Alert archive / Colorado / Winter Storm Warnings in 2020

Winter Storm Warning 9, NWS Grand Junction, CO

September 7, 202014 counties in Colorado; Daggett County, Uintah County, Utah

NWS Grand Junction, CO issued this winter storm warning at Sep 7, 2020, 3:36 AM MDT for 14 counties in Colorado; Daggett County, Uintah County, Utah. It took effect at Sep 8, 2020, 12:00 AM MDT. It was in force for 60 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Sep 7, 2020, 3:36 AM MDT (09:36 UTC)
In effect from
Sep 8, 2020, 12:00 AM MDT
Expired
Sep 10, 2020, 12:00 PM MDT
In force
60 hr
Issued by
NWS Grand Junction, CO

Counties Archuleta County, CO, Delta County, CO, Dolores County, CO, Garfield County, CO, Gunnison County, CO, Hinsdale County, CO, La Plata County, CO, Moffat County, CO, Montezuma County, CO, Montrose County, CO, Ouray County, CO, Rio Blanco County, CO, San Juan County, CO, San Miguel County, CO, Daggett County, UT, Uintah County, UT

The radar

The Grand Junction radar (KGJX), 46 km from the middle of the area, began a volume at 09:41 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Grand Junction, CO (KGJT), launched 00:00Z, 9.6 hours before the alert went out and 63 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Grand Junction, CO at 00:00Z on 2020-09-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 6 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Grand Junction, CO at 00:00Z on 2020-09-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 43 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
6 J/kg
Mixed-layer CIN
-33 J/kg
Mixed-layer LCL
4514 m above ground
0-6 km bulk shear
8 kt
0-1 km storm-relative helicity
43 m²/s²
0-3 km storm-relative helicity
75 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this winter storm warning went out, 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 this winter storm warning went out at Sep 6, 11:22 PM MDT, 4 hours 14 minutes earlier.

Area forecast discussion, Sep 6, 11:22 PM MDT, 4 hours 14 minutes before
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Hazardous weather outlook, Sep 6, 5:26 AM MDT, 22 hours 10 minutes before
Hazardous Weather Outlook
National Weather Service Grand Junction CO
526 AM MDT Sun Sep 6 2020

COZ001>014-017>023-UTZ022>025-027>029-071130-
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-
526 AM MDT Sun Sep 6 2020

This hazardous weather outlook is for eastern Utah and western
Colorado.

.DAY ONE...Today and Tonight

Critical fire weather conditions are expected today over northern
portions of the forecast area.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Critical fire weather conditions continue on Monday with gusty
winds ahead of a strong cold front. Freezing temperatures will
likely affect an area from roughly Dinosaur to Craig to Steamboat
and points north on Tuesday morning. Higher elevation snow is
likely on Tuesday as high temperatures drop 20 to 30 degrees from
the previous several days. Low temperatures Wednesday morning may
drop to the mid 20s for the northern valleys...with freezing
temperatures possible as far south as Cortez and Durango.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

The office that day

Everything else NWS Grand Junction, CO issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 6, 9:38 PM MDTWinter Storm WatchGJTArchuleta, Delta, Dolores, Eagle, Garfield, Gunnison and 8 more6 hr
Sep 7, 3:36 AM MDTWinter Weather AdvisoryGJTDelta, Eagle, Garfield, Gunnison, Mesa, Moffat and 4 more50 hr
Sep 7, 4:01 AM MDTFreeze WatchGJTEagle, Garfield, Moffat, Pitkin, Rio Blanco, Routt24 hr
Sep 7, 4:01 AM MDTFreeze WarningGJTRoutt30 hr
Sep 7, 4:12 PM MDTWind AdvisoryGJTRoutt29 hr
Sep 7, 4:12 PM MDTHigh Wind WarningGJTUintah29 hr

Nearby

Winter Storm Warnings in Colorado, 2020Winter Storm Warnings in Utah, 2020Every winter storm warning in 2020

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.