textproduct: Burlington

WHAT HAS CHANGED

As of 243 AM EDT Thursday...

No significant changes.

KEY MESSAGES

As of 243 AM EDT Thursday...

1. Wildfire smoke will continue to degrade the air quality. An Air Quality Alert is in effect for northern New York and southern Vermont today.

2. Thunderstorm chances today and over the weekend.

3. Seasonably warm temperatures and a brief dry period are expected early next week, then another round of showers and potential storms towards midweek.

DISCUSSION

As of 243 AM EDT Thursday...

KEY MESSAGE 1: Wildfires in western Ontario have been emitting significant plumes of smoke into the air and persistent west to northwest flow is bringing them toward the region. Enough northerly flow behind the cold front pushed the smoke south for the overnight, but flow becomes more westerly this morning and it will renter southern and central areas. A reinforcing cold front comes through this afternoon and should push it back to the south for the evening and Friday. However, flow becomes more westerly to southwesterly heading into the weekend and it will try to re-enter the region. An Air Quality Alert is in effect for northern New York and southern Vermont today where the smoke will be the worst, but reduced air quality is expected everywhere. The Air Quality alert is in the unhealthy for sensitive groups level.

KEY MESSAGE 2: A cold front moves down from the north today and it will bring a broken line of showers and storms. The best forcing is farther east so the storms will likely be more widespread and robust over Vermont. Instability will be meager, with mean HREF SBCAPE values under 500 J which will significantly limit the convection. However, there will be strong dynamics and 0-6 KM shear will be in the 40-60 KT range. Therefore, an isolated strong to severe storm is possible. That being said, the shear is strong enough that storms will struggle with the low instability and could get sheared off.

The next round of showers and storms is late Saturday and Saturday night. An anomalously strong sub 1,000 MB low looks to take a general track up the St. Lawrence Valley or close to that. Showers look more widespread close to the international border on Saturday as the warm front and center of the low would be closer. A powerful cold front looks to 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. However, with such strong dynamics and shear, the potential for a couple of strong to severe storms is there, particularly if the front comes through earlier in the day. Otherwise, temperatures will be quite seasonable during this stretch.

KEY MESSAGE 3: Precipitation chances will be decreasing on Sunday as drier air flows into northern New York and Vermont. High pressure and weak ridging will control the weather pattern Sunday night into Monday, allowing temperatures to climb back towards or slightly above seasonal averages in the 70s to mid 80s each afternoon. Nighttime temperatures will fall into the upper 40s to mid 60s. Another trough is expected to come through sometime toward midweek. Models diverge in their solutions for this Tuesday-Wednesday system, particularly in terms of timing, but most project a surface low crossing through Canada dragging the frontal boundaries through our area and returning highs to the 70s and lower 80s.

AVIATION /06Z THURSDAY THROUGH MONDAY/

Through 06Z Friday...VFR conditions currently prevail across all terminals. Wildfire smoke continues to impact the region, with some reductions in visibility possible, however given low confidence and uncertainty haze has been left out of the forecast for now. Smoke, last night's rain, and winds aloft could also affect fog formation tonight one way or the other. At the moment, confidence is too low to include fog, but it is possible at the favored locations. Breezy west/northwest winds will trend light and variable overnight, with KRUT developing it's typical drainage wind. Winds will once again be increasing during the day, with gusts between 20 to 30 knots expected at all terminals.

Outlook...

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

BTV WATCHES/WARNINGS/ADVISORIES

VT...Air Quality Alert from 6 AM this morning to 11 PM EDT this evening for VTZ011-019>021. NY...Air Quality Alert until midnight EDT tonight for NYZ026>031- 034-035-087.