temps (lower to mid 80s) today with mostly sunny skies (just a few high-based Cu and a bit of cirrus filtering in late), deep mixing, and offshore flow giving way to afternoon coastal sea breezes.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... Shortwave upper ridging thru Wednesday gradually flattens Wed Night into Thu as a shortwave tracks through the Great Lakes and then southern Canada. At the surface, high pressure slides offshore Wed, with a weak frontal system approaching Wed Night into Thu. Potential for a bit of radiational cooling (patchy fog) tonight for outlying areas with light winds, with limiting factor being cirrus advecting in aloft with a weak lead shortwave energy over ridge. Return flow strengthens Wed as high pressure moves offshore and gradient tightens ahead of frontal system well to the west. Fair conditions (sun may be filtered by high clouds) and moderately strong hybrid synoptic/seabreeze development likely. This will result in increasing humidity levels and near seasonable temps in the upper 70s/lower 80s along the coast to mid 80s to the west of the Hudson River. Upper ridging flattens, with a weak frontal system approaching Wed Night into Thu. Warm and muggy conditions Wed night in return flow. Weak shortwave/vort energy moving through the upper flow may be trigger for scattered shower development in vicinity of weak front in a moist environment on Thu. Cloud cover, weak mid-level lapse rates, weak instability/capping, and weak surface convergence point to limited deep convection and thunder potential. Certainly not a washout, but potential for a few showers, particularly aft/eve. Otherwise, very warm and humid conditions with continued WAA (lower 80s coast to mid to upper 80s NYC metro and areas N&W). && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Forecast continues to follow the NBM for the most part, except temps may be slightly warmer and dewpoints slightly less where latest extended MOS guidance suggests. A quasi-zonal pattern that will be in place to begin the period becomes more amplified, with a longwave trough setting up over the Northern Plains and upper Midwest, and a strengthening Western Atlantic ridge. As this occurs initially, the frontal boundary that approaches during mid week should stall nearby Thu night/Fri, then as a sfc low moves across the upper Great Lakes, a leading warm front should approach Fri night and lift through on Sat. Temps through much of the period should remain similar, with highs reaching the 80s to lower 90s, and lows mostly from the upper 60s to mid 70s. Humidity levels will be highest on Sat, making it the least comfortable day in terms of heat index values, which should approach 95 in spots in NE NJ on Fri and surpass 95 over most of the urban corridor of NE NJ on Sat. Fcst temps that day are mot quite as warm as the other days in the long term period, but a slight increase (not out of the the question if there is more sunshine than fcst) would bring 95+ heat index values to parts of NYC and some areas north/west in the lower Hudson Valley. With multiple frontal boundaries impacting the area through Sat night and then the last of these lingering into early next week, the forecast carries at least chance PoP for mainly diurnal convection through the period, though forced nighttime convection may also continue through Fri night into Sat AM ahead of the lifting warm front. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/...
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VFR as high pressure builds in. N flow 10 kt or less should become SE-S this afternoon. KLGA should lock in on an ENE Sound breeze from 15Z-20Z before S sea breeze arrives. S winds diminish tonight. NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... No unscheduled AMD expected. OUTLOOK FOR 06Z TUESDAY THROUGH SATURDAY... Wednesday: VFR. SE winds G20kt late. Thursday: VFR for much of the day, then MVFR or lower cond possible with any late day or nighttime showers/tstms. Friday and Saturday: MVFR or lower cond possible at times with chance of showers/tstms. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90
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&& .MARINE...
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High pressure builds across the area today with sub-SCA conditions. Southerly flow strengthens a bit on Wednesday with the high departing to the east and a weak frontal system approaching from the west. Marginal SCA gusts possible Wed aft/eve and Thu aft/eve at entrance to NY Harbor and western Great South Bay with coastal jet development. Ocean seas may approaching 5 ft in this area Thu. Sub advisory conditions for the remainder of the waters. Potential for minimal SCA conditions on the ocean E of Fire Island Inlet this weekend, as long fetch S flow increases to 20 kt, with some gusts up to 25 kt and seas building to 5 ft.
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&& .HYDROLOGY... A frontal system will approach Thursday into Friday, and possibly linger into the weekend. Additional frontal boundaries will affect the region into early next week. It is still too soon to determine the risk of any hydrological impacts from these multiple frontal boundaries affecting the area late this week into early next week. && .TIDES/COASTAL FLOODING... There will be a generally low rip current risk today with 1 to 2 ft S wind waves and SE swell, but could be locally moderate due to large tidal range. There will be a moderate risk for rip currents developing for the NYC and western LI ocean beaches Wednesday aft/eve with late day coastal jet and wind wave enhancement, with a low to moderate risk for the Suffolk ocean beaches. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...BG/NV NEAR TERM...BC/NV SHORT TERM...NV LONG TERM...BG AVIATION...BG MARINE...BG/NV HYDROLOGY...BG/NV TIDES/COASTAL FLOODING...