textproduct: Burlington

WHAT HAS CHANGED

As of 217 AM EDT Saturday...

No significant changes to the forecast.

KEY MESSAGES

As of 217 AM EDT Saturday...

1. Seasonable and dry conditions are expected today and tomorrow with less humidity.

2. Heat and humidity will briefly build back in to start next week, peaking on Tuesday.

3. A sharp cold front will pass south Tuesday night and Wednesday, and then bring more seasonable weather into the latter half of the week.

DISCUSSION

As of 217 AM EDT Saturday...

KEY MESSAGE 1: Ridging centered over the Great Lakes will begin to build into the region today with winds remaining from the north. With the north winds, temperatures today will be much cooler than recent days, only reaching the mid 70s to low 80s. Dewpoints will help create a comfortable day with values in the mid 40s to near 50. It will be a perfect weekend to get out and about. A light north to south channeled wind in the Champlain Valley will also linger (around 15 MPH) today and tomorrow before flow shifts to the southwest by the start of next week. As the high edges closer, skies will remain clear at night, with good radiational cooling. Overnight lows will dip towards the 50s, with perhaps some 40s in the usual cold hollows. In the Champlain Valley, warm Lake Champlain water temperatures will likely keep the surrounding locations to near 60 tonight through Sunday night. With the strong radiational cooling, some fog may be possible in the usual river valleys into this morning, tonight, and tomorrow night due to the recent rains and clearing skies. Any fog formation will become more delayed in time each subsequent night as we become detached from rain.

KEY MESSAGE 2: Temperatures and the humidity will begin to rebound back up to start off next week as an area of high pressure crests over the region by Tuesday. This warm up will be relatively short as compared to a few weeks ago, and only last a day. Temperatures begin the climb on Monday with winds shifting to the south and west with highs in the mid to upper 80s. Models still continue to have high agreement in anomalous warmth by Tuesday as ridging crests overhead. Thankfully, the humidity will not be as high as our last heatwave due to a displacement from good moisture advection off the Gulf or Pacific. However, some dewpoint advection is still anticipated with southwest flow Tuesday, keeping uncomfortable heat past sunset Tuesday. Contrary to the current NBM which is running hot compared to consensus, GEFS 850mb temperatures are only 20-23C which would suggest highs on Tuesday around the low to mid 90s. With any moisture advection, heat index values would be highest in the Champlain Valley, eastern Windsor County, and perhaps the St. Lawrence Valley (where dewpoints will be maximized). The latest thinking is that marginal Heat Advisory criteria will be reached; maximum heat index values could be in the middle 90s in the Champlain Valley and Lower Connecticut Valley with lower 90s in most other valley locations. Since this is expected to be a single hot day, heat-health impacts aren't anticipated to be as significant as a longer duration event but will be meaningful for vulnerable populations.

While the current forecast looks to remain dry through Tuesday, there are some ensembles denoting a few chances for rain. Ensembles denote a weak shortwave passage Monday night into Tuesday which could bring brief light rain to the northern Champlain Valley. Though confidence is relatively low with only a 10-20% chance of precipitation with dry low levels. Lastly, given how hot and humid Tuesday will be, some instability cannot be ruled out, particularly over the terrain. GFS soundings show up to 1500J/kg of elevated instability. However, limitations will be a strong low to mid level EML which may inhibit any convective initiation altogether, in addition to continued dry low levels. These small scale features will become more apparent in future forecast updates.

KEY MESSAGE 3: After the hot conditions on Tuesday, a sharp boundary will pass south overnight into Wednesday. A narrow tongue of enhanced instability will exist ahead of that boundary, but the air mass overhead will be on the dry side and better forcing appears more likely to our east. But if there is any activity, we could have some nighttime rumbles.

The boundary decelerates in crossing the area during the day on Wednesday. So we may have a sharp north-south temperature contrast, where areas south are still running upper 80s to mid 90s, while areas north will be in the lower 80s.

By Wednesday night, the boundary should be pushing well south, and then we'll have some refreshingly seasonable weather once again. PWATs will be running well below normal, but if the upper low that's forecast to develop gets trapped farther south, we may still have a few showers tied to it such that we can't totally promise accompanying dry conditions. Seasonable to possibly below normal temperatures are expected into the weekend.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

Through 06Z Sunday...Falling dewpoints are competing with temperatures falling below crossover temperatures and recent rain. It's keeping fog rather sparse, but river valley fog is still certainly possible, especially 8z-11z. After 11-12z, fog will lift across the region, with mostly clear skies. Winds are currently light and variable, and will become north 6-11 knots 15z-22z, and then fall back to light and variable. Conditions are expected to also be drier, and so nighttime fog appears less likely beyond 06z Sunday.

Outlook...

Sunday: VFR. NO SIG WX. Sunday Night: VFR. NO SIG WX. Monday: VFR. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: VFR. NO SIG WX. Tuesday Night: VFR. Chance TSRA, Slight chance SHRA. Wednesday: VFR. Slight chance SHRA, Slight chance TSRA.

BTV WATCHES/WARNINGS/ADVISORIES

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