Area Forecast Discussion
Issued by NWS Upton, NY

Current Version | Previous Version | Graphics & Text | 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. --
127 FXUS61 KOKX 250300 AFDOKX Area Forecast Discussion National Weather Service New York NY 1100 PM EDT SUN JUL 24 2016 .SYNOPSIS... High pressure moves offshore tonight. A cold front approaches on Monday and moves through the region Monday night. High pressure builds to the west Tuesday and moves off the southeast coast Wednesday into Thursday. A series of low pressure waves move across the region from Thursday afternoon through Sunday. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Slight adjustments were made to temperatures, dewpoints, and cloud coverage to better match observed trends. While convection in Pennsylvania has decreased, a lot of model guidance reinitiates some convection and has some QPF moving into the western parts of the region going into early Monday. 12Z model suite shows weak shortwave quickly moving east tonight, with embedded vorticity maxima tracking toward the area overnight and toward morning. Expect partly cloudy to mostly clear skies this evening giving way to increasing clouds overnight. Humidity levels begin to increase as a warm front to the west jumps north. An area of showers and thunderstorms will approach western sections toward morning ahead of the aforementioned shortwave. Very warm temperatures are expected tonight, with lows ranging from the upper 70s in and around NYC, to the upper 60s across the interior. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Initial shortwave/vort moves across or just south of the area in the morning per latest model suite. It appears that scattered showers and thunderstorms will accompany this feature, with better chance near the coast and south. Then, upstream trough approaches, along with sfc cold front. With increasing low level moisture, deep mixing and increasing surface based instability, numerous thunderstorms should approach and impact a good portion of the area late in the day. Moderate cape, and increasing shear will result in a few stronger to possibly severe thunderstorms, with the biggest threat gusty winds. With the cloud cover expected, it appears that temperatures may be a degree or lower than previously thought. Much depends on amount of sunshine that is realized as h8 temps increase to 18-20C. Went above mos numbers, and with dew points rising into the 70s, expect heat indices well in the 90s, and exceeding 100 in a few spots. The excessive heat watch for NYC and NJ metro has been converted to a heat advisory, and the heat advisory remains in effect for the remainder of the area. The only exception is eastern Long Island and SE CT where temperatures remain in the 80s due to clouds and south winds. As such, heat advisory has been cancelled for those locations. Any evening showers and thunderstorms move east and weaken in time. Another warm night is in store Monday night as the front slowly approaches and moves through. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Mainly zonal flow will continue across the northern tier and along the US/Canadian border as a high pressure ridge remains over the southern states and low pressure remains over eastern Canada Tuesday into 12Z Thursday. Heat and humidity will persist through Thursday. Shortwave energy is forecast to come ashore of the Pacific northwest late Tuesday and begin to dig an trough into the upper plains Wednesday. This shortwave is expected to reach the east coast Thursday afternoon. An eastern trough then remains into next weekend as an up stream ridge builds over the northern Rockies and into the southwest. A series of shortwaves rotate through the eastern trough through from Thursday through next weekend. Timing and placement of the waves is uncertain at this time. However, unsettled weather is expected with mainly diurnally driven convection each day. With the uncertainty will have slight chance and chance pops Thursday through Sunday, with higher pops inland and during each afternoon and evening. With the longwave trough digging into the eastern states the core of the hot air will be shifted to the south by Friday, with temperatures likely returning to more normal levels. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... High pressure moves offshore tonight. A cold front approaches Monday. Mainly VFR forecast through the TAF period with main exception being late Monday afternoon into Monday evening with any showers or thunderstorms. MVFR will also be possible for some terminals with haze forming Monday. There will be chance of showers and thunderstorms overnight into early Monday with the highest chances being late Monday afternoon into Monday evening which is when TAFs have a mention of thunderstorms. The timing of any thunderstorms in the TAFs could change 1-3 hours with subsequent forecasts. Winds will be mainly S-SW 5-10 kt for NYC terminals, becoming light and variable outside of city terminals overnight into early Monday. Winds will be primarily SW-W Monday near 10 kt with more of a SW flow for coastal terminals. Some gusts of 15-20 kt will be possible Monday mid to late afternoon. .OUTLOOK FOR 03Z TUESDAY THROUGH FRIDAY... .Monday Night...MVFR or lower possible in any remaining shra/tsra. .Tuesday-Wednesday Night...VFR. .Thursday-Thursday Night...Mainly VFR, except MVFR or lower possible in isolated to scattered showers and thunderstorms, mainly late in the day and at night. .Friday...Chance of MVFR or lower in scattered showers and thunderstorms. && .MARINE... Winds and seas forecast remain on track, with no changes at this time. High pressure moves offshore tonight. A cold front approaches the waters Monday and moves through Monday night. Sub SCA conditions are anticipated through Monday night. High pressure builds to the west of the forecast waters Tuesday and moves off the southeast coast Wednesday and Thursday. A series of weak low pressure waves will moves across the forecast waters Thursday afternoon through next weekend with scattered showers and thunderstorms possible. From Tuesday through Friday winds and seas are expected to remain below advisory levels across the forecast waters. && .HYDROLOGY... There is the potential for 1/4 to 1/2 inch of rainfall, with locally higher amounts, possibly 1 inch or more, in showers and thunderstorms Monday and Monday night. Dry weather returns for Tuesday and Wednesday. There is the potential for scattered showers and thunderstorms, mainly across the interior, during the afternoons and evenings Thursday through next weekend. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...Heat Advisory from noon to 8 PM EDT Monday for CTZ005>010. NY...Heat Advisory from noon to 8 PM EDT Monday for NYZ067>075-078- 080-176>179. NJ...Heat Advisory from noon to 8 PM EDT Monday for NJZ002-004-006- 103>108. MARINE...None. && $$ SYNOPSIS...MET/PW NEAR TERM...JM/MET/PW SHORT TERM...PW LONG TERM...MET AVIATION...JM MARINE...JM/MET/PW HYDROLOGY...MET/PW is the U.S. government's official web portal to all federal, state and local government web resources and services.