Rain Chances = More Severe Weather?

Some pretty good rain chances move in for Wednesday night and Thursday, which is good news for ongoing drought conditions. While we're not expecting anything that will break the drought, every little bit helps, and the latest models are showing a half inch of rain possible in our next storm system.

But it's been the case this summer that most rain chances come with the threat of severe weather. The Storm Prediction Center currently has us just north of a slight risk for severe weather on Thursday. Obviously, the situation can change between now and then, so we'll keep an eye on it, but don't be surprised if we see a few storms with gusty winds heading into Thursday.

Despite drought conditions gusty thunderstorms continue

When we think of drought we usually think of the dry and hot weather and lack of rainfall.  This has been the case for most of the summer but despite the current drought conditions, thunderstorms have moved through the area with some force behind them.  The Chicago National Weather Service examined the thunderstorms we've experienced so far this year paying particular attention to the wind gusts.  Here's what they found:

WHILE THE SEVERE WEATHER SEASON WAS QUIET AT ITS NORMAL PEAK TIME OF SPRING AND EARLY SUMMER ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA...IT HAS BECOME MORE ACTIVE SINCE THE TAIL END OF JUNE. NEARLY 80 PERCENT OF THE PRELIMINARY SEVERE WEATHER REPORTS ACROSS THE NWS CHICAGO COUNTY WARNING AREA THIS METEOROLOGICAL SUMMER /JUNE-AUGUST/ HAVE BEEN CONVECTIVE WIND DAMAGE AND/OR OBSERVED GUSTS. THERE HAVE BEEN APPROXIMATELY 225 PRELIMINARY REPORTS OF EITHER WIND DAMAGE OR SEVERE CRITERIA WIND GUSTS /58 MPH OR STRONGER/ RELAYED TO NWS CHICAGO SINCE JUNE 1ST.

SOME OF THE SEVERE WINDS HAVE BEEN EXTREMELY LOCALIZED IN THE FORM OF MICROBURSTS...WHILE OTHERS HAVE BEEN WIDESPREAD WIND EVENTS SUCH AS WHAT TRANSPIRED THIS PAST SATURDAY AUGUST 4TH. THUS IT IS CHALLENGING TO TRY AND QUANTIFY THE NUMBER OF THESE GUSTY THUNDERSTORMS VERSUS A NORMAL AND HAVE IT BE REPRESENTATIVE EVERYWHERE. LOOKING AT PEAK CONVECTIVE GUSTS AT TWO INDIVIDUAL AREA AIRPORTS CAN SHED SOME LIGHT HOWEVER.
            Rockford:  Summer 2012        1996-2011 Summer Average

Days with gusts >= 40 mph  6                   3
Days with gusts >=58 mph   1                 <1>

*Through August 6th

REGULARLY CAPABLE OF LONG-LASTING WIND EVENTS.
ROCKFORD HAD FOUR DAYS WITH 40 MPH CONVECTIVELY INDUCED GUSTS IN JULY ALONE...TYING IT WITH JUNE 1998...JULY 2003...AND JUNE 2008 FOR THE MOST IN ANY ONE SUMMER MONTH.

THE MORE FREQUENT GUSTY STORMS CAN BE...AT LEAST IN PART...ATTRIBUTED TO THE PERSISTENT HOT AND DRY CONDITIONS.  THE ONGOING VAST DROUGHT HAS LIKELY HELPED KEEP THE BOUNDARY LAYER DRIER THAN NORMAL THROUGH SIGNIFICANTLY LESS EVAPOTRANSPIRATION FROM WHAT WOULD TYPICALLY BE MOISTURE-LADEN CROPS...WHICH IS WHY THE DEW POINTS HAVE NOT BEEN FREQUENTLY IN THE 70S. DRIER NEAR-SURFACE AIR ALLOWS FOR DEEPER MIXING OF THE LOWER ATMOSPHERE AND OVERALL HIGHER CLOUD BASES. THUNDERSTORMS THAT ARE ABLE TO DEVELOP OR MOVE INTO SUCH AN ENVIRONMENT CAN HAVE A HIGHER LIKELIHOOD OF PRODUCING STRONG WINDS AS THEIR DOWNDRAFTS READILY ACCELERATE TO THE GROUND. IN ADDITION...THE PERSISTENT UPPER LEVEL RIDGE AND ASSOCIATED STAGNANT HEAT ACROSS THE MIDSECTION OF THE COUNTRY HAS ALLOWED FOR SCENARIOS IN WHICH THE UPPER PARTS OF THE ATMOSPHERE ACROSS THE REGION REMAIN WELL-MIXED...THROUGH WHAT METEOROLOGISTS CALL AN ELEVATED MIXED LAYER.  STORM GROWTH AND ASSOCIATED WIND STRENGTH CAN DEPEND HEAVILY ON THIS. THE HEAT DOME HAS ALSO ALLOWED FOR THE OCCASIONAL RING-OF-FIRE WEATHER PATTERN ON ITS PERIPHERY...WITH ORGANIZED STORM COMPLEXES

Cooler weather and a chance of storms

Our streak in Rockford of consecutive days with highs of at least 80 degrees may come to an end by Friday.  As of Monday, Rockford has seen 54 consecutive days with highs of at least 80 degrees.  This ranks as the 4th longest streak in Rockford's history.  The longest streak is 86 consecutive days back in 1895.  The last time Rockford's high temperature was less than 80 degrees was all the way back on June 13th.

If we can stay at or above 80 degrees through Thursday, that will put us 1 day short of the 2nd longest streak, which is 58 days back in 1936.  It's possible we will top out at 57 consecutive days (which would rank 3rd), as temperatures will likely cool into the 70s by Friday as strong high pressure in the southwestern part of the US and a trough of low pressure in the Great Lakes region will help to pull in cool Canadian air from the north.

We will see a slight chance of storms on Tuesday and Wednesday as a weak cold front to our northwest moves through the region.  A better chance of storms will come late Wednesday through Thursday as another disturbance and stronger front moves through.  The day 3 convective outlook from the Storm Prediction Center for Thursday shows the area of possible severe weather just to our south with that disturbance that will move through Wednesday into Thursday.  This will be something to keep an eye on as we head into the middle part of the week.

Ryan Kinnison - WTVO Intern

Comfortable weather ahead! Yippee!

A pattern change is in the works for the end of the week that will bring temperatures slightly below average.  A strong ridge of high pressure will continue to build in the southwest bringing triple digit heat through while a trough of low pressure strengthens across the Great Lakes and northeast.  This will keep modified Canadian air flowing into the region with temperatures dropping into the low 80s and possibly even the upper 70s by Friday, Saturday and Sunday.  If you ask me - it's a much needed change from the heat we felt in July!

A Fairly Comfortable Week on the Way

We reached the midpoint of summer on Sunday... August the 5th.  So, on Monday we will start the last half of summer.  There appears to be a change in the air.  It may be a little early to say, but the blistering heat we have had to endure for the past couple of months seems to be a thing of the past.  Here is the encouraging news...  As of this writing, only one 90 degree day is expected during the next week.  The National Weather Service longer range outlook indicates temperatures expected to be close to normal in the 6 to 10 day period, and the 8 to 14 day period.  That's fabulous news if it verifies because our area has been running above normal to much above normal for such a long time.  Time will tell. 

It will be cool overnight with clear skies and calm winds.  The low will be in the middle 50's.  High pressure will, shift slowly to the east on Monday.  After a cool start, it will warm into the mid 80's in the afternoon under sunny skies with low humidity.   It will be mostly clear again on Monday night, but it will not be as cool with a low around 63 degrees.  A cool front will slowly descend southward across Wisconsin on Tuesday.  Temperatures in advance of the front will heat up to around 90 degrees on Tuesday afternoon.  There could be some isolated showers and thunderstorms as the front approaches northern Illinois.  Fronts will be in the vicinity on Wednesday, and temperatures will drop a few degrees for afternoon highs into the middle 80's.  There could be some scattered showers and thunderstorms from time to time from Wednesday night through Thursday into Thursday night.  It does not appear as if there will be a lot of support for any needed significant rainfall, but at least, there is a chance of some rain.  Canadian high pressure will take control for the end of the week through next weekend, and provide some very pleasant weather for the Stateline.  Highs on Friday, Saturday, and Sunday will be in the upper 70's under mostly sunny skies.  Low temperatures at night will be in the upper 50's to the low 60's.

A Fabulous Sunday Coming Up!

A cool front pushed across the area early Saturday night. Mostly Cloudy skies will become partly cloudy. Storms have moved well off to the east, and will continue moving away from the area. Winds will switch from the west  to the northwest, but it will remain relatively warm overnight with a low in the upper 60's. High pressure over the plains will feed cooler and drier air into the Stateline on Sunday. It will be sunny with a refreshing northwesterly breeze 10-20 mph with gusts to 25 mph during the late morning through the mid day hours. The high will be in the low 80's.  High pressure over the northern plains will settle across Illinois on Sunday night.  It will be clear and cool with a low in the middle to upper 50's.  It will be sunny and seasonably warm on Monday with a high in the middle 80's.  Temperatures will warm into the upper 80's on Tuesday with high pressure shifting off to the east.  There could be some isolated showers and thunderstorms across southern Wisconsin on Tuesday as a cool front drops southward across the Badger State.  The front will stall out for a time to our north on Wednesday.  Skies will be partly cloudy, and it will be warm with a high around 87 degrees.  On Thursday the system will push into the Stateline.  There does not appear to be very much support for the system, so only widely scattered showers and thunderstorms are possible as a fresh push of cooler air moves in from Canada across the northern plains into the upper mid west.  Any showers that do get going will come to an end on Thursday night.  Friday will be mostly sunny and cooler with a high in the low 80's.  It will be sunny and pleasant on Saturday with a high in the upper 70's.

A Severe Thunderstorm Warming

A Severe Thunderstorm Warning has been issued for Jo  Daviess, Carroll, Whiteside, and Stephenson counties until 3 pm.  A line of severe thuderstorms is moving east out of Iowa crossing the MIssissippi River at 2:15 pm.  This line of severe thunderstorms has a history of producing wind damage across eastern Iowa with winds of 60 to 70 mph.  A new SEVERE THUNDERSTORM WARNING has just been issued for Southwestern Boone, western DeKalb, Lee, Ogle, and Winnebago counties until 3:30 pm.  Wind damage is expected with the passage of these storms.