Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 151038 AFDOKX Area Forecast Discussion National Weather Service New York NY 638 AM EDT Sun Jul 15 2018 .SYNOPSIS... Weak high pressure will remain in place through tonight with a couple of low pressure troughs moving across the region. A cold front will impact the area from late Monday into early Wednesday, with high pressure returning for the middle of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Showers and thunderstorms associated with an upper level shortwave continue to move across portions of the forecast area this morning, with the best chances across NE NJ and NYC. These storms should continue until 10 or 11 am as clusters of storms are lined up back into eastern PA and should move in a trajectory towards our region. Another upper level shortwave is forecast to move across the region later today, resulting in the need for at least chance pops this afternoon. POPs will generally range between 30-50 percent, and with some CAPES of 1000-1500 J/KG and steep low level lapse rates will continue to mention the threat of thunder. Expect mostly cloudy skies to start, with some clearing by late in the afternoon. Temperatures today will climb into the middle and upper 80s, except across Long Island and parts of CT, where lower 80s are forecast. MAV/MET/ECS was in good agreement and used. A moderate risk for rip current development is expected at the ocean beaches today.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... The shortwave exits the region tonight, with some ridging aloft builds into the area. Rain chance will quickly drop off by midnight as some drier air briefly works into the region. The high will slide offshore on Monday allowing a surface trough and cold front to approach from the west. A south to southwest flow will develop, allowing moisture levels to increase. Monday morning should be mostly dry, however POPs do gradually increase through the day for NYC and points west as some showers and thunderstorms develop as a thermal surface trough develops across the interior. Some of these storms will be capable of producing heavy rainfall and locally gusty winds. some of these thunderstorms may continue into Monday night and gradually spread eastward. Temperatures on Monday will climb into the upper 80s to lower 90s, except across Long Island and coastal Connecticut where highs will remain in the lower to middle 80s. Overnight lows will remain in the upper 60s and 70s both Sunday night and Monday night. A moderate risk for rip current development is expected at the ocean beaches on Monday. && .LONG TERM /TUESDAY THROUGH SATURDAY/... A cold front will move across the region during the early part of the long term period. PW values are expected to be close to the 97th percentile for this time of year on Tuesday, and potentially close to maximum values. Continued forcing for ascent with the approaching trough and attendant cold front will lead to at least isolated showers at any time, quickly increasing into the afternoon as the front approaches at a favorable time, diurnally. Any storms that develop in a discrete manner ahead of the front may produce locally gusty winds with a dry subcloud layer and downward momentum from heavy rainfall enhancing winds. Otherwise, flow will mainly be parallel to the frontal boundary, allowing storms to quickly spread with a line developing by afternoon. Heavy rainfall will be the primary threat until the front passes to the east Tuesday night into Wednesday morning. High pressure then follows, with a return to more seasonable temperatures and humidity levels. There is potential for an area of low pressure to approach from the southwest by the weekend, but details about placement and timing are too uncertain at this time to offer further detail. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... Broken line of showers and tstms has developed from KTEB vicinity back into into NW NJ, with a more significant cluster behind that over NE PA. This activity was moving steadily ESE and on its current motion should bring at least vicinity thunder impact initially to KTEB/KLGA/KISP, then also to KHPN and possibly KBDR. Additional showers with brief local IFR vsby were redeveloping south of the cluster of storms in NE PA, and may have to also amend all the NYC metros for brief IFR vsby impact and possible thunder. This initial activity should clear all the terminals by 12Z. Then mainly VFR conds should prevail into early afternoon, with light W flow backing more SW and increasing to 5-10 kt this afternoon, and becoming almost due S just over 10 kt at KJFK via greater sea breeze component to the wind. Could see another round of showers/tstms with MVFR/IFR flight cat and gusty winds late this afternoon. .OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY... .Late tonight...Chance of MVFR vsby developing at terminals mainly outside of NYC metro. .Monday...Chance of afternoon/nighttime showers/tstms with MVFR or lower flight cat. SW winds G15-20KT in the afternoon for coastal terminals. .Tuesday...Showers/tstms likely with MVFR or lower flight cat. SW winds G20-25KT into early evening. .Wednesday...Chance of AM showers with MVFR or lower flight cat possible. .Thursday...VFR. && .MARINE... Winds and seas will generally remain below small craft levels through Monday. Winds and seas will gradually increase ahead of an approaching front Monday night into Tuesday, with SCA-level seas expected by Tuesday. Some 5 ft seas are expected to remain on the eastern waters through Wednesday before falling back below SCA levels Wednesday night. Thereafter, high pressure builds across the area, allowing winds and seas to subside into late week. && .HYDROLOGY... Rainfall amounts through Sunday evening could total up to at least quarter to three-quarters of an inch across the area with the higher amounts generally NW of NYC. Local amounts above an inch will be possible due to the convective nature of the rainfall. Minor flooding could occur at any point in this period due to a relatively slow forward motion of potentially training cells, but overall flooding chances appear to be low. Another 3/4 to 1 1/4 inch basin avg rainfall likely with the slow moving frontal system from late day Monday into Wednesday morning. Locally heavy rainfall is possible Tuesday afternoon and night, with some potential for minor urban and poor drainage flooding. && .TIDES/COASTAL FLOODING...
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Astronomical tides will continue to run high due to a combo of a recent new moon and onshore flow/incoming long period swells promoting tidal piling. Additional rounds of localized minor flooding are likely tonight and again Monday night along the back backs of southern Nassau.
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&& .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...None. NJ...None. MARINE...None. && $$ SYNOPSIS...BC/MD NEAR TERM...BC SHORT TERM...BC LONG TERM...BC/MD AVIATION...Goodman MARINE...BC HYDROLOGY...BC/MD TIDES/COASTAL FLOODING... EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.