February 8-14, 2006
Midwest Weekly Highlights - February 8-14, 2006
Cold South, Warm North
There was a sharp contrast in temperature departures from normal from
north to south across the Midwest this week. Across the
northern
Midwest, temperatures averaged 2°F to 4°F above normal,
while
from southern Missouri east through Kentucky temperatures were from
4°F to 6°F below normal (Figure 1).
Milwaukee, WI
extended its streak of days at or above 30°F to 55 days as of
February 14. The old record was 31 days in December 1931.
The week's weather was characterized by a series of weak weather
systems, and precipitation was generally sparse, with most of the
region receiving less than 50 percent of normal weekly precipitation
(Figure 2). The notable exception was in Minnesota
and northwestern Iowa, where precipitation was above normal.
Precipitation approached 75 percent of normal around the Great
Lakes due to lake-effect snows, and in southern Kentucky and Ohio from
a storm late in the week (Figure 3).
The broad area of dry weather meant there was
little change in the status of the drought across the central Midwest
(Figure 4).
Spotty Snow
A series of fast-moving weather systems brought snow at times
to various parts of the Midwest during the week. On February
8 a clipper system moved southeast through Iowa and Missouri (Figure 5) brought
light to moderate snow to eastern Iowa, eastern Missouri, and
southwestern Illinois. Snowfall in the St. Louis
metropolitan area reached 4 inches (Figure 6, Figure 7), and numerous accidents were
reported in eastern Missouri and southwestern Illinois due to snow and
ice-covered roads.
A low pressure system and associated cold front passed through the
Midwest on February 10, producing more typical winter conditions across
the region. Snow fell across Minnesota, Wisconsin, and
Michigan north of the low pressure center, while colder air filtered
south. By the morning of February 11 a strong upper
level low had developed over Missouri and Illinois (Figure 8).
Bands of
convective snow showers developed in the cold unstable air over central
Illinois and Indiana. Areas in central Illinois experienced
heavy snow showers for much of the morning and afternoon. The highest
snow totals occurred in a 10 mile wide band from East Peoria southward
through the Springfield area, and a separate narrow band along the I-55
corridor between Springfield and Lincoln. A report form the Lincoln, IL
NWS office summarizes the weather conditions that led to this event:
"A large upper level storm system moved from Iowa...into
Illinois on
Saturday morning. This system strengthened a
bit more than what was
forecast, and in combination with sufficient low-level
moisture and weak
convergence at the surface (NNW winds over western
Illinois and NNE
winds over eastern Illinois), narrow bands of heavy
snow showers
developed. The intensity of the snow showers
was enhanced by the
thermal profile of the atmosphere which somewhat
resembled a summertime
setup when heavy convective rain showers can
occur. With the deep upper
level storm system over the region, temperatures aloft
were very cold
(<-35 degrees C at 500mb). Meanwhile,
temperatures at the surface were
in the 30s and lower 40s, thanks to some clearing and
sunshine reaching
the surface. This created a weakly unstable
atmosphere with CAPE values
on the order of 50-100 J/Kg. These
ingredients provided a situation
where convective snow showers could take advantage of
the low level
moisture and weak convergence. Areas that
received the highest totals
were in persistent low-level convergence that allowed
heavy banded snow
showers to redevelop over the same
locations. Snowfall intensity
exceeded 2 inches per hour in the most intense bands,
causing extremely
hazardous travel conditions and many accidents in the
Peoria and
Springfield metro areas. I-55 near
Springfield was closed for nearly 3
hours.
The highest snow total from this event was on the
south side of
Springfield, where 7.5 inches fell. As
little as 10 miles east or west
of this location only trace amounts were
noted."
Snowfall amounts from this unusual convective snow shower event are
depicted in Figure 9 (NWS). Visible satellite images from February 13,
when skies
had cleared over Illinois and Indiana, clearly depict the snow on the
ground over central Illinois and also over central Indiana (Figure 10).
Prelude to Major
East Coast Storm
As the upper low continued to intensify and dig southeastward, a
surface low developed over
eastern Georgia (Figure 11). Heavy snow developed north and east of the low
over eastern Kentucky and southern Ohio during the day Saturday,
February 11. The heaviest snow fell over higher
elevations in eastern Kentucky, where generally 3 to 5 inches inches of
snow accumulated, but with some local amounts as high as 10.5 inches
(Closplint, Harlan County, KY). Jackson, KY established a new daily
snowfall record of 4.3 inches for February 11, breaking the old record
of 2.9 inches set in 1986. Weather records in Jackson date
back to 1981. Lake effect snow up to 6 inches occurred in
the northeastern Ohio snow belts as cold air was pulled over
relatively warm Lake Erie. This storm continued on up the
eastern seaboard as Winter Storm Carson, bringing up to two feet of
snow and blizzard conditions to the northeast and New England.
Temperatures on the
Rise
Temperatures moderated toward the end of the period in the wake of the
winter conditions on February 11 and 12. High pressure
centered over the southeastern U.S. produced strong southwesterly flow
over the Midwest. Temperatures on February 14 soared into the
60s as far north as central Iowa (Figure 12),
with some new maximum temperature records. Cedar Rapids tied
a record of 63°F first set in 1954. Dubuque, IA set a
new record of 59°F, breaking the old record of 58°F in
1934. The warm, dry weather and worsening drought conditions
in southwestern Missouri contributed to the spread of a wildfire
southwest of Gravois Mills in Camden County, MO. By mid-afternoon on February 14, eight agencies
were battling the fire which had already burned 600 acres,
including barns and some mobile homes.
SDH