Area Forecast Discussion
Issued by NWS Albany, NY

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000 FXUS61 KALY 230540 AFDALY AREA FORECAST DISCUSSION National Weather Service Albany NY 140 AM EDT Tue Apr 23 2019 .SYNOPSIS... Showers will taper off across western New England overnight. Tuesday will be dry most of the day with chances for showers increasing by late in the day. Numerous showers are expected Tuesday night with scattered thunderstorms possible as a low pressure moves across the region. It will be cooler Wednesday with strong and gusty westerly winds. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... As of 108 AM EDT, lingering band of mainly light rain continuing across western New England, within an area of mid level frontogenesis around western periphery of coastal low. This band of rain should continue to weaken and shift east over the next few hours. In its wake, skies have become clear to partly cloudy across much of eastern and central NYS. As some clearing spreads into western New England, temps and wind should drop off, but with the boundary layer remaining fairly moist in areas which received rain, expect areas of fog to develop, some of which could become quite dense. This seems most likely to occur within/adjacent to the Housatonic River Valley (Berkshire County and Litchfield County) and the CT River Valley (in SE VT). Elsewhere, expect skies to be clear to partly cloudy overnight. Temps have already dropped to around 40 across the SW Adirondacks, and with mainly clear skies and light winds, expect temps to continue dropping into the lower/mid 30s in this area by daybreak. Elsewhere, mainly 40s to lower 50s are expected. Previous Discussions... As of 1040 pm edt...Coastal storm continues to swirl just southeast of the coast of southern New England. One last band of showers on the backside of this storm are still impacting western New England, but they are starting to diminish in coverage. Most areas should be done with seeing rain showers by midnight or 1 AM. Ridging at the surface and aloft will build in late tonight behind the departing low and ahead of another approaching low pressure system. It will continue to remain fairly cloudy with plenty of mid level clouds remaining in place. The north- northeast flow will diminish tonight becoming light and variable to calm overnight. Expecting lows in the 40s (around 10 degrees above normal). && .SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/... The surface ridging will quickly break down Tuesday as a low pressure system approaches from the Great Lakes region. The ridging aloft occurring ahead of a vigorous, compact mid-level short wave should keep the area dry most of the day. Chances for showers will be on the increase late in the day with numerous showers overspreading the area in the evening. The better chances for showers will be along and north of I-90 closer to the low and the upper support. There will be some instability and showalter values go negative across the area in the evening so have mention of the thunderstorms at this time. Expecting some lingering showers Wednesday especially in the morning along and north of I-90 with cyclonic flow. Westerly winds will become quite strong and gusty Wednesday with good mixing in cold air advection. Expecting wind gusts up to around 30 mph. Highs will be around 15 degrees cooler than Tuesday, closer to seasonable levels. Chilly Wednesday night with diminishing winds and decreasing clouds. Expecting lows mainly in the 30s with lower 40s in the mid Hudson Valley. Ridging between systems will result in a fair weather Thursday with temperatures rebounding into the 60s with 50s above 1500 feet. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Active weather is expected during the long term period. Both a southern stream and northern stream systems will be phasing together at the start of the period, as an area of low pressure moves across the region from the Ohio Valley and mid-Atlantic States. Most of our area will be on the northern side of this system, and a fairly steady area of rain is expected for Thursday night into Friday. With strong frontogenesis in place, the precip may be locally moderate to heavy at times, so will need to carefully monitor the exact track of the storm to determine where the heaviest precip will fall. With our area on the northern side of the system, will not include thunder at this time, but far southern areas could hear a rumble or two, especially if the low winds up tracking further north than currently forecast. Behind the system, precip will taper off to showers for Friday night. With colder air arriving in behind the storm, there`s a chance that some of the highest peaks of the Adirondacks and Greens could switch over to snow showers before ending, but little snow accumulation is expected. High pressure should brief allow dry weather to return for Sat and Sat night, although temps may be a little below normal. However, the break in the weather will be short lived, as another northern stream system will quickly be approaching for Sunday, with some more light rain showers. Dry weather should then return once again behind that system for Monday. Temps should be fairly close to seasonable levels for Sunday and Monday. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... Low pressure near Nantucket is sending clouds and a few showers westward. The edge of the cloud deck is approximately the Hudson River. MVFR clouds can be expected at KPSF for the next few hours before the system and its lower clouds drift east. There is a chance for some fog development 08-12Z at KPSF if the clouds can clear out before sunrise. At KALB/KPSF, VFR is expected to prevail with some broken clouds around 5-6 kft for the next few hours. At KPOU, higher moisture is combining with breaks in the cloud shield and calm winds to result in dense fog. It is unclear how long this fog will stick around, as drier air located just to the north may filter in. We have gone with this idea in the TAF, bringing an improvement to visibility after 09Z. Would not be totally surprised if it persisted through sunrise, however. VFR conditions are expected throughout the daylight hours Tuesday as high pressure briefly builds in. Midlevel clouds will increase during the afternoon and evening. After 00Z Wednesday, a fast moving system will bring bands of showers and a few embedded thunderstorms to the terminals. Dry low levels will likely keep conditions above IFR for the most part, although brief dips to IFR are possible in heavier downpours. Have included a PROB30 to account for possible thunderstorms and IFR visibilities. Winds will be from the north at 10 kt or less for the rest of the night, becoming light and variable toward sunrise. Winds will shift to southerly this afternoon into tonight at around 10 kt, with some gusts to 20-25 kt possible just ahead of the showers around 00Z. Have included low level wind shear conditions at KPOU 03-06Z as increasing winds aloft may not translate to the surface. We may have brief LLWS conditions at the other terminals if the rainfall can stabilize low levels enough around 02-06Z. Outlook... Wednesday: Moderate Operational Impact. Breezy. Chance of SHRA. Wednesday Night: Low Operational Impact. Breezy. NO SIG WX. Thursday: No Operational Impact. NO SIG WX. Thursday Night: Moderate Operational Impact. Chance of SHRA. Friday: Moderate Operational Impact. Chance of SHRA. Friday Night: Moderate Operational Impact. Chance of SHRA. Saturday: Low Operational Impact. Breezy. NO SIG WX. && .FIRE WEATHER... Tuesday will be dry most of the day with chances for showers increasing by late in the day. Minimum relative humidity values in the afternoon are expected to be in the mid 30s to lower 40s with higher values of mid 40s to lower 50s across western New England. Numerous showers expected Tuesday night with scattered thunderstorms possible. Cooler Wednesday with strong and gusty westerly winds. Expecting gusts up to around 30 mph. && .HYDROLOGY... Flood Warnings remain in effect on the Schroon River at Riverbank and on the upper Hudson River at Fort Edward. The Schroon River at Riverbank is cresting then will begin to gradually recede but will remain above flood stage for several more days. The Upper Hudson River at Fort Edward will be slow to drop below flood stage, should occur tomorrow afternoon. Please visit our Advanced Hydrologic Prediction Service /AHPS/ web page for specific area rivers and lakes observations and forecasts. Showers will be limited mainly to areas east of the Hudson River Valley and be most numerous across western New England through this evening. Widespread showers are expected Tuesday night with some thunderstorm possible in the evening. Renewed flooding is not anticipated but brief heavy downpours are possible. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...IAA NEAR TERM...IAA/Frugis/KL SHORT TERM...IAA/Thompson LONG TERM...Frugis AVIATION...Thompson FIRE WEATHER...IAA HYDROLOGY...IAA

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