The Abbeville messenger. (Abbeville, S.C.) 1884-1887, 1886-02-16
STT ~ OF T0RNADOES.
REGlONS IN WHICH THESE DE-
STIeUCTIVE STORMS PREVAIL.
The signal Service Soon to be Able IN
Give Trustworthy Warnings OF their
C~QhhfnR-How They are Formed I'm the
Upper Air.

The phenomena of tornadoes, to the
scientific study of which Lieutenant
John +. Finley, of the Signal Corps,
has devoted about eight years, are now
SO we'll understood ms to warrant the
bellct that trustworthy warnings may
soon be sent out to the inhabitants of
localities which may be threatened with
disastrous visitations. Daily prcdic-
tons are, in fact, being made at present,
having begun last year and continued
during the tornado season, and resumed
recently upon the return of Lieutenant
FINLEY from an inspection tour in the
West. The percentage of veritication
ls already gratifying, though the prcdic-
tons arc as yet largely experimental, and
are embodied in the daily published
bulletins of the Signal Office only when
the conditions favorable to the creation
OF tornadocs are very pronounced. In
such cases ''scvcre local storms'' are
noted as probable.
To n reporter of the Associated
Press Lieut.. Finley recently described
the known phenomena of tornadocs and
the ends toward which present researches
arc directed. These storms have dis
tinctly marked characteristics, and are
by no means to be COMPOUNDED with hur-
%ricanes, billiards., cyclones, or north
casters. Their tracks arc never more
than a few hundred yards wide, and
their forces arc generally exhausted by
the time they have travelled II course of
forty or fifty miles, though in this latter
respect they arc quite variable, some
having been traced by their lines of de-
VISITATION more than 100 miles. Their
rotary motion, which is greatest toward
the centre, sometimes caches the cnor-
nous rate Of 2, 900 miles an hour, while
their forward movement, always from
southwest to northeast, ordinarily does
not exceed forty or fifty mile. They
arc usually unaccompanicd by electrical
disturbances, and are believed to be I'M
influenced by electrical conditions,
though violent thunder storms sometimes
follow them a few miles away. There
is Il distinct and curious relationship be-
tween the tornado and the general storm
centre which is always apparent IN their
uniform relative positions, the tornado
always occurring enthusiastically from
the centre of low barometric pressure
and at a distance of from one to six
hundred miles. The shape of the gen
eral storm centre, the direction in which
its longest diameter lies, and the APP
pearancc of the upper and lower clouds,
enter rs minor elements into the prob
lem out of which the weather experts
hope to work IL complete system of tor
nado warning.
The visits of the tornado are COM
monty W the hours of 2 and g in
the afternoon. Its home is an area
which includes the whole of Iowa, all OF
Missouri except the southeastern corner,
the northern corner of Askansas, the
northeastern part of Indian Territory,
eastern Kansas, eastern Nebraska,
southern Minnesota, southern Wisconsin
and western Illinois. Here its season
extends from April to August inclusive.
1t is Il frequent visitor to two other re-
gions. One is a strip along the Gulf
and south Atlantic coast, which takes
in the central portions of Alabama,
Georgia, and South Carolina, with
tcrmini in Mississippi and North Caro-
lima, over which its d~cvastations arc con-
fined to the months of January, Fcbru-
airy and March. The other includes q
portion of southern and central Ohio, n
large part of Pennsylvania, Il small area
in Maryland, a strip across New York,
and Il corner each of Massachusetts and
Connecticut, where it is in season only
during the months Of August and Sep
TENDER.
Tie conditions which are favorable to
the creation of tornadocs IRE present
when a cool dry current Of air meets Il
warm moist current, bringing wide cX-
trcmcs both of temperature and humidity
into close proximity. The cold dry cur
rents come from the north, but such as
flow over the great lakes pick up in
their course both moisture and heat, and
their destructive forces are thus ncu-
tralized. Those blowing from the far
northwest down over the dry plains of
Manitoba and Dakota carry something
of their arctic characteristics far south,
and if in their course they meet one of
the heat and vapor laden brcczcs COM
ing up from the Gulf, the war of the cle-
mcnts begins ut the point of contact.
The storm always has its birth in the
upper mir, its irst visible manifestation
being the ominous funnel-shapc cloud,
whose pendant trunk is in form not un-
like that of an elephant. Within it the
furies arc confined, and when and where
its point touches the earth the path of
destruction begins.
When the isothcrms of the morning
signal map show the advancing columns
of mir with their wide contrasts of
temperature in proximity when the gen.
eral torn centre is in that relative posi-
ton which seems necessary to the cxer-
else of it's mysterious influence; when
the pressure is low toward the earth,
disclosing a vacuum into which the de-
hcctcd currents may advance without
ob~structions; when all these conditions
combine it should become but a simple
problem for the experts to determine
with reasonable probability from the
wind vclocitics whether the threatening