It's nearly August and not heat in sight

We are going to make it through the entire month of July without a single 90° day. Looking into the first week of August we should see seasonably warm conditions but probably nothing close to 90°. The cause is a persistant northwest flow aloft keeping it unseasonably cool. While this northwest flow keeps temperatures cool and humidity levels low, once in a while you can still get a nasty severe weather outbreak. When winds at the surface turn to the southwest and temperatures climb into the 80s the atmosphere becomes unstable and sheer develops. This change in wind direction with height can ocassionally lead to tornadoes like we saw in Boone county on Thursday.

This July will go down as the coolest since the official reporting site was moved away from the lakefront in 1942. The average temperature this July is only 69.4° which is nearly 4 degrees below normal. Our average high is now down to 83° and in less than 4 weeks our average high is back into the 70s

Deluge or drought

Gorgeous day in progress, and my only complaint is that I have still had less than 1" of rainfall at the Caplan ranch since June 20th. At the Chicago Botanic Garden, there has been less than 1" of rain this month.  Same goes for Aurora.  And across the Cheddar Curtain in Kenosha.  Others have gotten plenty. Lansing had better than 1.5" in just a few hours Tuesday afternoon. Farther south, in Paxton (Ford Co.) more than 3" flooded streets during the evening. 

 

A few t'showers may pop late tomorrow (except near me) but most of the day will be dry. Warmer temps may send the mercury into the mid 80s starting this weekend and that could last into the first few days of August.a

Gorgeous day in progress, and my only complaint is that I have still had less than 1" of rainfall at the Caplan ranch since June 20th. A few t'showers may pop late tomorrow (except near me) but most of the day will be dry. Warmer temps may send the mercury into the mid 80s starting this weekend and that could last into the first few days of August.

 

Mike

"Wake Low" brings gusty wind damage last night

I'll do a de-brief on this in more detail at 4pm, but last night's rippin' winds were caused by what's known as a wake low.  Put simply, behind a line of showers, occasioanly a stronger-than-normal sinking motion heats the air, and creates an area of lower pressure.  Ahead of that same line, a small high pressure is common. This causes a flow from the high to the low (south last night) which can be quite strong depending on the strength of the low.  Milwaukee Airport Terminal radar showed winds  of 70 knots 800 feet above the ground in most of Kenosha and Lake Counties last night around 11pm.  That area of intense wind migrated southward into Kane, Cook and DuPage Counties before weakening overnight.  Gusts reached 55 mph at Waukegan, 50+ at Streamwood, Addison, Portage, Elgin and Hampshire.  At O'Hare, a 46-mph gust was recorded.  Many folks lost tree limbs or had to collect their lawn furniture after last night's blow. 

A few storms will fire again this afternoon, especially south of the city.  Less humid air will filter in fromt he north for tomorrow.

Mike

Not much 'til nighttime

There's a tornado watch in effect for much of eastern Iowa this afernoon, mainly to deal with one supercell currently producing a radar-indicated tornado in Clayton County in the Hawkeye state.  That storm will dive south, and the weakening shower shield advancing toward Illinois this afternoon is likely to fizzle, providing little more than clouds for the area.  It remains to be seen whether our atmosphere will be able to destabilize enough to crank up new possibly severe storms after dark.  Our MicroCast computer model suggests it will, so stay tuned for possible watches and warnings tonight.

Mike

Encore

Workers are busy tuckpointing our building here at 190 N State, and the drumming sounds of steel vs. masonry are echoing through the weather office.  Despite the imminent headache, I am managing to monitor the LOT WSR-88D and it shows a few t'showers developing, ala Wednesday.  Get under one, and it'll pour for a while.  But as usual here lately, it's not going to be a widespread soaker.  Even tomorrow's event, which looked very promising for an area-wide 1/2"+, looks like another feast or famine rainfall.  There may be a few severe cells by the time the storms roll through mainly tomorrow night, but I'm not sold on that just yet. Some of the parameters we typically look for in a severe weather outbreak are forecast to be marginal or absent.  Mid 80s will be  possible tomorrow, with slightly cooler temps on tap for the weekend.

Mike

Great eclipse photo from China

Go check out www.spaceweather.com  It's a terrific sight for anyone interested in the skies both at night and during the day.  They have a gallery of today's total solar eclipse that's really worth a look!

Mike

Zip for most, buckets for some

An area of thundestorms has flared up along the lake breeze boundary this afternoon in Lake, Kane, McHenry and NW Cook Counties. The storms are moving very slowly to the WSW and are dumping locally heavy rain.  Watch out for standing water in these areas and frequent lightning.  The majority of the ABC-7 viewing area is currently rain free, but additional showers may develop through the afternoon hours.

Mike

Dry air pulls the reins on the rains

Showers galore to the west of I-39... not so much here. As expected, we have made it into the 80s in Chicago today, with clouds filtering the sunshine in most locations. I wish I could be more enthusiastic about the showers bringing prolific rainfall to the dry soils in need of it, but I am touting the drought drum again. Not perfectly dry, but not a beneficial soaking either.  The air is dry here, and as the showers migrate east, they should weaken considerably. Many areas have seen between 25% and 50% of normal rainfall since June 20th, and I fear that is a trend that will last well into August.  I repeat... this does not mean it won't rain at all the next few days... just that it looks like the showers will be light.

Mike

ATTENTION JUNIOR METEOROLOGISTS!!!

http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=lot&storyid=29663&source=0

Good morning, all!  I know many of you have children, are children or perhaps know a child who is interested in the weather!  I wanted you to know about a workshop that our local National Weather Service office is conducting.  The above link will explain the details!  This is a wonderful group of people who will engage kids on this subject which affects us all...no matter how old we are! 

I am back from the Delaware coast.  It is a location that my family has been traveling to for the past 25 years.  I returned to the same sort of weather which was in Chicago before I left!  Cooler than average.  And I don't see any promise for above average temperatures this week.  Many of you are excited about that.  You have saved on those air conditioning bills!  Here's to the positive side of our atypical summer pattern.

Tracy

The Cold Hard Facts on July

The National Weather Service is fresh out with some stats which support what we already know... this July (and this whole summer) has been unusually cool. In fact, the average temp through July 18th at O'Hare is only 68.5, placing it third coolest in Chicago since official records were moved away from cooler lakefront locations in 1942.  Our hottest day this month, July 6th, only hit 86.  No July since 1942 has failed to rpoduce at least one day with a high of 89 or more.  Between June1 and July 20, the average number of 80-degree days is 40.  We've seen but 26 in '09, ranking as the second fewest, tied with 1947 and behind the record pace of just 24 in 1967 through today.  Temperatures are expected to be a little milder this week, but will probably remain a few degrees below normal into the weekend.  Looking way ahead into the first week of August, I see no signs of a heatwave, although temps appear close to seasonal normals. 

Mike