Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 250557 AFDOKX Area Forecast Discussion National Weather Service New York NY 157 AM EDT MON JUL 25 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 THIS 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 THIS MORNING THROUGH 6 PM TUESDAY/... 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 NIGHT 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 /06Z MONDAY THROUGH FRIDAY/...
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A warm front lifts through the terminals during the pre-dawn hours as high pressure slides offshore. A cold front approaches this afternoon and passes through the region this evening. High pressure returns tonight. Primarily a VFR forecast for most terminals. Some convection associated with an approaching warm front developing over SE PA and W NJ will lift towards the region and could impact western terminals by 09-10Z. That wave of convection should pass through the terminals by 13-15Z. Brief MVFR conditions possible. MVFR VSBYs possible in HZ for KNYC terminals from late morning through early afternoon. VFR otherwise. Cold front approaches this afternoon. Convection will fire up west of the region and looks to impact western terminals from around 20Z-02Z. SW flow less than 10 KT will give way to afternoon sea breezes at coastal terminals 10-15 KT. Gusty winds and heavy rain possible in convection. VFR conditions expected tonight, but it is possible that outlying terminals, such as KHPN and KGON could have MVFR or lower VSBYs in fog late tonight. .OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY... .Tonight...SHRA/TSRA taper off from west to east. MVFR VSBY possible north and east of KNYC in fog. .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.
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&& .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...
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CT...Heat Advisory from noon today to 8 PM EDT this evening for CTZ005>010. NY...Heat Advisory from noon today to 8 PM EDT this evening for NYZ067>075-078-080-176>179. NJ...Heat Advisory from noon today to 8 PM EDT this evening for NJZ002-004-006-103>108. MARINE...None.
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&& $$ SYNOPSIS...MET/PW NEAR TERM...JM/MET/PW SHORT TERM...PW LONG TERM...MET AVIATION...MPS MARINE...JM/MET/PW HYDROLOGY...MET/PW

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