The Seattle post-intelligencer. [volume] (Seattle, Wash. Terr. [Wash.]) 1888-1914, 1892-11-20
WEATHER FORECASTS.

How and Where Made. How DisseEA-
mated and How Interpreted.
The daily weather predictions Tor TINS
state are made by the forecast oihciai at
Portland. Or. morning and evening, at
O'Clock Eastern time, and are based on the
observations taken by the regular oo-
servers OF the national weather bureau at
twenty-seven stations scattered through
out the Pacific slope, from Tatoosh island
to Fort Yuma, and from San Francisco to
Bismarck. These observations are tele-
graphed twice day 70 the forecaster at
Portland and are there entered upon the
forecasting charts issued at that station,
and from these the man of probabilities"
makes his deductions as to the probable
weather conditions that are likely to pre-
vail III Washington and Oregon during the
ensuing twenty-four or thrty-six hours
from the time the observations were made;
the forecasts are sent to some twenty dis
play stations in this state by telegraph
and at government expense; special
railway bulletin indicating the probable
weather for twenty-four hours Is also sent
out from the Port and office every night
and distributed by the railway mail clerk
along the route of the Northern Pacific
from Portland to its northern terminus to
each and every railroad station passed.
The forecasts issued in the morning are
based on the a. NJ. observations and are
for period of twenty-four hours from
noon on the day OF Issue till noon OF the
following day, when. however. the condi-
tons will warrant il the forecasts may he
made to cover period of thirty-six hours,
and sometimes seyenty-two hours. the lat
ter being considered the longest time for
which forecasters ever attempt to predict
the weather. The forecasts sent out at
night are based on the D. N. observations
and are for period of twenty-four hours.
from midnight of the day OF issue till mid
night of the following day. unless longer
period is named in the kilograms.
Owing to the enormous expense of tele-
graphing the forecasts of the national
bureau throughout this vast country, and
in order to keep within the limits of the
appropriations made each year by con-
gress for this purpose, the weather tele-
grams are necessarily very brief, yet sutfi-
Gently ineligible to convey the informa-
ton they are intended to give the public.
There are in all but five flags in use by
the weather bureau: No. ] is white flag,
feet square, and indicates clear or fair
weather; No. is blue flag, 6 feet square,
and indicates rain or snow; No. is a half
white and blue flag, feet square, and in
dicates light rain or snow; No. is black
triangular flag, 4 feet at its base and feet
long, and always refers to temperature
only-when floating above any of the
other flags il indicates warmer, and when
below any other flag colder weather, when
not displayed the indications are that the
temperature will remain stationary or
that it will not vary by more than degrees
either way; No. is white flag. feet
square. with a black square in the center,
and indicates that frost is expected to
| occur over the districts predicted for.
A prediction OF Fair, colder" made on
on the morning of, say, Monday, 29th,
means that clear, fair, cloudy or foggy
weather, but no rain or snow, is antici.
| pated, and that the temperature on Tues
| day morning will be lower COLDER than it
was the preceding morning by not less
| than ten degrees or more.
| A prediction of Rain: warmer" made
| on the same morning (Monday) would
mean that at any time during the twenty
! four hours from noon Monday till noon
| Tuesday rain or snow can be looked for,
| and that the temperature on Tuesday
morning will be higher (warmer) by ten
| degrees or more than it was on Monday
| morning.
| a prediction Of "Fair, followed by rain
stationary temperature" made on Monday
! evening, would mean that clear or fair
| weather is anticipated from midnigh,
! Monday till noon Tuesday, and rain or
| snow at any time after noon till midnight
| Tuesday; stationary temperature means
| that the maximum (highest) temperature
| on Tuesday will be the same as that OF
Monday. or that it will not vary from it
| by more than ten degrees either way.