Evening capital and Maryland gazette., 1914-01-21
THE WEATHER BUREAU
HOW IT FORECASTS
Storms, Frosts, FloOds-NOthing
Occult or Mysterious.
STORMS ARE LIKE PINEAPPLES.
They DO Not 0rigiuste is The United
States But Come From Na

there ls something mysterious And
occut about the work Of the Weather
Bureau in forecasting the coming OF
storms. frosts and floods.
Not a few think that the observers
must necessarily get their data by
reading the plane Is, the stars and the
moon AS a matter Of fact the fore
caster Of the Bureau foretells the
coming Of disturbances in a business
like way, very similar to that in
which man who has ordered a ship
ment Of goods would estimate the
date of its arrival.
Suppose a business man had order
ed a carload o. pinespples from the
Hawaiian Islands. He would know
the average time il would take the
steamer TO make the trip TO the
Pacific port. the average time Tor IN
loading and loading intC refrigerator
cars, and the averag number Of days
to be allowed these cars for their
trip across the continent 10 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 acci-
dent
Storms, like pinespples, as a rule,
DO not originate in the United States.
They co.ne 70 US from the Philip.
pine =, Japan, Siberia, Alaska, Canada
or the Golf of Mexico. The Weather
Bureau gets cable, telegraphic or
wireless notice of foreign storm.
Station after station, or vessel after
vessel reports the storms's arrival in
its neighborhood, so that the general
direction and rate of progress can be
determined very nearly. In fact, the
arrival Of some storms can be foretold
ten days in advance.
The forecasters watch for the re-
gion of low barometer, which is the
storm center around which the winds
slow. This whirl or eddy moves
bodily forward with the general east
ward drift of about $50 miles a day
in our ATTITUDES. As the lines of
equal pressure Gsobars) around the
low center crowd closer together, the
winds attending the storm increase
in force. The forecaster determines
the direction or movement of the
storm and its velocity.
When weather disturbances are re-
ported, the forecasters know from
experience about how long il takes
them to reach our Pacific coast, aui
then how long after they will reach
the Atlantic coast. For example, if
storm coming from Siberia drifts
eastward around the North Pole and
reeppears in Alaska, it should appear
in Washington in Oregon in about
two days; should get to the Great
Lakes in six days and to the Atlantic
Coast in seven or ei yht days.
Unexpe cted conditions may delay
st )rms or divert them from the
straight track just as a refrigerator
car may be thrown Off its schedule or
be shipped by accident on a wrong
road. Some of these storms deplete
themselves by running into regions
of high barometer which are Of great
er magnitude and extent than the
storm itself. Some of them, how
ever, travel completely around the
world.
To keep tab on COLI waves that
come into the United States from
Canada and Alaska, the Weather Bu-
reau studies the Canadian Weather
reports. England sends reports from
Iceland, the British Islands and Con-
tiuental Europe, and daily reports
come from St. Petersburg on the con-
ditions in Russia and Siberia. The
same business-like system used in
tracing the track of a storm is ap-
piled in determining the arrival Of
frosts.
Flood forecasts are made in much
the same way. Information as 10
the amount of rainfall at the head.
waters of streams that cause floods
are covered by teleg~aphic reports
sent by local observers. As ttis rain
reaches the main channel, the height
of the water in the channel is deter
mined by successive gauging stations.
Past records establish how much
height, say Of 20 feet at Dubuque,
lowe, will produce at Davenpor {,
another station so miles down the
Mississippi. This plan is followed
all the way down the river, and at
each point full allowance is made for
the effects of water from tributaries,
and from additional and local rain
fall.
As q result of these observations
in the recent food, the people Of
Cairo had warning a week or ten days
in advance. The Pittsburgh district
can be given only l2 to "a hours' no
tice, because a food is upon them
within "a hours after heavy rain
storm.