Flooding in Montana, March 12 to 13, 2003

Name: Flooding in Montana, March 12 to 13, 2003
Start: 2003-03-12T12:00
End: 2003-03-13T18:00
Location: Montana

March 12 to 13, 2003 · NWS TFX · 4 events in 4 counties and zones

The toll

Deaths: 0
Injuries: 0
Property damage: $750,000
Crop damage: None recorded
Events: 4

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.

With a major snowstorm falling in the mountains in the Helena Valley on March 6th through the 10th, and temperatures quickly rising to near 70 degrees by the 12th, a rapid snow melt occurred in the mountains. This snow melt quickly filled all small streams and creeks. As the snow continued to melt during the afternoon hours, the creeks began to overflow, as some culverts were blocked with ice and debris. The result was some nearby homes and roads next to the creeks were either damaged or washed out. Water was up to a foot deep in some locations. Damage reports in the Helena Valley included about 20 homes with flood damage, and a few secondary roads washed out. The damage cost was estimated at $250,000. In the Bozeman area, a few gravel roads were washed out, along with a small bridge. Damage costs were estimated at $500,000. Further north, flooding did occur on small creeks flowing out of the Bears Paw Mountains south of Havre. No damage was reported, but a few rural roads were under 6 inches of water during the afternoon hours on the 12th and 13th.

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 Mar 12, 9:00 AM MST, 3 hours earlier.

Area forecast discussion, Mar 12, 9:00 AM MST, 3 hours before

SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
900 AM MST WED MAR 12 2003

.SHORT TERM...WILL UPDATE ZONES AND STATE FORECASTS. STUBBORN ARCTIC
BOUNDARY (ORIENTED FROM NORTHWEST TO SOUTHEAST) IS STILL HUNG UP OVER
CENTRAL PART OF THE CWA. THE POSITION AND DEPTH OF THIS BOUNDARY HAS
MADE TEMPERATURE FORECASTS VERY DIFFICULT AS OF LATE. AT 830AM...IN
CASCADE COUNTY TEMPS WERE 37 AT MONARCH...32 AT THE GREAT FALLS
AIRPORT...BUT ONLY ABOUT 15 IN THE CITY OF GREAT FALLS. WINDS ALOFT
HAVE BEEN MUCH LIGHTER THAN FORECAST THIS MORNING...MAKING IT
DIFFICULT TO SCOUR OUT THE ARCTIC AIR IN THE LOWER ELEVATIONS.
HOWEVER...SUBSIDENCE BEHIND A DEPARTING DISTURBANCE MOVING INTO
EASTERN MONTANA SHOULD HELP TO START MIXING THE LOWER TROPOSPHERE.
ALSO...A DEVELOPING SURFACE TROUGH EAST OF THE ROCKIES AND
INCREASING WESTERLY FLOW ALOFT SHOULD FINALLY BE ABLE TO NUDGE THE
ARCTIC AIR OUT OF MOST OF THE AREA BY LATE AFTERNOON. WILL LOWER
TEMPS A BIT TO THE NORTH TO ACCOUNT FOR SLOWER THAN EXPECTED RETREAT
OF ARCTIC AIR. WILL ALSO MAKE SKY CONDITION MOSTLY CLOUDY SINCE A
THICK CHINOOK ARCH HAS FORMED. REST OF THE FORECAST LOOKS GOOD. WINDS
WILL INCREASE ALONG THE ROCKY MOUNTAIN FRONT LATE THIS AFTERNOON...SO
WILL LEAVE HIGH WIND WARNING AS IS. THERE IS A POTENTIAL FOR STRONG
WINDS ACROSS THE ADJACENT PLAINS TOMORROW. WILL TAKE A CLOSER LOOK
FOR THE AFTERNOON PACKAGE AND WILL CONTINUE THE HIGH WIND WATCH.
VILLANI

.EXTENDED...DEEP UPPER LEVEL TROUGH REMAINS OVER THE EASTERN PACIFIC
EARLY IN THE 4-7 DAY PERIOD. SOUTHWEST FLOW ALOFT CONTINUES OVER
MONTANA THROUGH SUNDAY...WITH DOWNSLOPE WINDS OVER THE PLAINS. HAVE
DROPPED POPS OVER THE PLAINS FOR MOST OF THE WEEKEND...BUT KEPT A
CHANCE OF PRECIPITATION FOR THE WESTERN MOUNTAINS AND SOUTHWEST. A
STRONG PACIFIC JET DRIVES THE UPPER TROUGH INLAND SUNDAY NIGHT INTO
MONDAY...WITH THE BULK OF THE ENERGY HITTING THE SOUTHWESTERN CONUS.
WEAKER TROUGHINESS MOVES OVER MONTANA...ALLOWING SURFACE DOWNSLOPE
FLOW TO WEAKEN AND SPREADING A CHANCE OF PRECIPITATION ACROSS THE
ENTIRE CWA ON MONDAY AND MONDAY NIGHT. A STRONG SURFACE LOW DEVELOPS
OVER THE SOUTHERN PLAINS...VEERING SURFACE WINDS TO THE NORTH FOR
COOLER TEMPERATURES THROUGH MID-WEEK. SPLIT FLOW ALOFT OVER THE
STATE WILL KEEP A SLIGHT CHANCE OF PRECIPITATION ACROSS THE CWA ON
TUESDAY. MPJ

.CCF NUMBERS
GTF EN 051/045 062/046 062 19000
    NEEEE 036/055 031/055 030/047 025/044 028 00022003332
CTB EN 044/039 059/042 059 19000
    NEEEE 032/050 026/051 026/043 024/041 027 00022003332
HLN EE 054/036 060/040 059 19200
    EEEEE 031/050 031/051 029/044 027/043 027 02233223332
BZN EE 052/036 058/037 058 19200
    EEEEE 030/051 029/054 024/045 022/044 022 12344323332
WEY CE 044/027 050/028 048 19312
    EEEEE 023/042 023/047 019/034 016/033 016 33344335532
DLN EE 052/037 058/036 053 1920-
    EEEEE 031/049 031/050 024/043 018/042 024 12333323332
HVR EN 039/032 062/037 061 19000
    EEEEE 031/052 031/052 032/045 027/043 027 00000003332
LWT EN 050/040 059/042 060 19000
    EEEEE 031/055 031/053 028/048 025/042 026 00022113332

.TFX...HIGH WIND WARNING FOR THE NORTHERN ROCKY MOUNTAIN FRONT LATE
       THIS AFTERNOON AND TONIGHT.
    ...HIGH WIND WATCH FOR THE ROCKY MOUNTAIN FRONT AND ADJACENT
       PLAINS FOR THURSDAY.

Hazardous weather outlook, Mar 12, 4:32 AM MST, 7 hours 28 minutes before

MTZ008>015-044>055-130110-
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREAT FALLS MT
432 AM MST WED MAR 12 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND SOUTHWEST
MONTANA

.DAY ONE...TODAY

A HIGH WIND WARNING IS IN EFFECT FOR THE NORTHERN ROCKY MOUNTAIN
FRONT FOR LATE THIS AFTERNOON THROUGH TONIGHT. REFER TO GTFNPWTFX
FOR ADDITIONAL INFORMATION.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

A HIGH WIND WATCH IS IN EFFECT FOR THE ROCKY MOUNTAIN FRONT AND
ADJACENT PLAINS FOR THURSDAY. REFER TO GTFNPWTFX FOR ADDITIONAL
INFORMATION.

.SPOTTER INFORMATION STATEMENT...

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

Event by event

4 flood. Local standard time, as filed.

Flood, Southern Lewis and Clark

When: March 12, 12:00 PM MST to March 13, 6:00 PM MST
Where: Southern Lewis and Clark forecast zone
Property damage: $250,000
Reported by: TRAINED SPOTTER

Flood, Gallatin

When: March 12, 12:00 PM MST to March 13, 6:00 PM MST
Where: Gallatin forecast zone
Property damage: $500,000
Reported by: TRAINED SPOTTER

Flood, Hill

When: March 12, 12:00 PM MST to March 13, 6:00 PM MST
Where: Hill forecast zone
Reported by: TRAINED SPOTTER

Flood, Blaine

When: March 12, 12:00 PM MST to March 13, 6:00 PM MST
Where: Blaine forecast zone
Reported by: TRAINED SPOTTER

What these are

Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.

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

The same day elsewhere

Every storm in Montana in 2003 Every state in 2003 This day in weather history Warnings in Montana, March 2003

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: 5345156, 5345486, 5345944, 5345945.