Sunrise 5:41 AM   Sunset 7:56 PM Moonrise 2:39 AM   Moonset 11:56 AM

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FXUS61 KBTV 012305 AFDBTV

Area Forecast Discussion National Weather Service Burlington VT 705 PM EDT Wed May 1 2024

SYNOPSIS
A potent upper level disturbance and weak surface low pressure system will bring a period of scattered to numerous showers to much of the forecast area late tonight through Thursday before high pressure and drier conditions return for Thursday night and Friday.
Saturday will be mainly dry with a low chance for showers across northern New York, with periods of showers likely for the latter half of the weekend.

NEAR TERM /THROUGH THURSDAY NIGHT/
As of 657 PM EDT Wednesday...
Watching upstream shortwave currently moving eastward over Ontario on satellite. As this shortwave moves into northern NY/VT overnight tonight, will see 50-200 J/kg elevated CAPE develop. This instability, coupled with observed lightning strikes upstream, is enough to warrant adding in a slight chance of thunder to the overnight forecast tonight, especially northern NY around and shortly after midnight. Given the elevated nature of the instability, no concerns for severe weather. Otherwise, just watching some light radar returns this evening move through. Enough dry air is present in the low levels to prevent much if any of this initial wave of showers from reaching the surface, so expect a quiet evening until the shortwave arrives closer to midnight.

Previous discussion...Quiet weather over the forecast area this afternoon will once again turn unsettled tonight as a potent shortwave trough currently moving east from Lake Superior will continue eastward through southern Ontario and Quebec tonight before diving southeastward across the North Country and Vermont on Thursday. A warm front currently draped across southern New York will be the focus for showers to develop on as it lifts northward into northern New York around midnight or shortly thereafter, with precipitation spreading eastward through central/northern Vermont through sunrise. Thereafter for Thursday, a cold pool aloft and steepening low level lapse rates will support scattered showers to continue across the region with perhaps some small hail or graupel as well until an upper level ridge begins to build in Thursday evening. Overall basin-averaged QPF will be light across southern zones with only a few hundreths to a tenth of an inch expected, but northward a light wetting rain of a quarter to third of an inch is likely. Clouds and low level moisture will keep temps mild overnight with lows mainly mid 40s to around 50, and highs will generally range through the 60s on Thursday. Cooler temperatures and dry conditions follow for Thursday night with lows in the lows and areas of fog possible.

SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/
As of 345 PM EDT Wednesday...An anomalously strong, but narrow, upper level ridge will slide eastward into the region during this period.
In the low levels, there will be less impressive low level warmth due to the position of high pressure to our northeast rather than east or southeast. As a result, while this pattern supports dry weather, we don't see anything unusually warm at the surface. Expect warmer spots such as the central/southern Champlain Valleys currently have about 50-60% chance of seeing 70 degree highs. As normal highs are now in the low to mid 60s, these temperatures could be considered seasonably warm. While southern St. Lawrence County sees the most favorable conditions under the ridge - with gentle downsloping easterly low level winds to warm well into the 70s, they also will likely see thickening high clouds arrive. Similar to the day of the solar eclipse last month, there may be a sharp north- south oriented line between thicker and thinner cloud cover.
Generally have mostly cloudy skies for much of the day in northern New York and partly cloudy in Vermont, but certainly not clear cut on the degree of cloud cover with some minor impact on high temperatures possible. Expect there will be enough mixing to overcome any lingering morning low clouds/fog, but that is another possible way to underachieve on temperatures. Lowering clouds will continue to be the gradual trend ahead of a shortwave trough that looks to slide northeastward across the Great Lakes Friday night, and have a slight chance of showers after midnight in the far western areas of northern New York. Precipitation chances and amounts will be limited by continued mid- level ridging and related lack of instability and forcing for ascent. It will be a mild night even where winds remain light. Overnight temperatures will be moderated by cloud cover and increasing, modest southeasterly gradient flow, as a ridge of high pressure in eastern New England strengthens while weak low pressure approaches from Ohio.

LONG TERM /SATURDAY THROUGH WEDNESDAY/
As of 345 PM EDT Wednesday...Aside from a bit more southerly wind, the pattern on Saturday is not too different from Friday. Ridging will slowly break down, setting up increasing shower chances through the day with greater chances west and lower chances as you go eastward. Especially across Vermont, even the wettest model solutions suggest if it does rain it will be very light and brief. A more significant shortwave will probably move through Saturday night, leading to much greater chances of showers. Have continued to leave out mention of thunder as elevated instability associated with this system looks meager and better southwest of our region.

Sunday looks like the coolest/cloudiest day of the long term period despite southerly winds and continued mild air aloft. Why? Thick cloud cover will likely be present as mid-level southwesterly flow increases with advection of moisture from upstream showers. A window of clearing ahead of a cold front seems to hold off until after sunset with the front passing through with nothing more than some scattered showers Sunday night. Weak high pressure will then build in for Monday, with seasonably warm and frankly beautiful weather in store for the beginning of the week. Model agreement in quiet weather is fairly high for the Monday-Tuesday period. The low level temperatures have modest spread, so how warm we get on Tuesday is a question. Widespread highs in the 70s look reasonable at this time.

Looking at the 12Z global model ensemble data, the joint probability of surface-based CAPE exceeding 500 J/kg and deep layer shear exceeding 30 knots suggests our next chance for notable convective weather returns on Wednesday. Although the signal for strong thunderstorms is greater to our southwest, one of the four global model clusters provides a plausible scenario with deep southwesterly flow bringing modest heat and humidity into our region, especially northern New York. In general, more active weather looks favored Wednesday and beyond.

AVIATION /00Z THURSDAY THROUGH MONDAY/
Through 18Z Thursday...A mix of BKN/OVC MVFR/VFR currently will trend to SCT/BKN VFR at all sites this afternoon into the evening hours. An upper level disturbance then lowers ceilings and vsby back down to MVFR/IFR after 07-09Z Thursday in scattered to numerous showers which persist through the remainder of the period. In addition, some MVFR/IFR BR/FG is possible at KMPV/KEFK before the rain arrives from 06-09Z. Winds will be light and variable this afternoon and tonight, trending westerly on Thursday at 5-8kts.

Outlook...

Thursday Night: Mainly VFR, with areas MVFR possible. NO SIG WX.
Friday: Mainly VFR, with local MVFR possible. NO SIG WX.
Friday Night: VFR. Chance SHRA.
Saturday: VFR. Slight chance SHRA.
Saturday Night: Mainly VFR, with areas MVFR possible. Chance SHRA.
Sunday: Mainly MVFR, with local VFR possible. Chance SHRA.
Sunday Night: Mainly MVFR, with areas IFR possible. Chance SHRA.
Monday: VFR/MVFR conditions possible. Slight chance SHRA.

BTV WATCHES/WARNINGS/ADVISORIES
VT...None.
NY...None.

Troy
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Wed -- 02:38 AM EDT     Moonrise
Wed -- 05:48 AM EDT     Sunrise
Wed -- 06:02 AM EDT     0.89 feet Low Tide
Wed -- 07:27 AM EDT     Last Quarter
Wed -- 11:42 AM EDT     5.51 feet High Tide
Wed -- 12:03 PM EDT     Moonset
Wed -- 06:50 PM EDT     0.59 feet Low Tide
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Albany
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Wed -- 02:38 AM EDT     Moonrise
Wed -- 05:48 AM EDT     Sunrise
Wed -- 05:52 AM EDT     0.89 feet Low Tide
Wed -- 07:27 AM EDT     Last Quarter
Wed -- 11:34 AM EDT     5.51 feet High Tide
Wed -- 12:03 PM EDT     Moonset
Wed -- 06:40 PM EDT     0.59 feet Low Tide
Wed -- 07:56 PM EDT     Sunset
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Albany, New York, Tide feet

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