Area Forecast Discussion
Issued by NWS Albany, NY

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000 FXUS61 KALY 151757 AFDALY Area Forecast Discussion National Weather Service Albany NY 1257 PM EST Mon Jan 15 2018 .SYNOPSIS... High pressure will remain centered over eastern Quebec today, with a ridge extending southward through the northeast U.S. This will allow for dry and cold conditions to persist through today. A low pressure system will then approach from the Great Lakes tonight into Tuesday, bringing increasing chances for light snow. This system, combined with a developing coastal low pressure area, is expected to bring at a moderate snowfall to much of the region late Tuesday into Wednesday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 1257 PM EST...Tranquil and cold conditions exist across the area early this afternoon courtesy of a strong area of high pressure over eastern Quebec, with ridging extending all the way southward through the mid Atlantic region. Temperatures are generally in the teens with a light northeast wind in place at the surface. Most areas are fairly clear this afternoon, although some lower stratus continues to be in place over the Catskills, Dutchess County and Litchfield CT. These clouds should start to dissipate during the afternoon, however, mid and high level clouds will be increasing within the broad southerly flow aloft by later this afternoon. It will be another chilly day, with high only in the teens to mid 20s. Clouds will continue to increase and thicken tonight associated with a weak low pressure system moving eastward across the lower Great Lakes region. Some weak warm advection will eventually lead to some light snow developing. Will mention mainly chance pops for spotty light snow reaching the ground. The low levels will be quite dry to start, and available forcing/moisture with this system will be fairly limited to start, thus the reluctance to go with likely pops overnight.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Winter Storm Watch has been issued for the southern Green Mountains of Vermont and the Berkshires of Massachusetts from Tuesday afternoon through Wednesday morning... Light snow will become more likely spreading eastward through the Capital District Tuesday morning, as weak warm advection continues. The low levels are expected to become saturated by then, with confidence in some light snow accumulating. The light snow will spread to areas east of the Hudson Valley, including western New England Tuesday afternoon. Then, the weak area of low pressure is expected to stall along a strengthening baroclinic zone across western New England Tuesday night. At the same time, a secondary area of low pressure is forecast to emerge off the Delmarva and track northeast along the edge of the baroclinic zone. A positive tilt trough aloft will be advancing eastward across the lower Great Lakes and Ohio Valley region. This set up looks to be conducive for some mesoscale banding to develop, and resembles a potential quasi-stationary band pattern from noted CSTAR research. Deterministic and ensemble model QPF has also increased from previous runs, which lends more confidence to a moderate snowfall event, especially for much of the area from the foothills of the southern Adirondacks south and east. Due to the best forecast 850-700mb F-Gen across SE NY and the southern New England coast, the most likely area for potential mesoscale banding looks to be across the southern Green Mountains of Vermont and the Berkshires based on the CSTAR research. So we have issued a Winter Storm Watch for this area due to at least 50 percent confidence of greater than 6 inches of snow. Elsewhere, it appears an Advisory will eventually be needed with snowfall forecast of generally 3-6 inches outside of the Watch area, and lighter 1-3 amounts in the west-central Adirondacks. The snow from the coastal low should persist through much of Wednesday morning, especially for areas east of the Hudson Valley. This system will likely impact the morning commute for much of the area. Wednesday afternoon, lake effect snow showers will start to develop downwind of Lake Ontario as westerly wind align with conditional lake-induced instability developing. So scattered snow showers will move back into the western Adirondacks before dark with some light accumulations possible. Lake effect snow showers will continue into Wednesday night across the western Adirondacks, but will be light due to lowering inversion heights. Otherwise, it will be mainly dry with near normal temperatures for the rest of the area. && .LONG TERM /THURSDAY THROUGH SUNDAY/... The weather is expected to be quiet with a gradual warm up through the weekend. Upper energy exits Thursday with upper ridging building into our region through the weekend. There could be some isolated to scattered snow showers in the southern Adirondacks by Friday night and Saturday, with isolated rain showers Saturday as Isentropic lift and warm advection increase. By Sunday strong upper energy in the central U.S. will begin its move east and as it amplifies, the downstream upper ridging in our region will amplify, further strengthening the warm advection. Increasing clouds and slowly increasing coverage of showers is possible Sunday. Highs Thursday in the upper 20s to lower 30s but mid 20s northern areas. Highs Friday in the lower to mid 30s with mid to upper 20s northern areas. Highs Saturday around 40 to mid 40s but mid 30s northern areas. Highs Sunday in the 40s with some upper 40s southern areas and lower 40s northern areas. There could be some more snow melt and ice jam flood issues as the temperatures warm next weekend and some rain approaches by the end of the weekend and beginning of next week. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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VFR conditions are in place for all sites this afternoon. KGFL/KALB/KPSF are seeing fairly clear skies right now with just some thin high clouds. Meanwhile, KPOU continues to see some lower stratus clouds, but ceilings are just over VFR criteria (around 3500 ft). These lower clouds may finally start to break up during the mid to late afternoon hours. Winds this afternoon will be very light out of the NE or calm. During the evening and into the overnight, mid and high level clouds will increase as a storm system approaches from the west. Some light snow showers are possible by late in the night towards daybreak at KGFL/KALB, but this activity will be fairly spotty/intermittent, so will only address with a PROB30 for now. Light or calm winds will continue into the overnight hours. As the storm system gets closer, a steady light snowfall looks to develop during the day on Tuesday for all sites, especially by the mid to late morning hours. Although the snow will initially be fighting some dry air at low levels, it should eventually moisten up the atmosphere enough to allow for IFR conditions by all sites towards the end of the TAF period. Southerly winds will be 5 to 10 kts on Tuesday. Outlook... Monday Night: Moderate Operational Impact. Chance of SHSN. Tuesday: High Operational Impact. Likely SN. Tuesday Night: High Operational Impact. Likely SN. Wednesday: Moderate Operational Impact. Chance of SHSN...SN. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: No Operational Impact. NO SIG WX. Thursday Night: No Operational Impact. NO SIG WX. Friday: No Operational Impact. NO SIG WX.
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&& .HYDROLOGY... Ongoing flooding due to ice jams will continue to be addressed with areal flood warnings. There could still be some lingering issues as any existing ice jams may tend to become frozen in place due to the very cold temperatures expected over the next few days. Warmer weather is not expected until the weekend. In terms of precipitation, a moderate snowfall is expected for much of the area from Tuesday into Wednesday, with heavy snowfall possible in the southern Green Mountains and Berkshires. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...Winter Storm Watch from Tuesday afternoon through Wednesday morning for MAZ001-025. VT...Winter Storm Watch from Tuesday afternoon through Wednesday morning for VTZ013-014. && $$ SYNOPSIS...JPV NEAR TERM...Frugis/JPV SHORT TERM...JPV LONG TERM...NAS AVIATION...Frugis HYDROLOGY...11/JPV

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