Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 211731 AFDOKX Area Forecast Discussion National Weather Service New York NY 131 PM EDT THU JUL 21 2016 .SYNOPSIS... High pressure builds just south of the region this afternoon and moves farther offshore tonight and Friday. A cold front approaches late Friday and moves through Friday night. High pressure returns Saturday afternoon through Sunday. Another cold front approaches on Monday and passes through Monday night. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Slight adjustments were made to the forecast database to reflect the latest observed trends. The forecast overall remains on track. Some more clouds were added to the forecast to account for cumulus development with diurnal heating as sea breeze develops and acts as a convergence boundary. The winds will be mostly out of the S-SW for the remainder of this afternoon. High pressure will be settling to just south of the region this afternoon. Upper trough axis remains just east of the area as large midwest ridge remains anchored and expands. Heights rise slightly today. Another dry day is expected today, with a good amount of sunshine, and slightly warmer temperatures. Look for readings well in the 80s today, with metro NJ zones approaching 90 due to increasing SW flow. There is a moderate risk for rip current development at ocean beaches this afternoon into evening due to the combination of 2 ft long period se swells and increasing southerly wind waves. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... Shortwave energy riding over the top of the expanding mid west ridge will approach the northeast this time frame. Associated PVA dives out of southern Canada across the northeast states by Friday night. At the surface, high pressure drifts offshore as a cold front approaches late Friday. A prefrontal trough will likely impact the area late Friday afternoon, with the actual front passing Friday night per most model solutions. Humidity levels begin to increase this time frame due to persistent southerly winds. Seasonably warm temps are expected tonight, with lows ranging from the 60s across the interior to around 70 or in the 70s closer to the coast. On Friday, high temperatures range from the middle 80s across eastern Long Island and SE CT to the middle 90s in metro NJ. The combination of temperatures and rising dew points will result in heat indices in the 90s across much of the area. Friday night will be warmer, with lows ranging from near 80 in NYC, to the 60s across the interior. As for sensible weather, will continue with chance thunderstorms beginning Friday afternoon and continuing into Friday night. Moderate instability and increasing shear will set the stage for potential strong to severe thunderstorms late in the day and at night. However, looks like support aloft may lag a bit, moving through Friday night. As such, extent of severe weather should be impacted by this. SPC has shifted the slight risk northward via latest day 2 outlook, with area still in a marginal risk for severe thunderstorms. A high risk for rip current development at ocean beaches is likely for Friday afternoon due to southerly wind waves increasing to 3 to 5 ft and a residual 2 ft se swell. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... High pressure starts building into the region Saturday and Sunday, with continued hot and humid conditions. Temperatures both days are forecast to reach the lower and middle 90s. Saturday`s heat indices are currently forecast to just meet criteria in NYC. The rest of the forecast area should remain below advisory criteria. Sunday, temperatures aloft drop a little, and surface dewpoints should be able to mix out again, so heat indices should be below 95 for just about everywhere. Another cold front approaches on Monday, but a warm front pushes through first. This will bring higher dewpoints across the area. Heat indices once again climb into the middle 90s, however there is some uncertainty for high temperatures due to potential thunderstorm activity and related cloud cover. 850MB temperatures don`t look to drop off all that much, if at all on Tuesday. Surface dewpoints will probably be lower, but heat advisory criteria could be met once again in the city on Tuesday. High pressure looks to continue the dry weather pattern on Wednesday. High temps and heat indices are forecast to be below 95. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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High pressure remains offshore through Friday with an approaching frontal system from the Great Lakes. VFR through the TAF period. S/SW winds 10 to 15 kt with local seabreeze enhancements this afternoon. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ KJFK TAF Comments: High confidence VFR. KLGA TAF Comments: High confidence VFR. Amendments possible to fine tune timing of afternoon seabreeze. KEWR TAF Comments: High confidence VFR. Late day seabreeze possible. KTEB TAF Comments: High confidence VFR. Late day seabreeze possible. KHPN TAF Comments: High confidence VFR. Amendments possible to fine tune timing of afternoon seabreeze. KISP TAF Comments: High confidence VFR. .OUTLOOK FOR 18Z Friday through Tuesday... .Friday afternoon through Friday night...MVFR or lower possible in SCT TSRA. S-SW winds 15-20 KT with 25 KT gusts across NYC and Long Island. .Saturday through Sunday...VFR. .Monday and Tuesday...MVFR or lower possible in SCT TSRA.
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&& .MARINE... South to southwest flow of 10 to 15 ft with ocean seas near 2-3 ft with some gusts to 20 kt can be expected this afternoon. This will be under the influence of high pressure as it moves just south of the waters. High pressure passes offshore late today and tonight. Wind speeds remain below SCA criteria late today for the most part. However, higher confidence in stronger winds Friday as the pressure gradient tightens ahead of a cold front, and as the high drifts further offshore. Will issue a small craft advisory for the ocean waters beginning Friday afternoon. Ocean seas build as well, likely reaching or exceeding 5 ft Friday afternoon and continuing Friday night. For the non ocean waters, winds increase but should remain below sca criteria through Friday night. Sub-SCA conditions are expected for all of the area waters Saturday through Monday. && .HYDROLOGY... No adverse hydrologic impacts are anticipated with scattered showers and thunderstorms Friday/Friday night and Monday/Monday night. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from noon to 6 PM EDT Friday for ANZ350- 353-355. && $$ SYNOPSIS...BC/PW NEAR TERM...JM/PW SHORT TERM...PW LONG TERM...BC AVIATION...DW MARINE...BC/JM/PW HYDROLOGY...BC/PW is the U.S. government's official web portal to all federal, state and local government web resources and services.