Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 221133 AFDOKX Area Forecast Discussion National Weather Service New York NY 733 AM EDT Tue Aug 22 2017 .SYNOPSIS... A cold front will approach today and pass early Wednesday. High pressure then remains in control through the end of the week with a much drier and cooler airmass. && .NEAR TERM /THROUGH TONIGHT/... Forecast update to include some fog, mainly across portions of CT and the Lower Hudson Valley through 13z. Also, some stratus has developed across the region so have increased sky cover just a bit. Otherwise, Increasing ssw llvl flow will ramp up the humidity today. As this occurs, a hotter airmass will be building in as well, resulting in heat indices in the 90s to around 100. A heat advy remains in effect for those areas where a heat index around 100 is fcst. Weak remnant pockets of energy will continue to pass thru the cwa today, potentially sparking isold tstms thru the day. The forcing increases this eve and tngt as the h3 jet gets closer, however the existing convection may outrun the main forcing, which could suppress additional development. High cape today along with good shear balance, particularly wrn areas. There will be svr chances with anything that pops in that environment. As the night progresses, strong h85 winds around 50kt traverse the cwa. Damaging winds possible in the stronger storms in this environment. There are still several hours for mesoscale analysis and another run of the models to better refine the threat for late this aftn and tngt, so generic tstms are in the fcst with the hwo/ehwo still based on spc swody1. Under this scenario however it would not be surprising to get some overnight severes. Waves will get increasingly choppy this aftn as ssw winds increase. A high rip current risk remains in effect for today. && .SHORT TERM /WEDNESDAY/... The actual cold front will be lagging behind and pass during the day. The prefrontal trof however and preceding tstms are progged to clear out most of the instability before the front gets here. As a result, only low chances for tstms will remain in the fcst until the fropa. The thermal trof will be exiting, however, the hot air aloft should mix down early resulting in a warm day, especially ern areas, but with less humidity. Because of this, heat indices should be cooler than Tue. A blend of the guidance was used for temps. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Canadian high pressure builds into the region Thursday through early next week, providing dry and sunny conditions. Temperatures will remain below normal as highs only reach the 70s to near 80 each day. There could be some isolated showers/tstms on Sunday as an upper trough moves through the Northeast. Most model guidance has the upper level energy passing to the north of the CWA so have not included in the current forecast, however this may change in subsequent forecasts. An area of low pressure may pass south of Long Island early next week. While it should remain dry, an increasing easterly flow is expected to develop. && .AVIATION /11Z TUESDAY THROUGH SATURDAY/... A cold front approaches the region late today and crosses tonight. MVFR/IFR cigs/vsby improving to VFR through mid to late morning. S/SW winds strengthen during the late morning into early afternoon. Gusts of 20 to 25 kt expected for aft/eve push, with occasional gusts 25 to 30 kt possible for LI and NYC/NJ metro terminals. Widespread shra/tsra development expected across Central NY/PA late this afternoon, weakening but likely working into NYC/NJ terminals and NW terminals aft 02z with mvfr conds. Potential for ifr cig development for coastal terminals this evening. Showers/tstms push east of NYC/NJ metro terminals late tonight with MVFR cigs possible. ...NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ KJFK TAF Comments: IFR cigs improving to VFR btwn 13-15z. S gusts 25-30 kt likely aft 20z. The afternoon KJFK haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KLGA TAF Comments: MVFR cigs improving to VFR btwn 13-15z. S gusts 25-30 kt likely aft 21z. The afternoon KLGA haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KEWR TAF Comments: MVFR cigs improving to VFR btwn 13-15z. SW gusts 20-25 kt likely and G25-30 kt possible between 19-23z. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: MVFR cigs improving to VFR btwn 13-15z. S gusts 25 kt possible between 19-23z. KHPN TAF Comments: MVFR/IFR cigs improving to VFR btwn 13-15z. S gusts 25 kt possible between 19-23z. KISP TAF Comments: MVFR/IFR cigs improving to VFR btwn 14-16z. S gusts 25 kt likely aft 20z. .OUTLOOK FOR 12Z WEDNESDAY THROUGH SATURDAY... .Wednesday...Low prob of -shra/MVFR AM...mainly eastern terminals. Becoming VFR in AM. W-NW G15KT possible. .Wednesday night-Saturday...VFR. && .MARINE... Winds will increase today ahead of a strong cold front. The sca has been expanded to all waters for this aftn and tngt. On Wed, seas may linger abv 5 ft on the ocean, especially during the mrng. Elsewhere, wind and seas blw sca lvls. Sub-advisory conditions are expected Wednesday night through the weekend with tranquil weather. && .HYDROLOGY... Showers and thunderstorms today and tngt may cause minor nuisance/urbanized flooding. No widespread hydrologic impacts are forecast through the rest of the week. && .TIDES/COASTAL FLOODING... Tides are running high astronomically. Water levels will approach minor flood levels across mainly the south shore bays areas with tonight`s high tide, but are likely to remain just below. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...Heat Advisory from noon today to 6 PM EDT this evening for NYZ071>075-176-178. High Rip Current Risk through this evening for NYZ075-080-081- 178-179. NJ...Heat Advisory from noon today to 6 PM EDT this evening for NJZ004-006-104>108. MARINE...Small Craft Advisory from 3 PM this afternoon to 6 AM EDT Wednesday for ANZ330-335-338-340-345-350-353-355. && $$ SYNOPSIS...BC/JMC NEAR TERM...BC/JMC SHORT TERM...JMC LONG TERM...BC AVIATION...NV MARINE...BC/JMC HYDROLOGY...BC/JMC TIDES/COASTAL FLOODING... is the U.S. government's official web portal to all federal, state and local government web resources and services.