Dense Fog, Grand Flat and Arches
- When
- January 4, 9:00 PM MST to January 5, 7:00 AM MST
- Where
- Grand Flat and Arches forecast zone
- Reported by
- LAW ENFORCEMENT
- Coordinates
- 38.982, -109.570 (the zone’s center; the record gives no point)
Dense Fog in Utah, January 4 to 5, 2002
Dense fog developed during the evening and reduced visibilities to 1/4 mile or less for about 10 hours.
Where it happened
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. 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
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 GJT wrote it up.
Dense fog developed during the evening and reduced visibilities to 1/4 mile or less for about 10 hours.
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 Jan 4, 1:54 PM MST, 7 hours 6 minutes earlier.
Area forecast discussion, Jan 4, 1:54 PM MST, 7 hours 6 minutes before
WESTERN COLORADO & EASTERN UTAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 154 PM MST FRI JAN 4 2002 UPPER TROUGH OVER THE AREA MOVING SLOWLY EAST. PRECIP HAS DECREASED IN MOST AREAS TO JUST A FEW SNOW SHOWERS/FLURRIES...EXCEPT IN OROGRAPHICALLY FAVORED LOCATIONS WHERE OCCASIONAL LIGHT SNOW IS EXPECTED TO CONTINUE INTO THE EARLY EVENING HOURS. ADDITIONAL ACCUMULATIONS IN MOUNTAINS THROUGH EARLY EVENING SHOULD BE AN INCH OR LESS. CLEARING SHOULD OCCUR IN ALL AREAS OF OUR CWA TONIGHT AS UPPER RIDGE REBUILDS OVER THE GREAT BASIN AND SUBSIDENCE INVERSIONS STRENGTHEN. ENOUGH SURFACE MOISTURE EXPECTED TO REMAIN OVERNIGHT FOR PATCHY VALLEY FOG TO DEVELOP...ESPECIALLY BY SUNRISE...AND CONTINUE INTO MID MORNING. OTHERWISE...SUNNY CONDITIONS FOR SATURDAY WILL PRECEDE OVERRUNNING MOISTURE SATURDAY NIGHT AHEAD OF NEXT SHORTWAVE TROUGH. MODELS INDICATE SUFFICIENT MOISTURE IN NORTHERN MOUNTAIN ZONES SATURDAY NIGHT IN THE H7-H5 RANGE TO PRODUCE A FEW SNOW SHOWERS MAINLY WHERE OROGRAPHIC LIFT IS EXPECTED. THEN THE SHORTWAVE WILL BRUSH OUR CWA ON SUNDAY...BUT WITH WEAK DYNAMICS. OROGRAPHICS ON SUNDAY SHOULD BE THE PRIMARY LIFTING MECHANISM. AGAIN...SNOW SHOWER ACTIVITY SHOULD BE MAINLY ON N AND NW EXPOSURES OF NORTHERN MOUNTAIN ZONES. CLEARING EXPECTED SUNDAY NIGHT AS UPPER RIDGE CONTINUES TO DOMINATE OUR WX PATTERN. SHOULD SEE LITTLE CHANGE IN TEMPS THROUGH SUNDAY NIGHT...EXCEPT THAT MINS SATURDAY NIGHT SHOULD BE A LITTLE HIGHER THAN MODEL GUIDANCE PRESENTLY INDICATES....ESPECIALLY FOR NORTHERN ZONES. PRINGLE IN THE EXTENDED (MON-FRI): AFTER A LOOK AT THE LATEST AVN...WHICH SUPPORTS MRF IN KEEPING WEDS WAVE A ONE-DAY EVENT...WILL SEPARATE WED FROM THU...THEN LUMP THU AND FRI. OTHERWISE NO REAL CHANGES TO THE EXTENED. HO-HUM PATTERN OF DIRTY RIDGE OVER THE WESTERN U.S. WILL PERSIST WITH INTERMITTENT WEAK PACIFIC WAVES MOVING ACROSS THE RIDGE. MEAN RIDGE POSITION STAYS TO OUR WEST SO OUR FORECAST AREA WILL REMAIN IN NORTHWEST FLOW. THEREFORE THE NORTHERN PORTION WILL STAY THE FAVORED AREA FOR ANY ACTIVITY. ONE WEAK SHORTWAVE MOVES OUT BEFORE THE PERIOD STARTS...THEN THE NEXT SHORTWAVE MOVES THROUGH WED. HOWEVER THIS ONE LOOKS RELATIVELY WEAK AT THIS TIME. RIDGE REBOUNDS AFTER SHORTWAVE AND MOVES A TAD TO THE EAST LATE IN THE PERIOD. FLOW OVER THE AREA WILL WEAKEN AND BECOME MORE WESTERLY BY FRI...FOR DRY CONDITIONS AND ABOVE NORMAL TEMPS. HEFFERNAN .GJT...NONE.
The radar
The national radar mosaic for the moment the first event began.
Event by event
1 dense fog. Local standard time, as filed.
What these are
- Dense Fog
- Fog reducing visibility to a quarter mile or less, filed where it caused accidents or disruption.
After NWS Directive 10-1605, the rules offices file Storm Data by.
The same day elsewhere
- Extreme Cold in North Carolina, January 4, 2002
- Frost and Freeze in Florida, January 4, 2002
- Frost and Freeze in Florida, January 4 to 5, 2002
- Heavy Snow in Colorado, January 4 to 5, 2002
- Extreme Cold in Florida, January 4, 2002
- Dense Fog in California, January 4, 2002
- Blizzard in Alaska, January 4, 2002
- Cold in Alaska, January 4 to 5, 2002
- Blizzard in Alaska, January 4 to 5, 2002
- Dense Fog in Colorado, January 4 to 5, 2002
More
Every storm in Utah in 2002Every state in 2002This day in weather historyWarnings in Utah, January 2002
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: 5278790.