April 17-23, 2006
Midwest Weekly Highlights - April 17-23, 2006
Mild Weather Persists
Most of the Midwest enjoyed mild spring weather this week. While not as
warm as the previous week, temperatures were above normal across the
entire region, ranging from 1°F to 2°F above normal in
western
Iowa and southwestern Minnesota to 9°F above normal from
southern
Missouri east through southern Kentucky (Figure 1).
An area from northwestern Minnesota through the Michigan UP was also
very warm with temperatures running at least 8°F above normal.
Precipitation was heavy in a band extending from south-central
Minnesota southeast through Illinois, Indiana, and much of Kentucky,
averaging 150 to 200 percent of normal (Figure 2).
Rain from thunderstorms on April 16, on top of rain from the
previous week, left water standing in many fields thus delaying spring
planting. Minor flooding occurred on the Embarass River in
eastern Illinois and the Wabash River (Illinois/Indiana).
Drought - A Mixed Bag
The frequent waves of showers and thunderstorms over the central
Midwest continued to lessen drought conditions across northern Illinois
and southern Iowa. It was a different story across
west-central
and southwestern Missouri where lack of rain coupled with unseasonably
warm weather has intensified and expanded the drought (Figure 3).
A number of communities in southwestern Missouri have
implemented
water conservation plans, and there is concern that if the drought
continues it could rival the drought of record in the early 1950s.
Rivers and streams in the region are running at 10 percent or
less of their normal flow. Flow in the Spring River near
Waco,
MO, northwest of Joplin (Jasper County), was recently measured at 17
cubic feet per sec (cfs). The mean flow for this time of year is
1,212 cfs, and the record low flow for this location is 4.2 cfs during
the drought of 1954. Showers and thunderstorms late in the period did produce some
significant rain over some portions of the drought-affected area of
central Missouri (Figure 4), but it was a proverbial drop in the bucket and much more
rain is needed.
A Rough Start...
The weather this week was relatively tranquil compared to the last
several weeks, although it got off to a rough start. On April 18
another low pressure system was winding up over southern Kansas. The
atmosphere became favorable for severe weather across
Missouri, southern Iowa, and Illinois as warmer and more humid air was
drawn northward. By late afternoon a tornado watch covered
much of central Missouri, followed by severe thunderstorm watches for
southern Iowa and western Illinois in the late evening. Storms reached
severe levels in the early evening hours over central Missouri,
producing four tornadoes and baseball-size hail in Livingston, Saline, and Howard Counties. The stronger storms
continued east across the Mississippi River into Illinois. A
tornado touched in Lincoln, IL (Logan County) and overturned a
semi-trailer truck on
Interstate 55, causing two injuries. The storms also produced
1.00 inch to 1.75 inch hail in Effingham and Jasper Counties , which
only two days earlier experienced tornadoes and large hail. While the
storms weakened as they worked their way east, they remained strong
enough to produce damaging winds, removing some roofs and downing
trees
and power lines.
Hail from severe thunderstorms was also observed in Minnesota during
the late afternoon, and across southern Indiana and Kentucky during the
late night hours of April 18 and the early morning hours of April 19.
...and a Mostly
Quiet End
An impressive upper level low spinning over Minnesota produced
cloudy, cool and rainy weather
over the northern Midwest April 19-21 (Figure 5),
while another low moving through lower Mississippi
Valley brought rain to eastern Kentucky and southern Indiana.
On
April 22 Minnesota residents enjoyed sunshine for the first time in
almost a week. A cold front trailing from the northern low
south
through the Midwest helped trigger showers and thunderstorms in
Michigan and Ohio, and a few of these were severe, producing large
hail.
Severe storms also developed across central Missouri on
April 22
and April 23 as the next weather disturbance approached from the
Central Plains. The storms produced hail up to two inches in
diameter and some wind damage.
SDH