An atmospheric river event impacted the Western Slope, bringing an abundance of Pacific moisture and a series of upper level disturbances. The first system moved through early in the week and brought moderate to heavy snow to the southern and central mountains.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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 GJT wrote it up.
An atmospheric river event impacted the Western Slope, bringing an abundance of Pacific moisture and a series of upper level disturbances. The first system moved through early in the week and brought moderate to heavy snow to the southern and central mountains.
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 Mar 19, 10:33 PM MST, 3 hours 27 minutes earlier.
Area Forecast Discussion
National Weather Service Grand Junction CO
1133 PM MDT Sun Mar 19 2023
.SHORT TERM...(Tonight through Monday night)
Issued at 402 PM MDT Sun Mar 19 2023
An active winter forecast kicks off tonight with the arrival of a
series of shortwaves fueled by a plume of moisture extending from
the British Columbia coastline southeastward through the Four
Corners. Frontal forcing will enter the picture on the northern
edge of a jet streak rounding the base of a Pacific Northwest
low. This jet streak will remain the driver for this week's winter
weather outbreak on the West Slope.(more details on this in the
extended portion of the discussion)
Winter highlights are in place starting overnight for the Flat Tops,
Park Range, Tavaputs, Grand Mesa, Central Mountains, and San Juans,
as well as the La Sals and Abajos of eastern Utah. Snowfall amounts
tonight and into Tuesday will range from 4-12 inches across the high
country north of I-70 to 1 to 2 feet across the San Juans. The best
forcing will initiate over the mountains south of I-70 around
midnight, before spreading northward and eastward by daybreak. Mixed
precipitation will create travel problems along the Highway 160
corridor from La Plata County and eastward to Wolf Creek Pass during
the morning commute Monday. Snowfall will continue through the day
Monday as the jet stream strengthens overhead. Height rises ahead of
the Pacific low will push weak ridging and a shot of colder/drier
air into northwest Colorado Monday night, tapering snowfall across
the region, with the exception of the San Juans, where snow will
persist into Tuesday morning and beyond.
Snow levels will remain, primarily, over the mountains, while lower
valleys will see mostly rain during this initial push tonight and
Monday. Cloud cover and precipitation processes will keep
temperatures below normals on Monday. Overnight lows tonight and
Monday night will moderate some thanks to the blanket of cloud cover
over the region.
.LONG TERM...(Tuesday through Sunday)
Issued at 402 PM MDT Sun Mar 19 2023
The 1st system of the week will lift east of the Divide by Tuesday
morning, resulting in a break from preciptation for much of the
forecast area. However, this period will be dictated by the strong
Pacific low moving inland along Northern California. Pressure
gradients along the south-southeastern periphery of the low will be
squeezed aloft, causing the sub-tropical jet to strengthen into a
140-150 kt jet over the next 24 hours. Southwesterly winds ramping
up across the Desert Southwest on Tuesday will maintain a pipeline
for Pacific moisture across southern zones. So, a break from precip
entirely is unlikely. For that reason, we have extended the
(upgraded) Warning for zone 19 to highlight the persistent snow for
this range all week.
Meanwhile, the next AR event starts trudging inland on Tuesday,
which will simultaneously lift a warm front across the region.
Expect an increase in precipitation from south to north Tuesday
afternoon. Due to the warm air advection, snow levels climb up the
mountain with this initial wave and pose a threat of low-mid level
snowpack receiving rain rather than snow. Rain on snow becomes
problematic, from a flooding stand point, if heavy rain falls on a
saturated snowpack because this ultimately increases runoff and
snowmelt. Areas of concern are focused across the southern valleys
and foothills across southwest Colorado, which are progged to see
convection early afternoon. Rain and increased runoff becomes less
likely as the front moves north overnight. Late night convection
could still feed off a wiggle of elevated instability, however,
the frontal boundary weakens overnight.
By Wednesday morning, the low's center starts to lift northwest,
which pushes a cold front across the region, nudging warm air away
from the CWA. Colder air (-6 to -9 deg C at 700mb) sliding in from
west to east will help dip snow levels back down below 6000 feet by
the afternoon. Fortunately, snow levels continue to drop behind the
cold front, which should reduce the risk of rain on snow events,
too. Though, ample moisture, dynamics and some mid-level instability
will favor another round of convection Wednesday afternoon/evening.
In addition, strong southwesterly winds aloft will mix down to the
surface, especially in convective regimes, which translates to
surface gusts around 50-60 mph over higher terrain. Additional snow,
falling heavy at times, in combination with blowing and drifting
snow could make for dangerous, if not impossible, travel
(particularly over mountain passes).
The bulk of QG lift associated with this system will exit the
region to the northeast by Wednesday night which truncates the
spread of precipitation to mountainous terrain. Impressive snow
totals are progged from this AR, including both the warm and cold
front. Nearly all mountain ranges are estimated to pick up another
5 to 10 inches of new snow. Breaking down snow totals per range;
the Southwest San Juans are most favorable in this AR regime,
where another 1 to 2 feet are possible with locally higher amounts
up to 3 feet. Portions of the Abajos, Grand Mesa, West Elks and
Elks could see localized areas up to 2 feet, while the remaining
ranges are capped closer to a foot. Unsettled weather persists
even in the wake of the AR, due to a prolonged period of troughing
across the Western CONUS. The third system is on track for a
Thursday evening delivery, though QPF and snowfall rates appear
weak attm. Regardless, abnormally moist northwesterly flow will
maintain the chance for precipitation across portions of the CWA
through next weekend.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1128 PM MDT Sun Mar 19 2023
Mid and low level clouds are on the increase as the next system
approaches. Scattered rain and snow showers are already ongoing,
although not affecting any terminals yet. Expect KDRO, KTEX, and
KGUC to be the first to see VIS impacts from shower activity. Also
expect to see KRIL, KASE, and KEGE to have CIGS drop below ILS
breakpoints over the next hour or two. By daybreak, all terminals
should be seeing at least VCSH if not active shower activity on
site. By the afternoon hours, showers will become more scattered
and convective. Rain showers will primarily affect valleys, while
mountains will see snow, which will not only lead to widespread
MVFR/IFR conditions at mountain terminals, but will also lead to
issues with mountain obscuration. Winds will be generally light
through the period, but will become primarily south to
southwesterly by daybreak.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory until 8 AM MDT Tuesday for COZ003-012.
Winter Storm Watch from Tuesday afternoon through Wednesday
evening for COZ003-004-009-010-012-013-017-018.
Winter Weather Advisory from 6 AM Monday to 8 AM MDT Tuesday for
COZ004-013.
Winter Storm Warning until 8 AM MDT Tuesday for COZ009-017.
Winter Weather Advisory until noon MDT Tuesday for COZ018.
Winter Storm Warning until midnight MDT Wednesday night for
COZ019.
Winter Weather Advisory until noon MDT Monday for COZ022-023.
UT...Winter Weather Advisory until 8 AM MDT Tuesday for UTZ025.
Winter Storm Watch from Tuesday afternoon through Wednesday
evening for UTZ023-025-028.
Winter Storm Warning until 8 AM MDT Tuesday for UTZ028.
&&
SHORT TERM...LTB
LONG TERM...ERW
AVIATION...TGJTHazardous Weather Outlook National Weather Service Grand Junction CO 314 AM MDT Sun Mar 19 2023 COZ001>014-017>023-UTZ022>025-027>029-200915- 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- 314 AM MDT Sun Mar 19 2023 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight High pressure today will give way to increasing shower activity this evening and through the overnight as a Pacific trough approaches the region. Valleys will see primarily rain while mountains see some accumulating snow. .DAYS TWO THROUGH SEVEN...Monday through Saturday Widespread showers are expected beginning Monday and continuing through at least Wednesday as this first and eventual second system push across the forecast area. Heavy mountain snow is expected, particularly across the favored southern slopes. Mostly rain will fall in the valleys before colder air moves in Tuesday night and into Wednesday. Unsettled weather will continue through the end of the week due to residual moisture and additional disturbances approaching from the Pacific Northwest. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
The national radar mosaic for the moment the first event began.
1 winter weather, 1 heavy snow. Local standard time, as filed.
An estimated 7 inches of snow fell at the East Willow Creek SNOTEL site.
Generally 8 to 16 inches of snow fell across the area with locally higher amounts of up to 21 inches estimated at the Camp Jackson SNOTEL site. 11 inches of snow fell in the town of Monticello.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2023Every state in 2023This day in weather historyWarnings in Utah, March 2023
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: 1078148, 1078149.