Boulder SKYWARN® & CWA Information
Office & CWA Overview
The National Weather Service Weather Forecast Office (WFO) in Denver/Boulder, Colorado provides forecasts, warnings, and decision‑support services for much of north‑central and northeast Colorado, including the foothills, Front Range urban corridor, and adjacent high plains east of the Continental Divide.
This County Warning Area (CWA) spans complex terrain from the Rocky Mountain foothills into the eastern plains, with a wide range of hazards: severe thunderstorms, large hail, tornadoes, flash flooding, downslope wind events, dangerous winter storms, and periods of elevated to critical fire weather.
[https://www.weather.gov/pimar/CWAbyWFO](https://www.weather.gov/pimar/CWAbyWFO)
Historic Weather & Office Background
Weather observations in the Front Range region date back well over a century, with cooperative observers, river‑gauge networks, and early Weather Bureau operations supporting agriculture, transportation, and water‑resource management in the growing corridor between Denver and Colorado Springs.
The modern Denver/Boulder forecast office and its WSR‑88D radar provide coverage from the high foothills across the metro area and onto the eastern plains, supporting aviation, hydrology, fire weather, and public forecast services for one of the most densely populated and rapidly changing regions in Colorado.
Today, WFO Denver/Boulder issues forecasts and warnings for the Front Range urban corridor, I‑25, I‑70 mountain passes, small‑town communities, ranching interests, and major recreation and transportation hubs across the CWA.
Notable Historic Weather Events in the NWS Denver/Boulder CWA
Severe Thunderstorms & Tornadoes
During the warm season, organized storm systems and isolated supercells can produce large hail, damaging winds, and tornadoes across the Front Range foothills, urban corridors, and the plains east of Denver.
Reports of hail size, wind damage, and rotation are critical for timely warnings and for communicating specific risks to outdoor events, schools, and transportation networks.
Flash Flooding & Urban Flood Events
Slow‑moving thunderstorms or cold‑front lift can produce intense rainfall over steep foothills, small drainages, and urban catchments, leading to flash flooding and rapid creek rises across the CWA.
Roads, underpasses, and low‑lying areas can fill quickly, threatening motorists, campers, and residents in burn‑scar regions where soils are less able to absorb water.
Downslope Wind Events & High Winds
Favorable pressure and jet‑stream patterns can trigger strong downslope winds along the Front Range, producing gusts well over 60 mph and creating hazardous conditions for travel, aviation, and outdoor structures.
These events can coincide with dry conditions, increasing the risk of wind‑driven wildfire spread and power‑outage cascades.
Winter Storms, Blowing Snow & Extreme Cold
Major winter storms bring heavy snow, blinding blowing snow, and whiteout conditions to the foothills and passes, while strong Arctic outbreaks can drive extreme wind chills across the plains and urban corridors.
Accumulating snow and drifting can shut down I‑70 mountain routes, secondary highways, and local roads, impacting commuters, emergency services, and critical infrastructure.
Fires in Northern Colorado
Dry, windy conditions helped accelerate the spread of the Cameron Peak fire to recording breaking acreage.
Cameron Peak Fire
Scroll through to learn about the largest fire in Colorado history.
Coordination between WFO Denver/Boulder, land management agencies, and SKYWARN® spotters helps track new fire starts, rapid‑spread events, and smoke that can reduce visibility and air quality across the region.
East Troublesome Fire
Thousands of acres burned in less than a month with the only hope to stop the fire being a dramatic change in the weather.
Scroll through to learn about the second largest fire in Colorado history.
Explore additional historic weather information, hydrologic resources, and forecast discussions for north‑central and northeast Colorado via the NWS Denver/Boulder office website .
Denver/Boulder SKYWARN® & Spotter Program
The Denver/Boulder WFO maintains a SKYWARN® spotter network across the Front Range and adjacent plains, relying on trained volunteers to report hazardous weather in areas where radar coverage and surface observations can be limited.
Spotters include amateur radio operators, emergency managers, law enforcement and fire personnel, transportation and utility workers, school and event staff, and engaged community members who provide critical ground truth during severe weather and winter storm events.
Denver/Boulder SKYWARN® Program
Overview of SKYWARN® in the Denver/Boulder CWA, including who can become a spotter, training expectations, and reporting basics.
Spotter Training & Reporting Guides
Online SKYWARN® and severe weather‑spotter training modules, along with spotter reporting guides tailored to the Front Range and plains.
Colorado Severe Weather Network
Amateur radio–based severe weather support for NWS offices across the central Rockies and High Plains, including coordination with Denver/Boulder during regional events. [web:8]
Colorado Severe Weather Network [web:8]
Training & Reference for Spotters
Use these topics to guide SKYWARN® training tailored to the Front Range, urban corridors, and high‑plains environments in the Denver/Boulder CWA.
- Convective storms – Supercells, bow‑echoes, and pulse storms producing large hail, damaging winds, and occasional tornadoes in urban and rural areas.
- Flash flooding – Rapid rises in urban channels, street drainage systems, and small streams, especially following heavy thunderstorms or rapid snowmelt events.
- Winter weather – Heavy snow, ice storms, and strong winds affecting the foothills, I‑70 corridor, and adjacent plains, including snow levels and drift impacts.
- Fire weather – Dry thunderstorms, gusty outflows, very low humidity, and shifting winds that can rapidly spread grass and timber fires.
Local live and virtual SKYWARN® training sessions are announced on the Denver/Boulder website and through partner agencies.
Significant Weather Event Reporting Criteria
National Weather Service – Denver/Boulder Forecast Office
How to Report
- Online: Use the national NWS Storm Report Form when available for your area.
- Phone: Use contact numbers provided during your local SKYWARN® training or listed on the Denver/Boulder SKYWARN® web page.
- Email: Use the email contact listed on the Denver/Boulder SKYWARN® page for reports and photos.
- Social Media: Tag @NWSBoulder on supported platforms when appropriate, following NWS guidance.
Flooding, Flash Flooding & Heavy Rain
- Rapid rises in creeks, streams, storm drains, or urban streets.
- Water flowing faster or higher than normal, especially in low‑lying underpasses or culverts.
- Water covering or threatening roads, campgrounds, homes, or trail crossings.
- One inch or more of rain in a short period, or intense bursts that cause quick runoff.
- Debris flows or mudslides, particularly near recent burn areas.
Winter Weather
- Measured snowfall amounts with location and time period.
- Snow depth and drift depths in valleys, urban areas, and along major corridors.
- Freezing rain, ice glazing, or mixed precipitation reports.
- Blowing snow, whiteouts, or closure‑level impacts on major roads and I‑70 mountain passes.
Fire Weather
- New wildfire starts or notable flare‑ups.
- Smoke reducing visibility below 2 miles, especially near highways or populated areas.
- Strong, erratic winds impacting fire behavior or suppression efforts.
Convective / Thunderstorm Weather
- Tornado / Funnel: Any rotating funnel, whether or not it reaches the ground.
- Hail: Any size, with measurements and comparison objects.
- Wind: Damage, downed limbs or power lines, or estimated winds ~50 mph or greater.
- Lightning: Frequent cloud‑to‑ground strikes or unusual lightning behavior causing impacts.
High Wind & Blowing Dust
- Strong winds producing blowing dust and visibility reductions.
- Wind‑blown damage to structures, trees, or vehicles.
- High‑profile vehicles affected along major corridors such as I‑25 and I‑70.
NWS Boulder Video Library
This section hosts curated videos specific to the Denver/Boulder CWA, including severe thunderstorms, flash floods, winter storms, and SKYWARN® operations across the Front Range and adjacent plains.
NWS Boulder 2023 Basic SKYWARN®
This is a recorded virtual basic SKYWARN class hosted by Boulder/Denver NWS forecast office.
June 21, 2023 Washington County Tornadoes and Hail
This radar animation runs from 3:10 PM MDT - 7:30 PM MDT. On the left is 0.5 degree base reflectivity, and on the right is 0.5 degree base velocity. Radar KFTG is located just north of I-70 east of Denver/Aurora.
TDEN Radar Animation from the May 18, 2025 Tornadoes
This animation shows reflectivity (left) and Doppler velocity (right) from the TDEN Terminal Doppler Radar from 1-2 PM MDT on May 18, 2025. Each tornado is labeled and will move with the animation. The tornado label is always to the right and sometimes down from the actual tornado location. Damage tracks are overlaid on every frame for each of the 4 tornadoes. Green track #2 is EF-1 intensity, yellow tracks (tornadoes 1, 3, 4) are EF-2 intensity.
Flash Flooding in the Foothills
Embedded video: Flash flood and debris‑flow event in the Front Range foothills (to be added).
Planned content: Visual examples, safety lessons, and reporting priorities for steep terrain and burn scars.
June 21, 2023 Washington County Tornadoes and Hail
This radar animation runs from 3:10 PM MDT - 7:30 PM MDT. On the left is 0.5 degree base reflectivity, and on the right is 0.5 degree base velocity. Radar KFTG is located just north of I-70 east of Denver/Aurora.