Evening star., 1934-05-13
BY THOMAS r. HENRY.

The great drought which now grips
the Northwest has been 40 years in
the making.
1t appears to be a quite different
phenomenon from the almost un-
precedented 1880 drought, according
to J. B. Kincer, chief of the Weather
Bureaus Genealogical Division. That
hitherto unprecedented dry season
over the East, the Ohio Valley and
the Central Mississippi Valley, had
no apparent cause. 1t was preceded
and followed by normally wet weather.
But for the Northwest bad drought
sooner or later was inevitable. Mr..
Kincer has the official rainfall rec
ords for st. Paul for almost a CEN
tury. He has analyzed them by the
"10-year moving average" method,
which reveals the true trend of
meteorological conditions. His charts
reveal that there have been two pre-
vious severe droughts for that part of
the country-one in 1859 and another
in 1894. Each has been little worse
than the previous. This one prom
ises to be the worst of all.
This does not mean that each year
has been dryer than the year before.
Within the 40-year period of which
this year seems the elimination there
have been some fairly wet years. But,
generally speaking, the average rain
fall for each year and the nine years
preceding it has been lower than the
average for the year before and the
nine preceding years. The rainfall
curve began to go down very rapidly
from 1927
This declining rainfall phenomenon
obtains from the States of Montana,
the Dakotas, Minnesota, Nebraska and
Iowa. States south of this block show
almost the opposite type of curves.
Rainfall Marches"
To Northwest.
There has been a good deal Of argu
ment as to where the Northwest gets
its water anyway.
Most of it comes from the Gulf
of Mexico. Some comes from the
Pacific Ocean, across the Rockies.
But in both cases-and especially as
respects the Gulf-the water that
falls on Montana and the Dakotas
as rain comes across the country in
series of long steps. 1t starts at
the Gulf and is precipitated as rain
fall somewhere in the southern Mis-
sissippi Valley. Again it is raised by
evaporation from the damp soil, the
puddles and the trees to fall as rain
! perhaps a hundred miles farther
north. There the process is repeated.
But when this marching rain" final
| " reaches Montana there Is not much
of it left.
Everywhere a drought is cumulative.
The longer the rainless period the
less likelihood of rain. This is espe-
cially true for the Northwest because
of this marching" phenomenon. If
there is no water to be evaporated
there can be no rain until there is
great upset In meteorological condi-
tions. The hope of the countryside
is in the fact that the two rainiest
months of the year for the affected
areas are just ahead when there is a
high normal probability for just such
an upset.
| Once a rain cycle starts it can be
expected to keep going. But there is
no artificial way of starting it. Mean
while the land is being irreparably
damaged.
Cold Weather Point
OF Origin Changes.
| Meteorologists can't put their fng-
ers on the why Of it all.
1t may be associated in some way
with a change that has taken place
over the Arctic Ocean, where all the
cold weather comes from. A few
years ago the strategic point for the
weather of the United States was the
valley of the Mckenzie River in
northwestern Canada. It was a per-
feet cold air-or "high'-trough lead
ing southwark. The great cold waves
came down east of the Rockies right
over the area now in the grip of the
drought. Somewhere to the SOUTH
ward they were turned in an easterly
direction and caused many Of the