957 FXUS61 KALY 061350 AFDALY AREA FORECAST DISCUSSION National Weather Service Albany NY 950 AM EDT Mon Sep 6 2021 .SYNOPSIS... There will be a chance for a few showers and an isolated thunderstorm today with a weak cold front, especially across the southern Adirondacks. Pleasant weather is expected Tuesday, but there will once again be a chance for showers and thunderstorms Wednesday with a few lingering showers possible for the end of the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Dense Fog Advisory has expired for portions of the Hudson River Valley... As of 945 AM EDT, earlier dense fog within portions of the Hudson River Valley has lifted into a patchy low stratus cloud deck, as moisture remains trapped beneath low level inversion around 980 mb. We expect these low clouds to gradually mix out over the next 1-2 hours. Otherwise, regional radars indicate bands of showers and embedded thunderstorms upstream across western NYS extending into the Tug Hill region. These showers/storms are associated with a potent shortwave trough currently traversing western Lake Ontario/Erie. As this trough continues pivoting east/northeast, strong dynamics and at least some low/mid level instability, supported by dewpoints in the 60s over Lake Ontario and across portions of eastern NY, should allow for these bands of showers/thunderstorms to continue spreading/developing eastward across the southern Adirondacks over the next 1-2 hours, and perhaps as far south/east as the Mohawk Valley, Lake George/Saratoga region, and southern VT around midday through early afternoon, with some possibly reaching northern and eastern portions of the Capital Region. The aforementioned strong dynamics, with H500 winds of 50-60 KT, along with dry mid level air, may support some strong wind gusts and small hail within the taller convective elements. Isolated damaging wind gusts can not be ruled out, especially if thunderstorms form into bowing line segments. This potential appears greatest across the southern Adirondacks including the Lake George region, where SPC maintains a Marginal Risk area for severe thunderstorms. Trends will need to be watched in case this possibility extends slightly farther south into the Mohawk Valley, Capital Region, southern VT and Berkshires. Outside of the showers and storms, there should be intervals of sun and winds will become west and breezy in the afternoon, especially in the wake of the shortwave passage later this afternoon, when some gusts of 25-30 mph could occur, especially within the Mohawk Valley/Capital Region and Berkshires. So, with some sun and some mixing with the winds, highs today in the mid 70s to near 80 but cooler in higher terrain, with some portions of the southern Adirondacks only reaching 65-70. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... Clearing tonight and partly to mostly sunny Tuesday and dry. Highs Tuesday in the mid 70s to near 80 and upper 60s to lower 70s higher terrain. Clear much of Tuesday night, then some mid and high clouds possible by daybreak as warm advection strengthens. Upper energy in Canada will track north of the Great Lakes and lifts northeast into eastern Canada Wednesday night and beyond. The associated mean upper trough is slow to build east but the associated low level cold front should track through our region Wednesday afternoon and night. There is an increasing consensus from sources of guidance/ensembles that the timing of the front looks to be later Wednesday afternoon and through Wednesday night. Boundary layer flow becomes southwest and increases through the day Wednesday and there is a fairly distinct wind shift to the west over our region Wednesday evening and night. This suggests that there should be enough sun and enough winds mixing to the ground to warm many areas into the upper 70s to lower 80s with a little cooler in higher terrain. Instability is expected to be considerable with CAPEs potentially above 1000 j/kg with considerable shear. Some storms should be strong with small hail and gusty winds possible along with locally heavy rain and ponding of water on roadways. Will have to watch the trends, though, to determine what areas may have chances for severe thunderstorms and/or training of thunderstorms with potential standing water in low lying areas. Showers and storms will be slow to build east and some of the stronger storms will continue in our area during the evening, especially the Hudson Valley into western New England. By daybreak Thursday, there could still be some lingering showers, especially in western New England but just scattered to isolated elsewhere. && .LONG TERM /THURSDAY THROUGH SUNDAY/... In the wake of a surface cold front, an upper level trough will be moving from the Great Lakes towards the Northeast for Thursday into Friday. With the cyclonic flow and lower heights in place, a few showers are possible, especially in areas downwind of the eastern Great Lakes, as the cool temps aloft moving across the warmer lake waters will allow for some lake effect rain showers. Have gone with slight to low CHC POPs for Thursday through Friday, with the highest POPs in the western Adirondacks, as well as upslope favored areas of western New England. Despite the lower heights, good mixing should still yield high temps in valley areas around the lower to middle 70s, which is still seasonable for early-mid September. Overnight lows should be in the 50s, although some upper 40s are possible across the higher terrain. Over the weekend, the flow aloft will flatten out and become fairly zonal. Although dry weather is expected for Saturday, a weak disturbance passing within the westerly flow aloft could allow for a few showers on Sunday, mainly for northern areas. Temps will continue to be in the 70s for highs, with upper 40s to upper 50s at night. && .AVIATION /14Z MONDAY THROUGH FRIDAY/... As clouds cleared out overnight, the moist low levels and light winds contributed to the development of fog at the valley TAF sites. KPSF hasn't seen fog, but the low level moisture has contributed to low clouds there. At all sites, IFR/LIFR fog is ongoing, but it should start to dissipate with sunrise underway. Will include TEMPOs through about 13z-14z for all sites, as fog and low clouds should be dissipating by then. Once the fog is gone, VFR conditions will return and skies will become just sct around 4-6 kft. These clouds may gradually become bkn by the late morning for KGFL and possibly KALB/KPSF. A brief shower or maybe even a t-storm is possible for the late morning through mid- afternoon, mainly at KGFL, so will include a VCSH for that possibility. Otherwise, flying conditions will be VFR with southwest winds eventually become westerly by the mid to late afternoon hours. KALB/KPSF will see winds as strong as 10 to 15 kts with a few higher gusts as well, with lighter winds at KGFL/KPOU. Skies will be clearing out for this evening into tonight. Dewpoints will be falling, so the threat for widespread fog looks likely less likely for tonight as compared to this morning, but can't rule out some brief patches near KGFL/KPSF for late in the overnight. Westerly winds around 5 to 8 kts on this evening will eventually become light to calm for all sites by later in the overnight. Outlook... Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: Moderate Operational Impact. Chance of SHRA...TSRA. Wednesday Night: High Operational Impact. Likely SHRA...TSRA. Thursday: Low Operational Impact. Slight Chance of SHRA. Thursday Night: No Operational Impact. NO SIG WX. Friday: Low Operational Impact. NO SIG WX. Friday Night: No Operational Impact. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. && .FIRE WEATHER... There will be a chance for a few showers and an isolated thunderstorm today with a weak cold front, especially across the southern Adirondacks. Pleasant weather is expected Tuesday, but there will once again be a chance for showers and thunderstorms Wednesday with a few lingering showers possible for the end of the week. RH values will exceed 50 percent through Tuesday with 80 to 100 percent at night. Near calm winds this morning will become west by midday at near 15 mph with some gusts around 20 mph this afternoon. Winds diminish to less than 15 mph tonight. Winds should be west at less than 15 mph Tuesday. && .HYDROLOGY... Scattered showers and thunderstorms are expected today, mainly along and north of the Mohawk Valley to southern VT. Basin average amounts look fairly light, with rainfall amounts generally between 0.1-0.25" or less, except across the southern Adirondacks where up to a half inch is possible. As a result, this rainfall won't be enough for a significant response and area rivers and streams will continue to slowly fall. After a dry day on Tuesday, more showers and thunderstorms are possible for Wednesday. Thunderstorms could produce locally heavy rain Wednesday afternoon and night, resulting in ponding of water on roadways and standing water in low lying areas. 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...KL/NAS NEAR TERM...NAS SHORT TERM...NAS LONG TERM...Frugis AVIATION...Frugis FIRE WEATHER...NAS HYDROLOGY...NAS