Fog in Chicago

Tuesday morning was a foggy one for many across the Great Lakes.  This is a picture of the fog as it was rolling into Chicago!  Pretty cool! It actually stayed around through a good part of the day in some spots along Lake Michigan.

Excessive Heat Warnings Continue

So far there have been at least 13 fatalities possibly related to the heat across the Midwest and after reaching 100° Tuesday afternoon, temperatures will be in the same territory once again today.  That's why the Excessive Heat Warnings will continue through Thursday evening. 

A break will finally come, from the humidity at least, early next week but some indications are suggesting that another warm up will be in the makings around the first week of August.

Severe Thunderstorm Watch for Boone/McHenry

2:00am Update:  The line of storms that prompted the Severe Thunderstorm Watch will continue to move to our east.  As a result the watch has been cancelled for our counties.

Boone and McHenry counties are under a severe thunderstorm watch until 3am. A line of thunderstorms now in central Wisconsin is moving to the southeast at 50mph. These storms have had a history of producing 60mph winds in northwest Wisconsin earlier this evening, along with frequent lightning and heavy downpours. Although these storms appear to be weakening somewhat and may miss the area to the east, we will continue to monitor these storms.

Excessive Heat Warning Starting Tomorrow AM

WINNEBAGO-BOONE-OGLE-LEE-DE KALB-KANE-KENDALL-NEWTON-JASPER-
INCLUDING THE CITIES OF...ROCKFORD...BELVIDERE...OREGON...DIXON...
407 PM CDT TUE JUL 19 2011

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 7 AM CDT WEDNESDAY...
...EXCESSIVE HEAT WARNING IN EFFECT FROM 7 AM WEDNESDAY TO 4 AM
CDT FRIDAY...

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED AN EXCESSIVE
HEAT WARNING...WHICH IS IN EFFECT FROM 7 AM WEDNESDAY TO 4 AM CDT
FRIDAY. THE EXCESSIVE HEAT WATCH IS NO LONGER IN EFFECT. A HEAT
ADVISORY REMAINS IN EFFECT TONIGHT UNTIL 7 AM CDT WEDNESDAY.

* TEMPS AND HEAT INDEX...HIGH TEMPERATURES IN THE MID TO POSSIBLY
UPPER 90S COMBINED WITH HIGH HUMIDITY WILL RESULT IN AFTERNOON
HEAT INDICES OF 105 TO 110 DEGREES THROUGH THURSDAY. IN
ADDITION...LITTLE RELIEF IS EXPECTED DURING THE NIGHTTIME HOURS
WITH LOWS IN THE MIDDLE OR UPPER 70S.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A HEAT ADVISORY MEANS THAT A PERIOD OF HOT WEATHER IS EXPECTED.
HIGH TEMPERATURES AND HIGH HUMIDITY WILL COMBINE TO CREATE A
SITUATION IN WHICH HEAT ILLNESSES ARE POSSIBLE. DURING VERY HOT
WEATHER IT IS CRITICAL TO STAY HYDRATED BY DRINKING PLENTY OF
WATER. IN ADDITION CHECK UP ON RELATIVES...ELDERLY AND NEIGHBORS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE EXTRA PRECAUTIONS...IF YOU WORK OR SPEND TIME OUTSIDE. WHEN
POSSIBLE...RESCHEDULE STRENUOUS ACTIVITIES TO EARLY MORNING OR
EVENING. KNOW THE SIGNS AND SYMPTOMS OF HEAT EXHAUSTION AND HEAT
STROKE. WEAR LIGHT WEIGHT AND LOOSE FITTING CLOTHING WHEN
POSSIBLE AND DRINK PLENTY OF WATER.

TO REDUCE RISK DURING OUTDOOR WORK...THE OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION RECOMMENDS SCHEDULING FREQUENT REST BREAKS
IN SHADED OR AIR CONDITIONED ENVIRONMENTS. ANYONE OVERCOME BY
HEAT SHOULD BE MOVED TO A COOL AND SHADED LOCATION. HEAT STROKE
IS AN EMERGENCY...CALL 9 1 1.

AN EXCESSIVE HEAT WARNING MEANS THAT A PROLONGED PERIOD OF
DANGEROUSLY HOT TEMPERATURES WILL OCCUR. THE COMBINATION OF HOT
TEMPERATURES AND HIGH HUMIDITY WILL CREATE A DANGEROUS SITUATION
IN WHICH HEAT ILLNESSES ARE LIKELY. DRINK PLENTY OF FLUIDS...STAY
IN AN AIR-CONDITIONED ROOM...STAY OUT OF THE SUN...AND CHECK UP
ON RELATIVES AND NEIGHBORS.

TAKE EXTRA PRECAUTIONS...IF YOU WORK OR SPEND TIME OUTSIDE. WHEN
POSSIBLE...RESCHEDULE STRENUOUS ACTIVITIES TO EARLY MORNING OR
EVENING. KNOW THE SIGNS AND SYMPTOMS OF HEAT EXHAUSTION AND HEAT
STROKE. WEAR LIGHT WEIGHT AND LOOSE FITTING CLOTHING WHEN
POSSIBLE AND DRINK PLENTY OF WATER.
TO REDUCE RISK DURING OUTDOOR WORK...THE OCCUPATIONAL SAFETY AND
HEALTH ADMINISTRATION RECOMMENDS SCHEDULING FREQUENT REST BREAKS
IN SHADED OR AIR CONDITIONED ENVIRONMENTS. ANYONE OVERCOME BY
HEAT SHOULD BE MOVED TO A COOL AND SHADED LOCATION. HEAT STROKE
IS AN EMERGENCY...CALL 9 1 1.
A HEAT ADVISORY MEANS THAT A PERIOD OF HOT WEATHER IS EXPECTED.
HIGH TEMPERATURES AND HIGH HUMIDITY WILL COMBINE TO CREATE A
SITUATION IN WHICH HEAT ILLNESSES ARE POSSIBLE. DRINK PLENTY OFFLUIDS...STAY IN AN AIR-CONDITIONED ROOM...STAY OUT OF THE SUN... AND CHECK UP ON RELATIVES AND NEIGHBORS. CHILDREN AND PETS SHOULD NEVER BE LEFT UNATTENDED IN VEHICLES UNDER ANY CIRCUMSTANCES. THIS IS ESPECIALLY TRUE DURING HOT WEATHER WHEN THE CAR INTERIOR CAN REACH LETHAL TEMPERATURES IN A MATTER OF MINUTES!

100 Degrees Today - We Tie a Record

The Rockford Airport recorded a high temperature of 100 degrees this afternoon just before 3:30pm today. This is the first time we've hit 100 degrees since July 10, 1989. Here's the report from the NWS Chicago:

RECORD EVENT REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
352 PM CDT WED JUL 19 2011

...RECORD HIGH TEMPERATURE FOR JULY 19TH OF JULY TIED AT ROCKFORD IL TODAY...

THE TEMPERATURE REACHED 100 DEGREES AT 229 PM CST (329 PM CDT) TODAY
AT ROCKFORD IL...WHICH TIED THE RECORD HIGH FOR JULY 19TH SET IN
1930.

Storm chances this afternoon/evening

Starting to notice a few cumulus clouds building late this morning and those will probably continue to build as we go into the afternoon.  There is a weak lake breeze that is beginning to develop as a northeast wind comes off of Lake Michigan.  This also combines with another weak boundary from the cool front that moved in yesterday.  Behind this weak front the heat and humidity has created a very unstable airmass with CAPE values (convective available potential energy or how much energy is available in the atmosphere) nearing 5000 J/KG (that's pretty high).  We're currently watching storms that have developed right around the Twin Cities thanks to that stationary front but also a little support from the mid-levels.  The storm in the Twin Cities will likely move southeast towards the high CAPE values, however, the further south it gets the further away it becomes from any upper level support. 

Should thunderstorms get going across the area this afternoon the potential will exist for them to develop rapidly due to the very unstable airmass in place.  Damaging winds and heavy rainfall would be the primary concerns.  Radar and visible satellite trends will be monitored throughout the afternoon to see if the any outflow boundaries from the storms to the northwest along with the lake breeze are able to interact with each other. 

What more can we say about the heat....

...except it's going to last awhile!  First off, Excessive Heat Warning continues through Thursday for Green, Rock, Walworth, Stephenson, Jo Daviess, Carroll and Whiteside counties.  A Heat Advisory will remain in effect for Winnebago, Boone, McHenry, Ogle, Lee and DeKalb counties through this evening.  An Excessive Heat Watch will then go into effect for those following counties Wednesday.  The reason - simply put: it's going to get very hot. 

The center of the upper level ridge has been centered across the middle of the country the past couple days placing the Great Lakes in what's known as 'northwest flow'.  This means the upper level winds are coming in from the northwest, even though our surface winds are coming in from the south.  With this flow storms tend to form across the northern Plains and dive southeast as they follow the flow of the jet stream (which has been happening for the past couple of days). 

By Wednesday the center of the upper level ridge will shift a little further east as an area of low pressure moves across southern Canada.  This will change our northwest flow to more of a southwest flow, causing temperatures to warm even more as our threat for any storms or cloud cover decreases.  Right now I'm going with a high or 97° Wednesday afternoon.  The last time we hit 100° was back on July 10th, 1989!  If we have too much moisture in the atmosphere we probably won't be able to hit the century mark but either way you look at it, it's going to be very uncomfortable Wednesday.