Area Forecast Discussion
Issued by NWS Upton, NY

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
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 161123 AFDOKX Area Forecast Discussion National Weather Service New York NY 723 AM EDT Mon Jul 16 2018 .SYNOPSIS... High pressure remains offshore today and tonight. A cold front will approach from the west on Tuesday and move through Tuesday night. A weak surface trough will linger on Wednesday, then high pressure will build across on Thursday, and pass east on Friday. Low pressure and an attendant warm front will slowly approach from the south this weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Forecast is on track with only minor changes made. A typical summer time Bermuda high pressure type system will be in place off the East Coast for Monday, which will continue to pump in heat and humidity on a southerly flow. Temperatures will rise into the upper 80s to lower 90s while dew points rise into the lower 70s. This will produce heat index values of 95-99 today. Upper level ridge will move in from the west today. This will help to limit the development of showers and thunderstorms in the morning. POPs have been cut back to only a slight chance starting at 9 am, mainly across northeast New Jersey, the Lower Hudson Valley and southwestern Connecticut. It is possible that any showers and thunderstorms may hold off until after 11 am or thereafter. As the ridge progresses east, the chances for showers and thunderstorms increases for wester areas such as northeast New Jersey, the Lower Hudson Valley, and southwest Connecticut. Sea breeze development may stabilize coastal areas, and therefore, only chance of showers are possible here from late morning onward. There is a moderate risk of rip currents for the ocean beaches today. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... A warm and humid air mass will remain in place as the high pressure remains off shore. With clouds increasing, temperatures will not drop much, 70s region-wide. Some upper 70s are possible in the New York City metro area. The chances for precipitation will decrease somewhat overnight, especially for northeast New Jersey, the Lower Hudson Valley, and southwest Connecticut as the sun sets and those areas lose diurnal heating. Tuesday will see POPs continue to increase as the cold front slowly moves through. There will be a chance for heavy rain associated with the frontal passage. PWATs are near 2.50", which is very high for this time of year given climatology. So although storm total precipitation is around an inch, some isolated areas may receive upwards of two inches. This could lead to some urban and small stream flooding. Widespread flash flooding looks unlikely as much of the tri-state has been relatively dry lately. In fact, New London County is in a DO in the US Drought Monitor. Associated upper level trough will approach Tuesday. With dew points in the 70s region-wide, instability will increase despite clouds cover. Most unstable CAPE values in the NAM are showing 2000 J/kg. The cold front could produce enough of a lifting mechanism to produce some strong to severe storms. 0-6 km shear will be 25-35 kt. This has prompted the Storm Prediction Center to put much of our CWA in a marginal risk for severe storms where the primary threat would be strong winds. Temperatures will not be as warm on Tuesday as Monday, given clouds and precipitation, but it will remain very humid. Heat indices of 95-99 are still possible for the New York metro area, and Heat Advisories will continue here based on 2 consecutive days. However, for Nassau and the Lower Hudson Valley, heat indices are forecast to remain below 95-99 on Tuesday. Therefore, the Heat Advisory for those areas have been cancelled. The cold front will move through Tuesday night and winds will shift to the northwest. Dew points will drop into the lower to middle 60s by sunrise Wednesday for much of the area, with some lingering showers and thunderstorms for eastern areas. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... After the sfc cold front moves east on Wed, a sfc trough will linger mainly over Long Island and CT, while a wave of low pressure along the front passes well to the SE. With low level convergence/moisture pooling and the upper trough still off to the west to provide forcing, think SE CT and E Long Island could still see isolated to scattered tstms through the day on Wed, and perhaps into Wed evening. High pressure should then build in and remain into at least Friday. possibly Saturday per slower 00Z ECMWF. For later this weekend, an upper trough will dig into the OH Valley, with downstream ridging amplifying in response over the western Atlantic and up into the Canadian Maritimes. Some phasing with leftover mid level vort maxima from an old frontal zone over the NE Gulf of Mexico and SE coast may take place, which would draw a weak sfc low and attendant warm front up the coast. Ignored entertaining but very unlikely 00Z GFS solution showing a compact low of subtropical origin riding up the coast on Sunday. Still, warm fronts at this time of year can have their surprises in terms of heavy rain and severe weather, so this could bear some watching as we go into early next week. Temps through the period should be right around seasonal averages. Humidity levels remaining relatively comfortable through at least Fri and possibly Sat, then conditions become muggy by Sunday as dewpoints increase to near 70. && .AVIATION /12Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
High pressure will drift offshore today. Mainly VFR today. During the afternoon, local MVFR conditions are possible in isolated thunderstorms, mainly NW of NYC metro. Any isolated thunderstorms diminish this evening. Patchy fog and stratus should develop after midnight tonight. MVFR/IFR possible. Winds will be light SW/W in the NYC metro area early this morning, and light and variable to calm at the outlying terminals. A south flow develops later this morning, increasing to 10-15 KT in the afternoon. S/SW winds persist this evening and lighten somewhat. 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: Light W/SW winds will become south, and timing of wind shift and wind speed increase could be off an hour or two. The afternoon KJFK haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KLGA TAF Comments: Light W/SW winds will become south, and timing of wind shift and wind speed increase could be off an hour or two. The afternoon KLGA haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KEWR TAF Comments: Light W/SW winds will become south, and timing of wind shift and wind speed increase could be off an hour or two. Low chance for a thunderstorm late this afternoon. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Light W/SW winds will become south, and timing of wind shift and wind speed increase could be off an hour or two. Low chance for a thunderstorm late this afternoon. KHPN TAF Comments: Low chance for a thunderstorm late this afternoon. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY... .Tuesday...Showers/tstms likely with MVFR or lower conditions, mainly in the afternoon. S winds G20KT into early evening. .Wednesday...VFR. A slight chance of showers in the morning east of the NYC terminals, with MVFR possible. .Thursday-Friday...VFR.
-- End Changed Discussion --
&& .MARINE... Waves build to 4 ft on the ocean waters tonight and to near 5 ft on Tuesday on a southerly flow out ahead of an approaching cold front. Waves diminish on Tuesday night. Winds may approach 25 kt on the ocean waters Tuesday ahead of the cold front, but right now it looks marginal and will hold off on issuing a Small Craft Advisory. No long term issues foreseen as high pressure builds across later this week. && .HYDROLOGY... Showers an thunderstorms may be capable of producing locally heavy rain, with potential for minor localized flooding, mainly late tonight into Tuesday. Urban and poor drainage flooding will be possible. Storm total rainfall of around an inch is forecast with two inches possible in isolated spots. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...Heat Advisory from noon today to 6 PM EDT Tuesday for NYZ072>075-176-178. NJ...Heat Advisory from noon today to 6 PM EDT Tuesday for NJZ004- 006-103>108. MARINE...None. && $$ SYNOPSIS...Goodman/JP NEAR TERM...JP SHORT TERM...JP LONG TERM...Goodman AVIATION...PW MARINE...Goodman/JP HYDROLOGY...Goodman/JP EQUIPMENT...

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.