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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KOKX 301519 AFDOKX Area Forecast Discussion National Weather Service New York NY 1119 AM EDT THU JUN 30 2016 .SYNOPSIS... High pressure will move over the area today, with a warm front approaching on Friday. A cold front will move across Friday night, followed by high pressure Saturday through Monday. Another low will approach next Tuesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... As weak high pressure moves east across the region, it will provide abundant sunshine with temps in the mid to upper 80s away for nyc/nj metro and interior...with lower 80s for south coastal areas with early afternoon seabreeze development. Humidity levels will be comfortable with dew points in the 50s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... A warm front approaches the region tonight with a weak area of low pressure developing along this boundary. Winds will shift to the south tonight and then the southeast by Friday as the front moves closer on. This will once again introduce a humid air mass. There is just a slight chance for showers and an isolated thunderstorm late tonight. The warm front continues its approach on Friday, while at the same time, a surface cold front approaches from the west. A digging upper level trough over the Great Lakes region will also approach in conjunction with the cold front. Most models have some sort of negative tilt with this trough, with the NAM being the most tilted. This could allow for the development of some strong to possibly severe storms across the CWA. A inverted V shape sounding was noticed in the forecast soundings, indicating that gusty winds would be a primary threat. Other factors lending to strong to severe storms are the frontal boundaries that will be in the vicinity, providing lift, a humid airmass that will be in place, with surface dew points likely approaching 70, and at least some instability, though this does not look overly impressive. Surface based CAPE only looks to be 1000-1500 J/kg and most unstable CAPE is near 2000 J/kg. 700-500mb lapse rates of 5-6 degrees only points to a weak threat. We are also under an 850 mb jet, but the jet speed is also not that impressive. Overall, parameters point to either a weak to possibly moderate severe threat for Friday and SPC has place the western portions, mainly west of NYC, in a marginal risk for severe weather. For now, used enhanced wording of gusty winds and heavy rain Friday afternoon into the evening. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Potential for Severe Thunderstorms Friday Evening The SPC is forecasting a Marginal Risk for isolated severe TSTMs producing wind gusts up to 60 mph across the Lower Hudson Valley and Northern NJ Fri aftn and eve with the approach of a well defined cold front moving into a warm moist unstable maritime tropical air mass. Saturday...Weather will feature increasing fire danger as WNW winds increase to 10-20 mph and humidities decrease to 30-40 pct as high pressure moves southeast from the Great Lakes. Fair weather with near normal temperatures are on tap for the July fourth weekend through Monday as a large area of high pressure moves slowly SE across the region. The next chance of rain will occur next Tuesday with the approach of a short wave moving SE along the upstream ridge accompanied by a low lvl flat wave mvg toward the mid atlantic coast. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... High pressure will build east this morning and then to the south this afternoon. A surface trough sets up to the north and west of NYC in the afternoon. VFR. Light flow this morning gives way to late morning/early afternoon seabreeze development. Due to the light nature of the winds, there will likely be some variability until the seabreeze works across the terminals. There is low confidence of showers moving in after 06Z Friday. Chances increase toward late morning. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ KJFK TAF Comments: Seabreeze likely to cross terminal 16 to 17z. KLGA TAF Comments: Light NE wind off the sound will persist until sea breeze passage, which may occur 1-2 hours off from forecast. KEWR TAF Comments: Wind direction may vary from the NE to the W before sea breeze passage. Timing of seabreeze likely to vary 1-2 hours. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Timing of seabreeze likely to vary 1-2 hours. KHPN TAF Comments: Timing of seabreeze likely to vary 1-2 hours. KISP TAF Comments: Timing of seabreeze likely to vary 1-2 hours. .OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY... .Friday and Friday night...MVFR or IFR conditions possible in showers/tstms. .Saturday...VFR. NW winds G20-25KT. .Sunday and Monday...VFR. && .MARINE... Winds and seas should remain below SCA conditions for the short term as weak high pressure moves over the waters provides a lack of a pressure gradient. Friday Night and Saturday...Weather conditions will approach Small Craft Advisory/SCA levels of 25 kt winds and 5 ft seas across the Atlantic Ocean coastal waters. Scattered TSTMs along with S winds 10- 20 kt will precede and accompany an approaching cold front. Winds will shift from the WNW 10-20 kt with the passage of the front around Sunrise Saturday and will continue through the day Saturday. Sunday through Monday will be tranquil with winds and seas remaining below SCA levels as high pressure moves SE across the region. && .HYDROLOGY... No significant rainfall expected for the short term. Friday Aftn/Night...Scattered showers and TSTMs will bring up to 1/4-inch rainfall with isolated higher amounts, otherwise, no significant rainfall is forecast. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...GC/JP NEAR TERM...GC/JP SHORT TERM...JP LONG TERM...GC AVIATION...DS/DW MARINE...GC/JP HYDROLOGY...GC/JP is the U.S. government's official web portal to all federal, state and local government web resources and services.