April 24-30, 2004
Midwest Weekly Highlights - April 24-30, 2004
A Spring Weather Buffet in the Midwest
Everything from snow and record cold to severe thunderstorms and record
heat could be found in the Midwest this week.
During the last week of April preicpitation was quite variable across
the region, but for the most part reflected the pattern for the month (Figure 1). In addition to
the far northern and southern portions of the region,
precipitation this week was also well above normal across northwestern
Iowa and western Illinois. The last half of April was significantly
wetter than the first, but despite the increase in the number of events
the last two weeks of the month (including some snow) precipitation was
still below normal across all but the far northern and far southern
portions of the region (Figure 2). The driest portion of the Midwest was a broad band
extending from the southeastern half of Illinois through Indiana into
southern lower Michigan. Within this band April precipitation was less
than 50 percent of normal, and a small area in northern Indiana and
southern Michgian was less than 25 percent of normal.
Temperatures this week reflected the colder air pulled south by the
weather systems moving through the region (Figure 3). Temperatures were 3F to 5F below
normal in northern Wisconsin and Minnesota, and generally 1F to #F
beklow normal northwest of a Chicago-St. Louis-Springfield, MO.
line. South of this line temperatures ranged from 0F to 2F above
normal. Temperatures for the month of April ranged from 1F below
normal to 3F above normal (Figure 4). The warmest portion of the region coincided with the area
of dry weather from Illinois through southern Michigan.
Rain Soaks Ozarks
Heavy rain over southern Missouri the third week of April carried into the last week, with some locations receiving more than nine inches of rain in a four-day period (Figure 5). The rounds of heavy showers and thunderstorms produced record rainfall at a number of locations and major flooding in the Ozarks. On April 23 1.49 inches of rain fell at the Joplin Regional Airport, breaking the previous record of 1.35 inches set in 1970. On April 24 West Plains, MO set a new daily rainfall record of 4.40 inches, shattering the old record of 1.58 inches established in 1957. It is also the 13th wettest day in record for West Plains. The greatest rainfall total reported was in Noble, MO where 9.70 inches of rain fell April 19-26. By April 24 there was widespread flooding of roads and many roads crossing creeks and streams were washed out. In Cassville (Barry County) a car was swept off the road by floodwaters and carried away. The occupant of the car was able to escape and was uninjured.
Snow in Michigan
A strong cold front pushed through the Midwest on April 26, and in its
wake parts of Michigan experienced a late taste of winter. On
April 27 Marquette set a new record low temperature of 15F degrees,
breaking the old record of 19F set in 1996. Up to an inch of snow
fell along the northwestern shore of Lake Michigan, and a few tenths
accumulated farther inland. Grand Rapids received 0.2 inches of
snow, setting a new record for the date. No measurable snow had
previously occurred on this date, although trace amounts were observed
on April 27 in four other years.
Strong Winds Lash Midwest
By the morning of April 28 the cold high pressure system had moved to
the southeastern U.S., and another strong low pressure system was
spinning over North Dakota (Figure 6). The difference in air pressure between these two systems
produced strong gusty winds throughout the Midwest, prompting the
National Weather Service to issue Wind Advisories for much of Missouri,
Iowa, and Illinois. Sustained winds from 25 to 25 mph gusted to
over 50 mph at times during the day on April 28, and continued into the
evening hours. There were numerous gusts in excess of 60 mph in
reported in Iowa. A 2-3 foot tree was blown over on the campus of
Iowa State University in Ames, and there were many other reports of
wind damage throughout the state. The winds delayed flights for
two hours at O’Hare International Airport and knocked out power to
6,700 Commonwealth Edison customers. A CTA station was closed in
Chicago because of the threat of debris falling from a nearby
wind-damaged building. A building engineer spotted a six-foot-long
piece of metal hanging from the 17th floor of the building. Winds
fanned a four-alarm blaze in Chicago which destroyed one building and
heavily damaged four others. In Minnesota, thunderstorms reached
severe levels in the warm humid air drawn northward by the low pressure
system. Thunderstorm wind gusts of up to 70 mph were reported in
northeastern Minnesota (arrowhead), knocking down trees and power
lines. Lightning strikes caused structure and grass fires.
Several record temperatures were tied or set across Minnesota and
Wisconsin on April 28 (Figure 7). In Minneapolis the old record of 87F set in 1934 and tied again
in 1952 was shattered when the mercury reached 91F. St. Cloud, MN
soared to 92F, breaking the old record of 86F also set in 1934.
La Crosse, WI tied the record high of 87F.
Flood Threat Rises Again in Southern Missouri
A strong but slow-moving cold front was making its way through the central Midwest on April 30 (Figure 8, Unisys). A large area of showers and thunderstorms developed ahead of the upper level system in Kansas and Oklahome, moving into Missouri during the day. By late afternoon flash flood warnings were again being posted for counties in southern Missouri as thunderstorms with heavy rain moved over areas that had received significant rainfall earlier in the week. A Severe Thunderstorm watch was issued for a large portion of Missouri. There were several reports of wind damage and large hail from the thunderstorms in southern Missouri, southern Illinois, southeastern Indiana, and northwestern Kentucky (Figure 9, SPC).