Dense fog formed in the Four Corners region as low level moisture remained trapped under a surface-based inversion.
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The episode as NWS GJT wrote it up.
Dense fog formed in the Four Corners region as low level moisture remained trapped under a surface-based inversion.
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 Dec 31, 10:45 PM MST, 2 hours 15 minutes earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 1045 PM MST Sat Dec 31 2016 .UPDATE... Issued at 656 PM MST Sat Dec 31 2016 Dense Fog Advisory issued for the Four Corners and San Juan River basins through 9:00 am on New Year's Day. Have received multiple spotter reports of dense fog in the Route 160 and Route 490 corridor, with CEZ and DRO visibilities dropping as the evening has progressed. && .SHORT TERM...(Tonight through Sunday night) Issued at 143 PM MST Sat Dec 31 2016 An area of deformation and mid-level frontogenesis on the north side of a closed low over New Mexico will keep a band of rain and snow showers over extreme SE UT and Montezuma county in SW CO this evening. Have issued a winter wx advisory for those areas through midnight. By midnight this feature should weaken as it moves over the southern extent of the San Juan mountains and the higher elevations north of Durango and Pagosa Springs. Am expecting sub-advisory level accumulations (LT 5 inches in the mountains and LT 3 inches at lower elevations). Sunday and Sunday night are somewhat "in-between" days, waiting for the next stronger trough to affect the area. Another closed low is projected to travel just south of the U.S. and Mexico border with a weak trough and deformation zone stretching from the four corners north through central CO. The winds aloft will be from the west. The moisture won't be abundant but there should be enough for light snow accumulations on west-facing slopes from the orographics and minor dynamics. By the end of the night the nose of the polar jet will be entering SW UT and west winds aloft will start increasing ahead of the next strong system. .LONG TERM...(Monday through Saturday) Issued at 143 PM MST Sat Dec 31 2016 Monday morning the 140 kt jet maxima will move from NV and SW UT northeast through central and northern UT and central and northwest CO. The favorable quadrant of the jet will push north of the forecast area by noon. At the same time, the southern jet stream begins to intrude into our area via northern AZ. Late Monday afternoon and night 120 to 140 kt winds at 300 mb will stretch across the entire forecast area. The best moisture was previously forced to the north but there appears to be enough moisture in this westerly flow over the forecast area Monday night through Wednesday. Wednesday night through Friday the GFS shows a trough moving across the area by Friday morning while the ECMWF shows a weaker feature moving across 6 to 12 hours slower. The coming week looks unsettled and somewhat stormy but at this point it is hard to nail down when days will produce the best or worst weather. Model solutions are changing as well so uncertainly is rather high. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1040 PM MST Sat Dec 31 2016 IFR conditions will persist overnight at DRO. Main forecast challenge was to determine the likelihood of fog versus low- stratus south of the San Juan Mountains. Have gone with a low- stratus IFR ceiling forecast for the overnight period as hourly obs have trended in that direction with dense fog more likely to the north of DRO. Elsewhere, expect VFR conditions overnight. Ceilings area-wide will thicken and lower on Sunday afternoon as the next system moves south. Aviation challenges will include timing any precipitation during the afternoon hours. Expect VFR conditions area wide through the morning north of the San Juans with MVFR in mountain terminals by the afternoon. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Dense Fog Advisory until 9 AM MST Sunday for COZ021>023. UT...Dense Fog Advisory until 9 AM MST Sunday for UTZ022. && UPDATE...MAC SHORT TERM...CC LONG TERM...CC AVIATION...MAC
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND JUNCTION CO 448 AM MST SAT DEC 31 2016 COZ001>014-017>023-UTZ022>025-027>029-011200- LOWER YAMPA RIVER BASIN-CENTRAL YAMPA RIVER BASIN- ROAN AND TAVAPUTS PLATEAUS-ELKHEAD AND PARK MOUNTAINS- UPPER YAMPA RIVER BASIN-GRAND VALLEY-DEBEQUE TO SILT CORRIDOR- CENTRAL COLORADO RIVER BASIN-GRAND AND BATTLEMENT MESAS- GORE AND ELK MOUNTAINS/CENTRAL MOUNTAIN VALLEYS- CENTRAL GUNNISON AND UNCOMPAHGRE RIVER BASIN- WEST ELK AND SAWATCH MOUNTAINS-FLAT TOPS- UPPER GUNNISON RIVER VALLEY-UNCOMPAHGRE PLATEAU AND DALLAS DIVIDE- NORTHWEST SAN JUAN MOUNTAINS-SOUTHWEST SAN JUAN MOUNTAINS- PARADOX VALLEY/LOWER DOLORES RIVER- FOUR CORNERS/UPPER DOLORES RIVER-ANIMAS RIVER BASIN- SAN JUAN RIVER BASIN-SOUTHEAST UTAH-EASTERN UINTA MOUNTAINS- EASTERN UINTA BASIN-TAVAPUTS PLATEAU-ARCHES/GRAND FLAT- LA SAL AND ABAJO MOUNTAINS-CANYONLANDS/NATURAL BRIDGES- 448 AM MST SAT DEC 31 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN UTAH AND WESTERN COLORADO. .DAY ONE...TODAY AND TONIGHT WIDESPREAD SNOW WILL FALL OVER MUCH OF SOUTHEAST UTAH AND SOUTHWEST COLORADO THIS MORNING WITH RAIN BELOW 5000 TO 5500 FEET. THE RAIN/SNOW LINE WILL RISE TO AROUND 6000 TO 6500 DURING THE AFTERNOON AS TEMPERATURES RISE. THE SYSTEM RESPONSIBLE FOR SNOW WILL MOVE FROM NORTHERN ARIZONA TO NORTH-CENTRAL NEW MEXICO LATE THIS AFTERNOON. AS THE SYSTEM SHIFTS EASTWARD SNOW WILL DIMINISH FROM WEST TO EAST. SNOW ACCUMULATIONS ARE EXPECTED TO BE LIGHT. SNOW WILL INCREASE AGAIN LATE TONIGHT AS THE NEXT SYSTEM BEGINS TO APPROACH FROM THE SOUTHWEST. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY SNOW IS EXPECTED TO SPREAD INTO ALL MOUNTAINS AND SOME ADJACENT VALLEYS ON NEW YEARS DAY AS THE NEXT STORM DRAWS DOWN ON THE AREA. PERIODS OF SNOW WILL CONTINUE THROUGH FRIDAY AS A DEEP ARCTIC SYSTEM LINGERS OVER THE REGION. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED TODAY OR TONIGHT...HOWEVER SPOTTERS ARE ENCOURAGED TO REPORT SNOWFALL AMOUNTS TO THE NATIONAL WEATHER SERVICE IN GRAND JUNCTION.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
703 PM MST SAT DEC 31 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0701 PM SNOW 5 NNE CHIMNEY ROCK 37.27N 107.15W
12/31/2016 M2.5 INCH ARCHULETA CO PUBLIC
MEASURED AT 6900 FEET.
&&
JCPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
723 PM MST SAT DEC 31 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0245 PM SNOW 1 NW YELLOW JACKET 37.54N 108.74W
12/31/2016 E3.5 INCH MONTEZUMA CO TRAINED SPOTTER
.
&&
JCPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
727 PM MST SAT DEC 31 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0245 PM SNOW 1 WNW YELLOW JACKET 37.54N 108.74W
12/31/2016 M6.0 INCH MONTEZUMA CO TRAINED SPOTTER
.
&&
JCThe national radar mosaic for the moment the first event began.
1 dense fog. Local standard time, as filed.
Dense fog occurred across southeast corner of Utah as visibilities dropped down to a quarter mile or less.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2017Every state in 2017This day in weather historyWarnings in Utah, January 2017
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: 680362.