A mid-level plume of monsoon moisture moved up from Arizona into northern Utah and produced widespread high based thunderstorms over the area. High based convection and very dry air from near mountain top level down to the valley surfaces provided the necessary ingredients for widespread microbursts.
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.
The episode as NWS SLC wrote it up.
A mid-level plume of monsoon moisture moved up from Arizona into northern Utah and produced widespread high based thunderstorms over the area. High based convection and very dry air from near mountain top level down to the valley surfaces provided the necessary ingredients for widespread microbursts. The high winds affected areas along the I-80 corridor west of Salt Lake City, along the Wasatch front from Brigham City to Sandy, and in the Utah portion of the Cache valley. The high winds blew off three roofs and damaged several others in the Young Ward, Providence, College Ward, and Logan areas of the Cache Valley. Power outages were common in the Cache Valley and Wasatch Front areas. Two thousand customers lost power in and around the Logan area with about 4500 losing power in Salt Lake County. No injuries were reported.
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 Salt Lake City, UT wrote its last area forecast discussion before the first event at Jul 9, 2:30 PM MST, 30 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SALT LAKE CITY UT 330 PM MDT FRI JUL 9 2004 .SYNOPSIS...A WARM SOUTHWEST FLOW WILL BE OVER THE UTAH THROUGH THE WEEKEND THEN TURN MORE SOUTHERLY EARLY NEXT WEEK. THE AIR MASS WILL REMAIN SOMEWHAT MOIST AND UNSTABLE OVER MAINLY THE EASTERN HALF OF THE AREA. && .DISCUSSION...SHORTWAVE MOVING NORTH THROUGH THE GREAT BASIN HAS AN AXIS EXTENDING TOWARD THE UINTA BASIN AT THIS TIME. WHAT CONVECTION WE ARE SEEING TODAY IS NORTH OF THAT AXIS WHICH WILL BE OVER SOUTHWEST WY BY ABOUT 00Z. THERE HAS ALSO BEEN SOME CONVECTION IN THE COMMA HEAD OVER CENTRAL NV AND THAT COULD CLIP THE EXTREME NORTHWEST CORNER OF OUR AREA LATE THIS EVENING. OTHERWISE ONLY LIMITED ACTIVITY EXPECTED THROUGH EARLY THIS EVENING. THE BEST CHANCE FOR THAT IS OVER THE SOUTHERN MOUNTAINS WHERE SUBSIDENCE BEHIND THE SHORTWAVE HAS PROBABLY BEEN KEEPING THINGS CAPPED BUT CUMULUS HAS INCREASED RAPIDLY OVER THE LAST HOUR OR SO. THE GENERAL MODEL TREND IS TO KEEP SOUTHWEST FLOW OVER THE AREA THROUGH THE WEEKEND AND THAT ALMOST HAS TO KEEP MOISTURE LIMITED OVER MOST OF THE AREA. SO PERHAPS A LITTLE LESS CONVECTION OVER THE WEEKEND THAN EARLIER THOUGHT. THE GFS DOES INCREASE PRECIPITABLE WATER VALUES A LITTLE OVER THE WEEKEND BUT WAITS UNTIL THE FLOW TURNS MORE SOUTHERLY AGAIN EARLY NEXT WEEK TO BRING A BETTER SURGE NORTH. EVEN WITH THE INCREASING MOISTURE IT WILL BE HARD TO GET VERY EXTENSIVE CONVECTION AS THE HIGH CENTER TENDS TO DRIFT OVER THE AREA WITH WILL KEEP THE UPPER LEVELS QUITE WARM AND LIMIT ANY DEEP INSTABILITY. SO MOST ACTIVITY WILL REMAIN CONFINED TO THE MOUNTAINS. THE LATEST GFS SUGGESTS SOME MOISTURE WILL REMAIN AVAILABLE THROUGH THE LATTER PART OF NEXT WEEK RATHER THAN GETTING BONE DRY. IF THAT HAPPENS WE WOULD HAVE SOME MOUNTAIN CONVECTION CONTINUING. THAT IN TURN COULD LEAD TO A LITTLE MORE CLOUDINESS THAN CURRENT FORECASTS SUGGEST. HOWEVER THIS TENDS TO GO A LITTLE AGAINST THE RECENT MODEL TRENDS AND FOR NOW WILL LEAVE THE LATTER PART OF THE WEEK JUST HOT AND DRY. RED FLAG WARNING FOR LOW HUMIDITY AND WINDS CONTINUING THROUGH THE EARLY EVENING HOURS AND EXPANDED TO COVER THE REMAINDER OF THE WEST DESERTS. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...RED FLAG WARNING WRN ZONES 800 PM MDT TODAY. WY...NONE. ID...NONE. && SANDERS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SALT LAKE CITY UT 600 AM MDT FRI JUL 9 2004 UTZ015>017-019-020-101300- CENTRAL AND SOUTHWEST MOUNTAINS-SOUTH CENTRAL UTAH-SOUTHWEST UTAH- UTAHS DIXIE AND ZION NATIONAL PARK-WEST CENTRAL UTAH- 600 AM MDT FRI JUL 9 2004 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE SOUTHWESTERN THIRD OF UTAH. .DAY ONE... TODAY GUSTY SOUTH WINDS...LOW HUMIDITIES AND ISOLATED DRY THUNDERSTORMS WILL CREATE HAZARDOUS FIRE WEATHER CONDITIONS ACROSS SOUTHWESTERN AND SOUTH CENTRAL UTAH TODAY. CONDITIONS WILL ABATE SOMEWHAT BY EARLY THIS EVENING AS THE AIRMASS MOISTENS UP AND THUNDERSTORMS BECOME WETTER. .DAYS TWO THROUGH SEVEN... SATURDAY THROUGH THURSDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
3 high wind, 1 strong wind. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2004Every state in 2004This day in weather historyWarnings in Utah, July 2004
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: 5422463, 5422464, 5422465, 5422466.