Weather watching
Orbiting satellites and clicking teletypes
work to photograph patterns, print data
but technology won’t change conditions
It’s still raining. It's supposed to con
tinue that way at least through the
weekend. A week ago it was sunny. And
if that doesn’t make sense, this rain isn’t
supposed to help the drought at all.
Who is responsible for all this crazy
weather? Certainly not the local weath
ermen — they just predict the weather
and it isn’t an easy job.
There are no fixed patterns in the
weather, making the weatherman's job
even more difficult, according to Nile
Woltman of the United States National
Weather Service office at Eugene's
Mahlon Sweet Airport, who has been in
the weather forecasting business for
about 15 years.
Forecasting weather begins with a
complicated set of equipment, including
maps made by orbiting satellites and a
computer shizzing away nearly 24 hours
a day. The weather service’s offices con
tain such machines as a rotating beam
By KEVIN HARDEN
Of the Emerald
ceilometer, which measures the height
of a cloud ceiling and a transmissome
ter, which checks visibility in hundreds of
feet used mostly for aviation. Two tele
type machines click at 75 to 100 words
per minute to report national weather
information.
Weather information is gathered
around the nation by ground observation
stations and reported to the National
Meterology Center in Washington, D C.,
where it is fed into a computer. It is then
teletyped back to weather bureau offices
in specially coded zone reports.
Using predetermined grid points 300
kilometers apart, the computer plots a
print-out temperature map for the nation.
Atmospheric photos taken from orbiting
weather satellites are also teletyped to
bureau offices.
How do these help forecast the
weather? Since he doesn’t do the actual
forecasting, Woltman uses them with
the office’s wind direction and velocity
machines and barometer to compile a
synoptic forecast for the Eugene area.
“What we do is really put together an
adaptive forecast for this area from the
reports coming from the Portland office.
They have a much bigger set-up there,"
he said.
If, by some accident, all those
machines were to fail at once, Eugene
would not be without a weather forecast.
In addition to automation, the weather
bureau office also uses several manual
forecasting instruments. A gauge
measures soil temperature for agricul
tural forecast, another determines the
amount of moisture in the air, a house
hold thermometer records air tempera
ture and an instrument uses a system of
gears to weigh rain water.Weather bal
loons are also released to test air den
sity.
There can be problems in forecasting.
Often bad weather can only be predicted
three days in advance. Even good
temperature forecasts are only accurate
for three to five days. After that it is an
educated guess, says Woltman.
Sometimes there are gaps between
science and the forecasting art. This
could be attributed to the fact that some
weather changes are controlled to a
great extent by small-scale atmospheric
phenomena such as shallow fronts, is
lands of hot air rising from cities and
differences between land and sea
temperatures, all of which are largely
undetectable by even the most sophisti
cated instruments.
As for weather modification, Woltman
doesn t see how cloud seeding is going
to help Oregon's drought situation. With
the rainfall at about one-half the normal
precipitation level, Woltman says that
additional rain would only bring about
five more inches to the total, making al
most no difference.
While most climatologists confine
themsleves to the search for patterns of
past climate changes, Woltman doesn't
see the past as a valid argument for the
present drought. “For all we know an
unseasonably dry year may be normal
every hundred years or so; we just don't
have any records further back than
1900, so we don’t know,” he said.
What Woltman does agree with is the
fact that certain changes in climate can
bring abrupt changes in agriculture pat
terns. A temperature change of one de
gree centigrade could result in shorter
growing seasons for several farm pro
ducts. More drastic changes could
eliminate some crops altogether. “A
Nile Woltman, a weather surveyor at Mahlon Sweet Airport, checks once again
for rain. He’s been finding some lately, but experts say we are too far below normal
precipitation levels for the little bit measured in this ram barrel to make much
difference
major climatic change," says a 1974
panel of the National Academy of Sci
ences, "would force economic and so
cial adjustments on a world-wide scale
Captive natural odors leak out and are
carried by the moist air which accom
panies storms.
Birds flying unusually high is a sign of
good weather. But when low-pressure
stormy air moves in, the birds need more
wingbeats to stay aloft So when gulls
are grouped on the ground or other birds
are roosting in large groups, watch cut
for high winds and rain.
When smoke is sluggish or returns to
the ground, or fireplaces backfire, it's a
sign that rainy weather is on the way
Smoke rising vertically means good ’
weather.
If unsatisfied with the day-to-day
weather forecast, people can use some
"old wives tale' methods once dismis
sed as inaccurate Some old proverbs
such as using natural odors, birds or
smoke to forecast upcoming storms or
pleasant weather have been found sci
entifically sound.
No cloudseeding: drought ends under natural forces
By E G. WHITE-SWIFT
Of the Emerald
The drought of ’77 ended Feb. 15, without the help of
cloudseeding, says an Oregon State University
meteorologist.
Fred Decker, a professor of atmospheric sciences,
determined that the winter drought ended with the break
down of a thermal ridge at 500 millibars or 18,500 feet.
The ridge, which extended from the Gulf of Alaska
through the Pacific Northwest to Louisiana, had been
self-sustained all winter by a continual flow of warm air.
“The warm air intensified the ridge, maintaining it for
an unusually long time,” says Decker. “Meteorologists
have yet to understand the source of the warm air. The
warm thermal ridge created a north-south flow of air,
rather than the usual eastward flow.”
The thermal ridge above the West Coast, combined
with a trough above the East Coast, has produced the
harsh weather. The eastern trough also acted to block the
thermal ridge from moving eastward, Decker says.
"The trough blocking the ridge was bound to break
down sooner or later,” he says, "because the increasing
heat produced by the northward movement of the sun
filled the trough, allowing for conditions to alter the
winter’s weather pattern.”
As the trough started to heat up in the middle of Feb
ruary, Decker noticed a lowering of the freezing level in
the Gulf of Alaska. The readings at weathership “Station
Pcentered in the gulf off of Alaska's western coast,
began registering cooler temperatures about Feb. 15.
As the cold air started to penetrate the thermal ridge,
the ridge weakened and a zonal flow of winds from west to
east began, bnnging storms and snow to the West Coast.
No cloud seeding occured in either Washington or
Oregon during late February," Decker says, "so we can
credit the rain and snow to nature!”
Decker believes that the weather should return to
normal for the rest of the spring, although the impact of the
winter drought will not be felt until next summer. Even if
the precipitation equals the wettest year on record, the
Pacific Northwest will have received only about 50 per
cent of the normal annual rainfall.