Kevin G. Stewart, Project Engineer
Floodplain Management Program


ALERT System Usage Increases

The District’s ALERT base station logged more than 3,500 modem connections during 1996. This base is only one of eight similar platforms currently used within the District’s Flash Flood Prediction Program (F2P2). Four other base stations located in Aurora, Boulder and Denver also have phone modems which are routinely accessed. In addition, Aurora provides ALERT data to the public via their Internet homepage.


The District provides its local government partner agencies and certain other cooperators with free access to the base station. In addition to ALERT data displays from 130 gaging stations (113 rain gages, 62 water level sensors and 8 weather stations), a full suite of weather products is also available including watches, warnings and advisories from the National Weather Service; and heavy precipitation outlooks, quantitative precipitation forecasts and internal message status reports from the F2P2 meteorologist, Henz Meteorological Services. Recent system enhancements have contributed to the increased usage by allowing remote users to more easily interpret data using graphics communication software. Warning areas may also be displayed using color-shaded maps. Emergency managers will find tools like these increasingly useful in directing early public safety actions.


Dedicated phone lines were added to District base station in 1996 to accommodate two Denver television stations (KCNC-Channel 4 and KMGH-Channel 7), the Evergreen Fire Protection District (FPD) and the National Center for Atmospheric Research (NCAR). With no direct cost to the District, conditional ALERT system access was approved by recognizing the public safety contributions each of these organizations provide.


The media lines were used by weather news teams headed by Larry Green at KCNC and Pam Daale at KMGH. An excellent working relationship has developed from this interaction and the viewers were well served.


The Evergreen FPD logged daily calls to obtain ALERT data from the Hiwan and Blue Mountain weather stations. This, along with other weather data from the Colorado State Forest Service (CSFS) and the USFS, was used to develop a more representative fire weather reporting system for the Jefferson County Mountains with daily information disseminated by the Sheriff’s Department to all county fire districts. Rather than reporting a single fire danger rating for the entire county as in the past, the additional weather stations permitted dividing the county into regions (north, central and south) to better assist fire districts with their wildland fire prevention and suppression activities. Readers wanting more information about this program should contact Chuck Dennis at CSFS or Brad Ruder with the Evergreen FPD.


NCAR’s dedicated access to the ALERT system was devoted to Doppler radar research lasting only through the summer months. Their study dealt with improving radar precipitation estimates using dual-polarity Doppler radar technology. Data was gathered from a transportable research radar located near the Denver NEXRAD radar, precipitation algorithms were processed and the results were compared with NEXRAD precipitation estimates. ALERT rain data was used to help validate the models and identify deficiencies. Readers wanting more information about this project may contact Ed Brandis at NCAR or visit their website.


Outside requests for ALERT data is also increasing. Records are retained of each request and appropriate disclaimers are attached with each transmittal. Anyone interested in obtaining ALERT data from the District may contact Kevin Stewart at kstewart@udfcd.org.


Loss of Mesonet

The Program for Regional Observing and Forecasting Systems (PROFS) at NOAA’s Environmental Research Laboratories (ERL) in Boulder recently discontinued a 22-station mesoscale network (or Mesonet) of weather stations which has been operating in northeast Colorado since the mid-1980s. Antiquated equipment, high maintenance costs and no federal funding were cited as the reasons for ending the project. This system has been available to the F2P2 and many others at no charge and its loss will be felt. For flash flood forecasting the Mesonet proved invaluable allowing meteorologists to observe changing weather conditions every 5 minutes; display wind fields and convergence lines; identify moisture sources; plot vertical profiles of temperature, wind and moisture up to mountain top levels; and predict storm development and movement.


The District will be taking some steps in 1997 to offset this loss by relocating ALERT weather stations in Boulder County and cooperating with Douglas County to develop three new sites there. The District is also planning to evaluate which Mesonet sites have proven to be most useful for flash flood prediction over the past decade and may consider replacing a few of these stations with ALERT equipment. ERL also has an ongoing project which may eventually lead to a cooperative of data providers contributing weather information to be assimilated in a common database and shared among the contributors.


Local Data Acquisition & Dissemination

The District’s ongoing weather information dissemination project with NOAA’s Forecast Systems Laboratory (FSL) has evolved in 1996 to include a surveillance component and a LAN link ALERT data ingest. This project is serving as a model and testing ground for how NWS offices will interact with emergency managers and other local agencies in the future. Readers wanting more information about this project may contact Rich Jesuroga at NOAA/ERL/FSL or visit their website.


Buffalo Creek Fire/Flood

Within hours following the closing session of a well-attended international symposium in Fort Collins marking the 20th anniversary of the Big Thompson Canyon flash flood, Coloradan’s received a grim reminder of how devastating mountain flash floods can be. Between 10 and 11 PM a 30-foot wall of water roared down the North Fork South Platte River causing two deaths and damages exceeding $5 million. Without question, the Buffalo Creek flash flood of July 12, 1996 was the headline flood news event of the year in Colorado. Buffalo Creek is a small mountain community in Jefferson County located outside the District approximately 25 miles southwest of Golden.


The flood resulted from a thunderstorm beginning at approximately 9:40 PM which produced an estimated 2 to 3.5-inches of rain within 30 to 90 minutes over a 10 to 30 square mile area. Sand Draw and the lower portion of Buffalo Creek, both running through the small Jefferson County community of Buffalo Creek, were hard hit. Estimated peak discharges (17,000 cfs maximum) exceeded FEMA’s 100-year flood estimates by 10 to 20 times. The storm was centered over a steep-sloped fire-scorched area just south of Buffalo Creek.


A 13,000-acre forest fire, which occurred less than two months prior to the flood, clearly contributed to the flood’s destruction. The intense fire significantly changed the runoff characteristics of the watershed by causing not only a near total loss of vegetation but also by altering the physical, chemical, and biological properties of the soil, producing “hydrophobic” conditions. Essentially this mountain watershed became the hydrologic equivalent of a massive shopping mall with lots of parking and no stormwater detention.


1996 Peak Flows (no records set)




Cherry Creek at Market St.


May 26

Cherry Creek at Steele St.


Sept. 18

Goldsmith Gulch at Eastman Ave.


July 12

Harvard Gulch Park at Logan St.


July 12

Ralston Creek at Carr St.


August 26

Sand Creek at Brighton Road


May 26

S. Platte River at Dartmouth Ave.


May 26

Toll Gate Creek at E. 6th Avenue


July 30

Westerly Creek at Montview Blvd.


July 19

By contrast, the 1976 Big Thompson flood was caused by a 12-inch storm oven an unburned forest and claimed 145 lives along US Highway 34 between Estes Park and Loveland. Fortunately, no major US highways run along the streams affected by the Buffalo Creek disaster and the population in harm’s way was much smaller on July 12, 1996 than it was on July 31, 1976.


Other Main Events

The District’s Flash Flood Prediction Program (F2P2) activated a record a number of 51 days this year. This program has been serving the Denver/Boulder metropolitan area since 1979, the same year in which the Boulder Creek early flood detection network became operational.


During 1996 the ALERT network measured one-hour rainfall amounts exceeding an inch on eight days (6/13, 7/9&12, 8/22&26, and 9/11, 12&14). The station at Morrison reported the heaviest amount where a total of 2.32” fell Wednesday evening, September 11, forcing cancellation of the “Hootie and the Blowfish” concert at the Red Rocks Park amphitheater.


Even though we experienced a very active season, all flooding that occurred within the District this year may be categorized as nuisance events, resulting mainly in traffic snarls, an occasional flooded basement, more than a few irritated sports enthusiasts and a small army of disappointed Blowfish fans. The table summarizes peak flows at locations.


From December 11, 1996 DRAFT of 1996 Flood Hazard News article…NOT PUBLISHED
Reformatted & edited by KGS 8/12/2020