Area Forecast Discussion
Issued by NWS Upton, NY

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532 FXUS61 KOKX 150742 AFDOKX Area Forecast Discussion National Weather Service New York NY 342 AM EDT Tue Oct 15 2019 .SYNOPSIS... High pressure builds today, and passes east tonight. A frontal system approaches Wednesday, with a rapidly intensifying coastal low tracking just southeast of the area Wednesday night. Low pressure will depart on Thursday with high pressure building in for the weekend. Another system will approach next Monday and Tuesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Upper shortwave to the north pivots east, with weak ridging between approaching shortwave that will track across the upper mid west today. Surface high pressure builds overhead by afternoon. Plenty of sunshine is expected today, along with seasonable temperatures in the 60s. Northwest winds ahead of the high lighten, and turn toward the south late in the day. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... Weak shortwave ridging and associated subsidence tonight will give way to approaching vigorous shortwave that will amplify as it tracks across the Great Lakes/Ohio Valley region. This trough will begin to become negatively tilted Wednesday and Wednesday night as it tracks overhead. Deep sfc low over the Great Lakes ahead of this trough tracks east, but coastal low pressure develops around the Mid Atlantic states, pivoting east and likely passing just southeast of Long Island by late Wednesday and Wednesday night, deepening as it does so. This will become the main low. A clear night tonight along with light winds will allow temperatures to cool into the 30s/40s, except lower 50s around NYC. Patchy frost development is expected, and included in the forecast. On Wednesday, the frontal system approaches, and deep lift ahead of the trough will result in rain development from west to east as the day progresses. With strong lift and plenty of moisture advection, heavy rain is likely from the afternoon into the evening. Drying occurs behind the system for western zones Wednesday night, with rain lingering across eastern zones through most of the night. Included thunder mention near the rapidly developing low, along the coast due to elevated instability. QPF of 1-3 inches is likely across the region. A few higher amounts are possible. Temperatures will rise into the 60s Wednesday as SE winds increase ahead of the front/low. Ahead of the low, a period of E/SE winds 20 to 25 mph with gusts 30-35 mph are likely along the coast Wednesday afternoon/evening. Then in the wake of low pressure, W/NW winds of 20 to 30 mph and gusts to 40 to 45 mph are expected late Wednesday night. && .LONG TERM /THURSDAY THROUGH MONDAY/... As low pressure wraps up and pulls away from the region on Thursday strong cyclonic flow will lead to a cool, cloudy and windy day. W/NW winds of 20 to 30 mph with gusts 40 to 45 mph are likely during the day on Thursday. The highest wind gusts will be along eastern Long Island and far southeastern CT. Winds will be slow to diminish Thursday evening, and may even continue into early Friday morning across the Twin Forks. Temperatures will likely stay in the 50s during the day and drop into the 40s at night. High pressure then builds in towards the region on Friday. With continued NW flow, it will still be a breezy day with below normal temperatures despite a mostly sunny sky. High temperatures on Friday will be in the upper 50s to lower 60s with lows dropping into the upper 30s across the interior overnight. Other locations closer to the coast will remain in the 40s. As upper level ridging builds and high pressure slides to the south into the weekend southwesterly flow will set up and temperatures will moderate to more seasonable levels. High pressure will then slide off the Mid-Atlantic coast on Sunday as another system develops across the Central Plains. As this system treks eastward, moisture will increase bringing the next chance of rain to the region late Monday into Tuesday. && .AVIATION /07Z TUESDAY THROUGH SATURDAY/... High pressure builds in through the TAF period. VFR conditions are expected for all terminals. Initially, winds will be NW 5-10 kts and these will eventually become more SW this afternoon at nearly the same wind speed with developing sea breeze for coastal terminals. Winds become light again tonight, 5 kts or less, and become generally more SE. .OUTLOOK FOR 06Z WEDNESDAY THROUGH SATURDAY... .Late tonight...VFR. Winds become more SE. .Wednesday...Rain developing. IFR late afternoon/evening, lingering past midnight at KGON. SE winds G25kt. LLWS also possible along the coast late afternoon/evening, mainly at KISP/KGON. Isolated thunderstorms possible for KISP and KGON late afternoon/evening. .Thursday...Possible MVFR with showers. NW winds G25-35kt. .Friday...VFR. NW winds G20-25kt. .Saturday...VFR. && .MARINE... Northwest winds across the waters this morning lighten as high pressure builds. Winds shift around to the south/southeast late today into tonight. SE winds increase to 20-25 kt as the day progresses Wednesday, so SCA has been issued. Seas build during this time. By Wednesday night, deep low pressure passes across the ocean waters, tracking east Wednesday night. SE winds will shift around the W/NW behind this deepening low. Gale force winds are likely at that time, and cannot rule out a few strong force gusts briefly right behind the low over the eastern waters. A gale Watch has been issued beginning Wed night. Gale conditions will remain on all waters for Thursday before falling back to SCA levels Thursday night. SCA wind gusts will subside late Friday afternoon. Winds and seas will then remain below SCA criteria through the weekend. && .HYDROLOGY... A significant rainfall of 1-3 inches is likely Wednesday afternoon into Wednesday night, with localized swaths of 2-4 inches possible. The bulk of the rainfall is expected in a 6-9 hr period late Wednesday afternoon through Wednesday evening. Urban, poor drainage, and low lying flooding is expected. There is a low probability of flash flooding along a few of the fast responding small rivers and streams in NE NJ and the Lower Hudson Valley if the higher rainfall amounts are realized. Additionally, localized flash flooding will also be an issue for coastal roads if heaviest rain coincides with the Wed night high tides. && .TIDES/COASTAL FLOODING... Tidal departures of generally 2 to 2 1/2 ft above astronomical are needed for minor flooding during the times of high tide late Wed Eve into Wed night. There continues to be quite a bit of spread in the ensemble guidance, partly due to some differences in the potential strength and position of low pressure/wind fields, and equally so due to timing of a wind shift from E-SE winds to NW as low pressure moves by. At this point, model consensus would indicate potential for widespread minor coastal flooding, with a low probability for localized moderate impacts where wave action combines with elevated water levels. If the heaviest rain coincides with the Wed night high tide, more widespread flooding could be experienced than would normally be expected. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO35 (162.55 MHz) remains off the air. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Gale Watch from Wednesday evening through Thursday afternoon for ANZ330-335-338-340-345-350-353-355. Small Craft Advisory from 6 AM to 6 PM EDT Wednesday for ANZ330-335-338-340-345-350-353-355. && $$ SYNOPSIS...CB/PW NEAR TERM...PW SHORT TERM...PW LONG TERM...CB AVIATION...JM MARINE...CB/PW HYDROLOGY...CB/PW TIDES/COASTAL FLOODING...PW EQUIPMENT...

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