Area Forecast Discussion
Issued by NWS Albany, NY

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000 FXUS61 KALY 220016 AFDALY Area Forecast Discussion National Weather Service Albany NY 816 PM EDT Wed Mar 21 2018 .SYNOPSIS... A coastal storm will bring some snow to southeastern parts of the region tonight. Generally fair but chilly conditions will return for Thursday into Friday, although a passing upper level disturbance could bring some snow showers for Friday. && .NEAR TERM /THROUGH THURSDAY NIGHT/... Winter Storm Warning for Litchfield County until 8 AM Thursday... Winter Weather Advisory for Ulster, Dutchess, eastern Columbia, and southern Berkshire Cos until 8 AM Thursday... As of 745 PM EDT...A challenging forecast for the southeast portion of the forecast area continues, as low-level dry air funneling southward from high pressure over Hudson Bay and western Quebec continues to erode the pcpn on the leading edge of the snow shield associated with low pressure near the Delmarva Region. We backed off the northward extent of the PoPs/QPF based on the radar, observations, and 3-km HRRR and NAMnest. We believe it will take a few more hours for the column to saturate near KPOU with sfc dewpts in the mid and upper teens. We have kept the headlines in tact for now, but may need to drop the advisories north of Dutchess and Litchfield Counties with the next update. Accumulations may only be an inch or so further north and west if the HIRES guidance/radar trends are on track. Previous near term... We expect saturation of the lower levels of the atmosphere, combined with increased forcing, to allow snow to finally reach the surface over the next 1-3 hours, initially across southern Litchfield Co and close to the I-84 corridor in NY, then expanding northward toward sunset farther north and west. However, overall QPF amounts from this point on are questionable whether warning level snowfall will be met. It appears that chances of warning level snows (7 inch/12 hours) are less for Dutchess Co, so therefore scaled back previous warning to an advisory, with forecast amounts generally 3-6 inches across the County, greatest closest to the I-84 corridor and across higher terrain across eastern portions of the County. For Litchfield Co, reaching warning level snow (6 inches/12 hours) may be a bit easier to reach, albeit still remains questionable. Current forecast has 4-8 inches for Litchfield Co (lowered from earlier amts), with greatest amounts expected across southeast portions of the County. Litchfield County will be more susceptible to any pivoting snowbands which may develop across southern New England/LI and develop northwest/westward tonight as well. Farther north and west, a general 1-4 inch snowfall is expected through Ulster Co, as well as eastern Columbia and southern Berkshire Cos, where perhaps up to an inch extending as far north and west as portions of the central Taconics including portions of Rensselaer Co. Within the immediate Capital Region, still can not rule out a coating to less than one inch of snow, especially south/east portions, with best chances for snow in this area actually after midnight through daybreak Thursday. Lows tonight mainly in the upper teens to mid 20s northern areas, and mid/upper 20s central and southern areas. North to northeast winds will remain brisk, esp across southern areas where some gusts up to 25 mph could occur. For Thursday, some lingering snow showers may be ongoing through the morning across the Taconics, Berkshires, Litchfield Hills, and even the Capital Region, before decreasing in the afternoon. Some breaks in the clouds are expected to develop in the afternoon. It will remain quite breezy, with northwest winds gusting up to 25-30 mph at times. Highs should reach the upper 30s to lower 40s in valleys, with mainly lower/mid 30s across higher terrain. Weak shortwave ridging should build across Thursday night, allowing for some clearing to occur. Temps may fall off more than currently forecast due to decoupling, with current forecast lows in the teens to mid/upper 20s, although again, may be quite a bit lower in some areas. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... An upper tropospheric shortwave trough will remain over the Northeast Friday through Sunday morning with multiple pieces of shortwave energy slipping southward over the region. Limited moisture and lift will inhibit precipitation beyond snow flurries or a few passing showers over the weekend. The Adirondacks and higher terrain in southern Vermont could see up to a few tenths of an inch of snow accumulation over the weekend. High temperatures on Friday and Saturday will be in the low 30s to low 40s with low temperatures in the upper teens to mid 20s. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... The mean longwave trough over the Northeast will begin to weaken by the end of the weekend, as a high amplitude ridge builds into the Northeast from the west/southwest with temperatures moderating closer to late March seasonal normal readings. Sunday...A large sfc Canadian anticyclone /1040 hPa/ attempts to ridge in from north-central Quebec, as an upper level trough moves across the region with some isolated rain and snow showers especially over the higher terrain south and east of the Capital Region. The cold pool with the upper low will focus some instability showers tied to the diurnal heating based on the latest 12Z GFS/ECMWF/GEFS/CMC. H850 temps will be in the -8C to -10C range. Highs will run below normal by 10 degrees or so with upper 30s to lower 40s in the valley areas, and upper 20s to mid 30s over the higher terrain. Sunday night into Monday Night...A high amplitude ridge builds in from the Southeast through the Great lakes Region and into eastern Canada. The H500 ridge folds over into the Northeast and the Canadian Maritimes early in the week with a big cutoff cyclone off the New England Coast. H500 heights increase to 570 decameters over southeast Ontario and southern Quebec. Fair and cold or cool weather will persist with lows in the teens and 20s, and highs on Monday getting into mid 30s to mid 40s. Tuesday will be the transition day where temperatures get closer to normal readings with the sfc anticyclone anchored over northern New England and the East Coast. A cold front will be approaching from the northern Plains and western Great Lakes Region. Highs reach the upper 40s to around 50F in the valleys with abundant sunshine, and upper 30s to mid 40s in the mtns. Tuesday night into Wednesday...Some differences with the medium range guidance and the ensembles on the timing of the break down of the ridge over the Northeast. A cold front, and a sfc low will be approaching from the Midwest and Great Lakes Region. We slowly increased a slight chance to chance of rain/snow showers late Tue night into Wednesday with seasonable temps for the forecast area. && .AVIATION /00Z THURSDAY THROUGH MONDAY/...
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Coastal storm continues to spin offshore, sending snow bands north and west across southern New England and southern New York. Moisture associated with the storm is battling a stout feed of dry air from the north, and currently the dry air is winning out. Snow potential at KALB/KGFL is little to none with VFR conditions prevailing under a midlevel stratus deck. Snow potential remains uncertain at KPOU/KPSF. Current thinking is that the column will eventually saturate enough to support snowfall at KPOU, but the timing was pushed back a few hours. Once snowfall begins, visibility will likely deteriorate quickly to IFR within an hour or two. The timing of the onset of snowfall remains uncertain, making this a highly challenging forecast. Even less confidence for snow potential at KPSF, but enough evidence to maintain a mention of MVFR snow showers with a TEMPO for IFR. Conditions improve at KPSF/KPOU late tonight as the coastal storm pulls away, with drier air raising ceilings to VFR late tonight or early Thursday morning. Winds will remain mainly northerly tonight at around 10 kt. Winds will become north-northwesterly at around 10 to 15 kt late Thursday morning into the afternoon, with some gusts of 20 to 25 kt possible. Outlook... Thursday Night: No Operational Impact. NO SIG WX. Friday: Low Operational Impact. Slight Chance of SHRA...SHSN. Friday Night: No Operational Impact. NO SIG WX. Saturday: Slight Chance of SHRA. Saturday Night: Low Operational Impact. Slight Chance of SHSN. Sunday: No Operational Impact. NO SIG WX. Sunday Night: No Operational Impact. NO SIG WX. Monday: No Operational Impact. NO SIG WX.
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&& .FIRE WEATHER... The Fire Weather season has officially begun across eastern New York and western New England. Despite this, snow cover is in place across much of the region, which will mitigate any potential fire weather hazards for the time being. Additional snowfall is expected today into tonight for southeastern parts of the area which will continue to prevent issues in the near future as well. A coastal storm will brush far southeastern parts of the region with some snow for tonight. Generally fair but chilly conditions will return for Thursday into Friday, although a passing upper level disturbance could bring some snow showers for Friday. && .HYDROLOGY... No hydrologic issues are anticipated through the week. Although northern areas will stay dry today into tonight, areas south and east of the Capital Region will see some snow for tonight, with the heaviest amounts across Dutchess and Litchfield counties. Total liquid equivalent in these areas will be up to one half of an inch, although areas outside Dutchess and Litchfield Counties will generally see less than a quarter of an inch. This snowfall won`t have any immediate impact on area rivers and streams. Behind this storm system, mainly dry weather is then expected for the remainder of the week and into the weekend. There could be a few passing snow showers or flurries for Friday through Sunday, but this will produce little to no measurable precipitation. A slow diurnal snowmelt is expected over the next several days, with temperatures above freezing during the day, and below freezing at night. There will be little impact on the waterways with minimal, if any, rises. 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 8 AM EDT Thursday for CTZ001-013. NY...Winter Weather Advisory until 8 AM EDT Thursday for NYZ061- 063>066. MA...Winter Weather Advisory until 8 AM EDT Thursday for MAZ025. VT...None. && $$ SYNOPSIS...Frugis/KL/Wasula NEAR TERM...KL/Wasula SHORT TERM...Cebulko LONG TERM...Wasula AVIATION...Thompson FIRE WEATHER...Frugis/KL HYDROLOGY...Frugis/KL is the U.S. government's official web portal to all federal, state and local government web resources and services.