Area Forecast Discussion
Issued by NWS Albany, NY

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894 FXUS61 KALY 171032 AFDALY Area Forecast Discussion National Weather Service Albany NY 532 AM EST Wed Jan 17 2018 .SYNOPSIS... A low pressure system positioned just off the Delmarva early this morning, will track northeast to near Cape Cod by this afternoon. This system continues to bring a moderate to heavy snowfall to much of the region. The system will move into the Canadian Maritimes this evening, with snow ending across our area during the afternoon. Seasonably cold and mainly dry weather is expected tonight through Thursday, with some lake effect snow showers across the western Adirondacks. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... As of 356 AM EST...Light to moderate snow continues to fall across much of the region early this morning. Pockets of heavy snow occurring in a few mesoscale bands across parts of Columbia, Dutchess, Berkshire and Litchfield counties. These bands line up well with cold cloud top enhancement on the GOES-16 clean infrared channel. Snowfall reports have been scant overnight, but estimates based on NYS Mesonet water equivalents are around 3 to 5 inches across much of the warning area, with 2 to 4 inches in the Advisory area from around the Mohawk Valley and Capital District south and east thus far. Much lighter snow is falling across the Adirondacks. Based on where the mesoscale bands have set up and current trends from the latest hi-res 3km NAM and HRRR, we plan on keeping the current headlines in place without any changes. Some minor modifications were made to snowfall totals based on obs and radar imagery showing where the mesoscale bands are. Maximum reflectivity values of around 25-30 dBZ indicate snowfall rates of around a half to one inch per hour, with weaker rates outside these bands. The heaviest bands are generally expected to remain within the warning area, although a few could migrate into northern portions of the mid Hudson Valley where some 6-7" totals are possible. The steadiest snow is expected to continue through the morning commute time, especially from the Capital District south and east. Snow will gradually taper off from west to east late this morning into early afternoon. However, hints of Hudson-Mohawk convergence noted in the model surface wind fields and forecast reflectivity from the 3km NAM/HRRR/WRF-ARW from around Albany north and east. So will linger mention of likely pops in these areas with an additional half inch to inch of snow this afternoon. Temperatures will be seasonable for mid January, ranging from lower 20s in the northwest part of the area to lower 30s in the southeast. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... A small ridge of high pressure will build in to much of the region tonight, although well-aligned westerly flow and conditional lake- induced instability will lead to some lake effect snow showers across the western Adirondacks. Snow showers will be light and scattered, due to forecast low inversion heights of only around 850 mb. Elsewhere, it will be partly cloudy with temperatures near normal with single digits to lower teens. Similar weather expected for Thursday, as a flat ridge of high pressure at the surface will be in place. The continued westerly flow will result in scattered light lake effect snow showers across the western Adirondacks, but dry elsewhere. High temperatures will be near normal in the 20s to lower 30s. Models in good agreement with a fast-moving and compact short wave trough moving through Thursday night. This will result in mainly isolated to scattered snow showers from around I-90 northward, with the greater coverage across the western/southern Adirondacks. A quick half inch to one inch of snow is expected in these areas. More flat ridging across the region on Friday with mainly dry conditions expected. Some light lake enhanced/upslope snow showers could linger into the western Adirondacks, but most areas will be dry. Tempertures will moderate slightly, with generally upper 20s to mid 30s expected for highs. Tranquil conditions in store for Friday night, with the flat ridge remaining in place. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
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Above normal temperatures expected with a low pressure system passing to our west and north across the Great Lakes region and eastern Canada early next week. Guidance is in general agreement with the longwave pattern featuring nearly zonal flow across the region over the weekend with ridging being induced along the east coast ahead of an approaching closed low Monday. However, there are amplitude and timing differences amongst the models. The ECMWF is deepen and slower with the system however the Weather Prediction Center indicates there was better clustering with the GFS, GEFS mean, EC mean and CMC so this timing was favored for the forecast. Based on this, the greatest chances for precipitation are Monday night. Have the chances for precipitation increasing Sunday night into Monday night. Precipitation types gets complicated as night time lows are expected to be mainly in the 30s Monday night. With uncertainty in both timing and temperature profile have gone with rain and snow forecast however there could be some freezing rain but that`s very difficult to determine that at this time. QPF amounts are very uncertain also. With ice jams in place across area will closely monitor expected temperatures and potential rainfall. With the passage of this system back to seasonable cold temperatures.
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&& .AVIATION /10Z WEDNESDAY THROUGH SUNDAY/... A double barrel low pressure system will continue impact the area. The primary low over upstate NY has begun to weaken as the secondary coastal low develops near DELMARVA. The coastal low will become the dominate low as it deepens and moves south of Long Island late this morning and quickly northeast of Cape Cod by the afternoon with the steady snow tapering to snow showers and flurries. The mesoscale band of snow is expected to impact KPOU and KPSF early this morning. There could be some lingering snow across the Capital District due to a brief period of Mohawk-Hudson Convergence into the afternoon. IFR and lower conditions through the overnight and morning hours with an improvement to MVFR expected by early afternoon and VFR by evening. Conditions expected to improve a bit quicker at KPOU. Light and variable to calm winds overnight and well into Wednesday morning with a northwest flow developing at 6 to 10 knots shifting to the west in the evening. Outlook... Wednesday to Thursday: No Operational Impact. NO SIG WX. Thursday Night: Slight Chance of SHSN. Friday to Sunday: No Operational Impact. NO SIG WX. && .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 continued cold temperatures over the next few days. Warmer weather is not expected until the weekend. In terms of precipitation, a moderate snowfall is ongoing for much of the area into today, with heavy snowfall from the mid Hudson Valley and Taconics eastward across western New England. Mainly dry weather is expected through the weekend except for some lake effect snow showers well north and west of the Capital District. 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...Winter Storm Warning until 3 PM EST this afternoon for CTZ001- 013. NY...Winter Weather Advisory until 3 PM EST this afternoon for NYZ032-033-038>043-047>053-058>060-063-082>084. Winter Storm Warning until 3 PM EST this afternoon for NYZ054- 061-064>066. MA...Winter Storm Warning until 3 PM EST this afternoon for MAZ001- 025. VT...Winter Storm Warning until 3 PM EST this afternoon for VTZ013>015. && $$ SYNOPSIS...JPV NEAR TERM...JPV SHORT TERM...JPV LONG TERM...IAA AVIATION...IAA HYDROLOGY...JPV

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