textproduct: Burlington

WHAT HAS CHANGED

As of 232 AM EDT Saturday...

No significant changes.

KEY MESSAGES

As of 232 AM EDT Saturday...

1. Thunderstorms and heavy rain this afternoon and evening.

2. Seasonably cool weather and intervals of wildfire smoke expected over the next few days.

3. Frontal passages bring chances for showers and thunderstorms Tuesday night into Wednesday before high pressure dominates our weather on Thursday and Friday.

DISCUSSION

As of 232 AM EDT Saturday...

KEY MESSAGE 1: An anomalously strong low for the time of year (~995 mb) will track eastward from Ontario through southern Quebec today and tonight. Showers will be more widespread close to the international border as the warm front and center of the low will be closer. A powerful cold front will come through in the afternoon and evening, bringing a round of showers and storms. The airmass ahead of the system will be relatively cool and not conducive to high instability. Peak mean HREF SBCAPE values are around 500-750 J during this time frame and earlier rounds of showers/clouds could prevent enough heating to reach these values. However, due to the strength of the low, there will be strong shear and dynamics. 0-6 KM shear is forecast to be in the 40-50 KT range. One thing lacking will be a significant surface wind shift/convergence with the front, with southwesterly synoptic flow expected behind the front until the center of the surface low pushes east. Height falls will be quite significant though. The main threat from the storms is by far the damaging winds, but there is a large amount of helicity where some low level rotation will be possible. Based on this information, the SPC continued the region in a split between a slight and marginal risk. These storms will contain heavy rain, but with strong background flow, the storms will move quickly and minimize the flooding threat. There also does not look to be a stalled axis of rain along the warm front on the front side that often occurs in these setups. However, the threat for flooding cannot be completely ruled out if areas see multiple rounds of heavy rain, with the greatest threat of that being along the international border. In summary, it is a conditional severe threat where little to no development could happen, but if just enough solar heating does occur, there could be several strong and severe storms this afternoon and evening.

KEY MESSAGE 2: Highs look to be in the 70s to mid 80s over the next few days, with slightly cooler conditions on Sunday. Lows will generally be in the 50s and dew points will be relatively low. The wildfire smoke makes a return for today as flow becomes westerly to southwesterly, bringing the smoke that is currently over the Midwest and Great Lakes into the region. Thankfully, behind the cold front on Saturday, winds eventually become northwesterly and push the smoke back to the south. The source of the smoke is fires in western Ontario.

KEY MESSAGE 3: A cold frontal boundary and upper level trough are both expected to cross the forecast area Tuesday night into Wednesday, bringing another round of showers with embedded thunderstorms. By Thursday morning surface high pressure will begin to ridge into the north country, bringing a return to drier weather once again. Headed into the weekend not a lot of model agreement on what will happen. Will monitor the mid week period for potential strong or severe storms as well as heavy rainfall. Highs for the mid and late week are expected to be around the 70s and lower 80s with lows in the upper 40s to lower 60s, though this may depend on how exactly the atmospheric pattern shapes up during this period.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

Through 06Z Sunday...Quiet/VFR aviation weather conditions are expected to prevail through 12Z Saturday. Light rain showers are spreading across our area overnight, but not expecting any reductions below VFR as activity remains light. Light and variable winds overnight will become southerly after sunrise with increasing gustiness; gusts to 25 kts are expected at BTV, especially during Saturday afternoon. A low level jet will also cross the region from SW-NE starting around 12Z-15Z, so LLWS is forecast at most of the TAF locations except RUT. Included some visibility restrictions during the daylight hours Saturday in haze and wildfire smoke. In terms of precipitation, currently seeing a leading band of -SHRA, followed by a stronger line of showers and possibly embedded thunderstorms during the late afternoon into the early evening hours. A few storms could be strong to severe late in the day, but are not currently mentioned in the TAFs due to uncertainties related to timing and spatial coverage of activity. Brief heavy rainfall and gusty winds will be possible.

Outlook...

Sunday: Mainly VFR, with local MVFR possible. NO SIG WX. Sunday Night: VFR. NO SIG WX. Monday: VFR. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: Mainly VFR, with areas MVFR possible. Likely SHRA, Chance TSRA. Tuesday Night: Mainly MVFR, with local IFR possible. Definite SHRA, Chance TSRA. Wednesday: MVFR/IFR conditions possible. Likely SHRA, Chance TSRA.

BTV WATCHES/WARNINGS/ADVISORIES

VT...Air Quality Alert from 6 AM this morning to 11 PM EDT this evening for VTZ001>011-016>021. NY...Air Quality Alert until midnight EDT tonight for NYZ026>031- 034-035-087.