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Albany, NY WFO Forecast Discussion
000 FXUS61 KALY 262025 AFDALY AREA FORECAST DISCUSSION National Weather Service Albany NY 425 PM EDT Sun Sep 26 2021 .SYNOPSIS... A warm front will bring scattered showers late tonight through Monday and milder temperatures on Monday with an isolated rumble of thunder possible. A cold front will bring another threat of showers Monday night into Tuesday morning with clearing and seasonable temperatures later Tuesday behind the front. Wednesday looks unsettled with below normal temperatures. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... Diurnal clouds will slowly decrease later this afternoon as sun`s heating weakens. A few light rain showers are possible over the southern Adirondacks this afternoon. Mid level clouds will again start to increase from west to east starting around sunset as warm front starts to approach from the southwest. High temperature will range from around 60 in the higher elevations to around 70 in the valleys. && .SHORT TERM /8 PM THIS EVENING THROUGH TUESDAY NIGHT/... 850mb warm advection increases tonight around ridge of high pressure south of our area. 850mb temps rise from +4 to +7C this evening to +9 to +13C by Monday morning. Lift associated with warm advection is forecast to produce clouds and showers across the northern half of the area from late tonight into Monday. Showalter indices go negative from time to time so can`t rule out an isolated rumble of thunder. Precipitation amounts look to be light, generally a quarter inch or less. Lows tonight generally in the 40s to around 50. With the mild 850 temps Monday afternoon temps should be above normal from the Mohawk Valley southward where breaks in the clouds should help temps rise into the mid 70s in the valleys. Northern high terrain areas look to be cooler with clouds and showers and highs in the 50s and 60s. Monday night, low pressure develops along the front and high pressure starts to push in from the upper Great lakes. The wave of low pressure looks to bring another round of showers to central and southern areas Tuesday night into Tuesday morning. Once again, showalter indices go negative so thunder can not be ruled out. With mostly cloudy skies Monday night low temps only drop to the 50s with some upper 40s possible in southern Adirondacks and higher terrain of southern vermont. By later Tuesday, low pressure near Maine and high pressure over Great Lakes combine to bring a northerly flow of cooler and drier air to the area. Skies should gradually clear during the afternoon. There will be a large range in high temperatures from the 50s over the southern Adirondacks and hills of southern vermont to the lower 70s across the far southern part of our forecast area. Tuesday night looks to be partly cloudy and cold. Some areas of frost are possible where skies remain mostly clear as 850 temps are generally between +1 an +5C. Lows forecast in the 30s and 40s. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... The main story for the long term period will be a closed low that perpetuates over the Northeast from Wednesday through potentially Friday as we remain on the east side of an omega block. However, riding from the Central CONUS gradually pushes eastward over the weekend, which should result in improving conditions. Read on for details. We start the long term on Wednesday with a closed ~550-555dm low over northern New England and a highly amplified ~585-590dm ridge over the Midwest. Blocked flow allows the closed low to persist over the Northeast through the second half of the week as multiple shortwaves rotate around the low. With 500hPa temperatures nearing -20C to -25C, mid-level lapse rates steepen to 6C/km to 7C/km which should result in stratocumulus clouds, especially during peak heating. In addition, the instability under the cold pool should generate scattered showers, especially in the higher terrain areas of the southern Adirondacks, Upper Hudson Valley, southern VT and the Berkshires. The deterministic guidance is in generally fair agreement that 850hPa temperatures drop to +1C to +3C with even hints on the GFS and CMC that northerly flow ushers sub-zero 850hPa air into the southern Adirondacks. We therefore show some pockets of rain/snow mix in the higher peaks of the southern Adirondacks Wed night. Such chilly temperatures aloft will also support seasonably cool temperatures at the surface Wed and especially Thurs when daytime highs may struggle to rise out of the low 60s. According to climatology, high temperatures in late September are in the mid 60s. Overnight lows will also turn chilly and fall-like with lows in the low to mid 40s Wed and Thurs night. By Friday, our closed low finally starts to exit into the Canadian Maritimes as strong ridging and surface high pressure builds northeastward out of the Southeast U.S. Deterministic guidance suggests that the ridging struggles to take control of the Northeast for very long as our cut-off low may maintain control just off shore from the Canadian Maritimes with additional shortwaves within the active northern branch of the jet stream sending more shortwaves our way which may act to flatten out any riding. There are still many differences between the ECWMF, CMC and GFS regarding how the synoptic pattern will evolve over the weekend so we maintained a generally dry forecast with seasonably daytime temperatures in the 60s and overnight lows in the 40s. && .AVIATION /21Z SUNDAY THROUGH FRIDAY/... A ridge of high pressure will build across the TAF sites this afternoon and evening. A warm front and upper level disturbance will then approach from the west tonight into Monday morning. VFR conditions are expected through at least sunset, and possibly through the end of the TAF period at KALB/KPSF and KPOU. At KGFL, there could be a brief period of fog development between roughly 03Z-08Z/Mon, which could lead to periods of MVFR/IFR Vsbys. A mid level cloud deck should advance across the TAF sites between 09Z-12Z/Mon. A few sprinkles or showers may fall from this cloud deck, especially between 13Z-17Z/Mon. Best chances for showers (possibly briefly moderate in intensity) will be at KGFL, where a PROB30 group has been indicated. There is a small possibility that some thunder could occur at KGFL during this time as well, however overall probability too low to include mention at this time. West to northwest winds will increase to 8-14 KT this afternoon, with some gusts of 20-25 KT possible, especially at KALB and KPSF. Winds will decrease to less than 8 KT after sunset, and may become calm at times overnight. Winds will then increase from the south to southwest at 5-10 KT toward and especially after 18Z/Mon. Outlook... Monday Night: Moderate Operational Impact. Chance of SHRA. Tuesday: Moderate Operational Impact. Chance of SHRA. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: No Operational Impact. NO SIG WX. Thursday Night: No Operational Impact. NO SIG WX. Friday: Low Operational Impact. NO SIG WX. && .FIRE WEATHER... A warm front will bring scattered showers late tonight through Monday and milder temperatures on Monday with an isolated rumble of thunder possible. A cold front will bring a threat of showers to southern areas Monday night into Tuesday morning with clearing and seasonable temperatures behind the front. Wednesday looks unsettled with below normal temperatures. RH values will rise overnight to 80 to 100 percent. RH values fall to 60 to 80 percent on Monday and recover to 80 to 100 percent again Tuesday morning. Winds will become light and variable tonight before increasing to 10 to 20 mph from the southwest on Monday. && .HYDROLOGY... Forecast precipitation during the next 7 days is one half inch or less. River levels should slowly recede during the period so no hydro issues are anticipated. 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...SND NEAR TERM...SND SHORT TERM...SND LONG TERM...Speciale AVIATION...KL FIRE WEATHER...SND HYDROLOGY...Thompson