Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 201127 AFDOKX Area Forecast Discussion National Weather Service New York NY 727 AM EDT Wed Mar 20 2019 .SYNOPSIS... High pressure will slide offshore today. A frontal system then impacts the area Thursday into Thursday night. Deepening low pressure lifts well to the north Friday into Saturday as high pressure builds Sunday. The high will give way to a cold front Monday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Light southerly flow has developed as high pressure slides to the east. With plenty of sunshine, highs will rise into the upper 40s to lower 50s, near normal for this time of year. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... With a frontal system approaching from the west and a surface low developing along the southeast coast, clouds will gradually increase this evening, although the majority of the overnight hours are expected to remain dry. Rain chances begin to increase towards daybreak for areas west of the city, with much of the region from New York City to the east remaining dry until after sunrise. Precipitation then gradually overspreads the area from southwest to northeast through the day on Thursday and continues into Thursday night before tapering off after midnight. While the vast majority of the precipitation is expected to fall as rain, the potential does exist for a rain/snow mix for a few hours well north and west of New York City Thursday morning if precipitation is able to move in fast enough. Any snow that does fall in this area is not expected to accumulate. Models are in generally good agreement with the track of the southeastern low, taking it near or just east of New York City Thursday night before continuing off to the northeast Friday morning. While timing differences still remain, the overall trend with this system over the past 24 hours has been for slower precipitation onset Thursday morning and a westward shift in the axis of heaviest precipitation. Rainfall amounts are expected to generally be around an inch from Thursday morning through Friday morning, with the highest totals across northeastern New Jersey, New York City and into southwestern Connecticut. With plenty of cloud cover, temperatures both Wednesday night and Thursday night are expected to be several degrees above normal, generally in the mid 30s to lower 40s. Highs on Thursday are expected to be near normal, in the upper 40s to lower 50s. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Two separate shortwaves pivoting around the main trough will consolidate into a closed low over the northeast Friday that will be slow to lift. As this develops, the sfc low that is passing across eastern sections of the CWA early Friday will move northward in time, deepening rapidly as it does so. As the shortwave dives out of SE Canada, forming the closed low, additional showers will likely move across portions of the area Friday afternoon and into the evening before lifting northward. Cyclonic flow will result in additional and persistent clouds Friday night into Saturday, but drier conditions are ushered in thanks to westerly downslope flow. As this low lifts northeast, brief ridging this weekend flattens, then heights fall once again early next week as shortwave dives out of Canada, lowering heights across the northeast. Before high pressure builds Sat night and Sunday, strong W/NW winds are expected behind the deepening low, increasing later Friday, and remaining quite strong Friday night and Saturday before diminishing Sat night. The high passes south and east Sunday, and a cold front will approach from the northwest Monday, passing Monday night. High pressure builds behind this front. Latest ECMWF is now indicating a dry frontal passage Monday, while GFS is much wetter tapping moisture from the south as it advects northeast along the front. Differences are noted in the upper levels as GFS progs a slightly more amplified trough as it moves across the northeast when compared to ECMWF. Both the ECMWF and Canadian global prog a stronger shortwave across the midwest during the Monday- Tuesday time frame. Will maintain chance pops for now on Monday. As for temps, near normal readings Friday will lower to below normal as colder air advects in Friday night-Saturday. Westerly flow Sun along with rising heights will result in a warming trend for Sunday- Monday (although Monday may be tricky depending on speed of front). Temps fall back below average on Tue as colder air settles in behind the front. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... High pressure gradually shifts offshore through tonight. Low pressure develops along the southeast coast late tonight and tracks north towards the terminals Thursday morning. Light SW flow increases this morning under 10 kt, gradually backing to the S-SE in the afternoon 10-12 kt. SE winds diminish after 23z before backing towards the E and increasing late tonight and Thursday morning. VFR through much of the TAF period with conditions beginning to lower to MVFR in developing -RA Thursday morning. ...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: Winds could shift to the SE 1-2 hours sooner than forecast this afternoon. The afternoon KJFK haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KLGA TAF Comments: Winds could shift to the SE 1-2 hours sooner than forecast this afternoon. KEWR TAF Comments: Winds could shift to the SE 1-2 hours sooner than forecast this afternoon. An occasional gust 15 to 18 kt possible around 19-22z. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Winds could shift to the SE 1-2 hours sooner than forecast this afternoon. KHPN TAF Comments: No unscheduled amendments expected. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY... .Thursday...MVFR/IFR in rain. SE G20-25kt. Chance of LLWS in the evening. .Friday...Mainly VFR, chance of rain/snow showers inland and rain showers near coast. W-NW G25-30kt. .Saturday...VFR. NW G25-35kt .Sunday...VFR. && .MARINE... Quiet conditions are expected on the waters through tonight as high pressure slides offshore. Winds and waves will then increase through the day on Thursday in response to an approaching area of low pressure, likely reaching SCA criteria on the ocean waters by Thursday afternoon. Winds and seas then remain elevated through Thursday night. As low pressure passes through early Friday, then deepens as it moves northward, westerly winds will increase, and seas will build or remain elevated. These windy conditions will continue Friday night and Saturday as the deep low is slow to depart to the northeast. High pressure builds Sunday, and winds will diminish, allowing seas to subside. && .HYDROLOGY... No hydrologic impacts are expected through tonight. Around an inch of rain is possible Thursday morning through Friday morning, which could result in some minor poor drainage flooding. Thereafter, no hydrologic impacts are expected through Tuesday. && .TIDES/COASTAL FLOODING... Astronomical tides will be rather high due to the full moon, and minor coastal flooding is possible beginning Thursday. At this time, it appears that the Thursday night high tide cycle will be the most vulnerable. Would expect widespread minor to perhaps locally moderate flooding during that tide cycle. Otherwise, local minor is possible during the daytime high tide cycle Thursday, and possibly Friday as well. && .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...None. && $$ SYNOPSIS...FEB/PW NEAR TERM...FEB/PW SHORT TERM...FEB LONG TERM...PW AVIATION...DS MARINE...FEB/PW HYDROLOGY...FEB/PW TIDES/COASTAL FLOODING... EQUIPMENT...

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