Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 190528 AFDOKX Area Forecast Discussion National Weather Service New York NY 1228 AM EST Mon Feb 19 2018 .SYNOPSIS... High pressure slides offshore overnight into Monday. A warm front slowly approaches from the south Monday night, then lifts to the north early on Tuesday. A cold front then approaches from the west Wednesday, then sinks to the south Wednesday Night into Thursday. This front then stalls near the region with waves of low pressure riding along it through the weekend. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... High pressure passing over the region overnight will result in light winds and mostly clear skies, with mainly a thin scattered to broken cirrus deck. And with a fresh snowpack across the interior, temps should be able to radiate well down towards 20 degrees overnight. Temperatures have fallen across the interior, and lowered overnight lows another degree or two. Also lowered temperatures across the pine barrens region of eastern Long Island. Elsewhere, generally upper 20s to lower 30s across much of the region. The one exception will be the NYC metro area, where lows will only fall into the middle 30s. The combination of snow melt and temperatures falling below freezing tonight for most of the region (except except areas adjacent to NYC) there is the potential for black ice to develop on untreated surfaces. Will continue to highlight this threat in the HWO. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... High pressure continues to slides offshore on Monday. Southerly flow will develop resulting in an increase in low level warm air advection. The warm frontal development and isentropic lift look to be delayed a few hours, into the afternoon, and initially strengthening across the western and interior areas. So updated probabilities to delay the onset of rain until the afternoon hours. The best chance of rain will be during the late afternoon into the early evening as a weak wave passes over the region. POPs gradually decrease overnight, however will continue to carry some chance/slight chance pops in case of any leftover weak showers. With the front in the vicinity of the region, will also have some patchy fog in the forecast for Monday night. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Anomalously strong deep layered Bermuda/Southeast US ridging will be in place midweek, aided by deep western US troughing. Successive pieces of energy will gradually move NE across the CONUS and towards the Great Lakes/Northeast US for the late week/weekend, resulting in a transition to a more suppressed but active sw upper flow. At the surface, the region will be under the influence of Bermuda/SE US ridging Tue/Wed. Meanwhile a slow moving frontal system will cross through the Great Lakes/Mississippi river valley the first half of the week. Its warm front pushes north of the region on Tuesday. An unseasonably mild SW flow is expected Tue/Wed around deep layered ridging, with near record highs around 70 possible for NYC/NJ metro and areas N&W on Tue and lower to mid 70s on Wed. With sunshine and mixing to 900 hpa, temps in this area have potential to max out in the lower 70s on Tue, and upper 70s Wed. Meanwhile coastal areas may struggle to get out out of the 50s both days due to the cold water temps and a strong inversion favoring stratus/fog maintenance. Coastal advection stratus/fog and nocturnal radiation fog is likely during this time. Thereafter, models in general agreement with the eastern ridging breaking down enough to allow a stream of shortwave energies to approach and push an approaching cold front towards and through the region Wed night/Thursday morning. Uncertainty continues on how far south this cold front pushes for Thu-Fri. With a train of shortwaves moving northeast in the flow, weather could be unsettled during this time. Enough cold advection may introduce the chance for wintry precip across interior portions of the region Thu Night/Fri. Otherwise, active and unsettled pattern likely continues through the weekend with frontal system stalling near the region and active upper/mid level flow allowing for a succession of frontal waves to affect the region. Temps during the period expected to average well above average, with high temps potentially 25-30 degrees above normal Tue and Wed for NYC/NJ metro and areas N&W. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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High pressure along the northeast coast moves offshore overnight into Monday. A warm front develops and approaches late in the day Monday. The front will likely become nearly stationary in the vicinity of Long Island Monday evening. Showers will be possible toward 21Z with MVFR conditions developing. There will be a few hours of showers into the evening. Conditions than lower to IFR in stratus and fog. There is some uncertainty as to conditions Monday evening, and will be dependent on where the warm front sets up. LLWS for a few hours will be possible, from late in the afternoon into the early evening. However, not confident at this time to include in the terminals. Winds light and variable overnight become light SE toward 10Z along the coast. Winds then become S around 10 kt Monday, and possibly become light and variable again Monday evening. .OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY... .Mon night...IFR in stratus and fog. Drizzle possible. .Tue...MVFR or IFR possible in the morning and again at night, otherwise VFR with SW wind G20KT possible. .Wed...Mostly VFR. Chance of showers with MVFR. SW wind G20KT possible. .Thu...MVFR in rain. .Fri...CHC MVFR in rain.
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&& .MARINE... With the center of high pressure moving into the western Atlantic south of Long Island winds have become light to near calm across the forecast waters, So lowered wind speeds until late in the overnight as the high moves farther east and a return flow develops. In response to the lighter wind, ocean seas were around 1 ft or less, so lowered until toward morning. The high moves east on Monday and Monday night. Expect conditions to remain below small craft levels on all waters through this time period. A moderate SW flow on the ocean waters Tue thru Wed may may have seas building to marginal SCA levels. Conds should subside below SCA Thu/Fri in the wake of a weak cold front and as high pressure passes to the north. && .HYDROLOGY... No significant hydrologic impacts are expected through this week. && .CLIMATE... Temperatures may flirt with or break record highs in a few spots Tuesday and Wednesday. Record Highs for Tuesday February 20, 2018 Location........Record/Year. Newark..............70/1939. Bridgeport..........54/1991. Central Park........69/1939. LaGuardia...........63/1943. J F Kennedy.........61/1949. Islip...............62/2016. Record Highs for Wednesday February 21, 2018 Location........Record/Year. Newark..............69/1953. Bridgeport..........59/2002. Central Park........68/1930. LaGuardia...........68/1953. J F Kennedy.........63/2002. Islip...............63/2002. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...BC/NV NEAR TERM...BC/19/NV SHORT TERM...BC/19 LONG TERM...NV AVIATION...19 MARINE...BC/19/NV HYDROLOGY...BC/NV CLIMATE... EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.