Area Forecast Discussion
Issued by NWS Upton, NY

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566 FXUS61 KOKX 191110 AFDOKX Area Forecast Discussion National Weather Service New York NY 710 AM EDT Wed Sep 19 2018 .SYNOPSIS... High pressure builds down from the Canadian Maritime Provinces through Thursday. A warm front passes to the northwest Thursday night, followed by a cold front crossing the Tri-State late Friday night and Saturday morning. The front settles to the south into early next week as high pressure builds to the north. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Deep layered ridging builds in from the southwest today. There should be sufficient subsidence as a result to keep things dry. Forecast is generally on track with previous thinking to cloud forecast today. Have made some adjustments to sky mainly for the first half of the day based on latest sat imagery and the thinking that stratocu will develop shortly after heating commences in areas where it is currently clear. Unclear how far west the stratus deck over eastern areas will make it, which also makes the temp forecast challenging. Western areas should be warmer than eastern and tried to reflect that in the MaxT forecast. A blend of the CMCReg (which was also the starting point for the cloud forecast) and the BCCONSRaw was used for highs, although MaxT forecast has high bust potential. Patchy fog will dissipate over the next hour or so as well. There is a moderate risk for the meteorological enhancement of rip current formation at Atlantic Ocean Beaches Today.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... Deep layered ridging continues to build in from the SW through Thursday. Continue to believe that subsidence under the building ridging should keep things dry. However, associated subsidence inversion should keep low clouds that moved in today around through tonight and quite possibly into Thursday morning. It appears that enough dry air should be transported down from aloft (due to the subsidence under the ridge) that the clouds should abate (to at least partly vice mostly cloudy) by around mid morning, except for possibly over far western zones, where elevation could help keep things mostly cloudy through the day (harder to scourer out lo level moisture once outside of the coastal plain and into foot hills/ridge and valley regime). For lows tonight, weighed towards warmest guidance due to cloud cover. For now used a blended approach for highs on Thursday. However, if the cloud cover does not dissipate, could end up 5 or so degrees cooler than forecast. There is a moderate risk for the meteorological enhancement of rip current formation at Atlantic Ocean Beaches through Thursday. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Upper level ridge axis shift to the east Fri morning as a shortwave trough over the upper Midwest dampens while tracking through New England Fri night. Quasi zonal flow then remains through the weekend with the H5 flow amplifying across the CONUS early next week, although differences in timing and amplitude are noted. At the sfc, a warm front associated with strengthening low pres over the upper Midwest, will pass to the NW Thu night as the low lifts into southern Ontario. The low will continue to track NE with it`s attending cold front passing through late Fri night/Sat morning. The best upper dynamics pass to the north so expecting a weakening trend as it moves through, thus no more than 30-40 PoPs are warranted. How far south the front pushes remains uncertain with the flow aloft becoming nearly parallel to it. Latest trends in the EC push it into the Mid Atlantic region, while the GFS is much closer to the local area. If the GFS ends up verifying, southern portions of the forecast area, could see some rain Sat night into Sun as a wave of low pressure tracks along the boundary. Have kept the forecast dry for now. Strong Canadian high pres builds in from the N into early next week, shifting into the Canadian Maritimes Mon night/Tue. Meanwhile, the old frontal boundary to the south will begin to lift back to the N passing through the local area on Tue. Temperatures vary through the period. Temps are expected to be a few degrees above normal on Fri as the area sits in the warm sector. Once the cold front passes, temps likely fall back to near normal Sat, below normal Sun and Mon, then back to near normal on Tue. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
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High pres builds towards the region today, and over the area on Thu. Some patchy fog this mrng gives way to increasing clouds from the ne thru the day. Heights in the 3-4k ft range, with the lowest cigs ne of NYC. As a result, mainly vfr in the city, but mvfr developing elsewhere. The clouds are expected to linger thru the entire taf period, with perhaps improvement to sct at times. Winds veer to the ne today. Some gusts to 15 kt possible aft 15z, then speeds in general decrease aft 20-22z. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component fcsts, can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: Low chance for a brief period of 300 ft cigs thru 12z. There is a chc that 3000 ft cigs develop today. The afternoon KJFK haze potential forecast is GREEN, which implies slant range visibility P6SM outside of cloud. KLGA TAF Comments: Low chance for a brief period of 300 ft cigs thru 12z. There is a chc that 3000 ft cigs develop today. The afternoon KLGA haze potential forecast is GREEN, which implies slant range visibility P6SM outside of cloud. KEWR TAF Comments: Low chance for a brief period of 300 ft cigs thru 12z. There is a chc that 3000 ft cigs develop today. The afternoon KEWR haze potential forecast is GREEN, which implies slant range visibility P6SM outside of cloud. KTEB TAF Comments: Mvfr or lower at times possible thru 13z. There is a chc that 3000 ft cigs develop today. KHPN TAF Comments: Mvfr or lower at times possible thru 13z. KISP TAF Comments: Mvfr or lower at times possible thru 13z. .OUTLOOK FOR 06Z THURSDAY THROUGH SUNDAY... .Tonight-Thursday...VFR. .Thursday night...Slight chance of showers with MVFR possible. .Friday-Friday night...VFR during the day, then a chance of showers and thunderstorms with MVFR at night. .Saturday-Sunday...An early shower Saturday, then VFR through the weekend.
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&& .MARINE... Seas over the coastal ocean waters west of Fire Island Inlet have fallen below 5 ft, so have cancelled the Small Craft Advisory (SCA) there. East of Fire Island Inlet, there could be a few hours of seas below 5 ft, mainly this morning, before seas build back on strengthening NE winds. Expect seas to build back to 5 ft west of Fire Island Inlet by this evening. As a result, have extended the SCA on the coastal ocean zones east of Fire Island Inlet through tonight and issued a new SCA for the coastal ocean waters west of Fire Island Inlet for tonight. On Thursday, the seas around 5 ft should continue on the coastal ocean waters, but am not quite at the required 80 percent confidence in this to extend the SCA through then. Sub-SCA conditions are expected on the non-ocean waters through Thursday, and on all waters Thursday night. A tightening pres gradient ahead of an approaching cold front is expected to produce SCA conds on most of the local waters late Fri/Fri night. Winds should diminish by Sat morning, although seas on the ocean will likely linger a bit longer. Sub Small Craft Advisory conditions are then expected on all waters through the weekend. && .HYDROLOGY... No significant hydrologic impacts are expected through Tuesday of next week. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from 6 PM this evening to 6 AM EDT Thursday for ANZ355. Small Craft Advisory until 6 AM EDT Thursday for ANZ350-353. && $$

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