Flash Flooding and Hail in Vermont, May 17, 2025

Area Forecast Discussion
National Weather Service Burlington VT
732 AM EDT Sat May 17 2025

.SYNOPSIS...
Warm and humid conditions will continue to support widely scattered
showers and thunderstorms this afternoon. Strong to severe
thunderstorms will be possible this afternoon. After the recent
stretch of warmth, much cooler conditions arrive SUnday and will
linger into the first half of next week.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 721 AM EDT Saturday...Showers and thunderstorms have
already begun popping up across the region this morning, with
several rounds of precipitation expected throughout the day. A
few minor adjustments were made with this update, with the
forecast generally on track.

Previous Discussion...An upper level low centered over the
Great Lakes will continue to meander eastward, with the showery and
active weather pattern continuing. Some patchy fog that developed
overnight in locations where rain fell yesterday will gradually
diminish through the morning. Several rounds of showers and possible
thunderstorms are expected today, with the first round of showers
moving through in the early morning and then additional convection
in the afternoon. The greatest chances for strong to locally severe
thunderstorms looks to be between noon and 8 PM, although some
convection may develop even earlier. SPC continues to maintain the
Slight Risk across the region. Tall CAPE profiles and high PWAT
values also support locally heavy rainfall rates in storms that do
develop. WPC continues to maintain a Marginal Risk ERO given the
higher rainfall rates, with the greatest threat for any flash
flooding in locations that receive multiple rounds of showers. In
general, about 0.5 to 1.0 of rain can be expected today, although it
will largely depend on where showers develop. Another day of warmer
temperatures is expected, with highs generally in 70s to near 80
degrees.

A cold front will push through the region late tonight, with a much
cooler airmass filtering into the region. Overnight low temperatures
tonight will be much cooler than previous nights, generally in the
upper 40s to mid 50s. Showers will continue to persist late tonight
into SUnday as the upper low tracks across northern New York. High
temperatures will struggle on Sunday, only climbing into the 50s and
low 60s after the recent warmth.

&&

.SHORT TERM /SUNDAY NIGHT/...
As of 413 AM EDT Saturday...A deep upper low will remain just to our
northeast on Monday, but will gradually pull away. During the day,
it will absorb another shortwave. With sufficient moisture
lingering, showers should redevelop, especially over northern
mountains. Breezy northwest winds 10 to 15 mph and gusts to 25
underneath abundant cloud cover will result in a well below normal
temperature forecast. Temperatures will mainly stay in the 50s,
though a spot 60 is possible in the lower Connecticut River Valley.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 413 AM EDT Saturday...For Tuesday, the upper low responsible
for our stretch of active weather will shift far enough east that
its influence should end. However, another upper low will quickly
take its place out of the north. Ensemble forecasts depict a range
of different scenarios due to disagreement on the track of the new
upper low. NBM probabilities of precipitation suggest keeping a
20-40 percent chance of rain in the forecast, mainly over northern
Vermont.

The overall weather pattern favors above normal precipitation. After
what appears to be a dry Wednesday morning, the new upper low phases
with a potent system across the Plains and then subsequently gets
blocked by an amplifying ridge across the Canadian Maritimes. A
broad, slow moving area of low pressure will loft precipitation
northwards late Wednesday as it moves up the Ohio River Valley. Then
the question will become when can stacked low pressure finally get
out of here. Ensemble MSLP suggests its still hanging near the Gulf
of Maine on Saturday. Expect wet and cool conditions to prevail the
latter half of next week.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
Through 12Z SUNDAY...VFR conditions currently prevail across
all terminals, with just some lingering IFR at KMPV from low
stratus and patchy fog. Several rounds of showers and
thunderstorms are expected throughout the day today, with
visibility restrictions possible within any heavier showers that
pass through. While confidence is high that showers and
thunderstorms will occur, there is lower confidence in the exact
timing and placement of these showers so PROB30 groups were
utilized throughout the forecast period. After all of the
precipitation, MVFR ceilings are likely to develop later this
afternoon into the overnight hours. Winds will continue out of
the southwest and could gust 15-20 knots at times, higher in
thunderstorms. Winds will become more westerly towards the end
of the forecast period.

Outlook...

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

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

SYNOPSIS...Kremer
NEAR TERM...Kremer
SHORT TERM...Haynes
LONG TERM...Haynes
AVIATION...Kremer

Hazardous Weather Outlook
National Weather Service Burlington VT
304 AM EDT Sat May 17 2025

NYZ026>031-034-035-087-VTZ001>011-016>021-180715-
Northern St. Lawrence-Northern Franklin-Eastern Clinton-
Southeastern St. Lawrence-Southern Franklin-Western Clinton-
Western Essex-Eastern Essex-Southwestern St. Lawrence-Grand Isle-
Western Franklin-Orleans-Essex-Western Chittenden-Lamoille-Caledonia-
Washington-Western Addison-Orange-Western Rutland-Eastern Franklin-
Eastern Chittenden-Eastern Addison-Eastern Rutland-Western Windsor-
Eastern Windsor-
304 AM EDT Sat May 17 2025

This Hazardous Weather Outlook is for northern New York, central
Vermont, northeast Vermont, northwest Vermont and southern Vermont.

.DAY ONE...Today and tonight.

Isolated to scattered strong to severe thunderstorms are possible
mainly from around noon through 8 PM Saturday. Damaging winds, large
hail, and localized heavy rainfall are the main threats. Locations
where multiple rounds of thunderstorms occur will be susceptible to
flash flooding. Have a plan in place for thunderstorms tomorrow and
be ready to head indoors.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Special Weather Statement
National Weather Service Burlington VT
743 AM EDT Sat May 17 2025

NYZ026-029-087-171230-
Northern St. Lawrence NY-Southeastern St. Lawrence NY-
Southwestern St. Lawrence NY-
743 AM EDT Sat May 17 2025

...STRONG THUNDERSTORMS WILL IMPACT CENTRAL ST. LAWRENCE COUNTY
THROUGH 830 AM EDT...

At 743 AM EDT, Doppler radar was tracking a cluster of strong
thunderstorms along a line extending from 11 miles northwest of
Morristown Village to near Kring Point State Park to near Fort Drum
to near Carthage to Whetstone Gulf State Park. Movement was north at
45 mph.

HAZARD...Wind gusts up to 50 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
De Peyster, Chippewa Bay, Morley, Talcville, South Edwards, Degrasse,
Newton Falls, North Gouverneur, West Fowler, West Pierrepont, East De
Kalb, Aldrich, Lisbon, Richville, Nelson Corner, Russell,
Fullerville, Hammond, Gouverneur Village, and Canton Village.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with these storms and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4441 7579 4442 7579 4442 7581 4443 7577
      4444 7579 4445 7577 4445 7578 4447 7577
      4447 7579 4451 7575 4473 7543 4476 7540
      4477 7541 4479 7536 4465 7508 4423 7496
      4407 7510 4440 7584
TIME...MOT...LOC 1143Z 195DEG 38KT 4470 7580 4435 7584 4409 7572 4394
7554 4369 7551

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

Haynes

Special Weather Statement
National Weather Service Burlington VT
819 AM EDT Sat May 17 2025

VTZ005-006-008-009-017-018-171315-
Eastern Chittenden VT-Western Chittenden VT-Washington VT-
Western Addison VT-Lamoille VT-Eastern Addison VT-
819 AM EDT Sat May 17 2025

...A STRONG THUNDERSTORM WILL IMPACT SOUTHERN LAMOILLE...NORTH
CENTRAL ADDISON...SOUTHEASTERN CHITTENDEN AND NORTHWESTERN WASHINGTON
COUNTIES THROUGH 915 AM EDT...

At 819 AM EDT, Doppler radar was tracking a strong thunderstorm over
Bristol, moving northeast at 40 mph.

HAZARD...Wind gusts up to 50 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
North Moretown, Irasville, Weybridge, Mount Worcester, West Lincoln,
Jericho Center, Huntington Center, Stowe, Bristol, Underhill Center,
Monkton Ridge, South Duxbury, Waterbury Village, North Duxbury,
Lincoln, Monkton, North Fayston, Waitsfield, Monkton Boro, and Little
River State Park.

This includes Interstate 89 between mile markers 57 and 81.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4398 7302 4405 7326 4456 7299 4447 7242
TIME...MOT...LOC 1219Z 218DEG 34KT 4413 7306

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

Haynes