Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 271151 AFDOKX Area Forecast Discussion National Weather Service New York NY 651 AM EST Mon Feb 27 2017 .SYNOPSIS... High pressure centered south of Long Island will continue to drift out to sea today. A warm front will lift north of the area on Tuesday, followed by a secondary warm front approaching from the south Tuesday night then pushes to the north Wednesday. A strong cold front crosses the area Wednesday night, followed by weak high pressure building in Thursday and Thursday night. A clipper system passes near the area Friday, followed by high pressure building over the area into Saturday then to the southeast through Sunday. && .NEAR TERM /THROUGH TONIGHT/...
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Made minor changes this update to reflect the latest trends in observations and guidance. The forecast appears on track. A clear sky this morning will give way to rapidly increasing mid and high clouds today. Based on satellite, the leading edge over southwestern Pennsylvania gets here by 13Z, with the thickest stuff over the Ohio Valley arriving by noon. It should be an overcast afternoon as a result. Subsidence today weakens by 00Z with some weak lift developing thereafter. At this point however the deepest moisture will be exiting, so the forecast has been kept dry right through tonight. Temperatures will rebound quickly as the inversion breaks this morning. The Pine Barrens on Long Island could be the big winner, where temperatures in the teens should shoot up around 20 degrees in a matter of minutes as the inversion mixes out. The guidance was in good agreement and reasonable based on temperatures aloft and southwesterly flow, so a blend was used through the period.
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&& .SHORT TERM /TUESDAY/... The main question is whether it actually rains. The models continue to back off, as they are just not supplying any moisture to the region. With the Gulf of Mexico opening up, there is a concern the models are not pumping enough moisture into the flow. As a result, chances for precipitation have been essentially been kept the same, with high chances by the end of the day. With regard to temperatures, it will be mild again with southerly flow. This temperature structure is likely to result in enhanced sea breeze flow particularly across southern portions of Queens and Nassau counties, as well as Brooklyn. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... A deep layered ridge axis lifts to the northeast Tuesday night, allowing for a moist SW flow to set up aloft, with southerly flow at the surface - this set up continues into Wednesday morning. This will allow for spotty light rain and areas of fog over the Tri-State from Tuesday night into Wednesday morning. As the secondary warm front lifts to the north by Wednesday afternoon, placing the region solidly in the warm sector, with the surface flow going SW as well. There should be sufficient instability at the surface inland and aloft over the CWA for scattered showers Wednesday afternoon (numerous far NW zones) with a chance of thunder NW 1/3 of the CWA and slight chance of thunder elsewhere. Showalter indices lower below zero everywhere Wednesday night, so increase chances of thunder to chance throughout, and pops to likely everywhere during Wednesday evening. Precipitation should tapper off from NW to SE Wednesday night as a 700-500 hPa trough builds in aloft and colder/drier low level air builds in behind the cold front. With a 60-65 kt low level jet passing just to the south, around 500-1000 J/kg over western interior zones and 60-70 kt of bulk shear, there is the potential for strong to possibly isolated severe storms across NE NJ/Lower Hudson Valley/SW CT Wednesday afternoon/evening. Lows Tuesday night should occur in the evening, then should see steady to slowly rising temperatures overnight. Wednesday should be rather warm - with highs in the upper 60s to Lower 70s across NE NJ/Lower Hudson Valley and Northern NYC, and from around 60 to the mid 60s elsewhere. This is around 15 degrees above normal and could approach record levels. See the climate section of the AFD for details. The best cold push won`t occur immediately behind the cold front, as is fairly typical, so lows Wednesday night will still end up closer to normal highs, if not a few degrees above them (and 15-20 degrees above normal lows). A northern stream trough exits to the east Thursday, followed by zonal flow Thursday night. It should be dry Through at least Thursday evening as a result. There are then timing/track differences between the models on a clipper system with the GFS running faster/a little stronger/a little farther N than the ECMWF. The GFS has been very consistent with this system so far, so opted for a blend of the two models late Thursday night/Friday. As a result, have introduced slight chance pops for snow late Thursday night and maintained a chance for snow across northern zones and snow and rain across southern zones on Friday. There is still a chance this system could miss the area completely, so not confident enough to go higher then low end chance pops at this time. At this time though, it appears that any accumulations should be relatively light, with a sub- advisory snow the most likely outcome with this system. NW flow aloft Friday night and Saturday gives way to northern stream ridging passing to the north Saturday night and Sunday. As a result it should be dry during this time frame. Temperatures Thursday-Sunday were based on the Superblend (with ECMWF 2-m temperatures blended in Friday-Saturday), and start out above normal Thursday, go below normal Friday and Saturday, then should return to above normal levels on Sunday && .AVIATION /12Z MONDAY THROUGH FRIDAY/...
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VFR through the TAF period as high pressure off the Mid Atlantic coast moves east. High confidence in SW flow less than 10 kt and increasing to 10-15G20KT by late morning and into the afternoon. Winds will then diminish for tonight and back to the S-SE late. ...NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http://www.weather.gov/zny/n90 KJFK TAF Comments: Start time of gusts may be off by +/- 2 hours. KLGA TAF Comments: Start time of gusts may be off by +/- 2 hours. KEWR TAF Comments: Start time of gusts may be off by +/- 2 hours. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Start time of gusts may be off by +/- 2 hours. KHPN TAF Comments: Start time of gusts may be off by +/- 2 hours. KISP TAF Comments: Start time of gusts may be off by +/- 2 hours. .OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY... .Tuesday...Chance of light rain/MVFR conds. .Tuesday night-Wednesday morning...Areas of fog with light rain continuing. MVFR/IFR and possibly lower. LLWS possible with SW winds 45-55 kt at 2kft. SW winds G15-20KT Wednesday morning. .Wednesday afternoon-Wednesday night...Showers and a chance of thunderstorms. MVFR or lower possible. SW winds G20-30KT. Winds become westerly late Wednesday night. .Thursday...VFR. W-WNW winds G20-30KT. .Friday...MVFR/IFR possible with a chance of light snow. WNW winds G20-25KT.
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&& .MARINE...
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Made minor changes this update to reflect the latest trends in observations and guidance. The forecast appears on track. Southwest winds will produce Small Craft Advisory conditions on the eastern two thirds of the coastal ocean waters today and tonight. Elsewhere, winds and waves are expected to remain just below criteria at this time. For Tuesday, light flow will allow seas on the ocean to remain below 5 feet. Small craft conditions are possible on the coastal ocean waters Tuesday night with seas maybe building to 5 ft on far southern portions of those zones, with sub-small craft conditions expected elsewhere. A deep marine layer will keep the bulk, if not all of a 60-65 kt low level jet from reaching the water Wednesday, but still should see small craft conditions on all waters. The pressure gradient remains tight Wednesday night, then low level cold advection Thursday should allow for small craft conditions to continue on all waters through most, if not all the day on Thursday. The winds should fall below SCA levels on all waters Thursday night, but maybe not the seas on the coastal ocean waters. There is the potential for SCA conditions on all waters with a low chance of gales on Friday, depending on the exact track and strength of a coastal low.
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&& .HYDROLOGY... Rainfall from Tuesday afternoon through Wednesday night should run from 0.5 to 0.75 inches, with locally higher amounts possible. Release from spring snow melt is occurring down the Connecticut and Housatonic Rivers. && .CLIMATE... Record highs for Wednesday March 1 Location.......Record High/Year Set.....Forecast High Newark..................75/1972...............72 Bridgeport..............59/1972...............60 Central Park............73/1972...............70 LaGuardia...............68/1972...............69 J F Kennedy.............58/2004*..............63 Islip...................60/2004...............62 * = and in previous years .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 AM EST Tuesday for ANZ350-353.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 AM EST Tuesday for ANZ350-353.
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&& $$ SYNOPSIS...12/Maloit NEAR TERM...12 SHORT TERM...12 LONG TERM...Maloit AVIATION...JE MARINE...12/Maloit HYDROLOGY...12/Maloit CLIMATE...

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