textproduct: Burlington

WHAT HAS CHANGED

As of 411 AM EDT Sunday...

The Storm Prediction Center has placed areas along the International Border in a Day 3 Slight Risk for the potential for severe damaging wind gusts late Tuesday into Wednesday.

KEY MESSAGES

As of 411 AM EDT Sunday...

1. Seasonable conditions today will trend more uncomfortable to start next week with increasing temperatures and humidity.

2. Precipitation chances increase early week. A sharp cold front will pass through the region late Tuesday into Wednesday bringing a chance for thunderstorms, some of which could be strong to severe.

3. Forecast trends suggest seasonable conditions, but the pattern predictability appears relatively low.

DISCUSSION

As of 215 AM EDT Sunday...

KEY MESSAGE 1: Beautiful summer weather will continue today with temperatures similar to yesterday, but a degree or two warmer, but remaining dry. Some localized valley fog in central Vermont and the Adirondacks may be possible through sunrise, but should dissipate by early to mid morning. Ridging centered over the Great Lakes will continue to slide east towards the region with strong subsidence aloft keeping winds light and variable today. Additionally, drying low levels will promote good mixing through the day today keeping the humidity low. Overnight lows will dip towards the 50s, with perhaps some 40s in the usual cold hollows with good radiational cooling tonight. In the Champlain Valley, warm Lake Champlain water temperatures will likely keep the surrounding locations to near 60 tonight through Sunday night.

Temperatures and the humidity will begin to rebound back up to start off next week as 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, though uncertainty is highest there. The latest thinking is that Heat Advisory criteria will be reached in the Champlain Valley; maximum heat index values could be in the mid to upper 90s in the Champlain Valley and the Upper Valley of Vermont with lower 90s in most other valley locations. Heat risk maps show widespread moderate heat risk for most valleys across the area, with isolated major heat risk in the Champlain Valley, focused over the central Champlain Valley of western Addison County. 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. Following a sharp cold front Tuesday night into Wednesday temperatures and subsequently heat index values will lower into the low to mid 80s on Wednesday, giving us a quick end to the one off high heat day.

KEY MESSAGE 2: While the current forecast looks to remain dry through at least Monday, there are some ensembles denoting a few chances for rain. Some ensembles denote a weak shortwave passage Monday afternoon, which could bring a brief light rain shower or sprinkle to the northern Champlain Valley. Though confidence is relatively low with only a 10-20% chance of precipitation with dry low levels. More likely than not, any radar returns on Monday afternoon will fall as virga with stout dryness in the low levels.

The more concerning forecast aspect is the potential for stronger thunderstorms late Tuesday into Wednesday with a sharp cold front. Given how hot and humid Tuesday will be, some instability cannot be ruled out, particularly over the terrain and across the Northeast Kingdom. GFS and NAM soundings show up to 2000J/kg of elevated MUCAPE instability late Tuesday into Tuesday night. Shear profiles are equally as impressive with soundings denoting a strong low level jet associated with the front. NAM soundings show nearly 80kts of surface to 500mb shear, focused over the Northeast Kingdom and sliding south into central Vermont with the front by early Wednesday morning. As of right now, most of this strong instability and dynamics looks to not become realized Tuesday night due to the presence of a strong EML, or warm nose in the low to mid levels. That being said, the pattern itself does bode confidence that there will be thunderstorms of some sort with a quasi-ridge running pattern from Canada. While guidance remains varied at this time due to competing inhibition and initiation forces, model evolution of these patterns, even from our recent events, has shown low predictability and poor resolution. SPC, with this pattern recognition in mind, has gone ahead and placed areas along the International Border in a Day 3 Slight Risk (level 2 out of 5), and the remainder of our area in a Marginal Risk (level 1 out of 5) for severe weather on Tuesday. Furthermore, SPC has added a CIG1 hatched area in the Slight Risk, denoting higher confidence in the potential for damaging winds. Should the EML realization become weaker with new model runs, or should any earlier convection help prime the evening convection, there could be some locally strong storms near the Vermont International Border and the Northeast Kingdom. With the high shear profiles, storms could become organized into bowing segments leading to a heightened damaging wind threat. Those with outdoor activities and/or camping plans Tuesday into Wednesday should keep a close eye to the forecast as it evolves over the next couple of days. Regardless of storm potential, winds Tuesday will increase to between 25-35 mph in the St. Lawrence Valley from channeling, the presence of the low level jet, and corresponding good mixing. Tuesday will be breezy to gusty for most areas as the front passes through.

KEY MESSAGE 3: Thursday is likely to be another day on the list of beautiful summer days in 2026 across Vermont and northern New York. Dry mid-level air and incoming cool air will produce pleasant weather conditions. A strong vort will angle southeast at the base of a broad upper low taking shape in far eastern Canada. With such dry air, it may be hard to produce much, but cannot completely rule out a shower or two across northern Vermont as that embedded upper trough approaches.

Then the pattern becomes increasingly uncertain. Model spread between the 25th and 75th percentile 500mb heights are maximized across the Pacific Northwest and New England. Some forecast scenarios depict precipitation Friday, while others are dry, and then some suggest a modest frontal boundary on Sunday, while others are dry. Personally, inclined to pose drier conditions considering PWATs will be running around 60-90% of normal, and probabilities of total QPF > 1" in the extended range has a relative minimum in our region. Given the large spread in model depictions on the underlying weather pattern, we'll hold off on making stronger assertions at this point. At the very least, we'll be outside the breadth of deep high pressure in the central US, and so we'll likely be relatively seasonable to perhaps below normal in terms of temperatures.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

Through 06Z Monday...Quiet aviation conditions are expected the next 24 hours. Some river valley fog is expected, but with conditions being drier today, the span of time will be shorter, and only placed fog at KMPV and KSLK from 08z-12z. After 12z, mostly clear skies will give way to fair weather cumulus with bases around 5000-7000 ft agl. Light northwest winds around 5 knots will prevail, with light and terrain driven flows returning after 00z.

Outlook...

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. NO SIG WX. Wednesday Night: VFR. NO SIG WX. Thursday: VFR. NO SIG WX.

CLIMATE

High temperatures on Tuesday will be hot, but we are at the climatological warmest part of the year. Therefore, it is far from a certainty that any records will occur. At this time, PBG, MPV, and MSS are the more likely long-term climate sites to set a record. See below for current records:

Max Temp Records Date BTV MPV MSS PBG SLK 07-14 100|1995 94|1952 92|2012 95|1952 95|1934

High Min Temp Records DatePBG 07-14 70|1974

BTV WATCHES/WARNINGS/ADVISORIES

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