August 11-17, 2005
Midwest Weekly Highlights - August 11-17, 2005
Significant Rain Welcome
In Extreme Drought
Area
A series of low pressure waves riding along a slow-moving cold front
finally brought much-needed rainfall this week to most of the area
designated as
in Extreme Drought on the U.S. Drought Monitor (Figure 1).
In particular,
the drought areas of Missouri, southeast Iowa, and northwest Illinois
received anywhere from one to three inches of rain during the
period. As a result of this significant and generally
widespread
rain, the August 16 U.S. Drought Monitor (Figure 2)
showed improvement of
one category in drought conditions over central Missouri and central
Illinois. As of August 17, August precipitation
is now near to above normal across the worst of the drought
area in Missouri, and 75 to 90 percent of normal across the northern
half of Illinois and southeastern Iowa (Figure 3).
However, the northern Midwest remained rather dry as the
front focused precipitation in the central Midwest.
Temperatures
during the week ranged from 4°F to 5°F above normal in
the Ohio
Valley to 5°F to 6°F below normal in northwestern
Minnesota (Figure 4).
Just
What the Doctor Ordered,
But a Little Late
A stationary front draped across the central Midwest provided the focus
for the development of widespread showers and thunderstorms during the
first few days of the period (Figure 5). Storms
erupted on August 11 across Iowa. Radar estimated rainfall
amounts as of 8:00 a.m. CDT on August 12 ranged from one to two inches
of most of eastern Iowa and northwestern IIllinois, and parts of
southwestern Wisconsin (Figure 6), with
pockets of three to four inch amounts. A
number of
locations in Iowa set new daily rainfall records on August
11.
Mason City, IA received 0.83 inches of rain on August 11, breaking the
old record of 0.70 inches set in 1926. Dubuque, IA received a
record 1.99 inches of rain, breaking the old record of 1.58 inches set
in 1949. In addition to torrential rain, the storms were
accompanied by large hail and damaging winds. Baseball-size
hail
(2.75 inch) accompanied by 70 mph winds was reported near West Branch,
IA, shattering
windows. Two semi trailers were blown
into a ditch on I-80, also near West Branch.
The storms continued to develop ahead and along the front through the
week as it slowly sagged southward through the Midwest. Heavy
rain fell acorss central and southern Missouri in August 15, with
Joplin, MO receiving a record 2.67 inches on that day,
breaking
the old record of 1.82 inches set in 1975. By August 17 the
front
had pushed south of the Ohio River (Figure 7),
leaving just some scattered showers in thunderstorms over south-central
Missouri. Meanwhile, another cold front was entering the
northern
Midwest, bringing one to three inches of much-needed rain to
northern and western Minnesota. Moorhead, MN received 4.62 inches of
rain from the storms, more than one and a half times their normal total
August rainfall. International Falls received 2.51 inches of
rain on August 17, breaking the old record of 1.02 inches set in
1985.
Although the rain made a significant dent in the drought over the
Mississippi Valley, the rain came too late for much of the corn crop in
the affected areas, and may be of marginal benefit to the soybean
crop. The persistent dry weather forced many soybean plants
in
the dry areas to drop pollinated flowers and thus not set as many
pods. The rain may help increase seed size in existing pods,
but
yield reductions in the worst drought areas of southeast Iowa,
northwestern Illinois, northeastern Missouri, and southern Wisconsin
will be significant. As of August 14, 39 percent of Illinois soybeans
were reported in poor to very poor condition, while in Missouri, 43
percent of the soybeans were in poor to very poor
condition. Sixty percent of Illinois corn was
reported in
poor to very poor condition; in Missouri, 45 percent of the corn was in
poor to very poor condition. Pasture conditions continued to
deteriorate, although the rainfall this week should bring some
improvement which may be reflected in in the August 21 crop condition
report.
Cold
Front Spawns Severe Weather
Thunderstorms developing in the hot, humid air south of the cold front
reached severe levels over the southern half of the Midwest on August
13-14, with the most damage concentrated in parts of Missouri,
Illinois, and Indiana (Figure 8).
On August 13 an F1 tornado
touched down near the town of Fulton in Fulton
County, IN. The
tornado downed power lines, damaged several large trees, several homes,
and rolled over a utility trailer. Hail from 1.00 to1.75
inches
was reported in other parts of Indiana. In Illinois, wind gusts
of 60 mph were measured in Coles
County, and trees and small
structures were damaged by thunderstorm winds in Christian
and
Effingham Counties. A
line of thunderstorms generating
downburst
winds caused extensive tree and limb damage in eastern Franklin
County
and St. Louis County, MO (Figure 9,
UCAR/RAP). Winds estimated at 65 to 75
mph were reported to have lasted as long as five minutes. The
winds also caused some damage to roofs of businesses in the
area.
There was also scattered wind damage in Madison,
St. Clair, and
Clinton Counties in Illinois,
and the storms weakened as they moved
further east. In Ohio and Kentucky storms knocked down
trees and power lines.