National Weather Service (2024)

Area Forecast Discussion
Issued by NWS Upton, NY

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-- Discussion containing changed information from previous version are highlighted. --502FXUS61 KOKX 201637AFDOKXArea Forecast DiscussionNational Weather Service New York NY1237 PM EDT Thu Jun 20 2024.SYNOPSIS...
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High pressure over the western Atlantic will remain in controlthrough late week. A cold front sliding down from the north onFriday will stall nearby by on Saturday, then return north as awarm front on Sunday, with a cold front to follow on Monday.High pressure will settle in on Tuesday and Wednesday.
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The forecast remains on track.High pressure weakens a little over the region today. Most of theforecast area will be dry, but a pre-frontal trough with moistureconvergence may help spark some showers/tstms across thenorthern zones. Any storms could produce a strong wind gust orsmall hail, but with weak shear, the threat of severethresholds being met will be limited to just off to our north,but not completely out of the question over here. This agreeswell with SPC marginal risk skirting our northern zones.The trough will also make it tough for dewpoints to mix out inits vicinity, so dewpoints across the northern zones willprobably hover around 70 for a good portion of the day. Farthersouth, a somewhat drier boundary layer and lower surfacedewpoints for the most part. H8 temps will be 18-20 deg C, soambient temperatures should be a little higher than yesterday`s.Heat advisories for this period remain unchanged.
-- End Changed Discussion --&&.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...A cold front approaches on Friday, stalls over or near the forecastarea late in the day into Friday night, then begins to retreat northas a warm front on Saturday. SBCAPES across the northern zones mayincrease to 1000-2000 J/kg. With lift from approaching front andsubtle shortwaves aloft, showers and sct TSTMs will be likely acrossthese zones in the afternoon and evening. PoPs capped at chance fornow across the rest of the forecast area. While a little strongerthan today, shear remains weak, but can`t rule out a strong tosevere wind gust north of the city.Temperatures and dewpoints for Friday continue to present somechallenges. It appears that the cold front and potentialconvection/associated clouds have been delayed by a few hours fromwhat was progged 24 hours ago. This will give the northern zones alittle more time to heat up, but there`s discrepancy among themodels regarding how hot it can get here beforehand. 850mb tempsvary from as little as 16-17C to as high as 19-20C, with the highervalues generally towards the west. Farther south, a little moreconfidence in the high temperature forecast. With the approachingfront, dewpoints in the lower 70s across the northern zones andupper 60s for most the southern zones.Regarding heat indices and advisories, there was enough confidence toextend the advisory for the Lower Hudson Valley as well as NorthernFairfield and Northern New Haven Counties. Farther east in CT,temperatures probably not warm enough to support another day ofwidespread 95+ heat indices. And while indices of at least 95 mightbe widespread in NYC, parts of the north shore of LI, as well asSouthern Westchester and Southern Fairfield Counties, it`s notanticipated to be the case today, thus falling short of the 2-daycriteria.With the stalled front, showers and thunderstorms will remainpossible Friday night and Saturday, with generally higher chancesacross the northern zones. PWATs climb to around 2 inches in thevicinity of the front Friday through Saturday, and with a relativelyweak steering flow, slow moving storms, potentially training alongthe cold front, introduce a chance of flash flooding. See thehydrology section below for more details.High temperatures on Saturday should be cooler than Friday`s, butthis may continue to trend warmer with a more northerly stalling ofthe cold front. Heat advisories may need to be extended intoSaturday, particularly across NE NJ.&&.LONG TERM /SUNDAY THROUGH WEDNESDAY/...**Key Points*** Hot and Humid on Sunday with showers and t-storms expected late Sunday into Sunday night.* A cold front with showers and t-storms slides through Monday which breaks the high humidity and heat.A warm front will lift north of the region early Sunday. A leadshortwave out ahead of the main trough / mid level shortwave isprogged by most guidance to arrive during Sunday evening. This willlead to another round of showers and t-storms late Sunday intoSunday night.Sunday appears to be the hottest and most humid day ofthe period with thickness ridging working in. The CWA gets purelyinto the warm sector and more of a SW flow. Heat index values willclimb into the 90s for a good chunk of the area, with some 100values in portions of NE NJ and the Lower Hudson Valley. Heat indexvalues likely remain in the 80s across eastern Long Islandeastern/coastal CT.A cold front moves across the area on Monday. Monday will remainunsettled, with showers likely along with the chances forthunderstorms. The front should clear the area Monday evening, andwith that the humidity gradually falls into Tue AM. Look for a drierW to NW flow to begin Tuesday as high pressure works in from thewest. It will only be a subtle air mass change with the humiditydropping some. The winds will likely shift more to the south late inthe day with humidity levels rising again Tuesday night andWednesday. Uncertainty remains with the eastward progression ofupper level energy and the southern extent of a frontal boundary bylate Wednesday into Thursday. Late day or evening convection is apossibility late Wed, but much, if not all of the day will be rainfree. Rain chances continue into Thursday.&&.AVIATION /18Z THURSDAY THROUGH TUESDAY/...VFR as high pressure remains over the Western Atlantic throughthe TAF period.Winds will be S-SW through the TAF period. Some gusts to 15-20kt will be possible this afternoon into early evening but mayonly be occasional. Otherwise, sustained winds will be mainlynear 5-10 kt through the TAF period.The afternoon KEWR, KJFK, and KLGA haze potential forecast isYELLOW...which implies slant range visibility 4-6SM outside of cloud. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...Occasional wind gusts to 15-20kt possible this afternoon.OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...Friday and Saturday: Mainly VFR. There is a chance for MVFRor lower conditions in showers and thunderstorms, mainly duringthe afternoon/evening hours.Sunday and Monday: Mainly VFR. There is a chance for MVFR orlower conditions in showers and thunderstorms, again mainlyduring afternoon/evening hours. For Sunday afternoon into earlySunday evening, S-SW wind gusts 15-20 kt.Detailed information, including hourly TAF wind componentforecasts, can be found at: https:/www.weather.gov/zny/n90&&.MARINE...
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Strengthening S flow due sea breeze circulations could push windgusts close to 25 kt near the NY Harbor entrance and theadjacent coastal waters late today into early this evening.Otherwise, conditions will remain below SCA levels through atleast Saturday.Ocean seas 5+ ft become become increasingly likely Sunday andSunday night, along with a few gusts up to 25 kt.These conditions will likely linger into Monday for a goodportion of the ocean waters.Conditions fall below SCA levels on the ocean on Tuesday,however can not rule out some lingering 5-ft seas Tue morning Eof Moriches Inlet.
-- End Changed Discussion --&&.HYDROLOGY...Showers and thunderstorms Friday afternoon through Saturday areexpected to produce an average of a half inch to an inch of rainfallnorth of NYC, and lower amounts for NYC, LI and NE NJ. There is athreat of higher amounts as the storms may redevelop along a stalledcold front and move slowly. There is therefore at least a low riskfor localized flash flooding during this period, mainly north of thecity, where the front will be stalled.Another round of moderate to locally heavy rainfall will be possibleSunday and into a portion of Monday. The uncertainty remains higharound potential hydrologic impacts for this time period.&&.TIDES/COASTAL FLOODING...
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There will be a moderate rip current risk for all ocean beachesthrough Friday due to a S-SW wind wave.
-- End Changed Discussion --&&.CLIMATE...Here are current record high temperatures for today and Friday.Thursday, June 20NYC: 98(1923)LGA: 98(2012)JFK: 94(2012)EWR: 98(2012)ISP: 93(1995)BDR: 93(1953)Friday, June 21NYC: 97(1988)LGA: 98(2012)JFK: 97(2012)EWR: 100(1953)ISP: 95(2012)BDR: 96(2012)&&.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Heat Advisory until 8 PM EDT Friday for CTZ005-006. Air Quality Alert until 11 PM EDT this evening for CTZ005>007- 009-010. Heat Advisory until 8 PM EDT this evening for CTZ007-008.NY...Heat Advisory until 8 PM EDT Friday for NYZ067>070. Air Quality Alert until 11 PM EDT this evening for NYZ067>075- 078>081-176>179.NJ...Heat Advisory until 8 PM EDT Friday for NJZ002-004-006-103>108. Air Quality Alert until 11 PM EDT this evening for NJZ002-004- 006-103>108.MARINE...None.
-- End Changed Discussion --&&$$SYNOPSIS...BC/JC/BGNEAR TERM...JC/BGSHORT TERM...JCLONG TERM...BCAVIATION...BC/DSMARINE...BC/JC/BGHYDROLOGY...BC/JCTIDES/COASTAL FLOODING...CLIMATE...