Area Forecast Discussion
Issued by NWS Upton, NY

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
682 FXUS61 KOKX 241750 AFDOKX Area Forecast Discussion National Weather Service New York NY 150 PM EDT TUE MAY 24 2016 .SYNOPSIS... Low pressure south of Cape Cod tracks northeast today and tonight, moving along the New England coast. High pressure builds in briefly for late tonight and Wednesday. A cold front moves through late Wednesday night into Thursday morning and lifts north as a warm front later in the day Thursday. High pressure remains situated over the western Atlantic through the first half of the weekend. A backdoor cold front moves through on late Saturday night into Sunday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... The forecast is pretty much on track here. There were some slight adjustments to better match observed trends with regards to temperatures, dewpoints, and pops for showers. Otherwise though, no remarkable changes were made to the forecast database. A weakening low south of Cape Cod tracks slowly northeast through today. A weak surface trough extends back from the low into the lower Hudson Valley. Meanwhile an upper closed, and nearly cutoff low, east southeast of the Delmarva, as seen on the water vapor loop, drifts north to northeast and begins to fill and get picked up by the northern stream. With areas of energy rotating around the low and the surface low, showers will continue through this morning, eventually becoming more scattered this afternoon. Instability is very weak this morning and generally less than 50 J/KG but this will increase this afternoon to a few hundred J/KG with increased daytime heating at the surface. Forecast includes isolated thunderstorms this afternoon. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... Tonight the upper low continues to fill and becomes an open wave after 06Z and the northern stream carries the low into Maine and Nova Scotia, merging with low pressure over eastern Canada. The surface low becomes nearly indistinguishable by late tonight, also merging with a surface low over eastern Canada. By 00Z precipitation is quickly ending as heights rise from as weak upper ridging builds to the west. This ridge builds through Wednesday with dry weather late this evening through Wednesday. Warmer air continues to move into the region tonight through Wednesday at the lower and mid levels. A dramatic warmup is expected across the entire region as a westerly flow allows even coastal areas to warm to well above seasonal normals. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... A weak area of low pressure over the Canadian Maritimes will push a cold front through the area Wednesday night. This front will then head quickly back north as a warm front, moving through Thursday afternoon. Thereafter, there will be a prolonged period of southerly flow as surface high pressure settles over the Western Atlantic. At the same time, ridging aloft will mean rising heights and therefore, warming temperatures, mainly for areas away from the coast. Closer to the coast, flow off the cooler ocean waters will keep these areas a few degrees cooler than inland. With a southerly flow, dewpoints will also be on the rise. By the weekend, dewpoints could be in the lower 60s, making it slightly uncomfortable for some. The 00Z ECMWF and the 00Z GFS are in better agreement on the passage of a back door cold front late Saturday night into Sunday (quicker than previously forecast). Thereafter, the 2 models differ. The GFS continues to nose a strong high pressure from southeastern Canada into the area, while the ECMWF keeps this high off the Atlantic coast, and is weaker. Though the 00Z ECMWF does nose the high pressure farther inland than the previous run. The GFS solution would keep the area dry for the beginning of next week, while the ECMWF would keep it unsettled. Due to the uncertainty, a blend of models seems reasonable. The cold frontal passages Wednesday night looks to come through dry with limited moisture to work with. There may be some showers and thunderstorms with the warm frontal passage on Thursday, mainly inland as the lower temperatures over the coastal areas stabilizes those areas. A thermal trough sets up over inland areas for Friday and Saturday, which will mean diurnal showers and thunderstorms for these areas. Showers and thunderstorms will also be possible with the backdoor cold front passage late Sunday into Sunday night. This will not be a continuous rainfall event from Friday through Sunday night. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
Isolated to scattered SHRA/TSRA will pass through the terminals through this evening. Will carry VCSH/VCTS in the 18Z TAFs through this evening, but confidence on timing and coverage is low. Generally a VFR forecast. Conds may briefly lower to MVFR in SHRA/TSRA. In addition, MVFR VSBY possible in areas of BR late tonight, mainly away from KNYC terminals. Winds generally ranging from N to NW at 5-10 KT. Winds become LGT/VRB this evening and tonight. ...NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: KJFK TAF Comments: Occasional SHRA/TSRA possible through this evening with brief MVFR conds. Low confidence on sea breeze development. KLGA TAF Comments: Occasional SHRA/TSRA possible through this evening with brief MVFR conds. Low confidence on sea breeze development. KEWR TAF Comments: Occasional SHRA/TSRA possible through this evening with brief MVFR conds. KTEB TAF Comments: Occasional SHRA/TSRA possible through this evening with brief MVFR conds. KHPN TAF Comments: Occasional SHRA/TSRA possible through this evening with brief MVFR conds. Low confidence on sea breeze development. KISP TAF Comments: Occasional SHRA/TSRA possible through this evening with brief MVFR conds. Low confidence on sea breeze development. .OUTLOOK FOR 18Z Wednesday through Sunday... .Wednesday through Thursday...VFR. .Thursday night through Friday morning...Occasional MVFR in showers/thunderstorms possible. .Friday-Saturday...MVFR possible in afternoon/evening tstms. .Sunday...VFR.
-- End Changed Discussion --
&& .MARINE... A weak pressure gradient force will be across the waters through Wednesday as a weakening low south of Cape Cod tracks to the northeast through tonight and high pressure builds in late tonight and Wednesday. The only hazard across the forecast waters will be isolated thunderstorms this afternoon into early this evening. Otherwise no hazardous conditions are expected. Winds and waves should remain below SCA criteria for the long term with light a pressure gradient. && .HYDROLOGY... Rainfall amounts of less than 1/4 inch are expected for the rest of today into this evening. Locally higher amounts will be possible in isolated thunderstorms. No concerns for hydrology Wednesday through Monday. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JP/MET NEAR TERM...JM/MET SHORT TERM...MET LONG TERM...JP AVIATION...MPS MARINE...JM/JP/MET HYDROLOGY...JP/MET is the U.S. government's official web portal to all federal, state and local government web resources and services.