Windstorm on
Groundhog Day
rattles Boulder

One of the fiercest chinooks in years pummeled the Front Range late Tuesday night (2/2-2/3/99). Buildings were unroofed and power poles knocked down across Boulder County as winds reached 100 mph as far east as Longmont. Although damage to UCAR sites wasn't catastrophic, there were some problems and a few close calls.

On the mesa

NCAR's supercomputers were safely returned to service by SCD operators after a lengthy ML power outage. The lab had no phone or lights until Public Service power was restored and stabilized about 5:30 a.m. By noon Wednesday, all of SCD's major machines except for antero and ute were back up and running. According to Bo Connell, the single operator on duty was able to shut down some of the supercomputers in the 20 minutes of uninterrupted power supply after the Public Service outage began. Rebooting was fairly orderly, although she adds that some jobs may have been lost during the outage.

Sandbags and boards were used to temporarily replace a damaged roof panel above the Frost Phytrotron. The cracked panel is at center. (Photo by Colleen Ertle.)

The Frost Phytotron lost one of its plastic roof panels (measuring roughly three feet by forty feet). "About ten percent of the roof was trashed," reports ACD's Bill Baugh, who inspected the greenhouse facility that sits just below the ML's circular drive. "Unfortunately, it looks like the damage is right above the heating and air duct system." Bill surveyed the damage on behalf of the scientists who work most closely with the Phytotron: Lee Klinger, who's on vacation, and Peter Harley and Alex Guenther, who are in the Amazon for a field project.

The exposure doesn't appear to have harmed the plants or compromised current research in the Phytotron, says Bill. The climate control system can still maintain the growing environment, and no chemical-exchange experiments are being conducted while Peter and Alex are in Brazil.

Elsewhere around the mesa, a window blew out from ML room 220, the common area for CGD's Climate Analysis Section at the west end of the A tower's second floor. "We had a plant in front of the window and it blew the dirt everywhere," says Liz Rothney. "Now we're in the midst of cleaning it all up." Graduate research assistant David Blankinship came to work and found part of his office's ceiling had collapsed, apparently pushed outward by an air duct. "At least a third to a half of it gave way to the point where the light fixtures came tumbling down and all the plaster started coming off," says David. Fortunately, the ravaged ceiling wasn't directly over the computers in his office.

Damage wasn't limited to the Mesa Lab itself. Three road signs recently installed by Facilities Support Services (FSS) along the mesa road bit the dust.

At the other sites

A set of bike lockers outside the FL4 and UV buildings took an unexpected journey. The lockers blew across half of the parking lot to end up against a row of large cottonwoods next to Anderson Ditch, some 50 feet from where they started. Two bicycles were retrieved from the lockers, some of which had disintegrated. Ironically, FSS had recently been contemplating moving the lockers to a different location. No other major damage was reported around the FL complex, although one car window was blown out. Intermittent power outages at FL caused localized problems, and afterward, MMM's main server was out of service for about half of the day Wednesday.

A van used by students enrolled in a COMET training course lost one of its windows at the Golden Buff Hotel. Nearby, at RL-3 (near 30th and Marine Streets), a truck was flipped over--unusually severe damage even for wind-prone Boulder.

Few problems were reported at Jeffco other than an extended power outage. Service wasn't fully restored until 10:30 a.m. Wednesday. The Electra aircraft sat outside the Jeffco hangar overnight but was tied down and suffered no apparent damage.

The numbers

Tuesday night's biggest winds kicked in around 10:30 p.m. A four-second average of 93 mph were recorded from the automated sensor atop the Mesa Lab just before the mesa lost power for the night around 11:30 p.m. Because the ML sensor has a battery backup, ATD's Forrest Cook was able to verify that the winds after the power loss never exceeded the 93-mph peak. Similarly, the Foothills Lab recorded top four-second averages of around 70 mph while power was up, but that appears to have been the highest FL wind of the night. The graphs below include the initial reports, while at the bottom of the page are weekly summaries that include the data collected during the power outages.

These GIF images show the data from ML (top) and FL (bottom) as posted to the Web. They do not reflect the battery-backup data. See the end of this article for images that are more complete, including the gusts collected on battery backup. Real-time plots for ML and FL can be accessed on the Web via the UCAR weather page.

Some other wind reports from around the area, as compiled by the National Weather Service:

    WONDERVU..........................119 MPH
    CARTER LAKE.......................107 MPH
    ROCKY FLATS.......................103 MPH
    BLUE MOUNTAIN.....................100 MPH
    LONGMONT..........................100 MPH
    CU/BOULDER.........................98 MPH
    GUNBARREL..........................80 MPH
    BROOMFIELD.........................80 MPH

Why do the ML and FL readings seem lower than comparable sites around the area? Forrest says that each reading represents the highest four-second average achieved within a five-minute interval. Thus, the readings are likely to be at least 10 mph lower than the peak one-second gust. After looking into the matter, Forrest readjusted the ML and FL sensors on 5 February to register one-second gusts, which should bring them more in line with other weather stations in Boulder. Details on the readjustment can be found at a Wind Gust Calculation Web page created by Forrest. --BH

The GIF images above show 24 hours of wind data from ML (top) and FL (bottom) from 5:00 p.m. Tues. 2/2 to 5:00 p.m. Wed. 2/3, including the gusts collected on battery backup Tuesday night.

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Edited by Bob Henson, bhenson@ucar.edu

Prepared for the Web by Jacque Marshall

Windstorm on Groundhog Day rattles Boulder