MIL-OSI USA: SPC Severe Thunderstorm Watch 418

Source: US National Oceanic and Atmospheric Administration

Note:  The expiration time in the watch graphic is amended if the watch is replaced, cancelled or extended.Note: Click for Watch Status Reports.
SEL8

URGENT – IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 418
NWS Storm Prediction Center Norman OK
215 PM MDT Sun Jun 15 2025

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Central and eastern Montana
North central Wyoming

* Effective this Sunday afternoon and evening from 215 PM until
1100 PM MDT.

* Primary threats include…
Scattered damaging winds and isolated significant gusts to 80
mph likely
Scattered large hail and isolated very large hail events to 3
inches in diameter likely
A tornado or two possible

SUMMARY…Thunderstorms are expected to increase in coverage and
intensity through the afternoon while spreading eastward from the
higher terrain. The storm environment initially favors supercells
with very large hail (2-3 inch diameter), while upscale growth into
clusters is expected this evening with an increasing threat for
60-80 mph outflow winds. Favorable storm interactions could also
support an isolated tornado or two this evening.

The severe thunderstorm watch area is approximately along and 100
statute miles north and south of a line from 30 miles west of
Harlowton MT to 10 miles east northeast of Baker MT. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU8).

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
3 inches. Extreme turbulence and surface wind gusts to 70 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
27020.

…Thompson

SEL8

URGENT – IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 418
NWS Storm Prediction Center Norman OK
215 PM MDT Sun Jun 15 2025

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Central and eastern Montana
North central Wyoming

* Effective this Sunday afternoon and evening from 215 PM until
1100 PM MDT.

* Primary threats include…
Scattered damaging winds and isolated significant gusts to 80
mph likely
Scattered large hail and isolated very large hail events to 3
inches in diameter likely
A tornado or two possible

SUMMARY…Thunderstorms are expected to increase in coverage and
intensity through the afternoon while spreading eastward from the
higher terrain. The storm environment initially favors supercells
with very large hail (2-3 inch diameter), while upscale growth into
clusters is expected this evening with an increasing threat for
60-80 mph outflow winds. Favorable storm interactions could also
support an isolated tornado or two this evening.

The severe thunderstorm watch area is approximately along and 100
statute miles north and south of a line from 30 miles west of
Harlowton MT to 10 miles east northeast of Baker MT. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU8).

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
3 inches. Extreme turbulence and surface wind gusts to 70 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
27020.

…Thompson

Note: The Aviation Watch (SAW) product is an approximation to the watch area. The actual watch is depicted by the shaded areas.
SAW8
WW 418 SEVERE TSTM MT WY 152015Z – 160500Z
AXIS..100 STATUTE MILES NORTH AND SOUTH OF LINE..
30W 3HT/HARLOWTON MT/ – 10ENE BHK/BAKER MT/
..AVIATION COORDS.. 85NM N/S /51SW LWT – 59WSW DIK/
HAIL SURFACE AND ALOFT..3 INCHES. WIND GUSTS..70 KNOTS.
MAX TOPS TO 550. MEAN STORM MOTION VECTOR 27020.

LAT…LON 47881046 47860406 44970406 44981046

THIS IS AN APPROXIMATION TO THE WATCH AREA. FOR A
COMPLETE DEPICTION OF THE WATCH SEE WOUS64 KWNS
FOR WOU8.

Watch 418 Status Report Message has not been issued yet.

Note:  Click for Complete Product Text.Tornadoes

Probability of 2 or more tornadoes

Low (20%)

Probability of 1 or more strong (EF2-EF5) tornadoes

Low (5%)

Wind

Probability of 10 or more severe wind events

Mod (60%)

Probability of 1 or more wind events > 65 knots

Mod (60%)

Hail

Probability of 10 or more severe hail events

Mod (60%)

Probability of 1 or more hailstones > 2 inches

Mod (60%)

Combined Severe Hail/Wind

Probability of 6 or more combined severe hail/wind events

High (>95%)

For each watch, probabilities for particular events inside the watch (listed above in each table) are determined by the issuing forecaster. The “Low” category contains probability values ranging from less than 2% to 20% (EF2-EF5 tornadoes), less than 5% to 20% (all other probabilities), “Moderate” from 30% to 60%, and “High” from 70% to greater than 95%. High values are bolded and lighter in color to provide awareness of an increased threat for a particular event.

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