Rainfall and lack thereof has been a center of interest of late
in Portland, with our 51 day rain streak coming to an end
Monday. But there have been days when it's sprinkled or rained
and yet did not get the elusive 0.01" needed to end our dry
streak. How does the rain gauge determine if the rain was enough
to measure or not? It depends on the weight of the accumulated
water. The Automated Surface Observation Stations (ASOS) used at
Portland Int'l Airport and many of the larger NOAA/FAA sites all
use rather new equipment called "AWPAG" -- Automated Weather
Precipitation Accumulation Gauge. They just in the past few
years replaced Heated Tipping Buckets (HTB -- this is the
government we're talking about and they never met an acronym
they didn't like.) Portland was upgraded on May 1, 2006. AWPAG
is newer technology that collects rain, then uses a precise
electrical sensor that can exactly determine the amount of rain
based on the weight of the water it has collected. It's coated
in an anti-freeze to prevent pr