Flash Flooding and Hail in Colorado, July 13, 2001

Name: Flash Flooding and Hail in Colorado, July 13, 2001
Start: 2001-07-13T13:24
End: 2001-07-13T20:15
Location: Colorado

July 13, 2001 · NWS BOU · 4 events in 4 counties and zones

3 flash flood, 1 hail, 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: 0
Property damage: $600,000
Crop damage: None recorded
Events: 4

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 13, 11:05 AM MST, 2 hours 19 minutes earlier.

Area forecast discussion, Jul 13, 11:05 AM MST, 2 hours 19 minutes before

NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER COLORADO
1205 PM MDT FRI JUL 13 2001

HAVE UPDATED ZONES AND ISSUED FLASH FLOOD WATCH BASED ON NUMEROUS
FACTORS.  RADAR SHOWS EASTERLY BOUNDARY MOVING BACK TOWARD THE
FOOTHILLS...PLATTEVILLE PROFILER WITH AN EASTERLY COMPONENT UP TO
600 MB...SURFACE DEWPOINTS IN THE UPPER 50S AND LOWER 60S...AND
P.W VALUES OF 1.1 INCHES ON THE DENVER SOUNDING THIS MORNING (HIGHEST
12Z AMOUNT THIS YEAR).  FORECAST SOUNDINGS SUGGEST SLOW MOVERS AND
RIGHT ENTRANCE REGION OF JET THIS EVENING MAY ENHANCE STORM COVERAGE
AND PROMOTE TRAINING CELLS.

BARJENBRUCH

.DEN...FLASH FLOOD WATCH FOR THE FRONT RANGE FOOTHILLS AND ADJACENT
PLAINS FROM 1 PM TIL MIDNIGHT...ZONES 35>36..38>43..45.

In the hours before

Local storm report, Jul 13, 7:42 AM MST, 5 hours 42 minutes before

LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
842 AM MDT FRI JUL 13 2001

...PRELIMINARY STORM REPORT FOR JULY 12 2001...

TIME(MDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0630 PM    2 E AMHERST               CO   60 MPH TSTM WIND GUST
07/12/01   PHILLIPS                       ESTIMATED BY SPOTTER
                                          COMBINED WITH MARBLE SIZED
    &                                      HAIL FOR SEVERE CROP DAMAGE

BARJENBRUCH

Special weather statement, Jul 13, 9:12 AM MST, 4 hours 12 minutes before

COZ030>051-132000-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER COLORADO
1012 AM MDT FRI JUL 13 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

...HEAVY RAINFALL AND FLOODING THREATEN THE AREA TODAY...

SYNOPSIS...A VERY MOIST AND UNSTABLE AIRMASS REMAINS IN PLACE ACROSS
NORTHEAST AND NORTH CENTRAL COLORADO.  AS DAYTIME HEATING REACTS
WITH THIS MOISTURE...ANOTHER ROUND OF HEAVY RAIN PRODUCING
THUNDERSTORMS CAN BE EXPECTED.  THE STORMS WILL FIRST DEVELOP OVER
THE MOUNTAINS AND FOOTHILLS BY NOON...AND THEN ON THE ADJACENT
PLAINS AFTER 1 PM MDT.  THE STORMS ON THE PLAINS WILL INITIALLY
DEVELOP NEAR THE FOOTHILLS AND ALSO OVER THE MONUMENT AND CHEYENNE
RIDGES...AND THEN SPREAD SLOWLY EASTWARD DURING THE LATE AFTERNOON
AND EVENING HOURS.

GIVEN THE ABUNDANT MOISTURE AND SLOW MOVEMENT OF STORMS TODAY...
EXTREMELY HEAVY RAINFALL RATES OF 2 TO 3 INCHES PER HOUR WILL OCCUR
WITH THE STRONGEST STORMS.  THIS MAY CAUSE FLASH FLOODING OF URBAN
AREAS...SMALL CREEKS AND STREAMS...AND LOW LYING AREAS.  PEOPLE
ACROSS NORTHEAST AND NORTH CENTRAL COLORADO ARE URGED TO REMAIN
ALERT TO RISING WATERS AND BE READY TO MOVE TO HIGHER GROUND.

THE POSSIBILITY OF ONE OR TWO SEVERE STORMS ALSO EXISTS...WITH HAIL
UP TO 1 INCH IN DIAMETER AND WIND GUSTS IN EXCESS OF 60 MPH.

SPOTTER ACTIVATION MAY BE REQUIRED THIS AFTERNOON AND EVENING.
REPORTS OF HEAVY RAINFALL...AN INCH OR MORE IN 30 MINUTES...ARE ALSO
APPRECIATED.

BARJENBRUCH

The radar

The Denver radar (KFTG), 58 km away, was scanning. The volume nearest the first event began at 20:22 UTC.

Open the radar archive at this moment

Event by event

3 flash flood, 1 hail. Local standard time, as filed.

Hail, Douglas

When: July 13, 1:24 PM MST
Where: Douglas County, 5 mi W of Castle Rock
Measured: 1.75 in hail
Reported by: TRAINED SPOTTER
Coordinates: 39.367, -104.950

Flash Flood, Denver

When: July 13, 3:15 PM MST to 4:30 PM MST
Where: Denver County, South Denver
Reported by: NEWSPAPER
Coordinates: 39.762, -104.876 (the zone’s center; the record gives no point)

Heavy rainfall caused localized flash flooding along some of the roadways near the Denver Tech Center.

Flash Flood, Arapahoe

When: July 13, 3:20 PM MST to 4:30 PM MST
Where: Arapahoe County, Greenwood Vlg
Reported by: EMERGENCY MANAGER
Coordinates: 39.650, -104.339 (the zone’s center; the record gives no point)

Three inches of rain reportedly fell near the Greenwood Village Police Department in the span of 15 minutes. Heavy rainfall caused Toll Gate Creek to jump its banks, flooding low lying areas of Parker Road.

Flash Flood, Weld

When: July 13, 6:55 PM MST to 8:15 PM MST
Where: Weld County, Greeley
Property damage: $600,000
Reported by: NEWSPAPER
Coordinates: 40.555, -104.392 (the zone’s center; the record gives no point)

Anywhere from 3 to 5 inches of rainfall reportedly fell in the Greeley area in less the 2 hours. As a result, several roads were inundated with up to 2 feet of water and many basements of homes and businesses were flooded. In the basement of Greeley City Hall, several boxes of documents dating back to the 1800's were drenched in the floodwaters. The roof of a local business collapsed during the deluge. Approximately 2300 homes and businesses in town suffered electrical outages.

What these are

Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.

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: 5267265, 5267267, 5267266, 5267268.