Area Forecast Discussion
Issued by NWS Upton, NY

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230 FXUS61 KOKX 230841 AFDOKX Area Forecast Discussion National Weather Service New York NY 441 AM EDT Wed Aug 23 2017 .SYNOPSIS... A cold front exits to the east this morning, followed by Canadian high pressure building into the region through the weekend. Low pressure may impact the area during the middle of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... There should be a few lingering showers mainly over Long Island early this morning, otherwise today should be mainly dry. Negative vorticity advection (NVA) from around 700-500 hPa in the wake of a northern stream shortwave will be responsible for causing the showers to come to an abrupt end. The strong NVA will also result in a fairly rapid clearing of the sky this morning as well. With abundant sunshine this afternoon, highs should reach up to 5 degrees above normal, with the largest departures over eastern zones. Highs should range from around 80 to the mid 80s across most of the area. There is a moderate rip current risk for today. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... A mean trough builds into the eastern 1/3 of the country tonight and Thursday, with the trough axis staying well to the west. At this time no significant shortwaves are progged to be embedded in the resultant SW flow aloft, so it should be dry tonight and Thursday with minimal cloud cover. With a mostly clear to clear sky and winds falling off to generally 5 mph or less outside of urban areas, should see some decent radiational cooling outside of urban areas. Lows should range from near normal in the NYC Metro to up to 5 degrees below normal elsewhere. Lows into the 50s are expected outside of the NYC Metro, western Long Island and the immediate CT coast, where 60s are forecast. Highs on Thursday will be around 5 degrees cooler than today, mainly from the mid 70s to around 80. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... A broad area of Canadian high pressure will build over the Northeast thru the weekend and into the beginning of next week. This will produce fair weather with blw average temps. A blend of the guidance was used which was in good agreement. Cyclonic flow aloft will result in diurnal cu at times, and an isold shwr cannot be ruled out. The exact coverage, placement and timing is too uncertain to include anything in the fcst attm except for nrn Orange county on Fri where there is a clustering of model output. A 15 pop was included there. The models are suggesting the development of low pres off the Mid- Atlantic during the middle of next week. Both the 00Z GFS and ECMWF have something. A consensus of all the models was used for pcpn potential, and pops were limited to the slight chance category due to the time window being a week out with high uncertainty. && .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... A cold front will move across the region this morning. The bulk of the precipitation has come to an end, however there may still be some left over lingering showers through 10-12Z. MVFR to locally IFR conditions have started to re-develop across the terminals, so have covered this with a TEMPO for now. Conditions should start to improve around 12Z with the cold frontal passage. Winds will gradually shift from the West-Southwest to the Northeast as the front comes through. Northwest flow may be just strong enough to preclude seabreeze development this afternoon. Otherwise...VFR. ...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: Timing of improvement to VFR may be off by an hour. Low chance of afternoon seabreeze development. The afternoon KJFK haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KLGA TAF Comments: Timing of improvement to VFR may be off by an hour. The afternoon KLGA haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KEWR TAF Comments: Timing of improvement to VFR may be off by an hour. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Timing of improvement to VFR may be off by an hour. KHPN TAF Comments: Timing of improvement to VFR may be off by an hour. KISP TAF Comments: Timing of improvement to VFR may be off by an hour. .OUTLOOK FOR 06Z WEDNESDAY THROUGH SUNDAY... .Wednesday night-Sunday...VFR. && .MARINE... The pressure gradient begins to relax today, with sustained winds up to 15 kt and some isolated gusts up to 25 kt possible on the coastal ocean waters. Seas on the coastal ocean waters will diminish through the day, falling to below SCA levels W of Moriches inlet by 11 am and E of Moriches inlet by 2pm. As a result have left the Small Craft Advisory (SCA) on the coastal ocean waters as is. With frequent wind gusts to 25 kt no longer occurring on the non-ocean waters, have canceled the SCA there. A light pressure gradient will set up over the waters by tonight and continue on Thursday, with winds 10 kt or less. Seas and waves will be below Small Craft levels as well tonight and Thursday. Wind and seas will remain below SCA levels Thursday night through Sunday night. && .HYDROLOGY... It will be mainly dry today, then dry tonight through the weekend. && .TIDES/COASTAL FLOODING... Tides are running high astronomically. Water levels may again approach minor flood levels across mainly the South Shore Bays of Long Island and NYC with tonight`s high tide, but high likely will run a half a foot or so below minor flood benchmarks. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 11 AM EDT this morning for ANZ353- 355. Small Craft Advisory until 2 PM EDT this afternoon for ANZ350. && $$ SYNOPSIS...JMC/Maloit NEAR TERM...Maloit SHORT TERM...Maloit LONG TERM...JMC AVIATION...BC MARINE...JMC/Maloit HYDROLOGY...JMC/Maloit TIDES/COASTAL FLOODING...

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