textproduct: Burlington

WHAT HAS CHANGED

As of 505 AM EDT Friday...

The Lake Wind Advisory for Lake Champlain has ended.

KEY MESSAGES

As of 223 AM EDT Friday...

1. A cold front will bring widespread showers to the region this morning into the early afternoon, with temperatures falling behind the front. Crisp, dry, and beautiful, fall weather will follow for the weekend.

2. A quick moving cold front will bring showers Sunday night into Monday with sharply colder temperatures.

3. A push of cold air will likely result in some frost/freeze midweek, and then moderating as we approach next weekend.

DISCUSSION

As of 223 AM EDT Friday...

KEY MESSAGE 1: GOES-19 water vapor depicts a good stream of sub- tropical moisture extending from SW Quebec to SE Texas along an elongated longwave trough. Radar shows scattered rain showers moving into the St. Lawrence Valley from the southwest with steadier rain to follow, currently over the southern Great Lakes. A surface cold front will continue to shift precipitation east by daybreak across northern New York and the Champlain Valley. Moisture associated with this system continues to anomalously high given PWs around 1.5-1.7 inches, however, an associated LLJ to 40-50 knots will keep the moisture corridor progressive, precluding any flooding threats. That said, some downpours from more moderate rain will be possible, especially across the Adirondacks around sunrise. The front continues to track east by midday today, with showers tapering off across much of the region after 2 PM. A secondary front will follow the main cold front this afternoon, clearing the region of any lingering shower activity and drying the region out. Along this secondary front, some convergent flow may allow for some lingering isolated showers across southern Vermont and along the central Greens, but all areas will see a drying trend by this evening. Total rainfall will be between a quarter to half an inch, focused mainly in northern New York and along the spine of the northern Greens. Good shadowing form the Adirondacks and Greens, may lead to lower amounts in the Champlain Valley, and especially in southeastern Vermont. Temperatures today will be tricky with how fast the front moves through. Many locations will generally stay in the low to mid 60s, however, areas in southeastern Vermont, like Springfield could break into the low to mid 70s with a delayed arrival of the front and associated precipitation.

Cloud cover will decrease quickly overnight tonight as drier northwest air advects into the region. Temperatures will cool into the 40s across the area, with a few pocket upper 30s possible in the Adirondacks. By Saturday, a picture perfect fall day is expected. High temperatures will be crisp in the mid 50s to around 60, with little wind outside of some light channeled north winds in the Champlain Valley. High pressure will move overhead Saturday night, so expect a chilly Saturday night with temperatures in the mid 20s to low 30s in the Adirondacks and NEK, to the upper 30s in the Champlain Valley and southern Vermont. Winds will turn southerly Sunday, bringing some warmer air as highs warm into the low to mid 60s. Clouds will also be on the increase Sunday afternoon, though no rain is anticipated during the daylight hours through Sunday evening. It should be a perfect weekend for leaf peeping, so hope everyone can get out and enjoy the foliage!

KEY MESSAGE 2: Our next chance for showers across the area will be Sunday night into Monday as a surface cold front passes through. Our flow pattern will amplify by the end of the weekend as a pair of systems moves through the eastern CONUS. An area of southern stream energy will remain shunted south, keeping the more moisture-rich air to our south Sunday. However, an area of northern stream energy associated with an occluding upper low over the Hudson Bay of Canada will glance the region with showers possible Sunday night. As the upper low occludes over northern Quebec, it will drag a surface cold front more north as well. As such, better precipitation chances look to be across our northern zones, and areas closer to the International Border. A tightening pressure gradient will also lead to a fairly strong 40-50kt LLJ Sunday into Monday, resulting in some gusty winds Sunday Night into Monday. Soundings support localized gusts in the Champlain and St. Lawrence Valley between 25-30 MPH. Behind the front, our air mass will turn more cold and drier, with sharply falling temperatures under strong caa. Highs Monday will only be in the low to mid 50s.

KEY MESSAGE 3: A vigorous upper low will shift the 1000-500mb 540 dam thickness line south of our forecast area. A sharp front will shift east with marginal moisture on Monday. It still may be capable of developing a solid, narrow line of rain given the vigorous forcing. Behind this front will be an impressive push of cold air tamping temperatures down into the 50s, except some 60s in the Upper Valley. Strong northwest flow will advect plenty of cold air Monday night into Tuesday, with widespread mid 20s to mid 30s, though areas near Lake Champlain will likely hover around 40. There should be some level of flow lingering into Monday night into Tuesday that should keep frost from developing. Of course, several places will simply go straight to freezing. Fall will very much be in the air on Tuesday with brisk winds and high temperatures lingering in the mid 40s to mid 50s. Then on Tuesday night, broad surface high pressure will set up overnight. It looks like we'll also be around the PWAT min across the region, and so very efficient radiational cooling is possible. Almost the entire region could experience a freeze, and the Champlain Valley remains in the alert window for this time. So this will likely be curtain call for all gardener's sensitive plants in the broad valleys for Tuesday night. Surface high pressure will amble east after Wednesday, and temperatures will start moderating. The next front will arrive next Friday with some scattered light showers.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

Through 12Z Saturday...Rain continues to stream across the St. Lawrence Valley, and is making steady eastward progress. Ceilings are mostly MVFR with intermittent ceilings as low as 400-800 ft agl at times. Visibility in rain has been somewhat lower than expected, occasionally falling to 1SM in the highest rainfall rates. KMPV and KRUT remain outside the region of MVFR or IFR flight rules, but this rain will continue to gradually shift southeast. So MVFR, and locally to IFR, conditions are expected through about 19-21z. The northwest to north wind shift is happening somehwat sooner as well, and adjusted winds to the north a bit sooner, keeping speeds around 5-9 knots. After 21z-23z, a trend to all VFR is expected with rain moving east of Vermont at that time. Partial clearing is expected overnight, and with the rain, it should promote fog formation. High clouds and winds may slow the onset of fog, and added 3SM at KMPV and KSLK after 06z.

Outlook...

Saturday: VFR. NO SIG WX. Saturday Night: VFR. Patchy BR. Sunday: VFR. NO SIG WX. Sunday Night: Mainly VFR, with local MVFR possible. Chance SHRA. Monday: Mainly VFR, with areas MVFR possible. Chance SHRA. Monday Night: Mainly VFR, with local MVFR possible. NO SIG WX. Tuesday: VFR. NO SIG WX.

BTV WATCHES/WARNINGS/ADVISORIES

VT...None. NY...None.