Area Forecast Discussion
Issued by NWS Albany, NY

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000 FXUS61 KALY 170600 AFDALY AREA FORECAST DISCUSSION National Weather Service Albany NY 100 AM EST Mon Feb 17 2020 .SYNOPSIS... A weak cold front will move across the region tonight with the best chance of snow showers north and west of the Capital District. High pressure will settle in from southeast Canada with fair and seasonably cold weather tomorrow. Clouds increase Monday night with the next storm system bringing snow and rain back into eastern New York and western New England. High pressure builds in for the mid to latter portion of the week with mainly cold and dry conditions. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... As of 1215 AM EST...Frontal boundary was progressing across the Dacks as local radar does show an increase in reflectivity the past couple of hours. NY Mesonet web cams, imagery available either once or twice an hour, has yet to show any visible snow across the Dacks. However, KSLK visibility has dropped to less than 3 miles in snow so we will keep PoPs in place for these areas. The other change was to the dewpoints as we are running a few degrees higher, especially across the Dacks with the cloud coverage. So did up those values a bit. Then the cloud coverage; skies were clear in the mid-Hudson Valley and NW CT and the southern Berks per the nighttime imagery with partial clearing across the Lake George and Glens Falls area. Stratus will linger across the Dacks, southern Greens and may expand a bit into the Schoharie Valley and Berks with upslope and low level convergence increasing with frontal approach. So did enhance the grids per trends and RAP/HRRR/NAM3km lower level RH fields. Lastly, winds have dropped to light and variable so did lower magnitudes here as well until sunrise. Prev Disc... A cold front will move south/southeast from the St Lawrence River Valley tonight. This frontal boundary will tap some lake moisture, and with the low-level convergence from the front and W/NW upslope it should focus some scattered snow showers across the western Adirondacks and expand southward into the Mohawk Valley/northern Catskills. Snow accumulations of a dusting to half inch are likely with perhaps a stray inch in a few spots. Further downstream, their will be little deep moisture for the front to lift and a few snow showers or flurries are possible predominately from I-90 northward including the Capital Region. Some light snow accumulations are possible along the southern Greens. Otherwise, cold advection will gradually spread southward across the region after midnight. The actual front may not clear the southern reaches of the forecast area until shortly before or just after daybreak Monday. Lows will be in the teens in the southern Adirondacks (a few single digits too), southern Greens, portions of the eastern Catskills, and western Mohawk Valley. Expect lower to mid 20s in most other locations. The winds will shift to the west to northwest at 5 to 15 mph. && .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/... Washingtons Birthday...Variable cloudiness will start the day with low-level cold advection continuing, but strong subsidence in the wake of the front, and with a 1030 hPa sfc anticyclone building in from southeast Ontario and southern Quebec, this should yield mostly sunny/sunny conditions by the late morning into the afternoon. Max temps will be near or slightly below normal for mid-Feb with highs in the 20s to lower 30s over the higher terrain, and 30s to spotty low 40s in the mid Hudson Valley and NW CT. Monday night...Initially clear/mostly clear skies and light to calm winds will start the evening. Temps should drop off quickly before midnight. However, low to mid level warm advection will begin in advance of a warm front approaching from the OH Valley, and its attendant sfc cyclone moving northeast into the central Great Lakes Region. Clouds will thicken and lower quickly with a south to southeast breeze increasing, as the sfc high quickly moves east of New Brunswick in the mid and upper level zonal flow. Some light over running snowfall may break out just after daybreak based on the 12Z EC/CMC/GFS...while the 12Z NAM is slower. The low-level dry air may inhibit the column to saturate quickly. Lows early on will be single digits north of the Mohawk Valley and Capital Region, and teens to lower 20s from these areas southward. Expect the temps to steady or slowly climb in the early to mid morning. Tuesday...The isentropic lift quickly increases on the 285K or 290K surfaces with a strong H850 LLJ impinging the region. The low-level jet between 12Z-18Z/TUE increases from the south at 40-55 kts based on the GFS. The 850 hPa +V-wind anomalies /southerlies/ increase to +2 to +4 STDEVs above normal. PWATS also increase to +1 to +2 STDEVs above normal based on the latest 12Z GEFS. A burst of snow is likely in the morning into the early pm, before transitioning to rain or very brief mix. The southern Adirondacks based on the south to southwest flow could get a quick moderate burst of snow where 4 to 6" is possible. The locations that will likely need a Winter WX Advisory are northern Herkimer, Hamilton, northern Warren, and northern Fulton, and possibly northern Saratoga (northwest corner). 2-4" are possible for the rest of the Lake George region and portions of southern VT (southern Greens). We will keep these areas highlighted in the HWO. We can not rule out some isolated 7" amounts in the southern Adirondacks and their are large QPF differences between the NAM/GFS in this areas vs. the ECMWF/CMC. Otherwise, 1-2" or 1-3" is possible in the Berkshires, eastern Catskills, Schoharie Valley, and northern Taconics, with an one inch or less in most of the Capital Region, mid Hudson Valley, southern Taconics, and NW CT. Snow to liquid ratios will likely be in the 8-12:1 range, and then lower considerably during the day. The low-level cold air does not look to remain locked in place so any brief mix of sleet or freezing rain, if it occurs, will be quick, as the primary wave passes well to north and west. A dry slot could creep in during the late pm. Any secondary cyclone development looks like it will be too far east over Cape Cod. Overall, another fast moving wave with another sloppy, gloppy snow to rain mix. Highs rise into the upper 30s to lower 40s in many of the valley areas, and lower to mid 30s over the higher terrain. South to southeast winds should increase to 10 to 20 mph with some gusts in the 25 to 40 mph range over the mountains and in the Capital Region. Tuesday night...The system pulls away to the northeast with an upper level disturbance focusing some lake effect and upslope snow showers for the western MohawK Valley, western Adirondacks, Catskills, and southern Adirondacks. Colder air moves back into the region with brisk west to northwest. Lows will be in the 20s to lower 30s with some teens in the Adirondacks Park. Additional light snow accumulations are possible west of the Hudson River Valley, and over the southern Greens and Berkshires. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Lingering upper energy and boundary layer moisture as well as low level flow off the Great Lakes will result in some lake effect snow shower activity into the southern Adirondacks, western Mohawk Valley, Schoharie Valley and eastern Catskills Wednesday and Thursday. More clouds than sun elsewhere. Highs Wednesday in the 30s to near 40 but 20s higher terrain. Deeper cold advection Thursday with the exit of the upper energy and the low level ridging building in. Highs Thursday in the mid 20s to around 30 but teens to around 20 higher terrain. Low level ridging builds east of our region Friday and Saturday with increasing warm advection but dry weather. Highs Friday around 30 to mid 30s but 20s higher terrain. Highs Saturday around 40 to mid 40s but 30s higher terrain. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... VFR conditions expected through the TAF period; 06z/Tuesday. A cold front will continue to move across the region overnight. There is very limited moisture associated with the boundary. High pressure will build in across the region through the day with the high centered over the region by early evening. Very light to calm winds will continue through overnight with a northwest flow developing Monday at 5 to 10 knots. Winds will diminish by late in the day/early evening. Outlook... Monday Night: Low Operational Impact. NO SIG WX. Tuesday: High Operational Impact. Windy. Definite RA...SN. Tuesday Night: Moderate Operational Impact. Breezy. Chance of SHRA. Wednesday to Friday: No Operational Impact. NO SIG WX. && .HYDROLOGY... No widespread hydro issues are expected over the next 7 days through next weekend. The next chance of widespread precipitation arrives Tuesday, with more snow and rain expected again. Total QPF looks to be in the quarter to two thirds of an inch range, with slighter higher amounts in parts of the southern Adirondacks. Much of this precipitation may be in the form of snow across the Adirondacks, and snow changing to rain elsewhere. Little impact on the rivers is expected. A trend to colder and drier weather will continue from the middle to latter part of the week. Some lake effect snow is possible on Wednesday into Thursday mainly west of the Hudson River Valley. 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...None. VT...None. && $$ SYNOPSIS...Wasula NEAR TERM...BGM/JLV/Wasula SHORT TERM...Wasula LONG TERM...JLV AVIATION...IAA HYDROLOGY...KL/Wasula

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