Area Forecast Discussion
Issued by NWS Albany, NY

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358 FXUS61 KALY 231107 AFDALY Area Forecast Discussion National Weather Service Albany NY 607 AM EST Thu Nov 23 2017 .SYNOPSIS... Mainly dry and continued chilly weather is expected today into tonight, with light snow showers possible over the Adirondacks. Temperatures will moderate on Friday, before an approaching cold front returns the chance for some showers on Saturday. It will turn colder again on Sunday with some lake effect snow showers. && .NEAR TERM /THROUGH TONIGHT/...
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As of 600 am, IR satellite imagery shows stratus finally having eroded...well, almost, as there are some lingering patches in portions of the Mohawk Valley, Capital District, and Berkshires. High pressure continues to nose into the region. Expect the gradual clearing trend to continue into the morning hours, although it will be tempered by high clouds approaching from the west ahead of loosely defined shortwave energy. Today, mainly dry and seasonably cool weather is expected. Sunshine will be interrupted by periods of mid and high cloudiness as the aforementioned shortwave energy passes, and perhaps lingering lower stratus. In the wake of the shortwave, the low/midlevel flow will align out of the west-southwest to support a period of lake effect snow showers over portions of the western Adirondacks this evening into tonight. Based on NAM forecast soundings at GTB/RME, inversion heights briefly get respectable around 3 km agl, but instability is marginal with surface to 850 mb delta Ts around 17C and falling through the night as warm advection takes place. As such, expect only minimal accumulation. May even see patchy light freezing drizzle late tonight as moisture profiles suggest that we lose cloud ice. Low temps tonight mainly in the 20s will be near to below normal roughly along and south of I-90, and perhaps a bit above normal north of there where a light to moderate southwesterly breeze may keep temps elevated.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... 850 mb warm air advection will continue Friday into Friday night ahead of a deep low pressure system crossing from northern Ontario into northern Quebec. Warm advection will be more muted at the surface, but a light to increasingly moderate southerly breeze with time along with the expectation of a good deal of sunshine should allow high temps to be several degrees warmer than Thanksgiving Day, back up toward normal values mainly in the 40s. Low temps Friday night are tricky. Skies are expected to be mostly clear overnight, so the driving factor for low temps will be the winds. Pressure gradient supports the continuation of a southerly breeze in many spots, especially over higher terrain and in north/south valleys, leading to mild temps. However, sheltered spots could decouple, allowing temps to drop toward the dewpoint in the 20s. 2m model temps are much warmer than MOS. Sided with the warmer 2m temps for northern portions of the forecast area, and cooler MOS for southern portions where winds are likely to be lighter. Forecast reflects relatively uniform lows in the upper 20s and lower 30s, but in actuality there will likely be sharp local gradients in the low temps. Saturday, the aforementioned low will drag its cold front across the forecast area. Model depictions of this system have weakened over the last several days. It appears the front will be somewhat washed out and out of phase with the best midlevel forcing/sharpest shortwave trough. Model QPF fields reflect this with a weakening band of showers Saturday morning along the front. As a result, have mainly chance PoPs for the forecast area. P-type should be mainly liquid during the daylight hours, with some snow mixing in over the Adirondacks. High temps near to a bit above normal ahead of the front. Gradual cold air advection will support a lake response Saturday night as the midlevel trough swings into the area. H850 temps forecast to fall to near -8C over the lake by 12Z Sunday. Light accumulations in the forecast over the Mohawk Valley/Adirondacks since the cold air advection looks to be gradual. Lows settling back into the mid-20s to mid-30s. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... The extended forecast will feature a moderating trend of temperatures into the middle of next week. The forecast area will be under the influence of cyclonic flow in the low to mid levels of the atmosphere to close the weekend, and as we enter Monday. One short-wave trough will move downstream of the region on Sunday with some lake effect and upslope snow showers persisting from the Capital Region north and west. Light snow accums are possible especially for the western Adirondacks, west- central Mohawk Valley, and the northern and eastern Catskills of a few tenths to an inch or so. It will be brisk and cold with highs in the mid 20s to lower 30s over the higher terrain, and lower to upper 30s in the valleys. High pressure will be attempting to ridge in from the Ohio Valley Sunday night, but another mid-level short- wave trough will dive across southern Quebec, northern NY from I-90 northward into New England with scattered snow showers and flurries based on the latest 00Z GFS/ECMWF/CMC/GEFS mean. The short-wave will be moisture starved with the best chance of some light accums once again being the western Adirondacks and western Mohawk Valley. Lows will be in the 20s with some teens over the Adirondack Park and southern Greens. A lowering subsidence inversion will end the snow showers across the western extreme of the forecast area on Monday. Heights begin to rise aloft, as the sfc anticyclone builds in from near the mid-Atlantic Coast. Temps rise back into the upper 30s to lower 40s in the valley areas with a few mid 40s in NW CT and the mid-Hudson Valley, and upper 20s to upper 30s over the mountains. Monday night through Tuesday night...High pressure drifts offshore with a warm front drifting north of the region Mon night. There is not much moisture for this boundary to work with, as clouds will increase and H850 temps rise about 1 to 2 STD DEVS above normal based on the latest GEFS. After a chilly start to the day with lows in the 20s, then expect high temps to be 10 to 15 degrees above normal with upper 40s to lower 50s in the valleys, and 40s over the higher terrain in the warm advection pattern on Tue. A cold front will be approaching from the west Tue night. The latest GFS is faster than the ECMWF with the front. We have gone with the slower timing based on the superblend of the guidance and WPC. Increasing clouds Tue night with maybe a shower over the western Adirondacks late. Lows temps will be in the mid and upper 30s with a few lower 30s in the sheltered valleys. Wednesday...the cold front moves through with limited low-level moisture associated with it. A low chance of showers was kept in the forecast north and west of the Capital District with a slight chance from the Tri Cities south and east. Highs will continue to be above normal by 10-15 degrees for late NOV before the cold advection kicks in later in the day in the wake of the frontal passage. Temps look to be above normal for the long term with pcpn likely below normal. && .AVIATION /11Z THURSDAY THROUGH MONDAY/...
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High pressure will continue to ridge in from the Midwest and Ohio Valley this morning. The surface high will drift eastward over the Mid Atlantic Region during the afternoon, as some clouds will increase ahead of the next upper level disturbance for tonight. Some moisture remains trapped below an inversion over parts of eastern NY and western New New England with stratus/stratocumulus lingering over KALB/KPSF, whereas the skies have cleared out over KGFL and KPOU. High MVFR clouds continue at KPSF in the 2.5-3.0 kft AGL range. The subsidence in the wake of the coastal low, and with the sfc high ridging in will allow the skies to clear at KALB/KPSF between 09Z-12Z. VFR conditions will continue during the late morning through the afternoon with some mid and high clouds increasing ahead of the next short-wave trough. Clouds bases will generally be broken in the 10-15 kft AGL range by 20Z-22Z. The clouds will continue to thicken and lower into the overnight period. The winds will be north to northwest at less than 8 kts at KGFL/KPOU early this morning, and 8-14 kts at KALB/KPSF with a few gusts around 20-22 kts at these two sites. The winds will be from the southwest to west at 10 kts or less during the late morning through the afternoon before becoming light and variable in direction shortly before 00Z/FRI. Outlook... Friday Night: No Operational Impact. NO SIG WX. Saturday: Moderate Operational Impact. Chance of SHRA. Saturday Night: Low Operational Impact. Slight Chance of SHRA...SHSN. Sunday: Low Operational Impact. Breezy Slight Chance of SHRA...SHSN. Sunday Night: No Operational Impact. NO SIG WX. Monday: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: No Operational Impact. NO SIG WX.
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&& .FIRE WEATHER... Mainly dry and chilly weather is expected today. RH values will fall to 40 to 70 percent, with the highest values in northern and high terrain areas. West-northwest winds at 5 to 10 mph today. Friday will be a bit milder with a southerly breeze at 5 to 15 mph and RH values bottoming out in the 45 to 65 percent range. Scattered light showers are possible on Saturday, with seasonable temperatures. && .HYDROLOGY... No hydrologic issues are anticipated through early next week. Aside from a few passing light lake effect snow showers or flurries over the Adirondacks this evening into tonight, mainly dry weather is expected through Friday night. A passing cold front may bring some light rain showers to the area on Saturday, possibly mixed with snow over the Adirondacks. There may be some additional lake-effect snow showers again for western areas on Sunday, otherwise, mainly dry weather is expected to end the weekend into early next week. This light precipitation will have little to no impact on rivers and streams. As a result, river and stream levels will generally hold steady. Temperatures will be below normal today, returning to seasonable values Friday and Saturday. 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...Frugis/Thompson NEAR TERM...Thompson SHORT TERM...Thompson LONG TERM...Wasula AVIATION...Wasula FIRE WEATHER...Thompson HYDROLOGY...Frugis/Thompson

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