332 FXUS61 KALY 080442 AFDALY AREA FORECAST DISCUSSION National Weather Service Albany NY 1242 AM EDT Fri Oct 8 2021 .SYNOPSIS... Fair weather is expected into the weekend as high pressure dominates. However, fog will develop again tonight and linger into Friday morning with some locally dense fog in the river valleys. Temperatures Friday will once again be above normal with cooler seasonable readings Saturday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... .UPDATE...Satellite imagery reveals some mid level clouds moving over top of the patchy valley fog across the northern half of the area. This could result in fluctuations in visibility, where fog will be more persistent during times of clearing and less pronounced where cloud patches drift overhead. Outside of the clouds, clear skies are giving way to fog development in valleys and sheltered locations near bodies of water. Fog will be dense at times, although does not appear to be as widespread as last night so far. .PREVIOUS[1023]...Mainly clear skies aside from a few areas of stratus over the North Country and southern Greens. Updated sky grids here. The stage is set for fog to develop once again. Seems that the only thing that could short-circuit fog is if the stratus expands over the area more than anticipated. Ridging remains over the region at the surface and aloft. Will have ideal radiational cooling conditions tonight so fog and stratus will develop again. Fog is expected to become locally dense in the river valleys. && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/... Surface high will weaken some and retreat Friday while the upper ridge axis crests over the region. Fog and stratus will linger into the morning hours, likely similar to Thursday. However, Friday will feature more clouds during the day as a weak positively tilted short wave trough moves into the Great Lakes Region. It will be another mild day with highs in the mid 60s to lower 70s. A strong high will build southward from Quebec into northern New England Friday night with the ridging extending southwest across our region over the weekend. Aloft, the upper ridge axis will weaken and shift eastward as the short wave trough dampens out as it passes to our northwest. A weakening cold front will press westward across the area Friday night into Saturday. The boundary will have limited moist so dry conditions should prevail, however there is a slight chance for showers/drizzle across the Berkshires and in the southeastern Catskills. The boundary will usher in a cooler airmass and this along with an onshore easterly flow and more clouds will result in a cooler day Saturday than recent days. Expecting highs in the 60s below 1500 feet and in the 50s across the higher terrain. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Long term period will feature a chance for some showers with near normal temperatures to end the weekend, with temperatures rising to several degrees above normal for at least the first half of next week. Cannot rule out some showers late Tuesday into Wednesday, but most of next week looks fairly dry. See below for more details... We begin the long term Sunday with upper-level ridging to our east and a shortwave moving to our north across southern Canada. This shortwave may produce a few showers across the southern Adirondacks, but forcing generally appears weak so not expecting too heavy or widespread. However, we will also be watching a surface low that is expected to develop off the East Coast Sunday and track northeastward towards our region. At this time, there is some disagreement in the guidance as to how far north and west this system will track. The GFS keeps all precipitation well offshore, but the Euro has been showing showers for at least our southern areas for the past several runs. Therefore, due to the uncertainty, will maintain chance PoPs mainly south of I-90 with slight chance PoPs elsewhere. Regardless of the track of the surface low, cyclonic flow around this system in conjunction with anticyclonic flow around a surface high located in the Gulf of Maine will result in low-level easterly winds for much of our region. Therefore, expecting skies to remain mostly cloudy, so highs should only be in the 50s for high elevations to mid 60s in the valleys. Sunday night, the surface low should continue to track northeastwards. Heights begin to rise aloft, so any showers during the day should begin to diminish Sunday night. However, low-level easterly flow looks to continue, we will likely have abundant cloud cover once again with moisture trapped below an inversion aloft. Therefore, only expecting lows to drop into the upper 40s (high terrain) to mid 50s (valleys). Monday through Tuesday...behind the departing shortwave, heights look to rise aloft with a ridge axis expected to be located over the area by MOnday evening. With surface high pressure still located to the northeast, low-level easterly flow may continue through a good chunk of the day Monday, especially for southern and eastern areas. Per collaboration with neighboring offices, kept temps in southern New England only slightly above NBM guidance, but increased temperatures by at least a few degrees over NBM further north and west as flow should be more southerly here and a warmer airmass aloft will move into the region in association with the upper-level ridging. For Tuesday, he surface high may actually retrograde westward towards our region, so southerly flow should not be a concern. With ridging aloft and fewer clouds, blended in NBM 90th percentile guidance in collaboration with neighbors as the general consensus was that the NBM was a few to several degrees too cool. Currently have high temperatures reaching the mid 70s for the Hudson Valley on Tuesday, and these values could even be adjusted further upwards in the coming days if forecast confidence in this warmer solution increases. Tuesday night through Wednesday...More uncertainty in this part of the forecast. Guidance suggests that an upper-level disturbance will approach from the west, but disagrees on if it will impact our region. This shortwave may track through the Great Lakes, which would bring a chance for showers to our region (especially northern areas), while it is also possible that upper-level ridging keeps this disturbance further north and west, which would result in drier weather for our area with warmer temperatures. Given run-to-run inconsistency in the guidance, will mention slight to low-end chance PoPs for northern areas during this timeframe with temperatures near NB guidance, which is still several degrees above normal with upper 60s (high terrain) to mid 70s (Hudson Valley). After this disturbance passes, upper-level ridging looks to build in once again for the end of the week. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... 00Z Fri through 00Z Sat...Main challenge in the aviation forecast is potential for fog similar to last night. The airmass does not appear to have changed substantially since last night. Ingredients for fog formation include high pressure overhead, clear skies, winds that should become calm, and low levels that are still somewhat moist. The forecast for this TAF cycle is similar to the 18Z cycle in terms of onset, which is expected to be similar to last night. Dense fog is a possibility at all TAF sites, with visibilities 1/4SM or less, especially 06-13Z. Visibilities should improve after 12-13Z, but some mist and/or low stratus may hang around until 14-17Z before skies clear back out. Winds will be around 5 kt or less from variable directions through the TAF period. Outlook... 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. Chance of SHRA. Sunday Night: Low Operational Impact. Slight Chance of SHRA. Columbus Day: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: No Operational Impact. NO SIG WX. && .FIRE WEATHER... Fair weather is expected into the weekend as high pressure dominates. However, fog will develop again tonight and linger into Friday morning with some locally dense fog in the river valleys. Chances for showers return Sunday mainly for areas along and south of I-90. Minimum relative humidity levels Friday afternoon are expected to be in the 60s with values in the mid 60s to mid 70s Saturday. && .HYDROLOGY... Little precipitation is anticipated into early next week. However there remains uncertainty for Sunday, at this time it appears any rainfall should be limited mainly along and south of I-90. 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 NEAR TERM...IAA/Thompson/JPV SHORT TERM...IAA LONG TERM...Main AVIATION...Thompson FIRE WEATHER...IAA HYDROLOGY...IAA