Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 311134 AFDOKX Area Forecast Discussion National Weather Service New York NY 734 AM EDT WED AUG 31 2016 .SYNOPSIS... A cold front slowly approaches from the Eastern Great Lakes today, pushing through late tonight into early Thursday morning. A large high pressure system then builds into the region through early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Clouds have moved in and developed across much of the region and increased cloud cover into this afternoon. In a south to southwest flow and with the onset of daytime heating temperatures along the coast have risen more quickly than forecast. Also dew points were a couple of degrees higher. Have increased both through this morning. Precipitation was breaking out well ahead of the front along the New York/Pennsylvania border as far east as Pike county PA. The latest HRRR was bringing precipitation into the lower Hudson Valley around midday. Based on this have increased probabilities across the northern and western zones. A cold front will slowly approach the area today as an upper level trough digs into the Great Lakes and the Ohio Valley. The front was moving into the eastern Great lakes region through lower Michigan. The bulk of the precipitation looks to hold off until mid afternoon for areas north and west of New York City. Temperatures today will be a couple of degrees warmer than yesterday with a continued southerly flow, in the middle to upper 80s. Humidity levels will also be rather high as dew points climb into the upper 60s. Some isolated areas may even see some lower 70s dew points. There is a high risk of rip currents at Atlantic Ocean beaches on today due to continued long period se swells from Gaston. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... The chance for precipitation will increase tonight as the cold front continues its approach toward the area. Precipitation will mainly be in the form of showers, however, a rumble of thunder is not out of the question, as lifted indices are in the 0 to -2 range, so continued the slight chance for thunderstorms. The front should move through late tonight into Thursday morning. Chances for rain will continue though as the trough axis remains to our west on Thursday. However, chances for rain will be on the decrease and begin to end from northwest to southeast as surface high pressure builds in. Clouds and a wind shift to the north will mean cooler temperatures for Thursday, upper 70s to lower 80s. Rainfall amounts should average between a quarter and a third of an inch, with locally higher amounts in any thunderstorms. Models do develop an area of low pressure along the front over the Virginias and move it northeast, near/over our area overnight. 00Z NAM is an outlier with the strength. It therefore has more in the way of rainfall. Because it is an outlier, thinking is that the rainfall amounts are overdone. Even if it the NAM does turn out to be correct, the heaviest of the rain would fall north and west of the low, and thus north and west of our area. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... A broad area of low pressure along with a surface cold front will be exiting the eastern forecast zones Thursday evening as an upper trough remains over the northeast and into the mid Atlantic region with an embedded shortwave moving off the northeast coast. With the slightly slower progression of the upper trough and surface low will have chance probabilities across southeastern Connecticut and eastern Long Island. Friday through Saturday the upper trough moves east while a strong ridge builds to the west and northwest with another ridge building into the central and western Atlantic. Late Friday into Saturday the upper trough will begin to interact with TD9 as the trough moves off the northeast coast. The eventual track will be dependent on the interaction with the trough and the ridge building to the west and the other over the Atlantic. Refer to the National Hurricane center forecasts and advisories for further details on TD9. At the surface a large Canadian high builds to the north and a cooler northeast flow develops behind the cold front. The high weakens to the north and another high builds over the southeastern states Sunday into Monday as the strong upper ridge builds into the mid Atlantic and northeast. With a return flow setting up Monday and Tuesday will see temperatures and humidity increasing. The forecast will be dependent of the interaction of the tropical system`s interaction with the upper trough and uncertainties remain Saturday into the beginning of next week. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... High pressure will drift eastward over the Atlantic today. A cold front approaches tonight. Some leftover Patchy IFR stratus may linger through 13Z. Then a return to VFR is anticipated. A combination of sea breeze and return flow around the exiting high pressure system can be expected today. Showers move in late in the TAF period. There is a low chance of MVFR cigs with any showers. There is also a chance of isolated tsra at KSWF this evening. Will leave out of the TAF for now, with low confidence on timing and placement of any storms. ...NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http://www.weather.gov/zny/n90 KJFK TAF Comments: Sea breeze development expected between 16z and 18z. Gusts to 20 kt possible after 20z. KLGA TAF Comments: Seabreeze development expected between 19z and 21z. Gusts 15-20 kt possible after 20z. KEWR TAF Comments: Seabreeze development expected between 20z and 22z. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Sea breeze development possible between 20z and 22z. KHPN TAF Comments: Sea breeze development possible between 20z and 22z. KISP TAF Comments: Sea breeze development expected between 17z and 19z. .Outlook for 12Z Thursday through Sunday... .Thursday...Showers possible with a cold frontal passage. Light winds with variable direction due to localized effects, becoming northwest late. .Friday...VFR with northwest winds. .Saturday and Sunday...Low probability for deep low pressure over the Atlantic to impact the area. Otherwise, VFR. && .MARINE... Winds and waves should remain below SCA criteria for the short term period. A persistent SE swell from distant Hurricane Gaston will keep seas around 4 ft over the coastal ocean waters through tonight and 3 to 4 ft on Thursday, with rough conditions likely at area inlets. Ocean seas will remain elevated into Thursday due to swells generated by Gaston. Thursday night into Friday night winds and seas are expected to remain below small craft advisory levels as a cold front moves east of the forecast waters Thursday evening and high pressure builds to the north. However, lingering long period swells of 2-3 ft from Gaston are expected to continue into Friday night. Then the winds and seas forecast become uncertain for the weekend and into the beginning of next week and will depend on the future track and intensity of TD9 as it moves from the Gulf of Mexico into the Atlantic. The forecast does not include any direct wind impacts, but does include ocean waves building to over SCA criteria Saturday and continuing through Monday. In addition, depending on the track of TD9 wind gusts across the ocean waters may be around small craft levels Saturday and Sunday. Refer to the National Hurricane center forecasts and advisories for further details on TD9. && .HYDROLOGY... Between a quarter and a third of an inch of rainfall is forecast. Flooding is not a concern with these amounts. Dry weather expected from late Thursday night into the beginning of next week. Moderate to severe drought conditions continue. The next local drought statement updated is scheduled for September 1st. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...High Rip Current Risk through this evening for NYZ075-080-081- 178-179. NJ...None. MARINE...None. && $$ SYNOPSIS...JP/MET NEAR TERM...JP/MET SHORT TERM...JP LONG TERM...MET AVIATION...BC MARINE...JP/MET HYDROLOGY...JP/MET

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