Area Forecast Discussion
Issued by NWS Albany, NY

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440 FXUS61 KALY 222338 AFDALY Area Forecast Discussion National Weather Service Albany NY 738 PM EDT Thu Mar 22 2018 .SYNOPSIS... Fair but chilly conditions are expected through the weekend. Isolated to scattered snow showers will be possible from time to time as disturbances in the upper levels of the atmosphere move over the region, with the best chances Friday afternoon, and again Saturday night into Sunday morning. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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As of 730 pm, no changes needed. Previous discussion follows. As of 415 PM EDT, mostly sunny skies prevail across the region with some thin high clouds departing across the Berkshires and Litchfield Hills. The strong late March sunshine and cold air aloft have allowed for deep mixing, propelling late day temperatures into the mid/upper 40s through much of the Hudson River Valley, even reaching 50 for the mid Hudson Valley, with 40-45 across the Mohawk Valley. Higher terrain areas are generally in the mid 30s to around 40. For tonight, weak mid/upper tropospheric ridging ahead of shortwave currently located near Lake Superior should allow for at least partially clear skies through midnight, before high clouds increase after midnight. This should allow for ideal radiational cooling with the dry air mass in place, so temps should drop off rather quickly after sunset, into the lower/mid 20s in many areas, with some teens possible where winds trend to calm, such as across the Adirondacks. There could be a few flurries developing across western areas toward daybreak.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... For Friday, the aforementioned PV anomaly near Lake Superior is expected to track southeast across the eastern Great Lakes, and into southern NY/central PA during Friday, with some slight strengthening. Models differ quite a bit regarding low/mid level moisture profiles, and resultant weather for Friday, with the NAM suggesting much greater low level moisture, and widespread clouds and scattered to numerous snow showers. Other global models suggest much less low level moisture availability, with only isolated snow showers/flurries mainly across higher terrain areas, along with perhaps some breaks in the clouds at times across valley areas. Have sided with the drier/more optimistic idea at this time, given current visible satellite imagery to the northeast of the PV anomaly, with only patchy high clouds noted. So the NAM may be overdoing the moisture availability based on current trends. Still have isolated to scattered snow showers (mixed with some rain/graupel in some valley areas) for the afternoon hours, but overall, not quite as widespread as the NAM would suggest. Have also sided with slightly milder max temps, reaching the lower 40s in most valley areas (which could still be too cool), and 30s across higher terrain areas. Friday night-Saturday, the aforementioned PV anomaly should depart late Friday evening, so still could be isolated/scattered snow showers in the evening, especially from the I-90 corridor south. Clearing expected later Friday night into Saturday morning, with some patchy clouds increasing Saturday afternoon, esp eastern areas. Lows Friday night in the 20s, with some teens possible across the Adirondacks. Highs Saturday should reach around or just over 40 in valley areas, with 30s across higher terrain. Saturday night-Sunday, an even stronger PV anomaly is forecast to swing southward across the region Saturday night into Sunday morning. With even stronger forcing, and perhaps a bit of mid level Atlantic moisture being pulled westward, there could be another round of at least scattered snow showers/flurries for late Saturday night into Sunday morning, with some minor accumulations possible, esp across higher terrain east of the Hudson River. Clearing for Sunday afternoon. Lows Sat nt mainly in the 20s, with late day highs Sunday reaching the lower 40s or slightly warmer in valley areas, with 30s across higher terrain. Could be quite gusty at times Sunday afternoon as well. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... Early next week, the eastern seaboard will be just downstream of a narrow ridge between a cutoff upper low drifting around in the north Atlantic and a broader approaching trough over the central CONUS. Good model agreement in subsidence with this flow pattern resulting in dry weather through at least Tuesday. Predictability breaks down Tuesday night onward as the latest GFS brings portions of the trough across the northeast US Tuesday night into Thursday, which would result in areas of precipitation, while the ECMWF keeps the flow more amplified with a slower, deeper trough. The ECMWF solution would keep the narrow ridge across the local area longer, resulting in dry weather through the period. The spread in the GEFS mean is high, but most members show at least some measurable precipitation Tuesday night into Thursday, so the forecast shows entry-level chance PoPs. As for temperatures, a warming trend is expected, with near to above normal temperatures anticipated. Expect the atmosphere to be warm enough to support rain as the dominant p-type. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/...
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Mid and high clouds will pass through the skies tonight associated with an oceanic low well offshore. VFR conditions should prevail into at least Friday morning. Moisture will increase modestly ahead of an approaching midlevel disturbance, with diurnal processes likely mixing into a stratus or stratocu deck of around 4kft during the late morning into the afternoon. Isolated to scattered snow showers may drift over the terminals from time to time, mainly after 18Z, so VCSH was added to the TAFs. Any heavier snow shower could briefly drop vsby to MVFR or IFR. Winds this evening from the northwest (northeast at KGFL) at around 10 kt will diminish to around 5 kt overnight. The winds will become northwesterly (north-northeasterly at KGFL) late Friday morning at around 10 kt with some gusts to around 20 kt possible in the afternoon. Outlook... Friday Night: Moderate Operational Impact. Scattered SHSN. Saturday: No Operational Impact. NO SIG WX. Saturday Night: Moderate Operational Impact. Scattered SHSN. Sunday: Low Operational Impact. Isolated 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... Fair but chilly conditions are expected through the weekend. Isolated to scattered snow showers will be possible from time to time as disturbances in the upper levels of the atmosphere move over the region, with the best chances Friday afternoon, and again Saturday night into Sunday morning. && .HYDROLOGY... No hydrologic issues are anticipated through at least early next week, as mainly fair weather is expected. Isolated to scattered snow showers are possible at times with little to no measurable precipitation expected. A slow diurnal snowmelt will occur 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...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...IAA/KL NEAR TERM...KL/Thompson SHORT TERM...KL LONG TERM...Thompson AVIATION...Thompson FIRE WEATHER...IAA/KL HYDROLOGY...IAA/KL is the U.S. government's official web portal to all federal, state and local government web resources and services.