textproduct: Burlington

WHAT HAS CHANGED

As of 244 PM EDT Sunday...

No significant changes made with this forecast package.

KEY MESSAGES

As of 244 PM EDT Sunday...

1. Showers ending by midnight tonight with some patchy fog toward sunrise on Monday expected in favored areas.

2. Several rounds of showers and thunderstorms possible Tuesday through Wednesday, but timing and placement of precipitation is very challenging.

3. Trending drier late week and into the weekend with seasonably cool conditions.

DISCUSSION

As of 244 PM EDT Sunday...

KEY MESSAGE 1: GOES-19 Day Cloud Phase Distinction product shows extensive cloud cover acrs our cwa this aftn, with some breaks and better instability north of Montreal ahead of approaching cold front. These breaks have allowed temps to warm into the 70s with sfc based CAPE values around 1000 J/kg, but <300 J/kg over our cwa, due to the clouds and lack of sfc heating. As boundary drops southward toward the International Border by 00z, a broken line of showers with a few rumbles of thunder wl be possible near the border, but thunder threat should be quickly dissipating around sunset. Have lowered qpf amounts by 25 to 35% acrs the board, as precip amounts have been less with minimal instability today, as temps struggle to reach 70F.

After fropa flow becomes north-northwest upslope with moisture trapped below developing/lowering subsidence inversion, which should allow for the development of low stratus type clouds, especially acrs the mtns. As subsidence inversion conts to lower toward morning and winds become light, thinking some patchy fog wl be possible acrs the trrn, favorable valley and areas that receive >0.10" of rainfall. Fog/low clouds wl slowly burn off by 10 AM Monday with increasing amounts of sunshine expected along with comfortable temps in the 70s.

KEY MESSAGE 2: Given the upcoming pattern the predictability of precip timing and placement is low, especially toward Weds/Weds night, as a large spread remains in latest guidance. Latest guidance indicates CAMs are much further north with axis of precip late Monday night into Tues, while larger scale guidance is mostly a miss to our south. Given the latest trends have cutback on pops Monday night/Tues morning and continued to show highest values south of a MSS to BTV to LEB line. Feel most of the precip remains south of our cwa thru 12z Tues, given the position of 1024mb sfc high pres nosing into the northern cwa with a developing sharp sw (1.40") to ne (0.45") pw gradient acrs our cwa. Furthermore, highest instability parameters, including elevated CAPE values stay mostly south of the NY State Thruway as northwest flow btwn 700-500mb keeps us on the cooler side of the boundary into Tues. Given these factors have trimmed back qpf and pops for Monday night into Tues, with highest chc/low likely near our cwa border with WFO ALY/BUF. Much lower values acrs the NEK of VT.

By Weds potent closed 850 to 500mb cyclonic circulation is progged to be north of the Great Lakes, with departing ridge acrs the north Atlantic. This wl increase the pres gradient acrs our cwa, with increasing winds likely, along with better chcs for showers and thunderstorms, especially on Weds aftn/evening. Height field analysis would suggest strong mid lvl flow btwn low pres to the north and high pres to the south, question wl be magnitude of instability and timing of best sfc convergence. For now have continued with NBM for pops with mention of showers and storms, but potential for a few strong/severe wl need to be watched.

KEY MESSAGE 3: An upper level low will remain around heading through the end of the week, so there will be the chance of a few showers each day, particularly in the afternoon due to diurnal heating. However, most of the time it will be dry. Heading into the weekend, the upper low will continue to push east and surface high pressure will build south out of Canada, causing conditions to trend drier. However, there is uncertainty among the ensembles for when the low moves out and when it becomes completely dry. Currently, probabilities of precipitation during the day are between 10-30 percent, mostly driven off EPS members. However, even if these wetter solutions verify, the greatest extent of rain would be some isolated to scattered showers. Highs should be in the 60s and 70s and lows should be in the 40s and 50s.

AVIATION /00Z MONDAY THROUGH FRIDAY/

Through 00Z Tuesday...VFR conditions are prevailing, with the exception of SLK where ceilings are in the MVFR category, at the start of the TAF period. Showers along the leading edge of a weak cold front are expected to diminish in intensity across northern Vermont, with only EFK expected to see rain and a slight chance of thunder. Chances of showers are low enough to have left out of the TAF elsewhere, but have noted one last area of thunderstorms south of Montreal; its remnants possibly will bring light rain to PBG/BTV towards 03Z-05Z.

The showers at EFK have produced only minor gusts (shifting westerly up to 20 knots), and anticipate winds generally will remain light with a trend towards northerly through the overnight hours. The light winds and areas of clearing skies will support patchy fog at the climo favored terminals including SLK/MPV/EFK, and possibly at BTV/PBG briefly. Onset probably will be delayed (roughly into the 08Z-10Z period) due to the remnant showers and associated cloud cover. Improving conditions where fog develops can be expected in the 13-14Z period with otherwise quiet aviation conditions with high pressure building in.

Outlook...

Monday Night: VFR. Chance SHRA. Tuesday: Mainly VFR, with local MVFR possible. Likely SHRA, Slight chance TSRA. Tuesday Night: Mainly MVFR, with local IFR possible. Chance SHRA. Wednesday: Mainly MVFR, with local IFR possible. Likely SHRA, Slight chance TSRA. Wednesday Night: Mainly MVFR, with local IFR possible. Chance SHRA, Slight chance TSRA. Thursday: Mainly VFR, with areas IFR possible. Chance SHRA. Thursday Night: Mainly VFR, with areas MVFR possible. Chance SHRA. Friday: Mainly MVFR, with areas IFR possible. Chance SHRA, Slight chance TSRA.

BTV WATCHES/WARNINGS/ADVISORIES

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