Hail and Damaging Wind in Montana, July 20, 2007

Name: Hail and Damaging Wind in Montana, July 20, 2007
Start: 2007-07-20T18:45
End: 2007-07-20T22:18
Location: Montana

July 20, 2007 · NWS TFX · 6 events in 3 counties and zones

Severe thunderstorms dropped half dollar sized hail across portions of North Central Montana on the 20th.

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 6

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.

Severe thunderstorms dropped half dollar sized hail across portions of North Central Montana on the 20th.

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 Jul 20, 4:17 PM MST, 2 hours 28 minutes earlier.

Area forecast discussion, Jul 20, 4:17 PM MST, 2 hours 28 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
517 PM MDT FRI JUL 20 2007

UPDATED AVIATION SECTION ONLY

.DISCUSSION...
TONIGHT THROUGH SUNDAY...IN A NUTSHELL...CONTINUED HOT AND MOSTLY
DRY. FORECAST AREA WILL CONTINUE UNDER THE INFLUENCE OF THE UPPER
RIDGE OF HIGH PRESSURE. AIRMASS IS UNSTABLE THIS AFTERNOON BUT AM
NOT SEEING TOO MUCH IN THE WAY OF LIFT. STILL EXPECT ISOLATED
THUNDERSTORMS TONIGHT. THERE IS ENOUGH INSTABILITY IN THE EAST FOR
A THREAT OF STRONGER THUNDERSTORMS. AIRMASS WILL EITHER BE STABLE
OR WEAKLY UNSTABLE SAT AND SUN AND DO NOT SEE ANY SHORTWAVES TO
WRITE HOME ABOUT SO WILL GO WITH A DRY FORECAST. EXCEPTION IS OVER
THE MOUNTAINS OF THE ROCKY MOUNTAIN FRONT ON SUNDAY WHERE THERE
COULD BE ENOUGH MOISTURE FOR A THUNDERSTORM OR TWO. BLANK

SUNDAY NIGHT THROUGH TUESDAY NIGHT...UPPER LEVEL RIDGE TO SLOWLY
MOVE EASTWARD WITH MOIST SOUTHWEST FLOW ALOFT TO MOVE OVER THE AREA.
CONTINUED WARM TEMPERATURES WITH ISOLATED THUNDERSTORMS INCREASING
TO SCATTERED THUNDERSTORMS DURING THE PERIOD. MODELS KEEP INDICATING
A MONSOONAL TAP TO BRING MOISTURE UP AND OVER AREA. HAVE RAISED POPS
SLIGHTLY OVER THE SOUTHERN PORTION OF THE ZONES TO INDICATE THIS
POSSIBILITY. CAMP

WEDNESDAY THROUGH FRIDAY...A STRONG UPPER LEVEL RIDGE IS PROGGED TO
MOVE EAST TO THE CENTRAL PLAINS. THUS...ALLOWING A MORE WESTERLY FLOW
ALOFT ACROSS MONTANA BY FRIDAY AS THE RIDGE FLATTENS. IT WILL
CONTINUE TO BE HOT...BUT SLIGHTLY COOLER FRIDAY. THERE WILL BE
ISOLATED/SCATTERED THUNDERSTORMS...MAINLY DURING THE AFTERNOON
THROUGH EARLY NIGHTTIME HOURS. WILLIAMSON DC

&&

.AVIATION...
UPDATED 2317Z.
AN UPPER LEVEL RIDGE WILL CONTINUE TO INFLUENCE THE REGION THROUGH
THE NEXT 24 HOURS. SCATTERED CUMULUS CLOUDS AND ISOLATED
THUNDERSTORMS ARE POSSIBLE OVER THE NORTHERN ROUTES THROUGH THE
EVENING WHILE CONDITIONS WILL REMAIN DRY OVER THE SOUTHWEST. SKIES
WILL CLEAR OUT AFTER 06Z EXCEPT FOR SOME LINGERING SMOKE FROM AREA
FIRES...VISIBILITY IS NOT EXPECTED TO DROP BELOW 6 STATUTE MILES.
SURFACE WINDS WILL BE ON THE INCREASE SATURDAY...ESPECIALLY AROUND
KCTB. THOMSON

&&

.FIRE WEATHER...
UPDATED 2100Z.
A RED FLAG WARNING IS IN EFFECT OF ALL OF SOUTHWEST MONTANA FOR THIS
AFTERNOON AND EVENING...AS ANOTHER DAY OF HOT TEMPERATURES...LOW
HUMIDITIES...AND BREEZY WINDS DEVELOP. THERE IS A THREAT FOR AN
ISOLATED THUNDERSTORM THROUGH THE EVENING HOURS. EXPECT SLOWLY
IMPROVING CONDITIONS AFTER 9 PM THIS EVENING. BREEZY CONDITIONS AND
LOW HUMIDITIES CAN BE EXPECTED OVER THE NORTHWEST REGION SATURDAY
AND A FIRE WEATHER WATCH HAS BEEN ISSUED FOR FIRE ZONE 112 FROM NOON
UNTIL 9 PM SATURDAY. ADDITIONAL FIRE WEATHER HIGHLIGHTS COULD BE
ISSUED TOMORROW FOR OTHER PORTIONS OF THE AREA FOR THIS WEEKEND. CAMP

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  66  97  61 100 /  20   0   0   0
CTB  61  91  58  94 /  20   0   0   0
HLN  64  98  61 101 /  10   0   0   0
BZN  59 100  57 103 /  10   0   0   0
WEY  51  87  50  90 /  10  10  10  10
DLN  56  91  56  94 /  10   0   0  10
HVR  65  99  60 102 /  20   0   0  10
LWT  63  94  60  98 /  20   0   0  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR MTZ118.

FIRE WEATHER WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY EVENING
FOR MTZ112.

&&

SHORT TERM...BLANK
LONG TERM...COULSTON
AVIATION...THOMSON

WEATHER.GOV/GREATFALLS

Hazardous weather outlook, Jul 20, 1:57 PM MST, 4 hours 48 minutes before

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE GREAT FALLS MT
257 PM MDT FRI JUL 20 2007

MTZ008-014-015-052-053-055-211200-
BEAVERHEAD-CENTRAL AND SOUTHERN LEWIS AND CLARK-MADISON-JEFFERSON-
BROADWATER-GALLATIN-
257 PM MDT FRI JUL 20 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST
MONTANA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A RED FLAG WARNING REMAINS IN EFFECT FOR MUCH OF SOUTHWEST
MONTANA THROUGH EARLY THIS EVENING. HOT TEMPERATURES...COMBINED
WITH LOW HUMIDITIES AND INCREASING WINDS WILL ALLOW FOR CRITICAL
FIRE WEATHER CONDITIONS TO EXIST. ADDITIONALLY...ISOLATED
THUNDERSTORMS MAY ALSO DEVELOP DURING THIS TIME. SOME OF THE
STRONGER THUNDERSTORMS WILL PRODUCE GUSTY ERRATIC WINDS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

MTZ009-010-044>046-211200-
NORTHERN ROCKY MOUNTAIN FRONT-EASTERN GLACIER-TOOLE-LIBERTY-
EASTERN PONDERA-
257 PM MDT FRI JUL 20 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
MONTANA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

ISOLATED THUNDERSTORMS ARE POSSIBLE OVER NORTH CENTRAL AND
CENTRAL MONTANA THROUGH THIS EVENING. AN ISOLATED STRONG
THUNDERSTORM IS POSSIBLE...WITH THE MAIN THREAT BEING A DAMAGING
WIND GUST...BUT A WIDESPREAD SEVERE WEATHER EVENT IS NOT EXPECTED
AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

BREEZY WESTERLY WINDS WILL DEVELOP ON SATURDAY ALONG THE NORTHERN
ROCKY MOUNTAIN FRONT AND ACROSS THE ADJACENT PLAINS. HOT AND DRY
CONDITIONS WILL ALSO CONTINUE ACROSS THIS AREA...WITH RELATIVE
HUMIDITIES IN SOME AREAS FALLING TO NEAR OR BELOW 20 PERCENT.
BECAUSE OF THIS EXPECTED COMBINATION OF DRY AND BREEZY
CONDITIONS...A FIRE WEATHER WATCH HAS BEEN ISSUED FOR THIS AREA
FOR SATURDAY AFTERNOON INTO EARLY SATURDAY EVENING.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

MTZ011>013-047>051-054-211200-
HILL-CASCADE-CHOUTEAU-BLAINE-SOUTHERN ROCKY MOUNTAIN FRONT-
EASTERN TETON-JUDITH BASIN-FERGUS-MEAGHER-
257 PM MDT FRI JUL 20 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
MONTANA...NORTH CENTRAL MONTANA AND SOUTHWEST MONTANA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

ISOLATED THUNDERSTORMS ARE POSSIBLE OVER NORTH CENTRAL AND
CENTRAL MONTANA THROUGH THIS EVENING. AN ISOLATED STRONG
THUNDERSTORM IS POSSIBLE...WITH THE MAIN THREAT BEING A DAMAGING
WIND GUST...BUT A WIDESPREAD SEVERE WEATHER EVENT IS NOT EXPECTED
AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

COULSTON/BRUSDA

In the hours before

Local storm report, Jul 20, 1:49 PM MST, 4 hours 56 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
249 PM MDT FRI JUL 20 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0715 PM     HAIL             20 N INVERNESS          48.85N 110.68W
07/19/2007  E0.75 INCH       HILL               MT   TRAINED SPOTTER

            MOST HAIL WAS PEA SIZED ... HAIL OCCURED IN FOUR SEPARATE
            VOLLEYS AND FELL THE MAJORITY OF THE TIME UNTIL ENDING
            AROUND 745PM MDT ... PENNY SIZED FELL ONLY AFTER 730PM
            MDT

&&

MCGINNIS

Local storm report, Jul 20, 1:55 PM MST, 4 hours 50 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
255 PM MDT FRI JUL 20 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0800 PM     HEAVY RAIN       20 N INVERNESS          48.85N 110.68W
07/19/2007  M2.25 INCH       HILL               MT   TRAINED SPOTTER

            RAIN FELL BETWEEN ABOUT 600PM AND 800PM MDT

&&

MCGINNIS

Local storm report, Jul 20, 2:18 PM MST, 4 hours 27 minutes before

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE GREAT FALLS MT
318 PM MDT FRI JUL 20 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0735 PM     HAIL             20 N INVERNESS          48.85N 110.68W
07/19/2007  E0.75 INCH       HILL               MT   TRAINED SPOTTER

            PENNY SIZED HAIL FELL ONLY FROM 735 PM THROUGH 745 PM.
            HAIL OCCURRED IN FOUR SEPARATE VOLLEYS BETWEEN 715 PM AND
            745 PM...BUT THE MAJORITY OF THIS HAIL WAS DIME SIZED OR
            SMALLER.

&&

MCGINNIS

The radar

The Great Falls radar (KTFX), 118 km away, was scanning. The volume nearest the first event began at 01:47 UTC.

Open the radar archive at this moment

Event by event

5 hail, 1 thunderstorm wind. Local standard time, as filed.

Hail, Chouteau

When: July 20, 6:45 PM MST
Where: Chouteau County, 20 mi SSE of Big Sandy
Measured: 1.25 in hail
Reported by: Public
Coordinates: 47.913, -109.954

A severe thunderstorm dropped 1.25 inch diameter hail at Big Sandy 20SSE.

Hail, Chouteau

When: July 20, 7:16 PM MST
Where: Chouteau County, 25 mi SE of Big Sandy
Measured: 0.88 in hail
Reported by: Fire Department/Rescue
Coordinates: 47.924, -109.738

A severe thunderstorm dropped .88 inch diameter hail at Big Sandy 25SE.

Thunderstorm Wind, Blaine

When: July 20, 8:00 PM MST
Where: Blaine County, 11 mi S of Chinook
Measured: 52 kt (60 mph) measured gust
Reported by: Trained Spotter
Coordinates: 48.421, -109.230

A severe thunderstorm produced a wind gust to 60 mph at Chinook 11S.

Hail, Chouteau

When: July 20, 8:05 PM MST
Where: Chouteau County, 3 mi NNE of Warrick
Measured: 0.88 in hail
Reported by: Trained Spotter
Coordinates: 48.110, -110.595

A severe thunderstorm dropped .88 inch diameter hail at Warrick 3NNE.

Hail, Hill

When: July 20, 9:30 PM MST
Where: Hill County, 12 mi E of Box Elder
Measured: 1 in hail
Reported by: Trained Spotter
Coordinates: 48.320, -109.759

A severe thunderstorm dropped 1 inch diameter hail at Box Elder 12E.

Hail, Hill

When: July 20, 10:18 PM MST
Where: Hill County, Havre
Measured: 1.25 in hail
Reported by: Law Enforcement
Coordinates: 48.550, -109.680

A severe thunderstorm dropped 1.25 inch diameter hail at the Hill County Sheriff's office in Havre.

What these are

Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
Thunderstorm Wind: Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.

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

The same day elsewhere

Every storm in Montana in 2007 Every state in 2007 This day in weather history Warnings in Montana, July 2007

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: 46056, 46057, 46058, 46059, 46060, 46061.