today
9 a.m. 15th Annual Plant Sale Bayside Grange
read >10 a.m. 35th Annual Daffodil Show Fortuna River Lodge
read >10 a.m. Peace Begins with ME Eureka Center for Spiritual Living
read >10 a.m. Annual Juggling Festival Humboldt State University
read >10:30 a.m. Learn How to Meditate Humboldt Area Foundation
read >11 a.m. Understanding Islam Arcata Library
read >noon Rainwater Harvest and Reuse Systems Living Earth Landscapes
read >2 p.m. Antigone Matinee College of the Redwoods
read >2 p.m. So Hum Tales Mateel Community Center
read >2 p.m. Open Jazz Jam Morris Graves Museum of Art
read >2 p.m. Irish Tea and Celebrity Cake Auction Fieldbrook Winery
read >2:30 p.m. Open Mic World Cup Cafe
read >6 p.m. Vintage Jazz (jazz) Chapala Cafe
read >6 p.m. Competitive Scrabble See Event Description
read >7 p.m. Open Mic Mosgo's
read >7:30 p.m. Zoe Boekbinder Westhaven Center for the Arts
read >8 p.m. Karaoke at Bear River Casino Bear River Casino
read >8 p.m. Karaoke Blue Lake Casino
read >8 p.m. Cabaret Arkley Center for the Performing Arts
read >9 p.m. Deep Groove Night Jambalaya
read >9 p.m. Piano Ben Six Rivers Brewery
read >previous columns
Feb. 7, 2008
Can You Predict Rain?
Yes, by simply learning how to interpret available data. The ...
read >Jan. 31, 2008
Stick-Slip Slug Slime
Banana slugs evolved from snails, and both are classified as ...
read >Jan. 24, 2008
Watts in Coffee, Pot and Brakes?
I am reading a full page ad in our local ...
read >Photos
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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