Damaging Wind in Colorado, September 19, 2004

Name: Damaging Wind in Colorado, September 19, 2004
Start: 2004-09-19T11:30
End: 2004-09-19T11:40
Location: Colorado

September 19, 2004 · NWS GJT · 1 event in 1 county or zone

Strong thunderstorm outflow winds totally destroyed a 12 foot by 60 foot Civil Air Patrol trailer at the airport. The trailer had rooms for office space, training, and briefing.

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: $40,000
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 GJT wrote it up.

Strong thunderstorm outflow winds totally destroyed a 12 foot by 60 foot Civil Air Patrol trailer at the airport. The trailer had rooms for office space, training, and briefing. A section of chain link fence at the airport was also destroyed when the trailer was blown through it. Numerous large trees were blown over or snapped off throughout the town, with at least one vehicle crushed and a mobile home damaged by falling trees.

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 Grand Junction, CO wrote its last area forecast discussion before the first event at Sep 19, 3:30 AM MST, 8 hours earlier.

Area forecast discussion, Sep 19, 3:30 AM MST, 8 hours before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
430 AM MDT SUN SEP 19 2004

.SHORT TERM (TODAY THROUGH MONDAY)...
TROPICAL MOISTURE PLUME...COURTESY OF FORMER HURRICANE JAVIER...
STREAMING NORTHWARD THIS MORNING.  LEADING EDGE OF DEEPER MOISTURE
IS RIGHT OF A LINE FROM PRICE UT TO MONTROSE.  DEEP SOUTHERLY FLOW
FROM BAJA CALIFORNIA WILL CONTINUE TO BRING DEEP TROPICAL MOISTURE
ACROSS OUR FORECAST AREA TODAY.  HAVE BOOSTED POPS TO CATEGORICAL FOR
ALL ZONES...CANNOT IMAGINE ANYWHERE STAYING DRY FOR THE NEXT 12 HOURS
FOR THE FOLLOWING REASONS.  IF DIVERGENCE ALOFT AND A DEEP SHEAR
LAYER WEREN/T ENOUGH FOR UPWARDS FORCING...A WAVE AT THE BASE OF
AMPLIFIED LONG WAVE WILL EJECT NORTHEAST ACROSS UTAH FOR ADDITIONAL
LIFT.  MOST LIKELY THE STRONG SHEAR WILL BE TOO MUCH TO SUPPORT
STRONG UPDRAFTS...BUT THERE STILL MAY BE A SMALL CHANCE THAT ONE OR
TWO CELLS MAY PRODUCE SEVERE WEATHER IN THE FORM OF HAIL AND/OR WET
MICROBURST WINDS...MAINLY NORTH OF I70.  SOUTH OF I70...THE MAIN
WEATHER THREAT WILL BE FLASH FLOODING.  EARLIER SHIFTS HAD ALREADY
HOISTED A FLASH FLOOD WATCH FOR PARTS OF SE UTAH AND SW COLORADO...
THIS LOOKS GOOD AND NO ADJUSTMENT WILL BE NEEDED THIS MORNING.

BY LATE AFTERNOON...MOISTURE PLUME WILL SHIFT A LITTLE EASTWARD AS
DEEP WEST COAST TROUGH SHIFTS INLAND.  AIR MASS IS CONSIDERABLY DRIER
WEST OF THE MOISTURE PLUME (ONE ONLY NEEDS TO LOOK AT THE DESERT ROCK
SOUNDING TO CONFIRM THIS).  DRIER AIR WILL SPREAD INTO EASTERN UTAH
AND NW COLORADO BY LATE AFTERNOON...BUT MOISTURE PLUME WILL CONTINUE
TO IMPACT THE SAN JUAN MOUNTAINS AND THE WEST CENTRAL MOUNTAINS
OVERNIGHT.  EXPECT RAINFALL RATES TO DIMINISH AS THE TROPICAL
MOISTURE TAP WILL BE WEAKENING.  ON THE OTHER HAND...AS THE WESTERN
EDGE OF MOISTURE PLUME SHIFTS EASTWARD...CONVECTIVE ACTIVITY MAY
INCREASE.  DON/T THINK WHAT/S OCCURRING OVER WRN ARIZONA THIS MORNING
WILL HAPPEN IN OUR FORECAST AREA SINCE THE UPPER WAVE WILL HAVE
MOVED AND WEAKENED OVER ERN IDAHO/WRN WYOMING BY EVENING...BUT
ISOLATED STRONG CONVECTION MAY STILL OCCUR.

ETA AND GFS MODELS DIVERGE BY LATE TONIGHT WITH RESPECT TO THE
SURFACE COLD FRONT...CURRENTLY POSITIONED NEAR THE WASATCH FRONT.
GFS IS SLOWER THAN THE ETA...AND THAT/S THE PREFERRED SOLUTION WITH
STRONG RIDGE OVER THE EASTERN CONUS...IN ADDITION TO THE DEEP
SOUTHERLY FLOW IN ADVANCE OF COLD FRONT THAT WILL SLOW ITS EASTWARD
MOVEMENT.  HOWEVER...MAV POP GUIDANCE APPEAR TOO LOW FOR MONDAY
GIVEN THE CLOSE PROXIMITY OF H7/H5 THERMAL GRADIENT.  ALSO...THE
PROBABILITY THAT THE SURFACE COLD FRONT REACHES EXTREME NW PORTION
OF COLORADO WILL INCREASE THROUGH THE DAY ON MONDAY.  SO WILL SPLIT
THE DIFFERENCE BETWEEN MAV AND ETA MOS GUIDANCE WITH CHANCE POPS
FOR THE NORTHERN ZONES.  MAV GUIDANCE LOOKS RESPECTABLE FOR THE
SOUTHERN ZONES WITH CHANCE POPS.

.LONG TERM (MONDAY NIGHT THROUGH SATURDAY)...GFS A LITTLE STRONGER
WITH INCOMING SYSTEM WITH A CLOSED LOW DEVELOPING AS THE TROF DEEPENS
OVER THE GREAT BASIN. THE EC MAINTAINS A OPEN TROF WHILE THE DGEX
IS ON BOARD WITH THE GFS SOLUTION WITH RESPECT TO TIMING AND
INTENSITY. MAIN MESSAGE IS A CHANGE TO A MORE UNSETTLED WEATHER
PATTERN WITH SIGNIFICANTLY COOLING TEMPERATURES. BY LATE IN THE WEEK
HIGH PRESSURE REBUILDS OVER THE REGION.

MONDAY NIGHT AND TUESDAY...THE TROF DEEPENS OVER THE GREAT BASIN
WITH A GOOD COMBINATION OF DYNAMIC FORCING AND MOISTURE
COINCIDING OVER OUR CWA FOR WIDESPREAD PRECIP. COLD FRONTAL
PASSAGE SHOULD BEGIN OVER THE NORTHWESTERN PORTIONS LATE MONDAY
NIGHT AND PROGRESS THRU THE CWA TUESDAY AS THE TROF AXIS BECOMES
SEMI-STATIONARY ALONG THE UT/CO BORDER. THE HEAVIEST PRECIP
SHOULD OCCUR OVER THE NRN MTNS OF COLORADO. SNOW LEVELS WILL
BE LOWERING TO NEAR 7000 FT BY EARLY TUE.

WEDNESDAY...THE ETA SHOWS A CLOSED LOW DEVELOPING NEAR THE FOUR
CORNERS WITH THE COLD POOL NEAR NW COLORADO. WHILE THE DGEX
SHOWS THE LOW CENTER FURTHER NORTH RESULTING IN LESS WEATHER
FOR THE CENTRAL AND SOUTHERN PORTIONS. TROF PASSAGE IS ALSO
EXPECTED DURING THE DAY WITH THE UPPER FLOW TRANSITIONING TO THE
NORTHWEST WHICH WILL PRODUCE UPSLOPE OROGRAPHIC DRIVEN SHOWERS
OVER THE NORTHERN MTNS. TEMPS WILL BE COLD ENOUGH TO PRODUCE
SNOW TO AS LOW AS 6500 FT. DRIER CONDITIONS WILL DEVELOP ACROSS THE
SOUTH BUT IT WILL REMAIN COOL.

THURSDAY THROUGH SATURDAY...A COOL BUT DRIER AND MORE STABLE
NORTHWEST FLOW WILL PREVAIL OVER THE AREA AS HIGH PRESSURE DEVELOPS
TO OUR WEST. THE RIDGE WILL SHIFT EASTWARD WITH TIME AS THE AXIS
PASSES TO OUR EAST AROUND SAT. TEMPS WILL GRADUALLY WARM AND
CREEP TOWARD NORMAL BY SATURDAY.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
.CO...FLASH FLOOD WATCH TODAY FOR SOUTHWEST COLORADO...INCLUDING
      ZONES 18...21...22 AND 23.
.UT...FLASH FLOOD WATCH TODAY FOR SOUTHEAST UTAH...INCLUDING ZONES
      22...28 AND 29.

&&

PF/MC/DJN

Hazardous weather outlook, Sep 19, 7:02 AM MST, 4 hours 28 minutes before

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
802 AM MDT SUN SEP 19 2004

UPDATED TO INCLUDE SEVERE THUNDERSTORM THREAT

COZ001>014-017-018-020-UTZ023>025-027-201200-
ARCHES/GRAND FLAT-CENTRAL COLORADO RIVER BASIN-
CENTRAL GUNNISON AND UNCOMPAHGRE RIVER BASIN-
CENTRAL YAMPA RIVER BASIN-DEBEQUE TO SILT CORRIDOR-
EASTERN UINTA BASIN-EASTERN UINTA MOUNTAINS-
ELKHEAD AND PARK MOUNTAINS-FLAT TOPS-
GORE AND ELK MOUNTAINS/CENTRAL MOUNTAINS-GRAND AND BATTLEMENT MESAS-
GRAND VALLEY-LOWER YAMPA RIVER BASIN-NORTHWEST SAN JUAN MOUNTAINS-
PARADOX VALLEY/LOWER DOLORES RIVER-ROAN AND TAVAPUTS PLATEAUS-
TAVAPUTS PLATEAU-UNCOMPAHGRE PLATEAU AND DALLAS DIVIDE-
UPPER GUNNISON RIVER VALLEY-UPPER YAMPA RIVER BASIN-
WEST ELK AND SAWATCH MOUNTAINS-
802 AM MDT SUN SEP 19 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST-CENTRAL AND NORTHEAST
UTAH...AND WEST-CENTRAL AND NORTHWEST COLORADO.

.DAY ONE...TODAY AND TONIGHT...

WIDESPREAD SHOWERS AND THUNDERSTORMS WILL OCCUR TODAY. ISOLATED
SEVERE THUNDERSTORMS ARE POSSIBLE. THE MAIN THREAT FROM THE STORMS
WILL BE WIND GUSTS UP TO 60 MPH...AND HAIL UP TO 3/4 INCH IN DIAMETER.
LOCALLY HEAVY RAIN IS POSSIBLE WITH SOME STORMS. SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO DECREASE THIS EVENING.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY...

THE CHANCE OF THUNDERSTORMS WILL CONTINUE ON MONDAY.  WITH COLDER
AIR MOVING INTO NORTHEAST UTAH AND NORTHWEST COLORADO ON MONDAY...A
CHANCE OF MOUNTAIN SNOW WILL BE POSSIBLE BY MONDAY NIGHT AND
CONTINUING THROUGH WEDNESDAY.  THE FIRST SIGNIFICANT SNOWFALL OF THE
SEASON MAY OCCUR MONDAY NIGHT AND TUESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED TODAY.

COZ019-021>023-UTZ022-028-029-201200-
ANIMAS RIVER BASIN-CANYONLANDS/NATURAL BRIDGES-
FOUR CORNERS/UPPER DOLORES RIVER-LA SAL AND ABAJO MOUNTAINS-
SAN JUAN RIVER BASIN-SOUTHEAST UTAH-SOUTHWEST SAN JUAN MOUNTAINS-
802 AM MDT SUN SEP 19 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST UTAH AND
SOUTHWEST COLORADO.

...FLASH FLOOD WATCH THROUGH 600 PM TODAY...

.DAY ONE...TODAY AND TONIGHT...

WIDESPREAD SHOWERS AND THUNDERSTORMS WILL OCCUR TODAY. HEAVY RAIN IS
POSSIBLE ALONG WITH ISOLATED SEVERE THUNDERSTORMS. THE POTENTIAL
EXISTS FOR FLASH FLOODING. WIND GUSTS UP TO 65 MPH AND HAIL UP TO 3/4
INCH IN DIAMETER IS POSSIBLE WITH SOME STORMS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY...

THE CHANCE OF THUNDERSTORMS WILL CONTINUE ON MONDAY.  WITH COLDER
AIR SPREADING ACROSS EASTERN UTAH AND WESTERN COLORADO BY MONDAY
NIGHT...A CHANCE OF MOUNTAIN SNOW EXISTS.  THE SNOW LEVEL WILL FALL
BELOW MANY MOUNTAIN PASSES MONDAY NIGHT AND TUESDAY NIGHT.  SOME
ACCUMULATIONS MAY BE POSSIBLE MONDAY NIGHT THROUGH WEDNESDAY...
MAINLY ABOVE 10000 FEET.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED TODAY.

TAL

The radar

The Cheyenne radar (KCYS), 185 km away, was scanning. The volume nearest the first event began at 18:29 UTC.

Open the radar archive at this moment

Event by event

1 thunderstorm wind. Local standard time, as filed.

Thunderstorm Wind, Routt

When: September 19, 11:30 AM MST to 11:40 AM MST
Where: Routt County, Steamboat Spgs
Measured: 53 kt (61 mph) measured gust
Property damage: $40,000
Reported by: TRAINED SPOTTER
Coordinates: 40.483, -106.817

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 Colorado in 2004 Every state in 2004 This day in weather history Warnings in Colorado, September 2004

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: 5423842.