Alert archive / Colorado / Winter Storm Warnings in 2021

Winter Storm Warning 6, NWS Denver/Boulder, CO

April 19, 20216 counties in Colorado

NWS Denver/Boulder, CO issued this winter storm warning at Apr 19, 2021, 4:26 AM MDT for 6 counties in Colorado. It took effect at Apr 19, 2021, 12:00 PM MDT. It was in force for 15 hr. 60 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued
Apr 19, 2021, 4:26 AM MDT (10:26 UTC)
In effect from
Apr 19, 2021, 12:00 PM MDT
Expired
Apr 20, 2021, 3:00 AM MDT
In force
15 hr
Issued by
NWS Denver/Boulder, CO

Counties Boulder County, CO, Broomfield County, CO, Grand County, CO, Jackson County, CO, Jefferson County, CO, Larimer County, CO

The radar

The Denver radar (KFTG), 100 km from the middle of the area, began a volume at 10:30 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.

What was reported inside it

TimeReportWhereRemark
Apr 19, 5:35 PM MDTSNOW 24 Ene Nederland, CO
Apr 19, 6:00 PM MDTSNOW 1.43 Ssw Boulder, CO
Apr 19, 6:18 PM MDTSNOW 33 Sw Longmont, CO
Apr 19, 6:40 PM MDTSNOW 41 Ssw Crescent Village, CO
Apr 19, 6:52 PM MDTSNOW 31 Wnw Niwot, CO
Apr 19, 6:54 PM MDTSNOW 4.33 Sw Longmont, COCURRENTLY HEAVY SNOW WITH A RATE OF 2 INCHES PER HOUR.
Apr 19, 6:54 PM MDTSNOW 7.23 Sw Longmont, CO
Apr 19, 7:00 PM MDTSNOW 3.32 Ne Longmont, CO
Apr 19, 7:11 PM MDTHEAVY SNOW 8.52 E Allenspark, CO
Apr 19, 7:15 PM MDTSNOW 3.72 Nw Fort Collins, CO
Apr 19, 7:29 PM MDTSNOW 41 Nne Longmont, CO
Apr 19, 7:34 PM MDTSNOW 4.91 Nw Niwot, CO
Apr 19, 8:00 PM MDTSNOW 63 E Horsetooth Mountain, CO1.5 INCHES LAST HOUR. SNOW BEGINNING TO DECREASE IN INTENSITY.
Apr 19, 8:03 PM MDTSNOW 3.51 Nnw Genesee, CO
Apr 19, 8:03 PM MDTSNOW 41 N Fort Collins, CO
Apr 19, 8:05 PM MDTSNOW 10.23 W Jamestown, CO
Apr 19, 8:11 PM MDTSNOW 4.11 Nnw Louisville, CO
Apr 19, 8:28 PM MDTSNOW 33 Nw Marshall, CO
Apr 19, 8:30 PM MDTSNOW 6.53 Ssw Boulder, CO5.1 INCHES IN LAST 2.5 HOURS.
Apr 19, 8:31 PM MDTSNOW 4.52 N Longmont, CO
Apr 19, 8:48 PM MDTSNOW 5.31 Wnw Niwot, CO
Apr 19, 8:50 PM MDTSNOW 7Pinewood Springs, CO
Apr 19, 8:51 PM MDTSNOW 3.62 Nw Loveland, CO
Apr 19, 8:52 PM MDTSNOW 51 Ssw Lafayette, CO
Apr 19, 8:53 PM MDTSNOW 7.5Boulder, CO
Apr 19, 8:54 PM MDTSNOW 92 Nw Boulder, CO
Apr 19, 8:56 PM MDTSNOW 94 Ene Nederland, CO
Apr 19, 9:00 PM MDTSNOW 32 Wnw Rabbit Ears Pass, CORABBIT EARS PASS SNOTEL. SWE 0.3 INCH.
Apr 19, 9:00 PM MDTSNOW 38 Sse Rand, COWILLOW CREEK PASS SNOTEL. SWE 0.3 INCH.
Apr 19, 9:00 PM MDTSNOW 511 S Rabbit Ears Pass, COBUFFALO PARK SNOTEL. SWE 0.5 INCH.
Apr 19, 9:00 PM MDTSNOW 56 Ssw Glendevey, CORAWAH SNOTEL. SWE 0.3 INCH.
Apr 19, 9:00 PM MDTSNOW 61 Nnw Genesee, CO
Apr 19, 9:00 PM MDTSNOW 71 E Trail Ridge, COWILLOW PARK SNOTEL. SWE 0.4 INCH.
Apr 19, 9:00 PM MDTSNOW 103 Sw Meeker Park, COCOPELAND LAKE SNOTEL. SWE 0.6 INCH.
Apr 19, 9:05 PM MDTSNOW 5.12 Nw Fort Collins, CO
Apr 19, 9:07 PM MDTSNOW 8.42 Wsw Boulder, CO
Apr 19, 9:11 PM MDTSNOW 6.13 S Boulder, CO
Apr 19, 9:17 PM MDTSNOW 93 Ssw Boulder, CO
Apr 19, 9:21 PM MDTSNOW 44 Wnw Arvada, CO
Apr 19, 9:30 PM MDTSNOW 8Poudre Park, COCOCORAHS STATION CO-LR-1245 BELLVUE 8.1 WNW.
Apr 19, 9:30 PM MDTHEAVY SNOW 8.11.8 Ssw Niwot, CO
Apr 19, 9:35 PM MDTHEAVY SNOW 142 E Allenspark, CO
Apr 19, 9:41 PM MDTSNOW 6.53 S Boulder, CO
Apr 19, 9:42 PM MDTSNOW 6.53 Wnw Lafayette, CO
Apr 19, 9:42 PM MDTSNOW 7.31 Sse Boulder, CO
Apr 19, 9:43 PM MDTSNOW 5Superior, CO
Apr 19, 9:50 PM MDTHEAVY SNOW 8.51.9 Se Boulder, CO
Apr 19, 10:00 PM MDTHEAVY SNOW 6.83 E Horsetooth Mountain, CO
Apr 19, 10:08 PM MDTSNOW 101 S Crescent Village, CO
Apr 19, 10:20 PM MDTSNOW 7.31 Nnw Louisville, CO
Apr 19, 10:55 PM MDTSNOW 13.51 Ssw Meeker Park, CO
Apr 19, 11:03 PM MDTSNOW 4.52 Nw Loveland, CO
Apr 19, 11:23 PM MDTSNOW 43 S Fort Collins, CO
Apr 19, 11:47 PM MDTSNOW 53 Nw Columbine, CO
Apr 20, 12:00 AM MDTSNOW 8.93 Ssw Boulder, CONWS OFFICE.
Apr 20, 12:01 AM MDTSNOW 62 Ese Ken Caryl, CO
Apr 20, 12:05 AM MDTSNOW 62 Wsw Louisville, CO
Apr 20, 12:20 AM MDTSNOW 52 N Aspen Park, CO
Apr 20, 12:50 AM MDTSNOW 5.82 Se Golden, CO
Apr 20, 1:00 AM MDTSNOW 58 Sse Rand, COWILLOW CREEK PASS SNOTEL. SWE 0.4 INCH.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Denver, CO (KDNR), launched 00:00Z, 10.4 hours before the alert went out and 204 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, Denver, CO at 00:00Z on 2021-04-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 12 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 00:00Z on 2021-04-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 33 square meters per square second.193958Sfc1 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
12 J/kg
Mixed-layer CIN
-8 J/kg
Mixed-layer LCL
2439 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
33 m²/s²
0-3 km storm-relative helicity
34 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

820 
WWUS45 KBOU 191026
WSWBOU

URGENT - WINTER WEATHER MESSAGE
National Weather Service Denver CO
426 AM MDT Mon Apr 19 2021

...HEAVY SNOW AND MUCH COLDER TEMPERATURES LATER TODAY...

.Snow will develop and become heavy at times from north to south 
across the Front Range this afternoon, and then continue through the 
evening. Snowfall rates around one inch per hour can be expected 
along the I-25 Corridor, and up to 2 inches per hour in the Front 
Range Foothills. Temperatures will drop quickly, causing a possible 
flash freeze on roads and very slick/hazardous travel conditions. 
The evening commute will likely be impacted, especially by 5 pm 
along the I-25 Corridor, and by 3 pm in the northern foothills.

COZ033-035-191830-
/O.UPG.KBOU.WW.Y.0025.210419T1800Z-210420T0900Z/
/O.NEW.KBOU.WS.W.0006.210419T1800Z-210420T0900Z/
South and East Jackson/Larimer/North and Northeast
Grand/Northwest Boulder Counties Above 9000 Feet-Larimer and
Boulder Counties Between 6000 and 9000 Feet-
Including the cities of Glendevey, Nederland, Rocky Mountain
National Park, Laramie and Medicine Bow Mountains, Red Feather
Lakes, Cameron Pass, Estes Park, Willow Creek Pass, and Rabbit
Ears Range
426 AM MDT Mon Apr 19 2021

...WINTER STORM WARNING IN EFFECT FROM NOON TODAY TO 3 AM MDT 
TUESDAY...

* WHAT...Heavy snow possible. Total snow accumulations of 6 to 14 
  inches possible within 12 hours. Winds could gust as high as 35 
  mph.

* WHERE...Rocky Mountain National Park and the Medicine Bow Range, 
  and The Northern Front Range Foothills.

* WHEN...From Noon today to 3 AM MDT Tuesday.

* IMPACTS...Travel could be very difficult. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in 
your vehicle in case of an emergency. The latest road conditions for 
Colorado can be obtained by calling 5 1 1 or by going to www.cotrip.
org

&&

$$

COZ039-191830-
/O.UPG.KBOU.WW.Y.0025.210419T2100Z-210420T0900Z/
/O.NEW.KBOU.WS.W.0006.210419T2100Z-210420T0900Z/
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield
County-
Including the cities of Boulder, Golden, Longmont, Arvada, and
Lakewood
426 AM MDT Mon Apr 19 2021

...WINTER STORM WARNING IN EFFECT FROM 3 PM THIS AFTERNOON TO 3 AM 
MDT TUESDAY...

* WHAT...Snow expected. Total snow accumulations of 5 to 8 inches, 
  most of it within 6 to 9 hours, with locally heavier amounts near 
  the base of the foothills.

* WHERE...Boulder and the western suburbs of Denver.

* WHEN...From 3 PM this afternoon to 3 AM MDT Tuesday.

* IMPACTS...Travel could be very difficult. The hazardous conditions 
  could impact the Monday evening commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in 
your vehicle in case of an emergency. The latest road conditions for 
Colorado can be obtained by calling 5 1 1 or by going to www.cotrip.
org

&&

$$

COZ034-036-191830-
/O.CON.KBOU.WW.Y.0025.210419T1800Z-210420T0900Z/
South and Southeast Grand/West Central and Southwest
Boulder/Gilpin/Clear Creek/Summit/North and West Park Counties
Above 9000 Feet-Jefferson and West Douglas Counties Above
6000 Feet/Gilpin/Clear Creek/Northeast Park Counties Below
9000 Feet-
Including the cities of Evergreen, Georgetown, Indian Peaks,
Idaho Springs, Eisenhower Tunnel, East Slopes Southern Gore
Range, Mount Evans, Central City, East Slopes Mosquito Range,
Breckenridge, Winter Park, Williams Fork Mountains, Bailey,
Kenosha Mountains, Westcreek, and Berthoud Pass
426 AM MDT Mon Apr 19 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO 3 AM 
MDT TUESDAY...

* WHAT...Snow expected. Total snow accumulations of 6 to 12 inches 
  along and north of I-70, 4 to 7 inches to the south. Lighter snow 
  accumulations of 1 to 4 inches west of the Eisenhower Tunnel. 
  Winds gusting as high as 35 mph.

* WHERE...The Mountains of Summit County, the Mosquito Range, and 
  the Indian Peaks, and The Southern Front Range Foothills.

* WHEN...From Noon today to 3 AM MDT Tuesday.

* IMPACTS...Travel could be very difficult. The hazardous conditions 
  could impact the Monday evening commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. The latest road 
conditions for Colorado can be obtained by calling 5 1 1 or by going 
to www.cotrip.org

&&

$$

COZ038-040-041-043-191830-
/O.CON.KBOU.WW.Y.0025.210419T2100Z-210420T0900Z/
Larimer County Below 6000 Feet/Northwest Weld County-North
Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe
Counties/East Broomfield County-Elbert/Central and East Douglas
Counties Above 6000 Feet-Central and South Weld County-
Including the cities of Eaton, Highlands Ranch, Castle Rock, City
of Denver, Elbert, Fort Collins, Aurora, Roggen, Kiowa, Loveland,
Greeley, Littleton, Nunn, Larkspur, Fort Lupton, Fondis,
Hereford, Parker, Denver International Airport, and Brighton
426 AM MDT Mon Apr 19 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 3 PM THIS 
AFTERNOON TO 3 AM MDT TUESDAY...

* WHAT...Snow expected. Total snow accumulations of 3 to 6 inches, 
  with locally heavier amounts near the base of the foothills.

* WHERE...Fort Collins, Denver, Castle Rock, and Greeley.

* WHEN...From 3 PM this afternoon to 3 AM MDT Tuesday.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the Monday evening commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. The latest road 
conditions for Colorado can be obtained by calling 5 1 1 or by going 
to www.cotrip.org

&&

$$

For more information from the National Weather Service, visit 
https://weather.gov/bou

Kriederman
4 follow-up statements
763 
WWUS45 KBOU 191701
WSWBOU

URGENT - WINTER WEATHER MESSAGE
National Weather Service Denver CO
1101 AM MDT Mon Apr 19 2021

...HEAVY SNOW AND COLD TEMPERATURES THROUGH TONIGHT...

.Snow will develop and become heavy at times from north to south 
across the Front Range this afternoon, and then continue through the 
evening. Snowfall rates around one inch per hour can be expected 
along the I-25 Corridor, and up to 2 inches per hour in the Front 
Range Foothills. Temperatures will be cold, causing a possible flash 
freeze on roads and very slick/hazardous travel conditions. The 
evening commute will likely be impacted, especially by 5 pm along 
the I-25 Corridor, and by 3 pm in the northern foothills.

COZ033-035-200300-
/O.CON.KBOU.WS.W.0006.210419T1800Z-210420T0900Z/
South and East Jackson/Larimer/North and Northeast
Grand/Northwest Boulder Counties Above 9000 Feet-Larimer and
Boulder Counties Between 6000 and 9000 Feet-
Including the cities of Glendevey, Nederland, Rocky Mountain
National Park, Laramie and Medicine Bow Mountains, Red Feather
Lakes, Cameron Pass, Estes Park, Willow Creek Pass, and Rabbit
Ears Range
1101 AM MDT Mon Apr 19 2021

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 3 AM MDT TUESDAY...

* WHAT...Heavy snow possible. Total snow accumulations of 6 to 14 
  inches possible within 12 hours. Winds could gust as high as 35 
  mph.

* WHERE...Rocky Mountain National Park and the Medicine Bow Range, 
  and The Northern Front Range Foothills.

* WHEN...Until 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. Travel 
  could be very difficult.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. Roads will be slick 
resulting in slow and hazardous travel. Allow extra time to reach 
your destination The latest road conditions for Colorado can be 
obtained by calling 5 1 1 or by going to www.cotrip.org

&&

$$

COZ039-200300-
/O.CON.KBOU.WS.W.0006.210419T2100Z-210420T0900Z/
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield
County-
Including the cities of Boulder, Golden, Longmont, Arvada, and
Lakewood
1101 AM MDT Mon Apr 19 2021

...WINTER STORM WARNING REMAINS IN EFFECT FROM 3 PM THIS AFTERNOON 
TO 3 AM MDT TUESDAY...

* WHAT...Snow expected. Total snow accumulations of 5 to 8 inches, 
  most of it within 6 to 9 hours, with locally heavier amounts near 
  the base of the foothills.

* WHERE...Boulder and the western suburbs of Denver.

* WHEN...From 3 PM this afternoon to 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. Travel 
  could be very difficult. The hazardous conditions will impact the 
  Monday evening commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. Roads will be slick 
resulting in slow and hazardous travel. Allow extra time to reach 
your destination The latest road conditions for Colorado can be 
obtained by calling 5 1 1 or by going to www.cotrip.org

&&

$$

COZ042-044>046-048>051-200300-
/O.EXA.KBOU.WW.Y.0025.210419T2100Z-210420T0900Z/
Northeast Weld County-Morgan County-Central and East Adams and
Arapahoe Counties-North and Northeast Elbert County Below
6000 Feet/North Lincoln County-Logan County-Washington County-
Sedgwick County-Phillips County-
Including the cities of Wiggins, Fort Morgan, Hugo, Otis,
Julesburg, Sedgwick, Briggsdale, Leader, Sterling, Pawnee Buttes,
Cope, Akron, Raymer, Amherst, Ovid, Matheson, Peetz, Grover, Deer
Trail, Byers, Agate, Haxtun, Last Chance, Goodrich, Stoneham,
Bennett, Crook, Holyoke, Brush, Limon, and Merino
1101 AM MDT Mon Apr 19 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 3 PM THIS AFTERNOON TO 3 
AM MDT TUESDAY...

* WHAT...Snow expected. Total snow accumulations of 2 to 5 inches. 
  Winds gusting as high as 35 mph.

* WHERE...Portions of east central and northeast Colorado.

* WHEN...From 3 PM this afternoon to 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. Plan on 
  slippery road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. Roads will be slick 
resulting in slow and hazardous travel. Allow extra time to reach 
your destination The latest road conditions for Colorado can be 
obtained by calling 5 1 1 or by going to www.cotrip.org

&&

$$

COZ034-036-200300-
/O.CON.KBOU.WW.Y.0025.210419T1800Z-210420T0900Z/
South and Southeast Grand/West Central and Southwest
Boulder/Gilpin/Clear Creek/Summit/North and West Park Counties
Above 9000 Feet-Jefferson and West Douglas Counties Above
6000 Feet/Gilpin/Clear Creek/Northeast Park Counties Below
9000 Feet-
Including the cities of Evergreen, Georgetown, Indian Peaks,
Idaho Springs, Eisenhower Tunnel, East Slopes Southern Gore
Range, Mount Evans, Central City, East Slopes Mosquito Range,
Breckenridge, Winter Park, Williams Fork Mountains, Bailey,
Kenosha Mountains, Westcreek, and Berthoud Pass
1101 AM MDT Mon Apr 19 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 3 AM MDT 
TUESDAY...

* WHAT...Snow expected. Total snow accumulations of 6 to 12 inches 
  along and north of I-70, 4 to 7 inches to the south. Lighter snow 
  accumulations of 1 to 4 inches west of the Eisenhower Tunnel. 
  Winds gusting as high as 35 mph.

* WHERE...The Mountains of Summit County, the Mosquito Range, and 
  the Indian Peaks, and The Southern Front Range Foothills.

* WHEN...Until 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. Travel 
  could be very difficult. The hazardous conditions could impact the 
  Monday evening commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. Roads will be slick 
resulting in slow and hazardous travel. Allow extra time to reach 
your destination The latest road conditions for Colorado can be 
obtained by calling 5 1 1 or by going to www.cotrip.org

&&

$$

COZ038-040-041-043-200300-
/O.CON.KBOU.WW.Y.0025.210419T2100Z-210420T0900Z/
Larimer County Below 6000 Feet/Northwest Weld County-North
Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe
Counties/East Broomfield County-Elbert/Central and East Douglas
Counties Above 6000 Feet-Central and South Weld County-
Including the cities of Eaton, Highlands Ranch, Castle Rock, City
of Denver, Elbert, Fort Collins, Aurora, Roggen, Kiowa, Loveland,
Greeley, Littleton, Nunn, Larkspur, Fort Lupton, Fondis,
Hereford, Parker, Denver International Airport, and Brighton
1101 AM MDT Mon Apr 19 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 3 PM THIS 
AFTERNOON TO 3 AM MDT TUESDAY...

* WHAT...Snow expected. Total snow accumulations of 3 to 6 inches, 
  with locally heavier amounts near the base of the foothills.

* WHERE...Fort Collins, Denver, Castle Rock, and Greeley.

* WHEN...From 3 PM this afternoon to 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. Plan on 
  slippery road conditions. The hazardous conditions will impact the 
  Monday evening commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. Roads will be slick 
resulting in slow and hazardous travel. Allow extra time to reach 
your destination The latest road conditions for Colorado can be 
obtained by calling 5 1 1 or by going to www.cotrip.org

&&

$$

For more information from the National Weather Service, visit 
https://weather.gov/bou

Meier
249 
WWUS45 KBOU 200114
WSWBOU

URGENT - WINTER WEATHER MESSAGE
National Weather Service Denver CO
714 PM MDT Mon Apr 19 2021

...HEAVY SNOW AND COLD TEMPERATURES THROUGH TONIGHT...

.Snow will be heavy at times this evening, and then slowly decrease 
from north to south by midnight. Snowfall rates will be as high as 1 
to 2 inches per hour this evening, with slick and hazardous travel 
conditions. Snow will gradually come to an end overnight, but slick 
spots will remain for the Tuesday morning commute.

COZ033-035-200900-
/O.CON.KBOU.WS.W.0006.000000T0000Z-210420T0900Z/
South and East Jackson/Larimer/North and Northeast
Grand/Northwest Boulder Counties Above 9000 Feet-Larimer and
Boulder Counties Between 6000 and 9000 Feet-
Including the cities of Glendevey, Nederland, Rocky Mountain
National Park, Laramie and Medicine Bow Mountains, Red Feather
Lakes, Cameron Pass, Estes Park, Willow Creek Pass, and Rabbit
Ears Range
714 PM MDT Mon Apr 19 2021

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 3 AM MDT TUESDAY...

* WHAT...Heavy snow possible. Total snow accumulations of 6 to 12 
  inches possible within 12 hours.

* WHERE...Rocky Mountain National Park and the Medicine Bow Range, 
  and The Northern Front Range Foothills.

* WHEN...Until 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. Travel 
  could be very difficult.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in 
your vehicle in case of an emergency. The latest road conditions for 
Colorado can be obtained by calling 5 1 1 or by going to www.cotrip.
org

Roads will be slick resulting in slow and hazardous travel. Allow 
extra time to reach your destination.

&&

$$

COZ039-200900-
/O.CON.KBOU.WS.W.0006.000000T0000Z-210420T0900Z/
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield
County-
Including the cities of Boulder, Golden, Longmont, Arvada, and
Lakewood
714 PM MDT Mon Apr 19 2021

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 3 AM MDT TUESDAY...

* WHAT...Snow expected. Total snow accumulations of 5 to 9 inches.

* WHERE...Boulder and the western suburbs of Denver.

* WHEN...Until 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in 
your vehicle in case of an emergency. The latest road conditions for 
Colorado can be obtained by calling 5 1 1 or by going to www.cotrip.
org

Roads will be slick resulting in slow and hazardous travel. Allow 
extra time to reach your destination.

&&

$$

COZ034-036-200900-
/O.CON.KBOU.WW.Y.0025.000000T0000Z-210420T0900Z/
South and Southeast Grand/West Central and Southwest
Boulder/Gilpin/Clear Creek/Summit/North and West Park Counties
Above 9000 Feet-Jefferson and West Douglas Counties Above
6000 Feet/Gilpin/Clear Creek/Northeast Park Counties Below
9000 Feet-
Including the cities of Evergreen, Georgetown, Indian Peaks,
Idaho Springs, Eisenhower Tunnel, East Slopes Southern Gore
Range, Mount Evans, Central City, East Slopes Mosquito Range,
Breckenridge, Winter Park, Williams Fork Mountains, Bailey,
Kenosha Mountains, Westcreek, and Berthoud Pass
714 PM MDT Mon Apr 19 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 3 AM MDT 
TUESDAY...

* WHAT...Snow expected. Total snow accumulations of 6 to 11 inches 
  along and north of I-70, 4 to 7 inches to the south. Lighter snow 
  accumulations of 1 to 4 inches west of the Eisenhower Tunnel. 
  Winds gusting as high as 35 mph.

* WHERE...The Mountains of Summit County, the Mosquito Range, and 
  the Indian Peaks, and The Southern Front Range Foothills.

* WHEN...Until 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. The latest road 
conditions for Colorado can be obtained by calling 5 1 1 or by going 
to www.cotrip.org

Roads will be slick resulting in slow and hazardous travel. Allow 
extra time to reach your destination.

&&

$$

COZ038-040-041-043-200900-
/O.CON.KBOU.WW.Y.0025.000000T0000Z-210420T0900Z/
Larimer County Below 6000 Feet/Northwest Weld County-North
Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe
Counties/East Broomfield County-Elbert/Central and East Douglas
Counties Above 6000 Feet-Central and South Weld County-
Including the cities of Eaton, Highlands Ranch, Castle Rock, City
of Denver, Elbert, Fort Collins, Aurora, Roggen, Kiowa, Loveland,
Greeley, Littleton, Nunn, Larkspur, Fort Lupton, Fondis,
Hereford, Parker, Denver International Airport, and Brighton
714 PM MDT Mon Apr 19 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 3 AM MDT 
TUESDAY...

* WHAT...Snow expected. Total snow accumulations of 3 to 6 inches.

* WHERE...Fort Collins, Denver, Castle Rock, and Greeley.

* WHEN...Until 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. Plan on 
  slippery road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. The latest road 
conditions for Colorado can be obtained by calling 5 1 1 or by going 
to www.cotrip.org

Roads will be slick resulting in slow and hazardous travel. Allow 
extra time to reach your destination.

&&

$$

COZ042-044>046-048>051-200900-
/O.CON.KBOU.WW.Y.0025.000000T0000Z-210420T0900Z/
Northeast Weld County-Morgan County-Central and East Adams and
Arapahoe Counties-North and Northeast Elbert County Below
6000 Feet/North Lincoln County-Logan County-Washington County-
Sedgwick County-Phillips County-
Including the cities of Wiggins, Fort Morgan, Hugo, Otis,
Julesburg, Sedgwick, Briggsdale, Leader, Sterling, Pawnee Buttes,
Cope, Akron, Raymer, Amherst, Ovid, Matheson, Peetz, Grover, Deer
Trail, Byers, Agate, Haxtun, Last Chance, Goodrich, Stoneham,
Bennett, Crook, Holyoke, Brush, Limon, and Merino
714 PM MDT Mon Apr 19 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 3 AM MDT 
TUESDAY...

* WHAT...Snow expected. Total snow accumulations of 2 to 5 inches, 
  heaviest south of Highway 34. Winds gusting as high as 25 mph.

* WHERE...Portions of east central and northeast Colorado.

* WHEN...Until 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. Plan on 
  slippery road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. The latest road 
conditions for Colorado can be obtained by calling 5 1 1 or by going 
to www.cotrip.org

Roads will be slick resulting in slow and hazardous travel. Allow 
extra time to reach your destination.

&&

$$

For more information from the National Weather Service, visit 
https://weather.gov/bou

Barjenbruch
731 
WWUS45 KBOU 200337
WSWBOU

URGENT - WINTER WEATHER MESSAGE
National Weather Service Denver CO
937 PM MDT Mon Apr 19 2021

...HEAVY SNOW WINDS DOWN TONIGHT...

.Snow will slowly decrease and come to an end from north to south 
across northeast and north central Colorado overnight. Roads will be 
snow covered in most spots, with slick and hazardous travel 
conditions.  Slick spots will remain for the Tuesday morning 
commute, so allow extra time to reach your destination safely.

COZ033-035-200900-
/O.CON.KBOU.WS.W.0006.000000T0000Z-210420T0900Z/
South and East Jackson/Larimer/North and Northeast
Grand/Northwest Boulder Counties Above 9000 Feet-Larimer and
Boulder Counties Between 6000 and 9000 Feet-
Including the cities of Glendevey, Nederland, Rocky Mountain
National Park, Laramie and Medicine Bow Mountains, Red Feather
Lakes, Cameron Pass, Estes Park, Willow Creek Pass, and Rabbit
Ears Range
937 PM MDT Mon Apr 19 2021

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 3 AM MDT TUESDAY...

* WHAT...Heavy snow ending overnight. Total snow accumulations of 6 
  to 12 inches, with up to 15 inches in the foothills of Boulder 
  County.

* WHERE...Rocky Mountain National Park and the Medicine Bow Range, 
  and The Northern Front Range Foothills.

* WHEN...Until 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. Travel 
  could be very difficult.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in 
your vehicle in case of an emergency. The latest road conditions for 
Colorado can be obtained by calling 5 1 1 or by going to www.cotrip.
org

Roads will be slick resulting in slow and hazardous travel. Allow 
extra time to reach your destination.

&&

$$

COZ039-200900-
/O.CON.KBOU.WS.W.0006.000000T0000Z-210420T0900Z/
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield
County-
Including the cities of Boulder, Golden, Longmont, Arvada, and
Lakewood
937 PM MDT Mon Apr 19 2021

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 3 AM MDT TUESDAY...

* WHAT...Heavy snow ending overnight Total snow accumulations of 5 
  to 9 inches, with up to 12 inches in parts of Boulder.

* WHERE...Boulder and the western suburbs of Denver.

* WHEN...Until 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in 
your vehicle in case of an emergency. The latest road conditions for 
Colorado can be obtained by calling 5 1 1 or by going to www.cotrip.
org

Roads will be slick resulting in slow and hazardous travel. Allow 
extra time to reach your destination.

&&

$$

COZ034-036-200900-
/O.CON.KBOU.WW.Y.0025.000000T0000Z-210420T0900Z/
South and Southeast Grand/West Central and Southwest
Boulder/Gilpin/Clear Creek/Summit/North and West Park Counties
Above 9000 Feet-Jefferson and West Douglas Counties Above
6000 Feet/Gilpin/Clear Creek/Northeast Park Counties Below
9000 Feet-
Including the cities of Evergreen, Georgetown, Indian Peaks,
Idaho Springs, Eisenhower Tunnel, East Slopes Southern Gore
Range, Mount Evans, Central City, East Slopes Mosquito Range,
Breckenridge, Winter Park, Williams Fork Mountains, Bailey,
Kenosha Mountains, Westcreek, and Berthoud Pass
937 PM MDT Mon Apr 19 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 3 AM MDT 
TUESDAY...

* WHAT...Snow ongoing. Total snow accumulations of 6 to 11 inches 
  along and north of I-70, 4 to 7 inches to the south. Lighter snow 
  accumulations of 1 to 4 inches west of the Eisenhower Tunnel. 
  Winds gusting as high as 35 mph.

* WHERE...The Mountains of Summit County, the Mosquito Range, and 
  the Indian Peaks, and The Southern Front Range Foothills.

* WHEN...Until 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. Plan on 
  slippery road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. The latest road 
conditions for Colorado can be obtained by calling 5 1 1 or by going 
to www.cotrip.org

Roads will be slick resulting in slow and hazardous travel. Allow 
extra time to reach your destination.

&&

$$

COZ038-040-041-043-200900-
/O.CON.KBOU.WW.Y.0025.000000T0000Z-210420T0900Z/
Larimer County Below 6000 Feet/Northwest Weld County-North
Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe
Counties/East Broomfield County-Elbert/Central and East Douglas
Counties Above 6000 Feet-Central and South Weld County-
Including the cities of Eaton, Highlands Ranch, Castle Rock, City
of Denver, Elbert, Fort Collins, Aurora, Roggen, Kiowa, Loveland,
Greeley, Littleton, Nunn, Larkspur, Fort Lupton, Fondis,
Hereford, Parker, Denver International Airport, and Brighton
937 PM MDT Mon Apr 19 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 3 AM MDT 
TUESDAY...

* WHAT...Snow ongoing. Total snow accumulations of 3 to 6 inches.

* WHERE...Fort Collins, Denver, Castle Rock, and Greeley.

* WHEN...Until 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. Plan on 
  slippery road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. The latest road 
conditions for Colorado can be obtained by calling 5 1 1 or by going 
to www.cotrip.org

Roads will be slick resulting in slow and hazardous travel. Allow 
extra time to reach your destination.

&&

$$

COZ042-044>046-048>051-200900-
/O.CON.KBOU.WW.Y.0025.000000T0000Z-210420T0900Z/
Northeast Weld County-Morgan County-Central and East Adams and
Arapahoe Counties-North and Northeast Elbert County Below
6000 Feet/North Lincoln County-Logan County-Washington County-
Sedgwick County-Phillips County-
Including the cities of Wiggins, Fort Morgan, Hugo, Otis,
Julesburg, Sedgwick, Briggsdale, Leader, Sterling, Pawnee Buttes,
Cope, Akron, Raymer, Amherst, Ovid, Matheson, Peetz, Grover, Deer
Trail, Byers, Agate, Haxtun, Last Chance, Goodrich, Stoneham,
Bennett, Crook, Holyoke, Brush, Limon, and Merino
937 PM MDT Mon Apr 19 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 3 AM MDT 
TUESDAY...

* WHAT...Snow ongoing. Total snow accumulations of 2 to 5 inches, 
  heaviest south of Highway 34.

* WHERE...Portions of east central and northeast Colorado.

* WHEN...Until 3 AM MDT Tuesday.

* IMPACTS...Snow covered roads will make travel hazardous. Plan on 
  slippery road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. The latest road 
conditions for Colorado can be obtained by calling 5 1 1 or by going 
to www.cotrip.org

Roads will be slick resulting in slow and hazardous travel. Allow 
extra time to reach your destination.

&&

$$

For more information from the National Weather Service, visit 
https://weather.gov/bou

Barjenbruch
424 
WWUS45 KBOU 200857
WSWBOU

URGENT - WINTER WEATHER MESSAGE
National Weather Service Denver CO
257 AM MDT Tue Apr 20 2021

COZ033-035-201000-
/O.CAN.KBOU.WS.W.0006.000000T0000Z-210420T0900Z/
South and East Jackson/Larimer/North and Northeast
Grand/Northwest Boulder Counties Above 9000 Feet-Larimer and
Boulder Counties Between 6000 and 9000 Feet-
Including the cities of Glendevey, Nederland, Rocky Mountain
National Park, Laramie and Medicine Bow Mountains, Red Feather
Lakes, Cameron Pass, Estes Park, Willow Creek Pass, and Rabbit
Ears Range
257 AM MDT Tue Apr 20 2021

...WINTER STORM WARNING IS CANCELLED...

Snow has ended, though a few flurries may still occur early this 
morning.

$$

COZ039-201000-
/O.EXP.KBOU.WS.W.0006.000000T0000Z-210420T0900Z/
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield
County-
Including the cities of Boulder, Golden, Longmont, Arvada, and
Lakewood
257 AM MDT Tue Apr 20 2021

...WINTER STORM WARNING WILL EXPIRE AT 3 AM MDT EARLY THIS MORNING...

Heavy snow has ended, though a few flurries may still occur for the 
next couple of hours, with little to no additional accumulation 
expected.

$$

COZ034-036-038-040-041-043-201000-
/O.CAN.KBOU.WW.Y.0025.000000T0000Z-210420T0900Z/
South and Southeast Grand/West Central and Southwest
Boulder/Gilpin/Clear Creek/Summit/North and West Park Counties
Above 9000 Feet-Jefferson and West Douglas Counties Above
6000 Feet/Gilpin/Clear Creek/Northeast Park Counties Below
9000 Feet-Larimer County Below 6000 Feet/Northwest Weld County-
North Douglas County Below 6000 Feet/Denver/West Adams and
Arapahoe Counties/East Broomfield County-Elbert/Central and East
Douglas Counties Above 6000 Feet-Central and South Weld County-
Including the cities of Eaton, Elbert, Westcreek, Roggen, Central
City, Breckenridge, Larkspur, Bailey, Williams Fork Mountains,
Evergreen, Georgetown, Indian Peaks, City of Denver, Aurora, East
Slopes Southern Gore Range, Mount Evans, Littleton, East Slopes
Mosquito Range, Berthoud Pass, Brighton, Highlands Ranch, Fort
Lupton, Loveland, Kiowa, Kenosha Mountains, Winter Park, Fondis,
Denver International Airport, Parker, Castle Rock, Fort Collins,
Greeley, Nunn, Idaho Springs, Hereford, and Eisenhower Tunnel
257 AM MDT Tue Apr 20 2021

...WINTER WEATHER ADVISORY IS CANCELLED...

Heavy snow has ended, though a few flurries may still occur for the 
next couple of hours, with little to no additional accumulation 
expected.

$$

COZ042-044>046-048>051-201000-
/O.EXP.KBOU.WW.Y.0025.000000T0000Z-210420T0900Z/
Northeast Weld County-Morgan County-Central and East Adams and
Arapahoe Counties-North and Northeast Elbert County Below
6000 Feet/North Lincoln County-Logan County-Washington County-
Sedgwick County-Phillips County-
Including the cities of Wiggins, Fort Morgan, Hugo, Otis,
Julesburg, Sedgwick, Briggsdale, Leader, Sterling, Pawnee Buttes,
Cope, Akron, Raymer, Amherst, Ovid, Matheson, Peetz, Grover, Deer
Trail, Byers, Agate, Haxtun, Last Chance, Goodrich, Stoneham,
Bennett, Crook, Holyoke, Brush, Limon, and Merino
257 AM MDT Tue Apr 20 2021

...WINTER WEATHER ADVISORY WILL EXPIRE AT 3 AM MDT EARLY THIS 
MORNING...

Heavy snow has ended, though a few flurries may still occur for the 
next couple of hours, with little to no additional accumulation 
expected.

$$

For more information from the National Weather Service, visit 
https://weather.gov/bou

Kriederman

Nearby

Winter Storm Warnings in Colorado, 2021Every winter storm warning in 2021

Sources

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