Chicago records its first 60+ temperature in nearly 4 months!

It’s official! Today’s temperatures have been the area’s warmest in nearly 4 months. It’s been a day which has delivered us the first official 60+-degree city temperatures since O’Hare’s 63-degree on November 14 last fall. The city’s official Wednesday highs were 62-degrees at O’Hare and 64-degrees at Midway. Temperatures first reached 60-degrees at the O’Hare observation site at 2:35 pm.
   Here are some other area highs off some of our Weather Bug sensors across the metro area:

Henry  66  Gary  66     Lansing 66   Pontiac 66     Kankakee 66    New Lennox 66
Griffith IN 65   Itasca   65   Schererville IN  65   Munster  65    Chesterton 65 
University Park  65    Buffalo Grove 65   Palos Heights 65    Flossmoor  65
Oswego 64    East Chicago 64    Blue Island 64

Lake cooled locations

Waukegan  49    Glencoe   53    Lake Geneva WI   54    Highland Park  55
Winnetka  56    McHenry  56     Fox Lake  57  Kenosha WI    52   Racine WI   48

Computer model rainfall numbers continue impressive over coming days. The first wave of organized rainfall begins later Thursday morning and continues in waves through Thursday evening. More rain and stronger, cooler northeast winds lock in Friday afternoon into Saturday–and even Sunday is showing signs of being showery. The latest National Weather Service “GFS” (Global Forecast System) model rain projections are 1.90″ at O’Hare and 1.90″ at Midway Airport through the weekend and the Weather Service’s WRF model is kicking out 1.59″ O’Hare and 1.49″ at Midway. More on our Wednesday evening WGN News weather segments at 5PM and 9 PM.

Tom Skilling

Tim's Weather World: Severe Weather Season's Slow Start

A tornado in Oklahoma is hardly big news but this year is different.  A twister that touched down earlier this week in Hammon, Oklahoma has received a lot of attention.  One reason for that attention is that this has been such a quiet year so far for severe weather.  There was only one tornado reported in the United States during the month of February, the fewest since 1950.  That tornado oddly enough was in southern California, not exactly the heart of tornado alley.

The other reason the Hammon tornado got a lot of attention is that it was captured on video by stormchasers.   They ventured a little too close and saw first hand the power of a tornado.

Hammontornado.JPGThe severe weather season may have started off quiet but don’t expect it to stay that way.  After El Nino influenced winters like this one there is usually a small increase in the number of tornadoes during the following severe weather season.

A 61-degree high would be the mildest here in 4 months!

Tuesday’s 51-degrees—the first 50+ and warmest temperature here in the 98 days since Dec. 1—isn’t likely to last long as 2010′s mildest reading to date. Highs Wednesday appear poised to exceed it by 10-degrees, reaching the low 60s for the first time since a Nov. 14 high of 63-degrees nearly four months ago.

A 60+ degree high this time of year is actually late. The average date for temperatures at that level over the past 81 years at Midway Airport has been on or about Feb. 28. Last year’s first 60-degree temp occurred a month earlier on Feb. 10, 2009 (61-degrees) and nearly two months earlier the year before on Jan. 6, 2008 (60 degrees.) It will be some time before a majority of high temperatures reach or exceed 60-degrees on a daily basis—on average, April 16. But with five of the past six months having posted temperature deficits, any sign of warmth is welcome and few in Chicago would turn the “warmth” away even if it was possible.

Getting early season warmth into this area intact is always a dicey proposition. The ground is often cold, if not snow covered, at this point of the year and and ever-present shallow pool of cold, comparatively dense air hugs Lake Michigan’s still frigid waters ready to run roughshod over any fledgling early season warm air masses which aren’t backed by powerful southerly winds.

A number of supportive factors appear ready to go to work Wednesday warming the area. The easterly winds of recent days are slated to become more southerly—especially in areas away from the lakeshore—once a northbound warm front trudges across the area. This flow is part of an expansive area of southery winds which extend from the Gulf of Mexico north to the Midwest. It’s occurring on the east side of a sprawling and still developing area of low pressure over the Plains. These south winds have access to a large reservoir of warm air which pushed Tuesday temperatures to 77-degree at Little Rock, Arkansas, 75 in Dallas and 66-degrees at Oklahoma City; 60s managed to make it as far north as Gary, Indiana.

Winds take on a more easterly component Thursday, traveling into eastern Illinois and Wisconsin after a chilly trek over 36-degree lake waters. This should cool lakeside locations while allowing readings in the south and far western suburbs to return to the 50s.
Predicting atmospheric blocking pattern threatens to keep rains coming here for days
Rainfall projections produced by a suite of computer models for Chicago and covering the coming 2 weeks remain impressive.  Estimates of precipitation from the nine most recent runs of the National Weather Service’s global forecast model average 2.28 inches—nearly twice the 1.19 inches considered normal for a 14-day period time of year. A series of rain-inducing impulses rotating around a huge storm system predicted to slow as it becomes trapped over the Midwest and Mid-Atlantic on the south end of a Canadian “blocking pattern” aloft are driving the big rainfall tallies.

Rainfall should pick up in coverage and intensity Thursday and Thursday night and again later Friday night and Saturday—though spells of precipitation are expected to occur from time to time through the weekend and into next Monday once the wet systems take control.
2010 U.S. severe weather season quiet by recent standards
The 2010 tornado season has been a comparatively mild one—at least so far. NOAA’s Storm Prediction Center has logged only 44 tornado reports to date this year compared to 86 by this time a year ago and 169 two seasons ago.

April 1961: Biggest late-season snowstorm to hit Chicago

Dear Tom,
In April 1961 I went camping in southern Indiana. It snowed on Sunday and on the way back we were stranded in Indianapolis for two days. What happened?

–Dennis Cusumano, Winthrop Harbor
Dear Dennis,
You were caught in the biggest late-season snowstorm to hit Chicago and portions of northern and central Indiana. The snow was accompanied by winds up to 50 mph and created 10-foot high drifts, closing roads and stranding thousands of motorists. The snow must have come as quite a shock because Saturday’s temperatures at your campsite were in the upper 60s. Thunderstorms hit overnight and by Sunday morning 2 to 4 inches of snow were on the ground. The heaviest snow fell between Indianapolis and Chicago with totals ranging from 5 to 9 inches; Chicago officially received nearly 7 inches.

9AM Update: Fog advisory has been canceled for most of the Chicago area

The fog situation continues to ease across most of the Chicago area.  The one trouble spot that may persist throughout the day is along the immediate lakeshore in Cook and Lake Counties.   Lake cooled air interacting with boundary layer moisture may keep lakeshore communities foggy into this afternoon.   

NE Illinois including Chicago:  A Dense Fog Advisory is in effect until 10AM Tuesday for Lake, McHenry and LaSalle Counties.  The advisory for the rest of northeast Illinois (including Chicago) has been canceled.   

NW Indiana:  The dense fog advisory has been canceled. 

Southern Wisconsin:  A Dense Fog Advisory is in effect for most of southern Wisconsin (including Kenosha, Racine and Walworth Counties) until 10AM Tuesday morning.

alerts_metro_650 3.9  8am.jpg

Above:  Counties shaded in grey are included in the Dense Fog Advisory through mid-morning