Hail and Lightning Strikes in Colorado, July 11, 2001

Name: Hail and Lightning Strikes in Colorado, July 11, 2001
Start: 2001-07-11T14:20
End: 2001-07-11T18:15
Location: Colorado

July 11, 2001 · NWS BOU · 7 events in 4 counties and zones

4 hail, 3 lightning, as filed by the National Weather Service.

Where it happened

Every event with a place to put it; 3 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 1
Property damage: $215,000
Crop damage: None recorded
Events: 7

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.

What forecasters said that day

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 Denver/Boulder, CO wrote its last area forecast discussion before the first event at Jul 11, 2:00 PM MST, 20 minutes earlier.

Area forecast discussion, Jul 11, 2:00 PM MST, 20 minutes before

NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER COLORADO
300 PM MDT WED JUL 11 2001

COLORADO AND THE ROCKY MOUNTAIN WEST REMAINS DIRECTLY CONNECTED TO
THE ITCZ FOR ANOTHER DAY.  THIS CONVEYOR BELT OF MOISTURE EXTENDS
FROM 10DEG N LAT NORTHWARD ACROSS MEXICO AND UP TO MONTANA.  WATER
VAPOR LOOP CURRENTLY SHOWING AN ABSENCE OF SIGNIFICANT DYNAMIC
LIFT...UNLIKE YESTERDAYS MORE PRONOUNCED CYCLONIC SPIN MOVING NORTH
OUT OF NEW MEX.  ETA ANALYSIS DOES RECOGNIZE A WEAK VORT CENTER
WHICH MATCHES PRETTY WELL WITH SOME SLIGHT H2O VAPOR BRIGHTENING
THIS MORNING OVR THE SAN JUANS WITH ANOTHER ONE ABOUT 200 MILES
BEHIND IT.  THIS FIRST AREA MAY BE THE KICKER DE JOUR FOR THE BOU
CWA.  THERE ALSO APPEARS TO BE A WEAK STATIONARY BOUNDARY ALONG THE
FRONT RANGE AS SEEN IN THE MSAS PRESSURE AND MOISTURE FIELDS.  THIS
WILL NEED TO BE WATCHED TO SEE IF CONVECTION FORMS ON A BOUNDARY
AWAY FROM THE URBAN CORRIDOR LIKE MONDAY OR IF CONVECTION INITIATES
ALONG THE FOOTHILLS LIKE YESTERDAY.  THETA-E RIDGE IS ORIENTED FROM
SOUTHEAST TO NORTHWEST OVR WASH AND NRN WELD COUNTIES.  THE DEN
MORNING SOUNDING IS A LITTLE WETTER THAN YESTERDAYS...HOWEVER
SOMEWHAT CONCERNED ABOUT THE WEAK CAP BETWEEN 580MB-550MB.  THIS MAY
NOT MEAN MUCH FOR LOCATIONS IN AND NEAR THE FOOTHILLS...BUT MAY
SUPRESS CONVECTION UNTIL LATER IN THE EVE ON THE PLAINS.  MESO-ETA
FCST SOUNDINGS ON THE PLAINS CONTAIN 1900-2400 J/KG OF ENERGY WHICH
IS LESS THAN THE DENVER POTENTIAL.  WITH ANY REASONING...WITH
HEALTHY AMOUNTS OF SFC MOISTURE...SEE NO REASON TO GO LESS THAN SCT
COVERAGE FOR CWA AND A FLASH FLOOD WATCH MAY BE NEEDED AGAIN.

THROUGH TIME...MDLS START TO SLOWLY RETROGRADE THE UPPER HIGH TO THE
WEST.  FOR THURSDAY AND FRIDAY...DECENT MID AND UPPER LVL MOISTURE
FROM THE TROPICS IS STILL UPON THE STATE.  MESO-ETA STILL SHOWS AN
UNSTABLE SOUNDING WITH HIGH POSITIVE ENERGY AND SOUTHEASTERLY SFC
FLOW TO HOLD SFC DEW POINTS UP EACH DAY.  SEE NOTHING IN THE
THURS-FRI PD TO SCOUR THE SFC DRY.  AGAIN DYNAMICS NEARLY IMPOSSIBLE
TO DETECT...BUT AVN AND ETA SWINGS A SERIES OF VORT CENTERS AROUND
UPPER RIDGE WHICH COULD BE FROM BURNT OUT ORGANIZED CONVECTION
COMING OUT OF MEX.  SCT COVERAGE SHD AGAIN BE THE RULE.

EXTENDED PD SATURDAY THROUGH WEDNESDAY...PREDICTED CENTER OF UPPER
HIGH RESTS OVR NEW MEX BY SATURDAY AS DRYER PACIFC AIR MOVES OVER
THE GREAT BASIN.  AVN CONTINUES TO HOLD HIGHER RHS IN THE LOWER LVLS
OF THE EAST.  RIDGE WEAKENS AND ELONGATES FOR SUNDAY AND MONDAY BUT
REBUILDS OVER THE SOUTHERN HALF OF THE STATE TUESDAY AND WEDNESDAY.
WOULD EXPECT SUBSIDENCE TO HAVE GREATEST EFFECT ON THUNDERSTORM
DEVELOPMENT AND COVERAGE FOR TUESDAY AND WEDNESDAY AND WILL TRIM
POPS ACCORDINGLY.  TEMP GUIDANCE HOLDS TEMPS WITHIN SEASONAL NORMS.

FREDIN

.DEN...NONE.

In the hours before

Special weather statement, Jul 11, 10:00 AM MST, 4 hours 20 minutes before

COZ030>051-112000-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER COLORADO...RETRANSMISSON
1100 AM MDT WED JUL 11 2001

THIS OUTLOOK PERTAINS TO THE FOLLOWING COLORADO COUNTIES

ADAMS     ARAPAHOE     BOULDER   CLEAR CREEK   DENVER       DOUGLAS
ELBERT    GILPIN       GRAND     JACKSON       JEFFERSON    LARIMER
LINCOLN   LOGAN        MORGAN    PARK          PHILLIPS     SEDGWICK
SUMMIT    WASHINGTON   WELD

SYNOPSIS...A MOIST SOUTH TO SOUTHWESTERLY FLOW ALOFT WILL CONTINUE
ACROSS NORTHEASTERN COLORADO THIS AFTERNOON AND TONIGHT.  THE MAIN
FOCUSING MECHANISM FOR THUNDERSTORMS TODAY WILL BE A STATIONARY
FRONT LOCATED JUST TO THE EAST OF THE INTERSTATE 25 CORRIDOR THIS
MORNING.

THE MAIN THREATS FROM THE STORMS THIS AFTERNOON WILL BE HEAVY
RAIN...FROM 1 TO 2 INCHES PER HOUR AND FREQUENT CLOUD TO GROUND
LIGHTNING.  A FEW STORMS COULD BECOME SEVERE PRODUCING HAIL UP TO AN
INCH IN DIAMETER AND DAMAGING WINDS....MAINLY ALONG AND EAST OF THE
BOUNDARY MENTIONED EARLIER.

URBAN AND SMALL STREAM FLOODING WILL LIKELY OCCUR WITH THE STORMS.
RESIDENTS IN THE HIGH MEADOWS...BUFFALO CREEK AND BOBCAT BURN AREAS
HOWEVER SHOULD BE ESPECIALLY ALERT TO HEAVY RAINFALL AS THE
THRESHOLD FOR FLASH FLOODING IS LOWER THERE THAN IN OTHER LOCATIONS.

A FLASH FLOOD WATCH MAY AGAIN BE NECESSARY FOR LATE THIS AFTERNOON
AND TONIGHT...AS THE GROUND IS FAIRLY SATURATED WITH MOISTURE FROM
THE PREVIOUS DAYS STORMS.

SPOTTER ACTIVATION MAY ALSO NECESSARY.  RAINFALL REPORTS WOULD BE
GREATLY APPRECIATED.

COOPER

Special weather statement, Jul 11, 12:00 PM MST, 2 hours 20 minutes before

COZ030>051-102000-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER COLORADO...RETRANSMISSON
1100 AM MDT WED JUL 11 2001

THIS OUTLOOK PERTAINS TO THE FOLLOWING COLORADO COUNTIES

ADAMS     ARAPAHOE     BOULDER   CLEAR CREEK   DENVER       DOUGLAS
ELBERT    GILPIN       GRAND     JACKSON       JEFFERSON    LARIMER
LINCOLN   LOGAN        MORGAN    PARK          PHILLIPS     SEDGWICK
SUMMIT    WASHINGTON   WELD

SYNOPSIS...A MOIST SOUTH TO SOUTHWESTERLY FLOW ALOFT WILL CONTINUE
ACROSS NORTHEASTERN COLORADO THIS AFTERNOON AND TONIGHT.  THE MAIN
FOCUSING MECHANISM FOR THUNDERSTORMS TODAY WILL BE A STATIONARY
FRONT LOCATED JUST TO THE EAST OF THE INTERSTATE 25 CORRIDOR THIS
MORNING.

THE MAIN THREATS FROM THE STORMS THIS AFTERNOON WILL BE HEAVY
RAIN...FROM 1 TO 2 INCHES PER HOUR AND FREQUENT CLOUD TO GROUND
LIGHTNING.  A FEW STORMS COULD BECOME SEVERE PRODUCING HAIL UP TO AN
INCH IN DIAMETER AND DAMAGING WINDS....MAINLY ALONG AND EAST OF THE
BOUNDARY MENTIONED EARLIER.

URBAN AND SMALL STREAM FLOODING WILL LIKELY OCCUR WITH THE STORMS.
RESIDENTS IN THE HIGH MEADOWS...BUFFALO CREEK AND BOBCAT BURN AREAS
HOWEVER SHOULD BE ESPECIALLY ALERT TO HEAVY RAINFALL AS THE
THRESHOLD FOR FLASH FLOODING IS LOWER THERE THAN IN OTHER LOCATIONS.

A FLASH FLOOD WATCH MAY AGAIN BE NECESSARY FOR LATE THIS AFTERNOON
AND TONIGHT...AS THE GROUND IS FAIRLY SATURATED WITH MOISTURE FROM
THE PREVIOUS DAYS STORMS.

SPOTTER ACTIVATION MAY ALSO NECESSARY.  RAINFALL REPORTS WOULD BE
GREATLY APPRECIATED.

COOPER

@RUKWBCeKDENWWUS85 KBOU 111900
SPSDEN
COZ030>051-112000-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER COLORADO...RETRANSMISSON
1100 AM MDT WED JUL 11 2001

THIS OUTLOOK PERTAINS TO THE FOLLOWING COLORADO COUNTIES

ADAMS     ARAPAHOE     BOULDER   CLEAR CREEK   DENVER       DOUGLAS
ELBERT    GILPIN       GRAND     JACKSON       JEFFERSON    LARIMER
LINCOLN   LOGAN        MORGAN    PARK          PHILLIPS     SEDGWICK
SUMMIT    WASHINGTON   WELD

SYNOPSIS...A MOIST SOUTH TO SOUTHWESTERLY FLOW ALOFT WILL CONTINUE
ACROSS NORTHEASTERN COLORADO THIS AFTERNOON AND TONIGHT.  THE MAIN
FOCUSING MECHANISM FOR THUNDERSTORMS TODAY WILL BE A STATIONARY
FRONT LOCATED JUST TO THE EAST OF THE INTERSTATE 25 CORRIDOR THIS
MORNING.

THE MAIN THREATS FROM THE STORMS THIS AFTERNOON WILL BE HEAVY
RAIN...FROM 1 TO 2 INCHES PER HOUR AND FREQUENT CLOUD TO GROUND
LIGHTNING.  A FEW STORMS COULD BECOME SEVERE PRODUCING HAIL UP TO AN
INCH IN DIAMETER AND DAMAGING WINDS....MAINLY ALONG AND EAST OF THE
BOUNDARY MENTIONED EARLIER.

URBAN AND SMALL STREAM FLOODING WILL LIKELY OCCUR WITH THE STORMS.
RESIDENTS IN THE HIGH MEADOWS...BUFFALO CREEK AND BOBCAT BURN AREAS
HOWEVER SHOULD BE ESPECIALLY ALERT TO HEAVY RAINFALL AS THE
THRESHOLD FOR FLASH FLOODING IS LOWER THERE THAN IN OTHER LOCATIONS.

A FLASH FLOOD WATCH MAY AGAIN BE NECESSARY FOR LATE THIS AFTERNOON
AND TONIGHT...AS THE GROUND IS FAIRLY SATURATED WITH MOISTURE FROM
THE PREVIOUS DAYS STORMS.

SPOTTER ACTIVATION MAY ALSO NECESSARY.  RAINFALL REPORTS WOULD BE
GREATLY APPRECIATED.

COOPER

Special weather statement, Jul 11, 12:32 PM MST, 1 hour 48 minutes before

COZ030>051-112100-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER COLORADO
100 PM MDT WED JUL 11 2001

THIS OUTLOOK PERTAINS TO THE FOLLOWING COLORADO COUNTIES

ADAMS     ARAPAHOE     BOULDER   CLEAR CREEK   DENVER       DOUGLAS
ELBERT    GILPIN       GRAND     JACKSON       JEFFERSON    LARIMER
LINCOLN   LOGAN        MORGAN    PARK          PHILLIPS     SEDGWICK
SUMMIT    WASHINGTON   WELD

SYNOPSIS...A MOIST SOUTHWESTERLY FLOW ALOFT WILL CONTINUE ACROSS
NORTHEASTERN COLORADO LATE THIS AFTERNOON AND TONIGHT.  THE MAIN
FOCUSING MECHANISM FOR THUNDERSTORMS TODAY WILL BE A STATIONARY
FRONT.  THE BOUNDARY EXTENDS FROM AROUND FORT COLLINS TO JUST EAST
OF DENVER INTERNATIONAL AIRPORT TO KARVAL...IN SOUTHEASTERN LINCOLN
COUNTY.

AT 1PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
ISOLATED THUNDERSTORMS DEVELOPING ACROSS EASTERN LARIMER AS WELL AS
GRAND COUNTY.  THUNDERSTORMS WILL BEGIN TO INCREASE IN COVERAGE
ACROSS THE FRONT RANGE FOOTHILLS THE REMAINDER OF THE AFTERNOON.

ACROSS THE URBAN CORRIDOR...SCATTERED THUNDERSTORM MAY MOVE INTO
URBAN CORRIDOR AFTER 4 PM...STRONGEST IN THE FORT COLLINS AREA
INITIALLY...THEN SPREADING SOUTH AND EAST INTO THE EVENING.
ALTHOUGH THE LOWER LEVEL MOISTURE IN THE DENVER AREA HAS DECREASED
SOMEWHAT THIS AFTERNOON...OUTFLOW GENERATED FROM THE THUNDERSTORMS
NORTH OF EAST OF DENVER MAY TRIGGER STRONGER THUNDERSTORMS THIS
EVENING.

THE MAIN THREATS FROM THE STORMS THIS AFTERNOON AND EVENING WILL BE
HEAVY RAIN...FROM 1 TO 2 INCHES PER HOUR AND FREQUENT CLOUD TO
GROUND LIGHTNING.  A FEW STORMS COULD BECOME SEVERE PRODUCING HAIL
UP TO AN INCH IN DIAMETER AND DAMAGING WINDS....MAINLY ALONG AND
EAST OF THE BOUNDARY MENTIONED EARLIER.

URBAN AND SMALL STREAM FLOODING WILL LIKELY OCCUR WITH THE STORMS.
RESIDENTS IN THE HIGH MEADOWS...BUFFALO CREEK AND BOBCAT BURN AREAS
HOWEVER SHOULD BE ESPECIALLY ALERT TO HEAVY RAINFALL AS THE
THRESHOLD FOR FLASH FLOODING IS LOWER THERE THAN IN OTHER LOCATIONS.

A FLASH FLOOD WATCH MAY AGAIN BE NECESSARY FOR LATE THIS AFTERNOON
AND TONIGHT...MAINLY NOSRTH AND EAST OF THE DENVER AREA.  SPOTTER
ACTIVATION MAY ALSO BE NECESSARY.

COOPER

The radar

The Denver radar (KFTG), 54 km away, was scanning. The volume nearest the first event began at 21:20 UTC.

Open the radar archive at this moment

Event by event

4 hail, 3 lightning. Local standard time, as filed.

Hail, Elbert

When: July 11, 2:20 PM MST
Where: Elbert County, 10 mi E of Kiowa
Measured: 1 in hail
Reported by: TRAINED SPOTTER
Coordinates: 39.350, -104.283

Lightning, Elbert

When: July 11, 4:10 PM MST
Where: Elbert County, 10 mi S of Kiowa
Injuries: 1 direct, 0 indirect
Reported by: NEWSPAPER
Coordinates: 39.287, -104.136 (the zone’s center; the record gives no point)

A 13-yr old boy scout was knocked unconcious when lightning struck a tree near his tent.

Lightning, Adams

When: July 11, 4:15 PM MST
Where: Adams County, Thornton
Property damage: $200,000
Reported by: NEWSPAPER
Coordinates: 39.874, -104.338 (the zone’s center; the record gives no point)

Lightning struck the roof of a home. Most of the damage was confined to the attic.

Lightning, Adams

When: July 11, 4:20 PM MST
Where: Adams County, Thornton
Property damage: $15,000
Reported by: NEWSPAPER
Coordinates: 39.874, -104.338 (the zone’s center; the record gives no point)

Lightning struck another home in Thornton. Most of the damage was confined to the attic.

Hail, Boulder

When: July 11, 4:53 PM MST
Where: Boulder County, 5 mi SE of Boulder
Measured: 0.75 in hail
Reported by: TRAINED SPOTTER
Coordinates: 39.967, -105.200

Hail, Weld

When: July 11, 5:45 PM MST
Where: Weld County, Keenesburg
Measured: 0.75 in hail
Reported by: TRAINED SPOTTER
Coordinates: 40.100, -104.517

Hail, Boulder

When: July 11, 6:15 PM MST
Where: Boulder County, Longmont
Measured: 0.75 in hail
Reported by: TRAINED SPOTTER
Coordinates: 40.167, -105.100

What these are

Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
Lightning: A lightning strike that killed, injured or caused damage.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Colorado in 2001 Every state in 2001 This day in weather history Warnings in Colorado, July 2001

Sources

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: 5267152, 5267262, 5267263, 5267264, 5267153, 5267154, 5267261.