textproduct: Burlington

WHAT HAS CHANGED

As of 414 PM EDT Wednesday...

Quick update to grids this aftn/evening to mention thunder acrs the SLV and increase pops into the likely/cat range based on lightning data and crnt radar trends. This should just impact the SLV thru early this evening, before lifting north of our cwa.

KEY MESSAGES

As of 246 PM EDT Wednesday...

1. Unsettled pattern prevails through Friday with several rounds of showers expected, with greatest concentration over the higher terrain.

2. Cooler and drier weather develops late Friday into Saturday, with patchy frost possible in the Champlain Valley on Saturday morning.

3. After a dry start to the weekend, showers look to return late Sunday into the start of next week.

DISCUSSION

As of 246 PM EDT Wednesday...

KEY MESSAGE 1: After the coolest start of the fall season, which saw temps ranging from 22F at East Haven, 25F at SLK, and 34F at BTV, temps have quickly rebounded into the 50s to lower 60s under gusty southerly winds. Peak wind gusts observed have been 41 mph at BTV and 51 mph at Colchester Reef so far today.

The core of the strongest 925mb to 850mb jet of 35 to 45 knots will be exiting our cwa by 06z, but localized gusts 30 to 40 mph will be possible acrs Lake Champlain and exposed ridges thru this evening.

GOES-19 mid lvl water vapor imagery shows initial s/w energy responsible for some lightning north of the eastern Great Lakes quickly shearing out to our west. Meanwhile, another potent s/w and stronger mid/upper lvl trof is quickly diving southeast toward our cwa and should be entering the SLV by 06z. This energy is accompanied by a left front quadrant of a 100-120 knot jet at 25h, which should help to enhance synoptic scale ascent acrs our region for a line of showers btwn 06-12z. Sounding analysis does indicate a weak layer of elevated instability with MUCAPE values of 150 to 300 J/kg, especially over northern NY, so a rumble of thunder is possible.

Meanwhile, additional s/w energy, along with better instability develops between 15z and 21z Thursday, supporting additional showers with embedded rumbles of thunder possible. The cooling temps aloft help to steepen sfc to 3km lapse rates, while MUCAPE values climb btwn 800-1200 J/kg. Given the relatively high EQL up to 25kft, a few stronger cores wl be capable of small hail/graupel, but probability of any severe is <5%. Just not enough confidence in areal coverage to mention small hail in grids attm. Highest probability and areal coverage of showers on Thurs wl be between 16z and 21z, based on moisture/instability and forcing parameters. Given the potential for high based showers with favorable deep layer lapse rates, localized gusty winds are possible in the stronger cores. Temps under caa aloft, warm into the mid 60s valleys to mid/upper 40s summits.

Mid/upper lvl trof continues to deepen acrs our cwa Thurs night into Friday with 925mb to 850mb caa prevailing. This favorable upslope flow and lingering 925mb to 700mb moisture wl continue to produce plenty of clouds with intervals of showers, especially northern Dacks into the central/northern Greens. Highest likely pops wl be focused acrs these area, especially on Friday morning. Progged 850mb temps drop to near 0C by 12z Friday, so given lingering moisture and cooling thermal profiles, a few wet flakes are possible above 3500 feet in the Dacks and northern Greens from Mt Mansfield to Jay Peak on Friday morning. Temps Friday struggle in the mid/upper 30s summits to mid/upper 50s warmest valleys.

KEY MESSAGE 2: A 1028mb high pres will be expanding acrs our fa late Friday into Saturday with cooler and drier weather anticipated. This cool and dry airmass with light bl winds wl allow for temps to quickly drop after sunset on Friday night. However, have noted some increasing 1000 to 500mb rh after 06z Saturday associated with modest waa. This moisture could result in some mid/upper lvl clouds toward sunrise on Saturday, preventing temps from completely bottoming out. Either way wl mention lows mid 20s to mid/upper 30s, very similar to this morning with some clouds increasing over northern NY toward sunrise. Saturday is a beautiful fall day with temps quickly climbing back into the mid 50s to lower 60s with developing southerly winds.

KEY MESSAGE 3: After a stretch of dry and seasonable weather to start the weekend, shower chances look to return late Sunday into the start of next week. Model guidance at this time shows the remnants of current Tropical Storm Isaias will move into the region towards the start of the week. At this time, the center of the low looks to remain to our south, but widespread precipitation is looking likely for Monday into Tuesday. The system will weaken significantly by the time it reaches the region, bringing beneficial rainfall. Once this system exits, it looks a strong cold front moves through the region towards mid-week. As usual with this time range, the trends for these systems will need to be monitored as we get closer. Temperatures will be on the warm side for Sunday and Monday, with highs in the 60s and even low 70s, but will trend cooler for next week with highs in the 50s to near 60 for Tuesday.

AVIATION /00Z THURSDAY THROUGH MONDAY/

Through 00Z Friday...VFR conditions are expected to mostly persist for the next 24 hours. The only exceptions will be this evening and again late tonight when scattered showers move through. While most of them will be too light to cause significant visibility reductions, occasional reductions to MVFR visibility are possible, especially at the northern terminals (MSS/SLK/PBG/BTV/EFK). A few thunderstorms will be possible as well, especially at MSS and SLK. S/SW winds remain on the breezy side this evening, especially at BTV where gusts around 25 kt are expected through midnight or so. Winds will decrease a bit thereafter and by 06Z, the gusts should mostly be below 20 kt. LLWS is expected to develop in places this evening, especially in Vermont outside the Champlain Valley.

Outlook...

Thursday Night: VFR. Chance SHRA. Friday: VFR. Chance SHRA. Friday Night: VFR. NO SIG WX. Saturday: VFR. NO SIG WX. Saturday Night: VFR. NO SIG WX. Sunday: VFR. Chance SHRA. Sunday Night: Mainly VFR, with local IFR possible. Likely SHRA. Columbus Day: Mainly MVFR, with areas IFR possible. Slight chance SHRA.

MARINE

A Lake Wind Advisory continues on Lake Champlain tonight with breezy to gusty south winds of 20 to 30 knots expected, along with localized gusts up to 35 knots, especially before midnight. As rain showers develop over the Lake toward midnight, winds will decrease below advisory levels. Waves will generally be 2 to 4 feet, with a few higher swells possible.

BTV WATCHES/WARNINGS/ADVISORIES

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