The Hood River glacier. (Hood River, Or.) 1889-1933, 1914-01-29
WEATHER BUREAU
FORECASTING METHOD

Many people have an idea that there
Is something mysterious and occult
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 planets, the
stars and the moon. As a matter OF
fact the forecaster Of the bureau for
tells the coming Of disturbances in a
businesslike 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 has ordered
carload Of pineapples from the Hs-
waiian Islands. He would know the
average time il would take the steam
er 10 make the trip to the Pacific port,
the average time for unloading and
loading into refrigerator cars, and the
average number of days to be allowed
these cars for their trip across the con-
tinent TO New York. His estimate,
however, would be subject to error be-
cause the steamship might be delayed
by fog, or the cars might meet with an
accident.
Storms, like pineapples. as rule do
not originate in the United States.
They come to US, some from the Phil
ippines, Japan, Siberia, Alaska. Cana
da or the Gulf of Mexico. The weather
bureau geo cable. telegraphic or wire
less notice of foreign storm. Station
after station, or vessel after vessel,
reports the storms arrival III its
neighborhood. so that the general di-
rectiOn and rate of progress can be de-
termined very. early. In fact, the ar
ival of some storms can be fOretold ten
days in advance.
The forecasters watch for the region
of low barometer which is the storm
center around which the wind blows.
This whirl or eddy moves bodily for
ward with the general eastward drift
Of about $50 miles a day in our lati-
tudes. AS the lines of equal pressure
(iosbars) around the low center crowd
closer together, the winds attending
the storm increase in force. The fore
caster determines the direction OF
movement of the storm and its veloc-
ity.
When weather disturbances are re-
ported, the forecasters know from ex-
perience about how long it takes them
to reach our Pacific coats, and then
how long after they will reach the At
lantic coast. For example, if storm
coming from Siberia drifts eastward
around the north pole and reappears in
Alaska, it should appear in Washing
ton and Oregon in about two days
should get to the Great Lakes in six
days and to the Atantic coast in seven
or eight days.
Unexpected conditions may delay
storms or divert them from the
straight track just as 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 greater
magnitude and extent than the 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
| lUc SdHduldu WCdtlSL ltpolto hh
gland sends reports from Iceland, the
British Islands and Continental Europe
and daily reports come from st. Peters
burg on the conditions in Russia anC
Siberia.
The same busineslike system in trac
! ing the track OF storm is applied II
determining the arrival of frosts.
Flood forecasts are made in mucl
the same way. Information as to th'
amount of rainfall at the headwater
of streams that cause floods are GOV
cred by telegraphic reports sent by 10
cal observers. As this rain reaches thu
main channel. the height of the waite
in the channel is determined by success
sive gaging stations. Past records es
tablish how much height, say of 2
feet at Dubuque, Iowa, will produce a
Davenport, another station so mile
down the Mississippi. This plan i
followed all the way down the river
and at each point full allowance i
made for the effects of water iron
tributaries, and from additional an,
local rainfall. AS result of these ob
servations in the recent flood, the pee
pie of Cairo had warning a week or te
days in advance. The Pittsburg dis
trict can be given only IL to "a hours
notice, because flood is upon then
within "a hours after a heavy raj
storm.