Area Forecast Discussion
Issued by NWS Albany, NY

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000 FXUS61 KALY 290606 AFDALY AREA FORECAST DISCUSSION National Weather Service Albany NY 206 AM EDT Thu Oct 29 2020 .SYNOPSIS... Dense fog tonight has reduced visibility in some river valleys but should improve towards morning. Widespread rainfall overspreads our region tomorrow before northerly flow funnels cold air southward. This will allow rain to mix with and change to snow Thursday night into Friday morning with the highest accumulations expected in the higher terrain areas. && .NEAR TERM /THROUGH TONIGHT/... Dense Fog Advisory in effect until 8am this morning for the Greater Capital District.... Consecutive hours of dense fog prompted us to issue a dense fog advisory which is in effect until 8am. Motorists are urged to use caution if traveling overnight as dense fog has reduced visibility to or below 1/4 SM. Otherwise, we adjusted temperatures a bit to match current readings from ASOS and NYS mesonet stations. Cirrus deck seen on the GOES16 IR continues to progress northward which should eventually spread into the Capital District towards 09 UTC where we have our dense fog. This should help warm temperatures a degree or two and thus increased the dewpoint depression which should help improve visibilities. This is why we only have advisory in effect until 8am. Previous discussion below...Conditions will deteriorate throughout the day on Thursday from south to north as the remnants of Hurricane Zeta phase with the upper level trough as it tracks across southern New England. This phasing of synoptic scale features will advect a plethora of gulf moisture into the Mid-Atlantic and southern New England. Models have continued to flip-flop in response to northern extent of the rich Gulf of Mexico moisture as the models struggle to resolve the phasing of these features. The 12Z guidance is in good agreement, especially if you omit the GFS, with bringing the moisture as far north as northern Herkimer county. Rainfall will overspread the region from south to north in response to this tropical system with periods of light to moderate rain expected throughout the day. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... The forecast becomes quite challenging as we head into Thursday night as cold air begins to bleed down the Hudson Valley and across the higher terrain of the Adirondack and Catskill Mountains. A transition from rain to a rain/snow mix and ultimately to snow is expected during the late afternoon/evening hours across the southern Adirondacks with a full transition to snow across much of the region by midnight. A strong area of 850mb to 700mb frontogenesis looks like it`ll set up over the southern Green Mountains in Vermont which will help maximize snowfall rates across southern Vermont Thursday night and Friday morning. As it stands now, it looks like 1-2 inches will be possible across the lower elevations of southern Vermont and southern Adirondacks. Higher accumulations of 3-6 inches will be possible above 3000 ft along the spine of the southern Green Mountains. The further south you get, the longer it`ll take for the cold air to bleed down the Hudson Valley. It`ll be a race against the clock as the cold air tries to filter into the region while the moisture quickly exits to the east. This should limit snow accumulations south of Albany to an inch or less. It wouldn`t be surprising to see impacts to the commute Friday morning given this will be the first widespread snow event of the season. Snow will transition back to rain and taper off through the morning hours on Friday. Much cold and drier arctic air will filter across the region throughout the day on Friday which will help to finally scour out the lingering cloud cover. Given the degree of cold air advection expected throughout the day on Friday, our highs are only expected to climb into the upper 30s to low 40s. The coldest temperatures of the season will be upon us Friday night and Saturday morning as lows are expected to drop into the mid teens to lower 20s. Temperatures should rebound nicely on Saturday but will likely remain below seasonal normals with highs in the lower to mid 40s. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Another cold and quiet night is on tap Saturday night but temperatures will be a bit more mild as the cold dome aloft begins to shift off to the east. High pressure will crest over the region Saturday evening before exiting to the east and allowing the surface flow to switch back to the southwest. This will help usher in a warmer air mass into the region on Sunday with highs expected to climb back into the low to mid 50s. However, the dry period of weather will come to an end with another strong cold front slated to move through the region during the afternoon hours on Sunday. Another round of rain will transition to snow Sunday night with minor snow accumulations once again possible across the entire region. Snow showers will likely continue in the wake of the cold front on Monday as the cold northwesterly flow aloft interacts with the warmer water of the Great Lakes. It won`t be until Tuesday that we can finally scour out the residual moisture and the upper level flow begins to shift to the west/southwest. In the mean time, another couple of well below normal days of high and low temperatures can be expected across the region Monday and Tuesday with lows in the 20s and highs in the 40s. Temperatures will begin to moderate back to seasonal normals on Wednesday once the upper level flow begins to switch to the southwest and we get back into a warm air advection regime. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... IFR/LIFR conditions with dense fog at KGFL-KALB and per satellite trends, could make its way into KPSF. So for the balance of the overnight period, we will keep these flight restrictions for KALB- KGFL. For KPSF and KPOU, we will watch trends closely but forecast MVFR conditions. After daybreak, rain will begin to push north, and ceilings will likely remain within MVFR between 14Z-18Z and predominant ceilings and visibilities will be reduced to MVFR in light rain, trending toward IFR, after 18Z at all TAF sites. Light winds at less than 6 Kt tonight, at times calm, will become north to northeast at 6 Kt or less Thursday morning and continue Thursday afternoon. As northeast winds increase toward sunset, especially aloft, we will introduce LLWS with magnitudes around 30kts. Outlook... Thursday Night: High Operational Impact. Definite RA...SN. Friday: Moderate Operational Impact. Chance of RA...SN. Friday Night: No Operational Impact. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: Moderate Operational Impact. Breezy. Chance of SHRA. Sunday Night: Moderate Operational Impact. Breezy. Chance of SHRA...SHSN. Monday: Moderate Operational Impact. Breezy. Chance of SHRA...SHSN. && .FIRE WEATHER... Drier conditions will develop over the next several hours but a wet day is expected across the Mid-Atlantic on Thursday as the remnants of Hurricane Zeta track across southern New England. Widespread rainfall is expected to overspread the region from south to north during the morning hours. Widespread wetting rainfall and light winds are expected to keep any fire weather concerns to a minimum. && .HYDROLOGY... A prolonged precipitation event is still expected Thursday into Friday morning. While this system will contain remnant tropical moisture guidance has trended faster and further south with its impacts across eastern NY and western New England. Overall, a total of 0.50 to 1.25 inches of precipitation is expected with a tight south to north gradient. The highest amounts are expected over the mid-Hudson Valley, eastern Catskills and NW CT with the least amount over the southern Adirondacks and Upper Hudson Valley. Higher elevations will likely see a changeover to snow Thursday night. While rivers and area streams should rise as a result of the widespread precipitation, especially over southern areas, guidance from MMEFS still suggests river flooding is unlikely. 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...Dense Fog Advisory until 8 AM EDT this morning for NYZ041- 048>050-052-053-083-084. MA...None. VT...None. && $$ SYNOPSIS...Speciale NEAR TERM...Speciale SHORT TERM...Speciale LONG TERM...BGM AVIATION...BGM FIRE WEATHER...Speciale HYDROLOGY...Speciale is the U.S. government's official web portal to all federal, state and local government web resources and services.