Damaging Wind in Idaho, September 18, 2010

Name: Damaging Wind in Idaho, September 18, 2010
Start: 2010-09-18T01:00
End: 2010-09-18T02:00
Location: Idaho

September 18, 2010 · NWS MSO · 1 event in 1 county or zone

A closed low off the California coast ejected impulses of moisture and energy in to the northern Rockies. This resulted in a few thunderstorms, mainly over north central Idaho.

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

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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 1

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 MSO wrote it up.

A closed low off the California coast ejected impulses of moisture and energy in to the northern Rockies. This resulted in a few thunderstorms, mainly over north central Idaho. The main threat produced with these storms was strong damaging wind, causing numerous trees and power lines to be blown down.

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 Missoula, MT wrote its last area forecast discussion before the first event at Sep 17, 12:33 PM PST, 12 hours 27 minutes earlier.

Area forecast discussion, Sep 17, 12:33 PM PST, 12 hours 27 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
233 PM MDT FRI SEP 17 2010

.DISCUSSION...
TONIGHT AND SATURDAY...THE UPPER FLOW PATTERN RESEMBLES A WEAK
RIDGE. HOWEVER...THERE IS CONSIDERABLE AMOUNT OF PACIFIC
MOISTURE CAUGHT UP IN FLOW OVER THE NORTHERN ROCKIES. COMBINE THIS
MOISTURE WITH LARGE-SCALE ASCENT PLUS A LOW LEVEL BOUNDARY DRAPED
OVER NORTHWEST MONTANA AND PERIODIC PRECIPITATION WILL REMAIN A
FIXTURE FOR NORTHWEST MONTANA. AN EASTERLY SURFACE PRESSURE
GRADIENT ACROSS WESTERN MONTANA WILL PROMOTE AN INFLUX OF COOLER
AIR THROUGH THE GAPS OF THE CONTINENTAL DIVIDE DURING THIS PERIOD.
LOCATIONS SUCH AS HELLGATE CANYON (NEAR EAST MISSOULA) WILL LIKELY
SEE GUSTS UP 30 MPH OVERNIGHT TONIGHT. THE WEST GLACIER REGION
WILL LIKELY SEE ADDITIONAL SNOW OVER THE HIGH COUNTRY (ABOVE 5500
FT) TONIGHT WITH ACCUMULATIONS 1 TO 2 INCHES. HIGHEST PEAKS IN THE
PARK COULD SEE UP TO 5 INCHES.

SATURDAY NIGHT AND SUNDAY...AS AN UPPER LEVEL TROUGH NEARS THE
WEST COAST...THE SUBSEQUENT FLOW UPSTREAM OVER THE NORTHERN
ROCKIES BECOMES MORE SOUTHWESTERLY. THIS WILL CAUSE COLD AIR TO
RETREAT EAST OF THE DIVIDE AS WARMER AIR IS DRAWN UP FROM THE
SOUTH. THE INFLUX OF PACIFIC MOISTURE WILL CONTINUE TO FEED INTO
THE IDAHO PANHANDLE AND NORTHWEST MONTANA...WHERE ELEVATED CHANCES
OF PRECIPITATION REMAIN. WEST-CENTRAL MONTANA AND LEMHI COUNTY
WILL BE EXPERIENCING DRYER AIR THAT WILL RESULT IN WARMER
TEMPERATURES AND MORE FAVORABLE CONDITIONS.

MONDAY THROUGH FRIDAY...THE ACTIVE WEATHER PATTERN THAT HAS
ENGULFED THE PACIFIC NORTHWEST WILL REMAIN IN PLACE THROUGH THIS
UPCOMING WEEK. WATER VAPOR IMAGERY SHOW MANY LOW PRESSURE SYSTEMS
TO THE WEST IN THE PACIFIC THAT HAVE THE POTENTIAL TO MOVE THROUGH
THE NORTHERN ROCKIES THROUGH THIS WEEK. THE FIRST TROUGH THAT IS
CURRENTLY OFF THE WEST COAST WILL ENCOUNTER A SHORTWAVE TROUGH
PASSING SOUTH OUT OF BRITISH COLUMBIA. THE TROUGH COMBINATION WILL
THEN PASS THROUGH THE NORTHERN ROCKIES ON MONDAY. THIS WILL KEEP
HIGH CHANCES FOR RAIN THROUGH MOST OF THE AREA ON MONDAY WITH THE
FOCUS MOVING TO NORTHWEST MONTANA INTO TUESDAY. MODEL GUIDANCE
LOSE MUCH OF THEIR CONTINUITY ON TUESDAY BUT IT DOES APPEAR THAT
SOME DRIER AIR COULD MOVE INTO THE REGION FOR THE MIDDLE OF THE
WEEK THAT COULD LESSEN THE CHANCES FOR RAIN FOR A SHORT TIME.

&&

.AVIATION...WEST TO SOUTHWESTERLY FLOW ALOFT WILL CONTINUE TO
FEED MOIST AIR OVER THE IDAHO PANHANDLE AND INTO NORTHWEST
MONTANA (EXTENDING AS FAR SOUTH AS MISSOULA). OCCASIONAL LOWER
CEILINGS AND LIGHT PRECIPITATION WILL OBSCURE HIGHER TERRAIN...
IMPACTING AIRFIELDS ACROSS THESE NORTHERN AREAS. LOCATIONS FARTHER
SOUTH...THE AIR MASS IS DRIER AND SKY CONDITIONS SHOULD BE MORE
FAVORABLE FOR AVIATION OPERATIONS.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&

SHORT TERM...MSJ
LONG TERM....KITSMILLER
AVIATION...MSJ

The radar

The Missoula radar (KMSX), 177 km away, was scanning. The volume nearest the first event began at 09:00 UTC.

Open the radar archive at this moment

Event by event

1 thunderstorm wind. Local standard time, as filed.

Thunderstorm Wind, Clearwater

When: September 18, 1:00 AM PST to 2:00 AM PST
Where: Clearwater County, 5.04 mi NNE of Greer
Measured: 50 kt (58 mph) estimated gust
Reported by: Trained Spotter
Coordinates: 46.450, -116.140

Numerous blow downs throughout Clearwater County. Spotter reported 18 and 20 inch diameter trees broken at the base and mid-section respectively. Power and phone service was knocked out. A 26 foot airstream trailer was moved off its jack. Fire starts from lightning were also reported from this storm.

What these are

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 Idaho in 2010 Every state in 2010 This day in weather history Warnings in Idaho, September 2010

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: 260315.