249 FXUS61 KALY 102355 AFDALY Area Forecast Discussion National Weather Service Albany NY 755 PM EDT Wed Oct 10 2018 .SYNOPSIS... Bands of showers and isolated thunderstorms some with locally heavy downpours will move across the area Thursday into Thursday night ahead of approaching cold front as tropical moisture moves into the region. Behind the cold front, a cooler and more seasonable air mass will build into the region Friday into the weekend, bringing an end to the summer-like warmth. && .NEAR TERM /THROUGH THURSDAY/... Flash Flood Watch in effect from 8 AM Thursday through 2 AM Friday for the following counties: Litchfield, Berkshire, Bennington, Windham, Columbia, Dutchess, Greene, Rensselaer and Ulster. Another very warm and muggy night. Tropical moisture from Michael is being drawn northward ahead of an approaching cold front. Expecting a tranquil evening with clouds on the increase with chances for showers increasing after midnight as isentropic lift increases over the area. PWATs will surge up rapidly through the night, getting close to 2.00 inches by daybreak Thursday. With high freezing levels and high PWATs, will expect warm rain processes to dominate, allowing for efficient rainfall and high rainfall rates. This may result in some heavier showers producing downpours that result in street flooding and ponding of water in low lying and poor drainage areas. This initial shot of rainfall looks to occur between the late night hours and through mid to late morning on Thursday. Despite widespread cloud cover, enough elevated instability may be present for some isolated thunder as well, but no severe threat due to the lack of surface-based instability which is only several hundred J/KG. There may be a brief break or lull in the shower activity before the next round of heavier showers (and embedded t-storms) rolls through ahead of the cold front from around mid-afternoon through the evening hours Thursday. As earlier, any shower will be capable of producing locally heavy downpours. If heavy showers repeat over the exact same location, then flash flooding is possible. Thus, the reason for the Watch across southern and eastern portions of the forecast area where PWATs will be the highest. Temperatures overnight are only expected to drop into the 60s with highs on Thursday in the mid 60s to mid 70s. Dewpoints are expected to be in the 60s to lower 70s with the highest values across the southeast portion of the forecast area. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... Showers will be ending from northwest to southeast as a cold front exits the region Thursday night. Much drier and cooler air will advect in behind the front on Friday, resulting in a more seasonable air mass. On Friday, the tropical system (Michael) will quickly lift into the eastern Atlantic from the Delmarva peninsula but should stay far enough south to keep any additional rainfall south of the forecast area. Upper level heights will also be on the rise, allowing for a dry but cooler day. High temperatures will average slightly below normal, in the low to mid 50s, with overnight lows dipping into 30s and low 40s. An upper level trough looks to swing through Friday night into Saturday, with some light rain showers possible. A few flurries will also be possible in the higher terrain Friday night into Saturday morning. No snow accumulation is expected. High temperatures on Saturday will be on the chilly side under cloudy skies, with low 40s in the high terrain to low 50s elsewhere. Saturday night, temperatures fall into the mid to upper 30s. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... The long term forecast period will begin with mid-level ridging and surface high pressure over the region on Sunday followed by multiple shortwave troughs swinging through the Northeast during early/mid next week. Sunday will remain dry across the region with the exception of the Adirondacks which could see a few isolated lake-enhanced rain showers. Temperatures will be seasonable with highs in the 40s and 50s and lows generally in the 40s. There will be multiple chances for precipitation during the early and mid week as pieces or shortwave energy swing through the region. At least two shots of cold reinforcing air will push into the Northeast with these shortwaves, bringing temperatures down slightly below normal. Global deterministic guidance resolves a low pressure system and associated cold front moving to our North, with a coastal low developing just on its heels Monday into Tuesday. The exact timing and location of cyclogenesis will have implications on the amount and type of precipitation associated with the potential coastal low, and confidence at this time is low. High temperatures will be in the 40s (higher terrain) and 50s (valley regions) with low temperatures in 30s and 40s. && .AVIATION /23Z WEDNESDAY THROUGH MONDAY/... Tropical moisture from Michael is being drawn northward ahead of an approaching cold front. Showers, locally heavy at times, as well as isolated thunderstorms will occur across the area late tonight through the end of the TAF period; 00Z/Friday. Clouds will be on the increase tonight with MVFR conditions expected to develop overnight. IFR conditions are expected to develop Thursday morning as the rain gets steadier. Do not have confidence to time any thunder at any TAF site. Any improvement to MVFR is possible very late in the TAF period as the heavier rain moves odd to the east. Light southerly flow will persist through the TAF period shifting more to the southwest Thursday afternoon ahead of the cold front. Winds should become gusty at KALB with gusts into the teens. Outlook... Thursday Night: Moderate Operational Impact. Chance of SHRA. Friday: No Operational Impact. NO SIG WX. Friday Night: Low Operational Impact. Slight Chance of SHRA. Saturday: No Operational Impact. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: No Operational Impact. NO SIG WX. Sunday Night: Moderate Operational Impact. Scattered SHRA. Monday: Moderate Operational Impact. Scattered SHRA. && .FIRE WEATHER... RH values will be elevated tonight into tomorrow with a widespread wetting rainfall expected. Cooler, drier and breezy conditions are expected on Friday. && .HYDROLOGY... Flash Flood Watch in effect for western New England as well as Greene, Columbia, Rensselaer, Ulster, and Dutchess counties of New York from 8 AM Thursday through 2 AM Friday. Dry weather is expected into this evening, allowing for river and stream levels to mainly hold steady across the region. Late tonight into tomorrow, a frontal boundary will be approaching from the west. Tropical moisture will be surging northward ahead of this boundary, allowing for PWAT values to reach close to two inches across the entire area. Bands of showers and isolated thunderstorms, some locally heavy, are expected to move across the region. With high rainfall rates expected (up to an inch an hour), this rain could cause flooding of urban, poor drainage and low lying areas. Isolated flash flooding may be possible, especially south and east of the Capital District. Larger river and streams levels may see some rises, but basin average rainfall amounts (about 1.0 to 2.0 inches) won't be enough to cause flooding of main stem rivers and streams. The rain should be done by Friday morning, allowing for water levels to recede slowly, as a cooler air mass will return to close the week and enter the weekend. 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...Flash Flood Watch from Thursday morning through late Thursday night for CTZ001-013. NY...Flash Flood Watch from Thursday morning through late Thursday night for NYZ053-054-058>061-063>066. MA...Flash Flood Watch from Thursday morning through late Thursday night for MAZ001-025. VT...Flash Flood Watch from Thursday morning through late Thursday night for VTZ013>015. && $$ SYNOPSIS...IAA/Frugis/JLV NEAR TERM...IAA/Frugis/11 SHORT TERM...JLV LONG TERM...Cebulko AVIATION...IAA FIRE WEATHER...Frugis/JLV HYDROLOGY...Frugis/JLV