WGN Weather Center Blog

Chicago area gears up for taste of summer

2009-07-03T03:10:54Z

Friday afternoon's predicted 80-degree temperatures over much of the metro area will mark the first time this week it's truly felt like summer. Many Chicagoans have openly voiced disappointment over the recent succession of lackluster daytime highs which have been more reminiscent of May than late June and early July. But increased sunshine Friday is to allow temperatures to surge. It's a move that finally returns temperatures here to seasonable levels.
Storm clouds loom Friday night into Saturday over sections of the Midwest. Thunderstorms that flared late Thursday over the Plains (with cloud heights towering as high as 57,000 feet and prompting a series of severe weather watches) are targeting sections of Iowa, Missouri, Downstate Illinois and Indiana.
A suite of computer projections has shifted these storms progressively farther north in recent days. Individual projections of potential Chicago rainfall late Friday night into Saturday varies widely across 15 models. The average of these forecasts calls for a total of 0.52 inches. A consensus of these forecasts places the axis of potentially heaviest rainfall across central Illinois and Indiana.

Much improved weather is due Sunday with sunshine allowing temperatures to surge back into the 80s in all immediate Lake Michigan shoreline locations where upper 70s are likely. Evidence that hot weather is preparing to stage a comeback later next week continues to mount. A dome of hot air is predicted to become established over the nation's mid-section by Thursday---a development which may well produce the Chicago area's next round of 90-degree temperatures. The heat could lead to increased rainfall. Rainfall estimates in the 1-2 week range here passed two inches in several computer projections, evidence a sporadically stormy "ring of fire" pattern could take shape, sending a succession of thunderstorm clusters running along the northern flank of the predicted dome of hot air across the Chicago area with some regularity.

July 4th rain prospects linked to eastbound storm; heat later next week

2009-07-03T03:07:08Z

What is "aphelion"?

2009-07-03T02:36:41Z

Dear Tom,
What is "aphelion"?
Susan Bosserman Fairview, NC

Dear Susan,
Our starry-eyed sky guru, Triton College astronomer Dan Joyce, informs us that today is Aphelion Day, the one day in the year on which the Earth passes farthest from the sun. That's right: farthest. Surprising, but true. We're farther from the sun during summer than during winter (but remember, it's winter in the Southern Hemisphere now).
The average Earth-sun separation is about 93.2 million miles, but the path the Earth traces as it orbits the sun is that of an ellipse, not a circle. When the Earth arrives at the end of the ellipse most distant from the sun, as it does today at about 9 p.m. CDT, the sun will be 94.4 million miles distant. Joyce says that point, in the parlance of astronomy, is aphelion. At perihelion, the point of closest approach (Jan. 3), the Earth-sun separation is 91.3 million miles.

Area corn running three weeks behind a year ago

2009-07-02T22:19:48Z

Our friend John Hazzard, who farms in western Will County, sends us this telling shot which features his nephew Mark Hazzard and his son Porter illustrating that corn has made it to "knee high by the 4th of July" benchmark this year--despite the late start to the planting season because of the incredible rains. As john points out in his report to us:

"Although the corn does look good, this time last year the corn would have been up to Marks shoulder so were a good 3 weeks behind a year ago. We will need ideal conditions the rest of the growing season to bring this crop in on schedule."

How true, John! MANY THANKS for the update and hope you and your family have a Great 4th!!

Tom Skilling

Photo courtesy of John Hazzard, Wilmington, Illinois

4th's weather here may be jeopardized by northward shift in stormy system

2009-07-02T18:20:35Z

The latest suite of computer model forecasts--and from more than one meteorological agency--are worrisome in terms of July 4 weather here. A number of the latest runs appear to heighten concern that sections of the Chicago area is in line for rainfall Friday night into Saturday. Thundery downpours have been predicted for the early weekend downstate--part of a swath of significant precipitation which has been expected extend from Missouri across sections of downstate central and southern Illinois and Indiana. In at least sections of that area, rains have been predicted to top 2" in the Friday night/Saturday period. But now (as of early Thursday afternoon), several models are aggressively shifting the eastbound storm onto a more northerly storm track increasing rain prospects over at least portions the Chicago area with rain accumulations trending heavier the farther south one travels. Hitting the northward shift in the wet Friday night/Saturday storm's movement are the Canadian, European and Navy global forecast models. Less impressive are the lighter, more scattered rains projected here by the Weather Service's GFS and WRF models. These models continue to highlight southern Illinois and Indiana as areas likely to be at the epicenter of the heaviest early weekend rains--south of a Quincy to Terre Haute line by in large.
If you've been following our weather programs this week, you know this is hardly a completely surprise---it's been a development we've viewed as a wildcard scenario for some time. We're in the midst of evaluating the new data and model runs and will have more here and on our 5:30pm and 9 pm programs and on our WGN radio reports this afternoon--and on the Chicago Tribune weather page Friday.

Tim's Weather World: So Long Soggy June

2009-07-02T11:19:22Z

7.18" of rain fell during the month of June. That makes June 2009 the 7th wettest on record. June is typically the third wettest month of the year with July being the 4th wettest on average.

There is little rain in the forecast for the next several days. Some of the computer models have a system slipping just south of us early on July 4th. There is a chance we could see a shower or thunderstorm in our far southern suburbs on Saturday but it appears most of us will stay dry.

Chicago has a rare chilly summer day

2009-07-02T03:10:39Z

What has happened to summer? That was the question from many area residents Wednesday amid May-level 60-degree temperatures. The day's high of 65-degrees marked the chilliest open to a July here since 1930 and was one of the three coolest July 1 readings on the books in 139 years of weather records since 1871. Summer temperatures at that level are truly rare. Of 7,452 meteorological summer (June through August) highs on the books since 1928 at Midway, only 184 of them--just 2 percent---have registered temperature as cool or cooler.

Scattered lake-enhanced rain showers amid the Wednesday's chill lowered cloud bases in the downtown area, obscuring the tops of skyscrapers while producing periods of upper 50-degree temperatures.

While Chicago missed the July 1 record low maximum of 61-degrees set 1904 and 1924, record low daytime highs occurred at Rockford (65-degrees) and downstate at Lincoln where the high was just 70-degrees.

Thundery downpours could be part of the holiday weekend downstate

Thunderstorms expected to erupt in the Plains later Friday threaten to track east/southeastward into sections of downstate Illinois and Indiana where they may produce downpours totaling 2 or more inches for a portion of the upcoming July 4 holiday weekend.

Warming in sight; past years with early July chill not without hot days

2009-07-02T02:41:40Z

Lousy Cape Cod weather

2009-07-02T02:33:14Z

Dear Tom,
Our family vacations every summer on Cape Cod, and we usually enjoy the sun,
ocean and beaches. But the weather there has been awful the last half of
June: fog, clouds, rain, chilly temperatures. Any thoughts on what has been
happening?
Ron Szafranski, Wheaton

Dear Ron,
Blame it on a large, stubbornly persistent atmospheric feature known in
weather circles as a "cutoff upper low." It consists of a huge (a few
hundred miles in diameter) nearly stationary pool of very cold air aloft
that has become isolated from prevailing upper wind patterns.

The weather beneath such systems is cloudy, rainy and chilly, and Cape Cod
was caught in that pattern while an unusually persistent cutoff upper low
sat just off the New England Coast. Now, though, it's gone and a more
typical summer weather regime has settled across New England: pleasant
temperatures, plenty of sun, but some showers too.

Indiana sunset south of Union Mills in La Porte County

2009-07-01T22:12:20Z

Mike Kellems share this beautiful Monday evening 6/29 Indiana sunset with us. It was taken south of the town of Union Mills in south-central La Porte County! THANKS Mike--a great photo!

Tom Skilling

Photo courtesy of Mike Kellems, La Porte, Indiana

Storms off Chicago sweep Lake Michigan last July 20

2009-07-01T22:05:01Z

Architect and mariner James Papoutsis sends us these photos of the storm which swept Chicago last summer on July 20. They were taken from his boat Renegade. THANKS for sharing them with us James!

Tom Skilling

Check this montage of shots out! Architect James Papoutsis shares this with us. The photos were taken from his boat the Renegade----James brother Tom is the boat's Captain. THANKS James! We love the photo!

Tom Skilling
CLICK ON IMAGE TO ENLARGE

Photos courtesy of James Papoutsis Copyright 2009

Storms sweep Branson, Missouri Tuesday as June, 2009 comes to a close

2009-07-01T21:58:31Z

Gary and Isabelle Kovarik send us these photos of storms which swept the area near Branson, Missouri early Tuesday morning, June 30, 2009. The Kovariks are there on vacation. They write:

"Photos were taken from the Peninsula Overlook at the State Park, facing north (Chateau on the right) and west."

These are amazing shots. Thanks Gary and Isabelle!

Tom Skilling

Photos courtesy of Gary and Isabelle Kovarik, Malta, Illinois

Climate Prediction Center's hazardous medium range weather outlook indicating Central U.S. Heat

2009-07-01T19:00:45Z

NOAA's Climate Prediction Center, in its daily 2 week outlook of possible severe or hazardous weather, indicates heat is a threat over much of the central and southern Plains in the July 9-12 period. You can check this out at:

http://www.cpc.noaa.gov/products/predictions/threats/threats.gif

O'Hare's temp slips to 59 early Wednesday afternoon; it's so cool, lake enhanced rain showers are falling

2009-07-01T18:26:29Z

Wow--what a July open! It feels more like May! Wednesday continues on track to become the coolest July 1 since the 65-degree high in 1930. The official high at O'Hare since midnight Wednesday as of this posting has been 65-degrees--the "normal" July 1 high here is 82. All this means we're experiencing May-level temperatures in early July--it's quite unusual. As of 1pm, the reading at O'hare has acutally slipped from 60s back to 59-degrees. (We won't set a record--but it will be close. The lowest July 1 max temperature on record was a 61-degree reading in 1924). Weather Bug sensors indicate the following 1pm readings across the sections of the Chicago area: 55 at the Cubby Bear in Wrigleyville--also at Highland Park and Wilmette, 56 at the Latin School on Chicago's South Side and at Lincolnwood and 57 at Niles and Kenosha.

Crazies like me actually like this--I prefer my summer heat in bursts, not prolonged assaults. But, that's just me. I know many of you who prefer your summer weather hot are quite disappointed by this temperature downturn. Well, take heart. In 1930--the last time July 1 was this cool---the month of July went on to produce 12 daily highs over 90-degrees--three of them above 100! And the heat hit inside of a week of the month's cool open. Also, a set of medium range computer forecast models--including the National Weather Service's GFS model (which is run out to 384 hours four times a day) and the European Center's ECM Ensemble model, continue indicating a big dome of hot air is to puff up across the nation's mid-section next week--probably mid and late week. The jet stream retreats north in this scenario. But the scenario does open the possibility of re-establishing a "ring of fire" type pattern in which clusters of thunderstorms flare at the periphery of the hot air, running from the Rockies into the northern Plains and possibly affecting the central and northern Midwest. If true, cooler outflow boundaries could have an effect on the northward extent of the hot air. But the building depth of the hot air mass is significant and should comfort those who prefer hotter weather than today's that summer's heat is far from history.

City may get chilliest start of July in 79 years

2009-07-01T03:04:56Z

The coolest late June air mass in decades spills over into Wednesday, but it is to loosen its grip on the area later this week in time for the 4th of July holiday weekend. The abnormally cool 65-degree high predicted Wednesday would deliver the Chicago area its coolest July opening in 79-years--since a 65-degree reading in 1930. A temperature at that level at this point in the season is more typical of early May and 18 degrees below normal for the date. It comes on the heels of the coolest June close in 23 years. Clouds and northwest winds were so pervasive that highs struggled to reach 66 at O'Hare International Airport. Northern Wisconsin and Upper Michigan highs failed to make it out the 50s. Rockford's 65 degree high Tuesday broke a record for the coolest June 30.

Cloudiest June in 4 decades

June 2009, which ended at midnight, closed as the Chicago area's cloudiest in the four decades since 1969, having only 51 percent of its possible sunshine. A typical June sees 68 percent.