today

9 a.m. International Education Week Humboldt State University

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noon Redwood Region Audubon Society Meeting Golden Harvest Cafe

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noon Dreamscapes The Oasis

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4:30 p.m. HomeWork Hotline Call for details

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5 p.m. Guitar Jazz Cafe Brio

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5 p.m. Henderson Center Holiday Open House Henderson Center

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6 p.m. Americans for Safe Access Bayview Courtyard Complex

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6 p.m. Matthew Cook Cher-Ae-Heights Casino

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6 p.m. Bill McBride and Friends Hotel Ivanhoe

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6 p.m. Kindred Spirits Mad River Brewing Company

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6 p.m. Watershed Restoration Week Celebration Wharfinger Building

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6:30 p.m. Seabury Gould at Gallagher's Gallagher's

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6:30 p.m. Share a Story: Growing Vegetable Soup Arcata Library

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6:30 p.m. 2008 Transgender Day of Remebrance Humboldt County Courthouse

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7 p.m. Blue Grass Jam Old Town Coffee & Chocolates

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7 p.m. Mr. Calamari's Jazz Machine Mosgo's

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7 p.m. All Ages Open Mic East Side Deli

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7 p.m. Don's Neighbors Gilded Rose

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7 p.m. KEET-TV's Annual Holiday Auction See Event Description

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8 p.m. Karaoke WAVE @ blue lake casino

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8 p.m. Karaoke at Bear River Casino Bear River Casino

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8 p.m. Smuin Ballet: The Christmas Ballet Van Duzer Theater at HSU

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8 p.m. Getting It Arcata Playhouse

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8 p.m. She Loves Me North Coast Repertory Theater

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8 p.m. The Medium Gist Hall Theater at HSU

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8:30 p.m. Keak da Sneak, San Quinn Mazzotti's Arcata

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9 p.m. Soldiers of Shangri-la Six Rivers Brewery

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9 p.m. Dancehall/Reggae Thursday with Rude Lion Sound DJ Jimmy Jonz The Red Fox Tavern

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9 p.m. Scotch Wiggly The Boiler Room

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9 p.m. The Common Vice, Silent Giants, Rooster McClintock Humboldt Brews

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9 p.m. Hillstomp, O'Death Jambalaya

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9:30 p.m. DJ Ray Ragg's Rack Room

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10 p.m. Music by DJ Sidelines

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10 p.m. Lightnin' Bill Woodcock Pearl Lounge

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previous columns

Feb. 7, 2008

Can You Predict Rain?

Yes, by simply learning how to interpret available data. The ...

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Jan. 31, 2008

Stick-Slip Slug Slime

Banana slugs evolved from snails, and both are classified as ...

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Jan. 24, 2008

Watts in Coffee, Pot and Brakes?

I am reading a full page ad in our local ...

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  • Illustration of radar station detecting storm clouds, by Don Garlick. Illustration of radar station detecting storm clouds, by Don Garlick.
  • Diagram of radar pulse and echo, by Don Garlick. Diagram of radar pulse and echo, by Don Garlick.
Use Your Local Radar

Use Your Local Radar

By Don Garlick

A National Doppler Radar installation is conveniently located on Bunker Hill south of Ferndale. To see its value in forecasting rain or snow you should visit www.weather.gov/eureka. The following is an introduction to this amazing technology.

Weather radar operates at two wavelengths, 5 cm & 10 cm, with ranges of 124 and 248 nautical miles. The microwave beams sweep a full 360 degrees and tilt at various angles above the horizon. Pulses of microwaves are emitted every millisecond and are scattered back by rain or snow (or flocks of birds), but not clouds or fog. The amount of energy returned decreases with distance squared (assuming the target fills the beam's width) and increases with the 6th power of raindrop diameter. Snow is not as reflective as rain, but melting snowflakes are very reflective because of the size effect. The distance to the particles is determined by the time delay of the returned echo: Distance = (time delay/2)x(speed of light). Click on Reflectivity and Loop to see a time-lapsed 1 second movie of 1.5 hours of storm motion.

When particles are approaching or receding, the wavelength (and frequency) of the reflected microwaves is changed, and although this Doppler effect is too small to measure directly, it does give rise to a displacement of the waves — termed a "phase shift" — between one echo and the next. The change in phase shift between one echo and the next (divided by the time interval between pulses) yields the radial speed at which wind-driven rain is approaching or receding. Click on Velocity to see radial wind speed in knots toward (green) or away from (red) the antenna.

When rain threatens, take comfort from knowing that you can watch it coming, and that our NOAA experts in Eureka are always watching.

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