Evening star. [volume] (Washington, D.C.) 1854-1972, 1895-12-28
Origin and Track of Storms.

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lows are considered.
Origin and Track of Storms.
Conspicuous features of the distribution
| of the origin and the tracks of storms, when
| the months of the year are compared with
| one another, are the facts that as the win
| ter approaches the number of storms form
| ing in the southwestern states increases
| decidedly, and that the tracks loop south
| ward over the Rocky mountain slopes. In
| the months May to December the average
number of Texas storms is six, but in the
months January to April 1t is seventeen
| for each month total for the ten years
| 1SS4-1S93. The effect of this is to cause
many more storms to cross the south CEN
| trail valleys, the gulf and the south Attain
| tic states. Also the storms beginning in
| the northwest are often forced southeast
| ward to the gulf states before they recurve
| 20 the Gulf of st. Lawrence. These effects
are apparently due to the great highs
| forming to the north of Montana, which
are driven forward to the south and propel
the storm in front of them in the tracks
| just indicated.
An examination of the types peculiar to
the several districts gives rise to the fol-
lowing data for January. In the ten years
| discussed there were So storms, 81 belong
ing to the Alberta type, 20 to the north
Pacific coast type, to the northern Rocky
mountain plateau type, 10 to the Colorado
type and p to the Texas type: others
formed on the south Pacific coast, 2 in the
eastern gulf and near the Ohio valley.
January Storms From the Pacific.
An examination of the international
| charts, regarding the causes producing
storms in the Saskatchewan valley, shows
that they are usually preceded by loop
from the Alaska low intrudng upon this
region, which is then broken of by the ac-
ton of the highs in the neighborhood. 1t is
seldom that any district gyra tory movement
of the wind is seen around an advancing
center, until the loop is in the valley east
OF the mountains, as far north as fifty de-
grees to fifty-f1ve degrees. If the same
cause operates more to the south, in lati-
tude forty-five degrees to fifty degrees, then
true cyclonic low is formed over the
ocean and advances upon the coast as one
of the north Pacific type. These two types
forming under the same general conditions,
embrace more than one-half of all the jan
uary storms. Two-thirds of these reach the
Atlantic coast north of the fortieth parallel,
and If they move in the northern circuit
over the lake region the succession of warm
and cold, stormy and fair days will be very
regular. If they are, on the other hand, de-
Elected southwark, the probable course of
the track is harder to determine. the rate
of advance, and the severity of the storm
will be more difficult elements to include
in the forecast. The average velocity of
eastward movement is thirty-seven miles
per hour. About two-thirds of the storms
of the Alberta type move eastward over
the lakes. but one-third are DETECTED as far
southwark as Missouri that being the aver
age place OF turning northeastward
Meteorological Peculinrftfes.
In Similar WY about one-third of the
North Pacific coast storms bend southeast
ward to nearly the same latitude-37 de-
grees-but they recurve further to the west
in the states ~ Colorado or Kansas The
tracks of this type are much more spread
out after crossing the mountains, but they
generally make the lower lake region and
advance down the Saint Lawrence valley.
An important feature regarding the precip-
ftation of the storms moving in the north
ern circuit is that before the center reaches
the Upper Mississippi valley the fall is
on the western or following side of 1t, in
Montana, the Dakotas and Minnesota; but
within few hours the precipitation is
transferred to the eastern side of the CEN
ter into the lake region, and then advances
before it over the middle states and New
England 1t is hard to include such facts
in the theory that rain or snowfall is es-
sential to the formation of storms or that
lows advance to the region of greatest pre-
cipitation. The order of events seems
rather to be that the lows are products of
the highs, and the precipitation effects of
of the lows.
Texas Storms Are TerrOrs.
In point of number and in severity of the
winter storms the Texas type stand in the
front rank, and deserve particular atten-
form in northern Texas, near the terminal
slopes Of the. mountains and they usually
advance to lower Michigan and reach the
Atlantic ocean in about forty-eight hours.
Others originate IN southern Texas, and
these are likely to move more to the east
ward ever Tennessee and Kentucky along
the Appalachian range, the march from
Texas to New England taking about two
days. Still others form In the western
gulf or near the Rio Grande river, and
these are usually fourd to skirt the gulf
and the Atlantic coasts and to reach the
New England coast in forty-eight hours.
In general, immense areas of rainfall adj
vance before these storms, covering the
Lower Mississippi valley and the Ohio
valley in twenty-four hours, the Atlantic
and New England states In the next twen-
ty-four hours. The rise of temperature in
the front is excessive, and the passage of
the storm is likely to be followed by a
severe drop in the temperature. with a
cold wave in the southern states, and clear
dry weather.
The northern and southern types now
mentioned comprise three-fourths of the
January storms. the others being sporadic
or else abnormal and depending upon the
relative location of the high areas and their
movements. One of the south Pacific storms
moved northeastward to the lake region,
and the other directly eastward to the South
Carolina coast: the two east gulf storms
followed the Atlantic coast line to the north;
the three Ohio valley storms moved to New
England. The northern Rock mountain (S)
and the Colorado QW storms. all moved with
great regularity to the northeast, except
that the former looped generally southwark
into Nebraska.
Cold Waves and Their Study.
The cold waves of the winter eeason, set
ting in during the second half of November
and continuing until April, are important
matters for the attention of the weather
bureau. The country is subdvided into four
districts, % west of the Mississippi and
north of the 37th parallel (2) east of the
Mississippi and north of the 37th parallel,
90 south of the 37th parallel and to within
100 miles of the gulf coast, "a the gulf coast
and Florida peninsula. The limits vary
somewhat In these districts, but on the
average cold wave consists of fall of six
teen degrees in twenty-four hours, and to
80 degrees 20 minutes In thirty-siX hours
"a degrees in forty-eght hours. and to the
same limit. In verifying signal ordered to
forecast cold wave, these conditions must
be fulfilled.
Cold waves come with the quick advance
Of high area from the north, and they
are materially strengthened by the passa ge
of a vigorous storm center northeastward
along the edge Of the HIGH the latter tend