Severe Thunderstorm Watch 521

Issued

Jul 17, 2025, 2:28 PM EDT (18:28 UTC)

Expired

Jul 17, 2025, 8:02 PM EDT

In force

6 hr

Issued by

the Storm Prediction Center

Largest hail expected

1 in

Strongest gust expected

55 kt

Counties Aroostook County, ME, Franklin County, ME, Oxford County, ME, Piscataquis County, ME, Somerset County, ME, Carroll County, NH, Coos County, NH, Grafton County, NH, Clinton County, NY, Addison County, VT, Caledonia County, VT, Chittenden County, VT, Essex County, VT, Franklin County, VT, Grand Isle County, VT, Lamoille County, VT, Orange County, VT, Orleans County, VT, Washington County, VT

The Caribou radar (KCBW), 144 km from the middle of the area, began a volume at 18:31 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

Two or more tornadoes

20%

One or more EF2 to EF5 tornadoes

5%

Ten or more severe wind reports

50%

One or more gusts of 65 knots or more

20%

Ten or more severe hail reports

5%

One or more hailstones of 2 inches or more

5%

Six or more combined severe hail and wind reports

60%

• Mesoscale Discussion 1698 Severe potential...watch likelyJul 17, 1:09 PM EDT
• Mesoscale Discussion 1700 Severe thunderstorm watch 521Jul 17, 4:40 PM EDT
• Mesoscale Discussion 1703 Severe thunderstorm watch 521Jul 17, 6:43 PM EDT

301 
WWUS20 KWNS 171826
SEL1  
SPC WW 171826
MEZ000-NHZ000-NYZ000-VTZ000-180100-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 521
NWS Storm Prediction Center Norman OK
225 PM EDT Thu Jul 17 2025

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Western and Northern Maine
  Northern and Central New Hampshire
  Far Northern New York
  Northern and Central Vermont

* Effective this Thursday afternoon and evening from 225 PM until
  900 PM EDT.

* Primary threats include...
  Scattered damaging wind gusts to 65 mph possible
  A tornado or two possible

SUMMARY...Scattered thunderstorms are forecast to develop and
intensify this afternoon across the Watch area.  A couple of
transient supercells are possible as well as a few organized
multicells.  The primary severe hazard will be strong to severe
gusts (50-65 mph) capable of wind damage, but a tornado is possible
with the more intense transient supercells.

The severe thunderstorm watch area is approximately along and 75
statute miles east and west of a line from 20 miles north northwest
of Caribou ME to 15 miles south southwest of Montpelier VT. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU1).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 55 knots. A few
cumulonimbi with maximum tops to 400. Mean storm motion vector
23030.

...Smith

Severe Thunderstorm Watches in Vermont, 2025Severe Thunderstorm Watches in Maine, 2025Severe Thunderstorm Watches in New Hampshire, 2025Every severe thunderstorm watch in 2025

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.