FLOOD01529

• County: Larimer
• Community: Big Thompson Canyon
• Stream Name: Big Thompson
• Title: Natural Disaster Survey Report 76-1: Big Thompson Canyon Flash Flood of July 31 - August 1, 1976
• Date: 10/1/1976
• Prepared For: Department of Commerce
• Prepared By: NOAA
• Floodplain - Doc Type: Flood Documentation Report

Because he was uncertain as to what was happening on the ground, he issued
this statement to keep some warning in effect until he could get reports
from ground observers. He was particularly concerned about the Cache la
Poudre River which drains the next valley north of the Big Thompson.

It wasn't until 11:00 p.m., after WSFO Denver received reports indicating
the location and seriousness of the flooding and that the "Big Thompson
had already crested at the mouth of the Canyon", that a flash flood warning
was issued.

BULLETIN
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE DENVER
11 PM MDT 31 JUL 1976
A FLASH FLOOD WARNING IS IN EFFECT UNTIL
4 AM MDT FOR PERSONS NEAR THE BIG THOMPSON RIVER
FROM NEAR LOVELAND TO GREELEY COLORADO
A FLASH FLOOD WARNING MEANS FLOODING IS IMMINENT.
TAKE NECESSARY PRECAUTIONS AS REQUIRED

Dissemination

NOAA WEATHER WIRE, a teletypewriter system, is the principal means of
distributing weather information to the news media for dissemination to
the public. The NOAA WEATHER WIRE SERVICE (NWWS) carried thunderstorm
and/or flood messages at 7:35, 9:00, 11:00, and 11:15 p.m. The following
summarizes dissemination actions by news media having NWWS drops:

AP
Denver

They moved a severe thunderstorm warning for E. Larimer County
at 9:07 p.m. This is either the warning sent out at 7:35 p.m.
or a combination of that warning with the statement issued
at 9:00 p.m.

At 11:10 p.m. they moved the flash flood warning issued at
11:00 p.m. Then, as information began to come in from the
flooded area and the Larimer County Sheriff's office, they
put out a story at 11:38 p.m. combining the flash flood
warning information with what they had from the scene.

~I
Denver

At 7:57 p.m. they sent out on their radio line the warning
issued at 7:35 p.m. The 9:00 p.m. special statement went
out at 9:34 p.m.

Then, at 9:37 p.m. they ran a story to the effect that the
Colorado State Patrol reported a number of cars washed off
the road in Big Thompson canyon by a massive flash flood.
This was followed at 12:28 a.m., August 1, by the 11:00 p.m.
flash flood warning from WSFO Denver.

KTLK
Denver

No newscasts were made after 1:51 p.m. on Saturday afternoon.
Prerecorded news spots are used. No one looks at NWWS after
the last live newscast until station opens the following morning.

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