Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 190932 AFDOKX Area Forecast Discussion National Weather Service New York NY 432 AM EST Sun Nov 19 2017 .SYNOPSIS...
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A strong cold will sweep across the area early this morning with high pressure building in its wake. The high will pass to the south Monday and Tuesday, followed by a cold front on Wednesday. Another area of high pressure will build late week, followed by low pressure moving across on Saturday.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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Prefrontal showers moving across the area early this morning. Although there were a few lightning strikes in southern and central NJ earlier, it appears that the airmass has become a bit more stable, most likely due to both low and mid level inversions. Thus, have left thunder out of the forecast. 09z obs indicate that the warm front has just lifted through all locations except the western half of Orange county. It should be dragged through the remainder of the county shortly before the cold fropa, which is quickly tracking eastward from central PA, with a brief increase in temps. Front timed to move through the metro area around 12z with showers ending, although there will be a burst of higher winds right behind it. Uncertainty is still high at this point regarding wind potential. The warm front has moved through coastal areas, with winds slowly increasing in its wake, though with a strengthening inversion above the surface, reflected by a developing stratus field across eastern Long Island and Connecticut. VAD wind profile data from KOKX and KJFK radar show 50-55kt at 2000 ft as the low-level jet moves across the area, and so depending on the height of the inversion at least wind advisory level sustained speeds and gusts may mix to the surface early this morning prior to the cold front arrival. Although winds will be strong, based on current observations and expected conditions, sustained winds near 40 mph and gusts near 60 mph appear less likely, so the high wind warning will be dropped from eastern areas. Otherwise, winds may briefly weaken as showers move through, before strengthening ahead of and behind the cold front. Thereafter, strong winds appear likely across all areas, particularly in the late morning and afternoon as the system departs. Current obs in Maryland are showing gusts in the range of 45-50 mph immediately following the frontal passage, so the wind advisory will remain in place. High temps will likely occur early this morning for many locations, before falling during the late morning and aftn from W to E as strong CAA commences.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
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Winds gradually decrease tonight, although will still remain quite gusty with the departing low still strengthening as it lifts into SE Canada and high pres building to the S. All high res guidance indicates that lake effect streamers remain N and W of the area, except perhaps for a few hours this eve in Orange County. Otherwise, partly cloudy skies tonight will give way to mostly sunny conds on Monday. Lows in the upper 20s to mid 30s tonight and highs in the 40s on Monday, although gusty winds will make it feel like its only in the 30s.
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&& .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Aloft, models agree early in the period as initial shortwave passes east/northeast. Downstream shortwave will then make fast eastward progress. Here is where some differences arise. Northern stream potent shortwave tracks across the Great Lakes region as it lifts northeast, with most of the energy and associated dynamics lifting well to our north Wednesday. Southern stream trough lags a bit as it moves across the Gulf states. By late Wednesday into Thursday, operational GFS seems to be a deep/strong outlier with regard to closed low around the Gulf states as the trough makes eastward progress. This upper trough weakens over the western Atlantic Thursday, with next shortwave in the northern stream moving eastward toward the northeast by next weekend. At the sfc, high pressure passes to the south Monday and Tuesday. Gusty NW flow will back around the SW as the high tracks east. Thereafter, a cold front passes Wednesday. This front is associated with northern stream shortwave. This looks like the best chance for measurable precipitation, late Tuesday night into Wednesday, chance pops. Waves of low pressure likely develop along the front well to our south in the Wednesday night/Thursday time frame. Again, GFS appears to be an outlier with wave of low pressure developing and passing close enough for measurable precip Thursday. Otherwise, model consensus suggest any precip remains to our southeast as ridge builds to the NW and waves remain far enough to the southeast. Will maintain a dry forecast as a result, leaning toward consensus. However, this will need to be watched. Dry through Friday before the next chance for precip arrives with the shortwave, clipper low Saturday. As for temperatures Monday-Saturday, followed a model/mos blend. Below normal temperatures Monday will warm to slightly above normal Tuesday as WAA occurs behind the high. Behind a cold front Wednesday, normal temps likely fall to below normal Thursday and Friday before rebounding yet again in WAA ahead of the clipper low Saturday. && .AVIATION /09Z SUNDAY THROUGH THURSDAY/...
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A cold front moves through around daybreak with high pressure building behind it through this evening. S flow will increase through the morning hours with gusts returning to all terminals between 9-11z. KJFK may see stronger sustained speeds without gusts initially until flow shifts more to the SW-W this morning. The gusts will initially be 20-30 KT, increasing to 30- 40 KT towards day break. Some eastern terminals may see peak gusts 45 KT. LLWS is also forecast until around 12z. S-SW winds shift to the W-WNW 12z-15z with gusts frequently 35-40 KT during the day. The gusts will begin to weaken late in the afternoon and early in the evening. Mainly VFR-MVFR conditions to start with conditions improving to VFR 12z-15z behind the cold front. .OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY... .Monday...VFR. W-NW winds G20-30KT. Gusts diminish gradually at night. .Tuesday...Mainly VFR. MVFR possible late Tuesday night in showers. SW winds G15-20KT. .Wednesday...MVFR possible with showers during the day. VFR at night. W-NW winds G15-20KT. .Thursday...VFR.
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&& .MARINE...
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Seas continue to build ahead of strong southwest flow. Gale-force winds are already occurring across the ocean waters and will spread elsewhere through the day, especially following the cold frontal passage later this morning. Less confidence exists in storm- force winds across the eastern Sound and ocean areas east of Fire Island, though given strong winds above the surface, potential certainly exists for these to mix to the surface. Gale-force winds will continue into tonight, before gradually weakening to SCA-levels tomorrow. SCA conditions may continue through Tuesday night before winds and seas gradually subside into Wednesday through Friday as high pressure builds across the area.
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&& .HYDROLOGY...
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A few bands of moderate to locally heavy showers with a strong cold frontal passage this morning should cause no more than local nuisance impacts. Additional rainfall of 1/4 to 1/2 inch, through late morning.
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&& .TIDES/COASTAL FLOODING...
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Latest surge is running between 1/2 to 1 1/2 ft on the south shore bays of LI. At this rate, minor coastal flooding benchmarks could be met, however winds will be shifting to the W/NW right before high tide, thus these values could decrease a bit in western portions of the bays and cause the start of tidal piling across eastern portions of the Great South Bay into Moriches Bay. Have maintained the coastal flood statement addressing brief and localized minor coastal flooding impacts.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Wind Advisory until 6 PM EST this evening for CTZ007>012. Wind Advisory from 7 AM this morning to 6 PM EST this evening for CTZ005-006. NY...Wind Advisory until 6 PM EST this evening for NYZ071>075- 078>081-176>179. Wind Advisory from 7 AM this morning to 6 PM EST this evening for NYZ067>070. NJ...Wind Advisory until 6 PM EST this evening for NJZ006. Wind Advisory from 7 AM this morning to 6 PM EST this evening for NJZ002-004-103>108. MARINE...Storm Warning until noon EST today for ANZ330-340-345-350-353. Gale Warning until 6 AM EST Monday for ANZ335-338-355.
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