The Minneapolis journal. [volume] (Minneapolis, Minn.) 1888-1939, 1906-01-14

or seven word message. These messages
are wired in to designated central
points where they are put on regular
circuits and transmitted to the several
district forecast centers and to map
stations with the least possible delay.
When the messages are received the
forecaster takes a large map, prepared
for the purpose, and copies down at
each station, the exact conditions that
prevailed at the time Of observation.
By drawing lines thru places Of equal
air pressure he locates the centers Of
the high and low pressure areas and
by comparison with the previous map
he notes the direction and velocity Of
translation. These lines also define the
limits Of the territory affected by the
storm area and show, by comparison
with the previous map, whether the
storm is increasing or decreasing in in
tensity. He draws lines thru places Of
equal temperature and can then note
at a glance the relative conditions Of
adjacent localities and also those places
where abnormal conditions exist. By
comparison with the previous map he
constructs g. chart Of temperature
changes and notes the drifts of warm
and cold areas that have occurred since
the preceding observation. Cloudiness
and rain areas are noted with their de-
velopments, and in fact, when the map
is completed, 1t presents practically a
bird 's-eye view Of the weather condi-
tons over the entire country.
Now, If the storm areas maintained
a constant form, a constant velocity
of translation, and a regular path
across the country, the matter Of fore
casting would be much simplifed. All
the forecaster would have. to do would
be to shift his conditions to twenty.
four and thirty-six hour points in theil
regular paths and write out the result
ing changes for different localities.
The easterly movement of the upper
atmosphere is comparatively regular
and would give these storm areas a uni
form direction and velocity Of trans
lation were it not that modifying force:
are continually encountered in the lowe
atmosphere. These forces sometime:
retard and sometimes accelerate
storm, and sometimes serve only to de
fleet it from it's normal path
Storm areas also change their form
great deal as they move across tn.
country. For example, when a low
pressure area enters on the Pacific
coast, the rain area is on the rear O.
westerly side for the reason that warn
moist air from over the ocean is flow
ing in on this side while the front O.
eastern side is being fed from the coo
dry. air of higher attitudes in the noun
tain region. When the storm are,
crosses the mountains the rear of tn,
storm is then being fed from the higl
dry mountain air or from the dry coo
air flowing out Of a high pressure area
while the moist air Of lower levels il
the Mississippi basin is flowing in o.
the eastern side. Consequently tn
rain area is then shifted from the rea
to the advance side Of the storm area
The conditions that have prevailed i'm
mediately preceding the storm are
must also be taken into account as tn
Developments Of a storm depend yer
materially on the conditions Of the al
nosphere which it is entering.
4 + !.
On nearly every map there are POI
tiens of the country for which the fore
cast can be made with almost absolut