The National tribune., 1891-07-16
THE WEATHER.


BY LIEUT.. J. P. FINLEY, U. 8. SIGNAL SERVICE.
Correspondence invited suggestions desired.
ami information cLaerfuI'y furnished. Every ef-
Ort employed TO make This Eureau OF practical use
o. our readers All communications zh0uId be adj
dressed Heather, IHE NArIOSAL TRIBUNE Office.
Washington. u. CT
California is subjected to a peculiar class Of
cold winds Ia summer, which are sometimes
injurious to vegetation and very uncomfortable
% man. / have called these winds cold we5ters.
because the peculiar weather they bring comes
from the West and over the Ocean.
The popular name for all westerly winds is
"tr1dC winds but this is misu0mer, and is
applied by tine people Of California because tho
winds blow with considerable regularity during
the Summer. The s0-called trade winds"
are confined 20 the Immediate coast, aad arise
from differences in temperature between the
land and water.
The cold westers are much more extensive
changes ia wind direction, and sometimes
affect the entire country west Of the iI2th
meridian. They result from mod fcatious Of
cyclOaIC aud auti-cyclOnic ciGculali0u, which
frequently embraces the Pacific Coast States and
British Columbia. A typical cold wcstsr
weather chart win show the anti-CvcIoue (area
Of highest barometFic pressureJ central in
Northern California or of the coast near
san Francisco. The cyclone or area Of lowest
pressure viii DO central in Nevada or
Utah The barometer ranges from 5000 to
3O.lj inches, in the high, and in the low from
% 80 TO 29.4O inches. The winds shift TO west
or.y in the Pacific Coast States with increasing
force, becoming brisk 20 high % to 80 miles
per hour in California and Nevada, and some
times in Arizona. With the high on the coast
and the low over the Middle Plateau Nevada
and UtahI the air flows from the former to the
latter region as water flows down hill. The
humidity Of the air over The land rapidly in
creasos and heavy clouaincss becomes general
/ throughout California. Light rains became
\ frequent turning o. snow iu the mountains II
7 the cold Wcstcr continues for two or three days.
\ The temperature falls very low and frOsts occur
where the air IS sufficiently clear and free i-Om
I strong movements. The earth is screened fron
tae suns heat dag and night, which finally re-
suits in producing a very cold and disagrecable
atmosphere near the earth. The winds are raw,
aud al animal and vegetable life suffer from
+ the chilling effects.
Tie following are three notable cases Of cold
wtstrrs: On May -. 1-s3. the temperature fell
\ 20 80. 3 at Los Angeles, 81 at isalia, AZ at
Red Biud, IS at Sacramento and 4J' at VIM
Hcmucca, New. Light rains, followed by severe
/ frosts, occurred in California and Nevada. On
I june 6, 1857, with the high at San Francisco
and the low in Arizona and Utah, the temper
aturo fell 10 f62 at Los Angeles. IS at Sacra-
meutO, aud 81 az Fort BidwelI and Winnie
CUrred in northern California and Nevada. On
May o, ISL with the high at san Francisco
and the low in Utah, the temperature fell to
2to 40 Fort Bidwel, 3S 40 Eureka, 90 no Red
+ Bluff, 81 az sacramento. tU' nc Keller, 80 at
salt Lake City, I6. 5 at Winnemucca. $50 Mt
/ KCsGbarg, 81 at Portland, and 20 as Boise
City. Frosts occurred in California Nevada,
and Oregon. Light rains in the valleys and
snow in the mountains This was one OF the
most remarkable cold wcsters ever experienced
on the Pacific Coast, and caused much damage
% crops.
I IL viii be seen that cold westers develop
under certain and easily-defned conditions of
I atmospheric pressure which can be- considered
I typical and thus employed in forecasting the
/ occurrence Of these cold waves They are not
cold waves in the sense in which this term
is applied to the immense areas Of cold air
\ that sweep southwark over Dakota and the
Missouri Valley. These latter consist Of masses
OF intensely cold, dry air coming from high
! attitudes and high attitudes. The cold westers
\ consist Of masses Of moist air from the ocean
7 which low inland and give rise TO heavy
/ ClOudiHess and precipitation, which screens
4 tue earth, and thus coOls the air resting upon
I it.