The Donaldsonville chief. [volume] (Donaldsonville, La.) 1871-current, 1914-01-24

How the Weather Bureaus Forecasts
Storms, Frosts and Floods. .
Many people have an idea there is
something mysterious and occult about
the work of the Weather Bureau in
forecasting the coming of storms
frosts and foods. Not a few think
the observers must necessarily get
their data by reading the planets, the
stars and the moon. AS a matter oi
fact tae forecaster of the Bureau fore
tells the coming of disturbances in a
business-like way, very similar to
that in which a man who has ordered
shipment Of goods would estimate
the date OF its arrival.
Suppose a business man had or
dered carload OF pineapples from
the Hawaiian Islands. He would
know the average time it would take
the steamer to MAKE the trip to the
Pacific port, the average time for
Indicating and loading into refrigera-
tor cars, and the average number of
days to be allowed these cars for
their trip across the continent to
New York. His estimate, however,
would be subject to error, because
the steamship might be delayed by
fog, or the cars might meet with an
accident.
Storms, like pineapples, as a rule
do not originate in the United States
Iney come to us, some from the Phi
lpp1nes, Japan, Siberia, Alaska,
Canada or the Gulf Of Mexico. The
Weather Bureau gets cable, telegra-
phlc Or wireless notice of a foreign
storm. Stallion after station, or ves-
sci after vessel reports the storms ar
rival in its neighborhood, so that the
general direction and rate OF progress
can be determined very early. In
fact, the arrival of some storms can
be foretold ten days in advance.
The forecasters watch for the re-
glon of low barometer which is the
storm center around which the winds
blow. This Whirl or eddy moves bod
lily forward with the general eastward
drift of about $50 miles a day in our
attitudes. AS the lines of equal pres
sure (isobars) around the low center
crowd closer together, the winds at
tending the storm increase in force
The forecaster determines the di-
rection of movement of the storm
and its velocity.
When weather disturbances are re
,orted, the forecasters know from ex-
perience about how long it takes
them to reach our Pacific coast, and
then how long after they will reach
che Atlantic coast. For example, if
a storm coming from Siberia drifts
around the north pole and
reappears in Alaska, iu should appear
IN gton and Oregon in about
TWO ,should get to the Great
LAX six days, And to the At
iantie in seveng gor eight daos.
Unexpected oondifR IONS may delay
storms l,I1 - dittniro y en-. 81 from the
u Be tipped By 81 q
wrong road. Some Of these storms
deplete Semselves by running into
regiqRs high barometer WhicW are
of magnitude and extent
than storm itself. Some OF
them, however, travel completely
around the world.
To keep tab on cold waves that
come into the United States from
Canada and Alaska, the Weather
Bureau studies the Canadian wealth
er reports. England sends reports
from Iceland, the British Islands and
continental Europe, and daily re-
ports come from St. Petersburg on
the conditions in Russia and Siberia.
The same business-like system
used in tracing the track of storm
is applied in determining the arrival
of frosts.
Flood forecasts are made in much
the same way. Information as to the
amount Of rainfall at the head wa
| tiers of streams that cause floods
are covered by telegraphic reports
sent by local observers. AS this
rain reaches the main channel, the
| height of the water in the channel
is determined by successive gaglng
stations. Past records establish how
| much a height, say of 20 feet at Du,
buque, Iowa, will produce at Daven
port, another station 80 miles down
| the Mississippi. This plan is fol-
lowed all the way down the river
and at each point full allowance is
made for the effects of water from
tributaries and from additional ane
local rainfall AS a result of these
observations in the recent flood, the
people of Cairo had warning Weef
or ten days in advance. The P1tts
burg district can be given only II K
"a hours notice, because flood II
upon them within "a hours after {
heavy rain storm.