High Wind in Montana, September 19 to 21, 2015

Name: High Wind in Montana, September 19 to 21, 2015
Start: 2015-09-19T22:00
End: 2015-09-21T11:00
Location: Montana

September 19 to 21, 2015 · NWS TFX · 5 events in 1 county or zone

An increasingly tightening pressure gradient ahead of a shortwave trough in zonal westerly flow brought strong winds over Central and Southwest Montana. While wind reports were widespread no damage or injuries were reported.

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 5

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS TFX wrote it up.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Great Falls, MT wrote its last area forecast discussion before the first event at Sep 19, 8:26 PM MST, 1 hour 34 minutes earlier.

Area forecast discussion, Sep 19, 8:26 PM MST, 1 hour 34 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
926 PM MDT SAT SEP 19 2015

.DISCUSSION...

TONIGHT...WINDS HAVE DIMINISHED ACROSS THE REGION AND TEMPS HAVE
FALLEN QUICKLY IN SOME LOCATIONS. LOWERED MIN TEMPS A FEW DEGREES
ACROSS THE CENTRAL ZONES. OTHERWISE CURRENT FORECAST LOOKS ON
TRACK. ZELZER

&&

.AVIATION...UPDATED 0002Z.

STRONG WEST WINDS ALOFT WILL CONTINUE THROUGH SUNDAY. GUSTY SURFACE
WINDS WILL DIMINISH THIS EVENING BUT STRENGTHEN AGAIN SUNDAY.
STRONGEST WINDS WILL BE ALONG THE EASTERN SLOPES OF THE ROCKIES AND
ADJACENT PLAINS, INCLUDING KCTB. THE AIRMASS WILL REMAIN DRY WITH
VFR CONDITIONS PREVAILING THROUGH THE NEXT 24 HOURS.

&&

.PREV DISCUSSION...
/ISSUED 603 PM MDT SAT SEP 19 2015/

STRONG WESTERLY FLOW ALOFT WILL CONTINUE. WEST WINDS WILL INCREASE
ALONG THE ROCKY MOUNTAIN FRONT OVERNIGHT AND ACROSS GLACIER COUNTY
ON SUNDAY. A HIGH WIND WARNING WILL REMAIN IN EFFECT FOR THESE
AREAS THROUGH EARLY MONDAY MORNING. THE PLAINS WILL REMAIN DRY AND
MILD BUT A COLD FRONT WILL DROP SOUTH OUT OF CANADA MONDAY AND
MOVE ACROSS THE AREA. VERY LITTLE MOISTURE IS ASSOCIATED WITH THIS
FRONT AND, ASIDE FROM A FEW ISOLATED SHOWERS OVER THE ROCKY
MOUNTAINS, THE MAIN EFFECT WILL BE COOLER TEMPERATURES.
TEMPERATURES WILL REMAIN ABOVE SEASONAL AVERAGES SUNDAY, DROPPING
BACK TO NEAR OR SLIGHTLY BELOW AVERAGES ON MONDAY.

MONDAY NIGHT THROUGH SATURDAY...MEDIUM RANGE MODELS REMAIN IN DECENT
AGREEMENT FOR MUCH OF NEXT WEEK BUT DIFFER SIGNIFICANTLY BY NEXT
WEEKEND. SHORTWAVE RIDGING WILL BE OVER MONTANA ON TUESDAY, ALLOWING
TEMPERATURES TO REBOUND FROM MONDAY. FOR WEDNESDAY THROUGH FRIDAY A
SOUTHWEST FLOW ALOFT WILL BE OVER THE STATE AS AN UPPER LEVEL TROUGH
DEVELOPS ALONG THE WEST COAST OF CANADA THEN DEEPENS ALONG THE
PACIFIC NORTHWEST COAST. TEMPERATURES WILL REMAIN ABOVE SEASONAL
AVERAGES DURING THIS PERIOD WITH ISOLATED SHOWERS AND POSSIBLE A FEW
THUNDERSTORMS EXPECTED WEDNESDAY AFTERNOON THROUGH FRIDAY MORNING.
STRONG MODEL DIFFERENCES ARISE FRIDAY AFTERNOON THROUGH SATURDAY AS
THE GFS MOVES THE UPPER TROUGH INLAND KEEPING GOOD RUN-TO-RUN
CONSISTENCY. HOWEVER, THE ECMWF DIFFERS SIGNIFICANTLY FROM EARLIER
RUNS AS IT CONTINUES TO DEEPEN AND ELONGATE THE TROUGH OFF THE
CALIFORNIA COAST RATHER THAN MOVING IT INLAND. HAVE OPTED TO GO WITH
THE STABLE GFS SOLUTION AND HAVE CONTINUED TO TREND POPS HIGHER FOR
FRIDAY NIGHT AND SATURDAY AS THE UPPER TROUGH MOVES INLAND. MPJ

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  49  77  52  67 /   0   0   0  10
CTB  50  73  47  59 /   0   0   0   0
HLN  49  78  52  72 /   0   0   0  10
BZN  41  76  42  73 /   0   0   0  10
WEY  29  63  31  67 /   0   0   0   0
DLN  42  74  45  73 /   0   0   0   0
HVR  47  77  50  61 /   0   0   0   0
LWT  46  77  48  69 /   0   0   0  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING FROM NOON SUNDAY TO 4 AM MDT MONDAY FOR MTZ010.

HIGH WIND WARNING UNTIL 4 AM MDT MONDAY FOR MTZ009-048.

&&

WEATHER.GOV/GREATFALLS

Event by event

5 high wind. Local standard time, as filed.

High Wind, North Rocky Mountain Front

When: September 19, 10:00 PM MST
Where: North Rocky Mountain Front forecast zone
Measured: 56 kt (64 mph) measured gust
Reported by: Mesonet

A 65 mph gust was reported at the Deep Creek RAWS sensor.

High Wind, North Rocky Mountain Front

When: September 20, 5:00 AM MST
Where: North Rocky Mountain Front forecast zone
Measured: 69 kt (79 mph) measured gust
Reported by: Mesonet

A 79 mph gust was reported at the Deep Creek RAWS sensor.

High Wind, North Rocky Mountain Front

When: September 20, 5:04 AM MST
Where: North Rocky Mountain Front forecast zone
Measured: 54 kt (62 mph) measured gust
Reported by: Department of Highways

A 62 mph gust was reported at the Two Medicine Bridge DOT sensor.

High Wind, North Rocky Mountain Front

When: September 20, 8:20 AM MST
Where: North Rocky Mountain Front forecast zone
Measured: 55 kt (63 mph) measured gust
Reported by: Department of Highways

A 63 mph gust was reported at the East Glacier Park DOT sensor.

High Wind, North Rocky Mountain Front

When: September 21, 11:00 AM MST
Where: North Rocky Mountain Front forecast zone
Measured: 74 kt (85 mph) measured gust
Reported by: Mesonet

A 85 mph gust was reported at the Deep Creek RAWS sensor.

What these are

High Wind: Sustained non-thunderstorm winds of 40 mph or more for an hour, or gusts of 58 mph or more.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Montana in 2015 Every state in 2015 This day in weather history Warnings in Montana, September 2015

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 599136, 599137, 599138, 599139, 599140.