Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 240256 AFDOKX Area Forecast Discussion National Weather Service New York NY 1056 PM EDT SAT JUL 23 2016 .SYNOPSIS... A weak cold front has moved across and this will be followed by high pressure going into Sunday. A warm front will move through Monday morning. A weak cold front approaches the area Monday and crosses Monday night. High pressure returns for Tuesday and Wednesday. A series of waves of low pressure pass through the region Thursday and Friday, with a cold front passing through Friday night. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... The cold front has moved across much of the region. It will pass through the ocean marine zones over the next 1-2 hours. Flow is switching to a more northerly flow and will become lighter with the decrease in pressure gradient overnight. This will advect in a relatively drier airmass into the region. Temperatures and dewpoints were adjusted to better match observed trends. Skies will clear out overnight. Min temperatures range from the lower 60s across interior rural areas to upper 70s for much of NYC. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Behind the cold front, day time high temperatures are forecast around 6 to 8 degrees cooler than highs Saturday. With dew point temperatures forecast mainly 55-60 degrees, heat index values are forecast to remain below 95 degrees. Therefore, a heat advisory will not be issued for Sunday. Morning light NW winds will be replaced with afternoon sea breezes, the strongest in the NY bight with S winds 10-15 kt aft 19z/3 pm. For Sunday night, as high pressure moves offshore, a warm front will approach from the SW. Low lvl warm air advection will cause an increase in clouds along with some patchy fog in suburban and rural locations. There is a moderate risk for rip currents along the Atlantic Ocean beaches for Sunday. && .LONG TERM /MONDAY THROUGH SATURDAY/... By the start of the extended period an upper ridge will be moving off the northeast coast as a shortwave moves through the nearly zonal flow, passing through the Great Lakes Monday into Monday night. An associated weak surface low moves through the Great Lakes with a cold front passing through Monday night. Temperatures and dewpoints will be increasing Monday as the region comes under the influence of a hot and humid airmass as a warm front passes Monday morning. With the shortwave passing showers and thunderstorms will be possible early Monday. The area destabilizes and by the afternoon CAPE increases to around 1000 J/KG and lifted indices will be around -3. There is a potential for heavy rain and gusty winds with the convection Monday afternoon and will include in the forecast. Depending on timing and the possibility of earlier convection destabilization may become limited. Regardless, with the hot and humid conditions, heat indices will be near 105 by the afternoon for most of northeastern New Jersey and into NYC. So an excessive heat watch has been posted. Tuesday and Wednesday will remain warm however drier air moves in behind the cold front. With the shortwave not very deep and passing to the north, the cold front does not moves too far south and becomes nearly stationary south of Long Island. Waves of low pressure are forecast to move along this boundary Thursday and Friday with a back door cold front pushing through as high pressure builds to the north. Timing if the backdoor cold front is uncertain and may not moves through until Saturday. However, at this time will have Saturday dry. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... A weak cold front has moved across. High pressure will build in going into Sunday. VFR expected through the TAF period. N winds mainly near 10 kt further lighten overnight. Winds Sunday start out N 5-10 kt and gradually back to a more westerly direction by late morning. Sea breezes develop in the afternoon for most coastal terminals. This will be delayed by a few hours for KLGA, KEWR, KTEB, and KHPN. The timing of the sea breeze is uncertain and could be off by 1-2 hours. The more southerly flow will increase to 10 kt with winds closer to 15 kt for KJFK before decreasing once again Sunday evening. .OUTLOOK FOR 03Z MONDAY THROUGH THURSDAY... .Sunday Night...VFR. .Monday-Monday Night...Mainly VFR, except MVFR or lower possible in scattered late day/evening thunderstorms. .Tuesday-Wednesday...VFR. .Thursday...Mainly VFR, except MVFR or lower possible in scattered late day/evening thunderstorms. && .MARINE... Winds and seas will further lower overnight as high pressure begins to build in from the north and west. Wind speeds and sea heights are forecast to remain below Small Craft Advisory levels through Sunday night. Afternoon sea breezes likely on Sunday, and have to monitor potential for locally strong onshore flow from Sandy Hook to Fire Island Inlet Sunday afternoon. With a weak pressure gradient force across the forecast waters Monday through Thursday, winds and seas are expected to remain below small craft advisory levels. A cold front is forecast to pass through the waters Monday night with thunderstorms possible. The front will remain south of the waters with waves of low pressure moving along the front Thursday into Friday. A backdoor front moves through Friday night. && .HYDROLOGY... No rain is forecast through Sunday night. There is the potential for 1/4 to 1/2 inch of rainfall, with locally up to one inch, in showers and thunderstorms Monday and Monday night. Dry weather returns for Tuesday and Wednesday. Then there is the potential for additional showers and thunderstorms, mainly during the afternoons and evenings Thursday and Friday. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...Excessive Heat Watch from Monday morning through Monday afternoon for NYZ072>075-176-178. NJ...Excessive Heat Watch from Monday morning through Monday afternoon for NJZ004-006-103>108. MARINE...None. && $$ SYNOPSIS...GC/MET NEAR TERM...JM/MET SHORT TERM...GC LONG TERM...MET AVIATION...JM MARINE...GC/JM/MET HYDROLOGY...GC/MET is the U.S. government's official web portal to all federal, state and local government web resources and services.