Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 170609 AFDOKX Area Forecast Discussion National Weather Service New York NY 109 AM EST Mon Dec 17 2018 .SYNOPSIS... Low pressure tracks from south of Long Island to near Nova Scotia by Monday evening. Meanwhile a series of cold fronts cross the area Monday afternoon and night. Deep low pressure over the Canadian Maritimes Tuesday gives way to high pressure mid week. Another low impacts the area Thursday and Friday, then moves into Canada next weekend. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Mostly light rain and drizzle remaining across much of the coastal locations tonight which will continue to decrease going into overnight. The rain will be mostly light. Some light snow is possible north and west of NYC before all precipitation ends. A cutoff low tracks to the southeast of Long Island through the overnight. Sfc low does the same. Expect precipitation to taper off from W to E overnight with the exiting of the the low level jet. Across interior zones, the question is how fast does low level cold air work in to change the rain to snow or perhaps sleet. For now have the potential for up to an inch of sleet and snow across northern interior zones, but could just as easily see no accumulation if the low level cold air does not arrive in time. Lows tonight should be around 5-10 degrees above normal. && .SHORT TERM /6 AM THIS MORNING THROUGH TONIGHT/... Northern stream shortwave ridging crosses the area Monday morning, with associated subsidence keeping things dry. The axis of a northern stream trough then pushes through the area Monday afternoon and then continues to push SE off the Mid- Atlantic and NE seaboard Monday night. Low levels likely will be too dry for any precipitation on downsloping low level NW flow - but given expected low level instability cannot rule out a stray flurry or sprinkle Monday afternoon. It will become quite gusty Monday afternoon and night with gusts of 25-35 mph Monday afternoon and 30-40 mph Monday night. At this time it appears the area should remain below wind advisory criteria Monday night. However, given either slightly stronger cold air advection or a tighter pressure gradient and low end wind advisory gusts could be achieved Monday night both near the coast and at higher elevations inland. Highs on Monday should occur by early afternoon with slowly falling temperatures later in the day. Highs should peak out in the lower to mid 40s and wind chills by late afternoon from the mid 20s to lower 30s. Lows Monday night should be near normal, with wind chills generally in the 10s by late Monday night(around 20 NYC). && .LONG TERM /TUESDAY THROUGH SUNDAY/... General model agreement noted as upper ridge and sfc high builds Tuesday-Wednesday ahead of digging shortwave energy that develops into an amplified trough over the Mississippi Valley by Thursday. The sharpening trough looks to close off near the southern Appalachians as a surface low deepens. The low moves north up the Appalachians on Friday. This stacked low lifts northward into Canada next weekend. A warm front approaches and lifts northward Friday, and lagging sfc front/trough passes Saturday as the low traverses well to the north. A noticeably less amplified overall mean flow is expected toward the end of the period. Looks like the best chance for rain occurs later Thursday night and through the day Friday as a broad area of moisture sweeps northward across most of the east coast. Gusty NW winds Tuesday will add to the chill, but winds diminish Tue night and Wednesday as the pressure gradient relaxes. E/SE winds increase Thursday-Thursday night ahead of the warm front, with gusty S/SW winds Friday. These winds veer to the west, and remain rather gusty through the weekend as a tight pressure gradient remains in place. Temps remain right around or slightly below normal Tuesday-Wednesday before rebounding to above normal Thu-Friday. Readings return to normal in CAA behind the storm next weekend, especially Sunday.day. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... Low pressure southeast of Montauk Point will move up the coast overnight and into Monday while deepening. By Monday afternoon the low will be in the Canadian Maritimes, and then move slowly north through Monday night. Variable conditions are likely overnight with mainly MVFR conditions through most of the overnight period. There will be periods of VFR possible, and a low chance of even brief IFR ceilings especially early in the forecast period. Toward 12Z Monday conditions improve to VFR. Winds will be northerly 10-15kt with gusts 20-25kt. Gusts become more occasional, and possibly end for several hours overnight. Winds will be backing to the NW overnight. NW to W winds and gusts increase during the day Monday, with the highest winds and gusts during the afternoon and into Monday evening. Sustained winds increase to around 20kt with gusts 30-35kt. .OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY... .Late Monday night...VFR. Gusty NW-W winds 15-20kt, G25-35kt, gradually diminishing. .Tuesday-Wednesday night...VFR. NW Wind G15-25kt possible Tuesday, W- WSW winds G15-20KT possible Wednesday. .Thursday...VFR, possibly becoming MVFR or lower late with rain. LLWS possible late. .Friday...MVFR or lower in rain. SE winds 15-20kt G30kt possible. LLWS. && .MARINE... SCA now in effect for all ocean waters for the remainder of overnight. SCA remains in effect tonight into Monday for all non ocean waters (gusts up to 30 kt through Monday). Gale gusts should return on the ocean waters by Monday afternoon and on all waters Monday night in response to strengthening low level cold advection. A Gale Watch for Monday and Monday night for the coastal ocean waters and for Monday night for the non-ocean waters remains in effect. Gusty NW winds persist Tuesday as deep low pressure moves along the Canadian Maritimes and a tight pressure gradient remains in place. Gale force gusts are possible, especially the ocean waters and eastern LI Sound before winds diminish Tuesday night and Wednesday. The diminishing winds are due to high pressure, as it builds over the waters. Winds eventually shift around the S, then E/SE Thursday as the high moves east and a warm front approaches from the south. The warm front likely moves north later Friday. Gusty winds are expected Thursday night through Friday as deep low pressure passes to the west of the local waters. Rough seas Tuesday will subside Wednesday into Thursday. In general, tranquil conditions are anticipated during the mid week period. Seas build once again Thursday night and Friday due to increasing winds. && .HYDROLOGY... Less than .25" western locations of additional rainfall is expected, with 0.50-1.0" east. There is a low chance of minor nuisance/poor drainage flooding through this evening as a result. The next chance for significant rainfall of at least a half an inch is expected to occur late in the week (Thursday night-Friday). Still too early to determine if there will be any hydrologic concerns with this potential late week event. && .EQUIPMENT... NYC Central Park winds are out of service until further notice. Loss of data is due to a severed cable. Parts are on order. NYC NOAA Weather Radio Station KWO35 (162.55 MHz) will remain off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Gale Watch from this evening through late tonight for ANZ330- 335-338-340-345. Small Craft Advisory until 6 PM EST this evening for ANZ330- 335-338-340-345. Gale Watch from 6 AM EST this morning through late tonight for ANZ350-353-355. Small Craft Advisory until 6 AM EST early this morning for ANZ350-353-355. && $$ SYNOPSIS...Maloit/JP/PW NEAR TERM...Maloit/JM/PW SHORT TERM...Maloit LONG TERM...PW AVIATION...MET MARINE...Maloit/JM/JP/PW HYDROLOGY...Maloit/PW EQUIPMENT...

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