Note:
The expiration time in the watch graphic is amended if the watch is
replaced, cancelled or extended.
Note: Click for Watch Status Reports.
SEL4
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 644
NWS Storm Prediction Center Norman OK
135 PM MDT Wed Sep 2 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Central Montana
* Effective this Wednesday afternoon and evening from 135 PM
until 800 PM MDT.
* Primary threats include...
Scattered damaging winds likely with isolated significant gusts
to 80 mph possible
Isolated large hail events to 1 inch in diameter possible
SUMMARY...High-based thunderstorms should continue to increase in
coverage and intensity this afternoon and evening while posing a
threat for mainly scattered severe/damaging winds as they move
quickly north-northeastward. Peak gusts may reach up to 70-80 mph on
an isolated basis. Occasional hail may also occur with the stronger
cores.
The severe thunderstorm watch area is approximately along and 100
statute miles east and west of a line from 50 miles northwest of
Havre MT to 25 miles southeast of Helena MT. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU4).
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.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 643...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 70 knots. A few
cumulonimbi with maximum tops to 400. Mean storm motion vector
20040.
...Gleason
Note:
The Aviation Watch (SAW) product is an approximation to the watch area.
The actual watch is depicted by the shaded areas.
SAW4 WW 644 SEVERE TSTM MT 021935Z - 030200Z AXIS..100 STATUTE MILES EAST AND WEST OF LINE.. 50NW HVR/HAVRE MT/ - 25SE HLN/HELENA MT/ ..AVIATION COORDS.. 85NM E/W /44NW HVR - 21SE HLN/ HAIL SURFACE AND ALOFT..1 INCH. WIND GUSTS..70 KNOTS. MAX TOPS TO 400. MEAN STORM MOTION VECTOR 20040. LAT...LON 49040834 46320953 46321373 49041276 THIS IS AN APPROXIMATION TO THE WATCH AREA. FOR A COMPLETE DEPICTION OF THE WATCH SEE WOUS64 KWNS FOR WOU4.
Watch 644 Status Report Messages:
STATUS REPORT #1 ON WW 644 VALID 022055Z - 022140Z SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 ENE DLN TO 60 N GPI. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 2206 ..MOORE..09/02/26 ATTN...WFO...TFX...MSO... && STATUS REPORT FOR WS 644 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MTC005-007-013-015-027-035-041-043-045-049-051-059-073-099-101- 022140- MT . MONTANA COUNTIES INCLUDED ARE BLAINE BROADWATER CASCADE CHOUTEAU FERGUS GLACIER HILL JEFFERSON JUDITH BASIN LEWIS AND CLARK LIBERTY MEAGHER PONDERA TETON TOOLE $$ THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. $$
Note:
Click for Complete Product Text.
Tornadoes
| Probability of 2 or more tornadoes |
Low ( |
| Probability of 1 or more strong (EF2-EF5) tornadoes |
Low ( |
Wind
| Probability of 10 or more severe wind events |
Mod (60%) |
| Probability of 1 or more wind events > 65 knots |
Mod (50%) |
Hail
| Probability of 10 or more severe hail events |
Low (20%) |
| Probability of 1 or more hailstones > 2 inches |
Low (10%) |
Combined Severe Hail/Wind
| Probability of 6 or more combined severe hail/wind events |
High (80%) |
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.