Area Forecast Discussion
Issued by NWS Binghamton, NY

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000 FXUS61 KBGM 111148 AFDBGM Area Forecast Discussion National Weather Service Binghamton NY 648 AM EST Mon Dec 11 2017 .SYNOPSIS...
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After scattered morning snow showers and flurries, things will be fairly quiet until a clipper system quickly moves through tonight into early Tuesday with accumulating snow. Lake effect snow will follow for Tuesday afternoon through Wednesday night in Central New York and perhaps some of the Northern Tier of Pennsylvania, as Arctic air descends across the region.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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645 AM Update... We were able to drop the winter weather advisory earlier, that had been in effect for Northern Oneida, since snowfall rates/banding were already significantly diminishing. That being said, around an inch or so of fluff will be possible from the last vestiges of lake effect this morning. Clipper system tonight-early Tuesday, plus the Arctic air and lake effect snow that will follow, are the main forecast concerns in the big picture. For details on that please refer to the short term portion of this area forecast discussion. Previous discussion... Lake Ontario band shifted north of the area much of yesterday, but with approach of a shallow cold front it is now reorienting as of 3 AM. It will bodily carry through northern Oneida county during the next several hours, likely reducing visibility to about a mile while dropping another quick 1 to 2 inches north of the NY Thruway. We will allow Winter Weather Advisory to continue up to the scheduled expiration of 7 AM this morning. As winds veer northwesterly behind the front, inversion heights will also rapidly drop to below the dendritic growth zone, which along with drier air will allow the lake effect to transition to multi-band snow showers and flurries after dawn this morning, before ending around midday. So south of the Thruway to about as far as Moravia-Cortland-Pharsalia-Morrisville-Waterville, accumulations this morning should be limited to a fluffy dusting to around an inch. Elsewhere just a few flurries are expected as the weak front passes; many locations especially in Northeast PA will see nothing at all due to the amount of dry air. Though there will be a gradual decrease in lake clouds, high thin clouds will quickly stream in ahead of the approaching clipper, and then thicken with time. This will hold highs back to generally in the mid 20s to mid 30s range.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... 400 AM Update...The highly advertised clipper low will strengthen as it tracks across the Great Lakes and into New York tonight and Tuesday. Light snow will break out in isentropic lift regime over CNY and NEPA by late evening with best forcing across NY portion of forecast area. Snow picks up with time heading into the Tuesday commute. Warm advection appears to be split into lift and warming of the boundary layer enough to significantly affect snow-liquid ratios and surface temps tomorrow morning. Arctic front with falling temperatures arrives late afternoon. The favorable dendrite crystal layer rises tonight to about 10K-13K feet with relatively mild air beneath. Dry slot also noted to come into play as strong jetlet rounds base of upper low Tuesday. Snow totals will not be easy with this one due to the above factors as there will likely be insufficient flake production, some stoppage of precip at times, and low level warming to melt what falls, or even provide some liquid flakes in some of the warmest locales. Looking for a quick 1-3"/2-4" accumulation in a S-N gradient overnight and nominal accums on Tuesday with some melting. Given this uncertainty, have held off on issuing winter advisories across the Southern Tier and NEPA pending further review. We have issued a Winter Storm Watch through Wednesday across the northern zones where confidence in several inches is highest. It looks to be just a tad colder overall, coupled with topographic enhancement along the Tug Hill and Mohawk Valley. Synoptic and hi-resolution models were simulating this with a QPF bullseye in this area. In addition...a good set up for LES along a 290-310 flow develops later Tuesday night and Wednesday post Arctic frontal passage. Lapse rates beneath inversion layer appear stout with limited shear and good support from synoptic moisture. Thus, multi-single band hybrid lake effect/enhancement should produce healthy squalls and accumulations through Wednesday for the Syracuse area and hilltowns to the south. A good portion of the area southeast of Lake Ontario is likely to see a bunch of snow by Wednesday afternoon. Watch (and/or Warnings) may need to be expanded slightly depending on confidence of inland extent to snow plumes. Turning much colder by Wednesday with highs struggling in the teens to lower 20s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... 400 AM Update...No significant changes to medium range with long wave pattern remaining in a broad trof and models consistent with 12Z runs. Previous discussion... Flow becomes more westerly and relaxes on Thursday so snow showers will taper off. However, unsettled weather will continue through Friday with trofiness aloft, a clipper moving into the Great Lakes, and systems running up the coast to our east. Confidence in forecast is low to moderate until Friday when global models diverge quite a bit on positioning and timing of disturbances diving around the base of the trof and interacting with the front along the coastal plain. Chance PoPs during this time and some moderation of temperatures with flatter flow and slight warm advection. Temperatures look to potentially warm above freezing into the mid-30s to lower 40s by next Sunday, as a storm system passes by well to our north. This system will bring chances for rain and snow showers, and perhaps some mixed precipitation. && .AVIATION /12Z MONDAY THROUGH FRIDAY/...
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Lake effect snow is winding down this morning, but between 12Z-15Z there will still be times of 1-4 mile visibility for KRME-KSYR. Brief high end MVFR ceiling and a light flurry will still initially be around KBGM-KITH, otherwise all terminals will go to VFR late morning through early evening. Wind is veering to west-northwest but less than 10 knots, becoming variable late afternoon to southeast tonight. With this busy pattern, a clipper system will already start moving across the region from 03Z onward with IFR to fuel alternate required conditions becoming likely through dawn Tuesday. Outlook... Tuesday morning...Lingering restrictions as a clipper system finishes moving through the region. Tuesday afternoon through Wednesday night...Gusty snow showers and associated restrictions, especially NY terminals. Thursday through Friday...Still a chance for snow showers and intermittent restrictions.
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&& .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...Winter Storm Watch from this evening through Wednesday afternoon for NYZ009-018-036-037. && $$ SYNOPSIS...MDP NEAR TERM...MDP SHORT TERM...JAB LONG TERM...JAB/MJM AVIATION...MDP

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