Several Downbursts & Damaging Straight-line Wind Swaths, But No Tornadoes in 2009, Thus Far………

Below is a Review of 2009 Severe Weather Events in the WLFI Viewing Area Beginning with Most Recent & Ending with the First Event of 2009…………………………

……………………………………………………………………………………………………………………………………………………………………………………………………………………

EVENT #6:  June 19, 2009

Two severe supercells developed in the evening:

THE SUPERCELLS:

#1: Fulton County

Looking at the updraft & hail size of this storm………..it had the potential to produce at least an EF2 tornado at its peak………….it did not, however.

HERE IS MY PERSONAL ANALYSIS AS TO WHY:

To even produce 3″ hail, a 100 mph t’storm updraft is required.  The speed of the updraft required to produce 4″ hail & the amount of energy required to produce such a strong, strong updraft is amazing.

The local directional & speed shear along the warm front may have not been potent enough to keep that RFD separate long enough to allow a tornado to form.  Certainly, a downdraft that allows 4″ hail takes at least a 125 mph-updraft & if that wind is funneled into the mesocyclone & then tornado, that would be enough for an EF2 tornado (EF2 = 111-135 mph winds).

EF2 TORNADO DAMAGE:

“Considerable damage.

Roofs torn off well-constructed houses; foundations of frame homes shifted; mobile homes completely destroyed; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground.”

OVERALL SYNOPSIS OF THE STORM:

The directional shear allowed the storm to rotate strongly & separate the updraft & downdraft & thus, suspend the hail longer.  However, once a weak tornado descended, that rear-flank downdraft choked it off & the strong cap eventually caused this supercell to collapse.

This was a classic HP supercell, which popped through the strong cap during this late afternoon & evening with very large hail up to grapefruit size & a large, rotating mesocyclone with a brief tornado touchdown.

It developed on the warm front, where shear was maximized, in a very unstable environment of 3000-4000 joules per kilogram with temperatures near 90 & dew points of 70-75.  This instability enables a strong enough updraft to develop to suspend hail in the cloud & allow it to grow to huge size & able to stand up to the wind shear.

#2: Vermilion to Montgomery County

This was a cyclical HP supercell with several cycles of rotation.  It occurred in locally-sheared environment courtesy of an outflow boundary left over from a morning complex of storms over our northeastern counties.  After producing wind damage near Champaign with large hail with rotation……………it weakened…….then it pulsed up strongly, put down 2 tornadoes & 2 microbursts…………..it weakened………….then it pulsed up, produced a wall cloud & funnel clouds over Fountain County with large hail……….it weakened………then pulsed up, blew down numerous trees, unroofed a home in Montgomery County……then weakened……upon merging into the the squall line, it produced a wind gust of 65 mph at Ladoga.

THE SQUALL LINE:

The remnants of a 70-90 mph derecho passed after producing widespread, significant wind damage across the northern half of Illinois.

I believe the the line weakened due to some instability being used up by those 2 supercells & persistent, then increasing capping or CINH suppressing t’storm upward growth as the evening continued.  This was especially prevalent in the heart of the WLFI viewing area.

Nonetheless, this passing squall line produced 45-55 mph winds from Lafayette southward in the WLFI viewing area.

These winds down several tree limbs……………

BELOW:  Supercell #1 & #2:

Remnants of derecho:

NEAR STATE LINE IN VERMILION COUNTY, ILLINOIS:

2 EFO tornadoes occurred in fields with no structural, nor tree damage.

2 microbursts occurred………….the first damaged 5 structures & numerous tree limbs & powerlines were blown down with estimated wind speeds at 70 mph…………..the second destroyed 2 outbuildings & damaged 3 homes, in addition to downing numerous trees & powerlines.  Estimated wind speed was up to 90 mph.

Straight line winds of up to 85 mph blew 40 railcars were blown off a railroad track.

Widespread 60-70 mph straight-line winds downed trees & powerlines across the county.

FULTON COUNTY:

Funnel cloud over field 2 miles north of Athens.

4″ diameter or grapefruit-sized hail fell 1 miles south of Talma.

1.75″ diameter or golfball-sized hail fell 3 miles north-northwest of Akron

A large rotating wall cloud was also reported near Akron, prior to producing a funnel cloud.

0.88″ diameter or nickel-sized hail fell 2 miles west of Walnut at U.S. 31 & Route 110.

WARREN COUNTY LINE:

Perrysville: After producing 2 EFo tornadoes in Illinois, this supercell produced a funnel cloud near Perrysville, near I-74.

Several large trees were reported down near the Vermilion (Illinois), Vermillion (Indiana) & Warren County lines intersection.  They were reported to all be laying in the same direction.

FOUNTAIN COUNTY:

1 mile south of Veedersburg:  0.88″ or nickel-sized hail fell with a funnel cloud observed.

3 miles southeast of Covington: a funnel cloud was observed.

4 miles north-northwest of Route 234 & U.S. 41 a rotating wall cloud was observed.

Construction signs were blown over at Route 63 & I-74.

Report of several trees down along I-74.

Several tree limbs were blown down on the Warren County line & across southern Fountain County.

MONTGOMERY COUNTY:

Home near Wingate completely lost it roof.

65 mph straight-line winds occurred at Ladoga

Several tree limbs were reported down in southeastern Montgomery County.

70 mph wind gust estimated on the Montgomery County line near U.S. 231

BOONE COUNTY:

50 mph winds were estimated at Lebanon, in Boone County

TIPPECANOE COUNTY:

Wind gust to nearly 50 mph was measured at WLFI

A few limbs were blown down in the city of West Lafayette & Lafayette

Chip Redmond, an Ohio State meteorology student took this picture of this supercell in Fulton County near Athens with an apparent funnel cloud & rotating wall cloud:

This is not a pic of the actual hail that fell in Fulton County.  This gives you an idea of how large it was.  Grapefruit-sized hail was reported from this storm (pic courtesy of NOAA):

(FYI: The largest hailstone ever recorded was nearly the size of a soccer ball or cantaloupe & fell on Aurora, Nebraska on June 22, 2003)

James Bogle took this picture of cloud-to-ground & in-cloud lightning as the squall line of storms moved through northern Montgomery County:

Tim Edwards took this picture of a shelf cloud on the leading edge of 45-55 mph winds as the squall line approached.  This cloud is illuminated by sheet & in-cloud lightning behind the clouds:

Dena Flangan on the southside of Lafayette took this picture of a shelf cloud, which develops on the leading edge of the rain-cooled, often gusty winds on the leading edge of a t’storm.  This shelf cloud occurred on the leading edge of the 45-55 mph winds with the squall line:

Dena also took a picture of these mammatus clouds on the storm anvil’s or top’s underbelly, as the storm approached.

Larry Sanson took this picture of his garden’s corn patch at Monticello.  Gusty t’storm winds blew most of his corn down.

Brian Tolley took these spectacular in-cloud lightning pics just north of I-65 & Route 28 in western Clinton County.

Here is another great picture from Brian!

That greenish color at the top of the pic is a result of debri, pollution & dust being sucked up into the storm by the updraft, or being kicked up by t’storm winds that can curl up, increase in elevation & cause the dust to be ingested by the storm:

Richard Beedle caught these pics of the severe t’storm near Attica.

These interesting nimbostratus clouds illuminated by the setting sun were taken by Annette Plante.

Wind damage near I-74 via supercell:

……………………………………………………………………………………………………………………………………………………………………………………………………………………

EVENT #5: June 2, 2009

Storms blow up on an old outflow boundary from morning storms north of U.S. 24 into a complex with torrential rains & embedded supercells.

CARROLL COUNTY: Numerous trees & powerlines down in the east-central part of the county.

Near Flora-70′ pine trees were reportedly snapped

Near Flora-Large tree reportedly fell on a home

WARREN COUNTY: 3 Miles Southwest of Rainsville-1.25″ diameter hail

2 Miles East of Pence-1″ diameter hail

TIPPECANOE COUNTY: Numerous 0.75″ hail reports on the south side of Lafayette

Shadeland-Several reports of 1.25-1.5″ diameter hail

Battle Ground-Trees down

WLFI-TV West Lafayette-Measured 54 mph wind gust

CLINTON COUNTY: Just North of Frankfort-0.88″ diameter hail

1 Mile south of Frankfort-60 mph wind gust estimated near Antioch

Near Antioch-Incipient tornado (within estimated 300′ of touch down & strongly rotating

Antioch-Tree down at Route 38 & 39 intersection

About 8 Miles West of Frankfort-Semi overturned by estimated 70 mph winds on I-65 near Route 28 exit

BENTON COUNTY: In Boswell-0.88″ diameter hail

Near Boswell-0.75″ diameter hail

Ambia-Trees down with minor structural damage to a few homes & several farm buildings

Near Ambia-Estimated 70-75 mph wind gusts

HOWARD COUNTY: Kokomo Municipal Airport measured a 58 mph wind gust

Across the Entire County-Widespread estimated 55-60 mph winds withy cores of +70 mph gusts

Across the Entire County-Dozens of trees down…..some blocking county roads

BOONE COUNTY: 10 Miles East-Southeast of Lebanon-Powerlines down

MIAMI COUNTY: Amboy-Trees & limbs down blocking roads

Richard Beedle caught this cloud-to-ground lightning strike with the severe t’storms near Attica.

Travis Trent took this amazing pick of the severe t’storm arriving into Antioch in Clinton County.

Elaine Snyder took this picture of incipient tornado near Antioch, in Clinton County……..an incipient tornado is one that is very, very close to touching down, but lacks a clear condensation funnel.  I cannot tell whether dust or debri is being kicked up due to the tree blocking the view…….if there is dust/debri field, then it is a confirmed tornado touchdown…….can anyone tell if there is anything kicked up to determine this??

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….

EVENT #4:  May 30, 2009

Large hail & macro/microbursts were the modes of the severe threat during this evening.  These storms resembled the high-based LP supercells, that are more typical in the western High Plains of the U.S.  There was a lot of dry air at the mid & low levels of the atmosphere, which gave an unobstructed view of the t’storm tops & their base elements & features, which are often obscured by lower clouds.

The micro/macroburst potential was high in these LP-like supercells due to mid & low-level dry air, which allowed rainshafts to partially evaporate on the way down, cool that air, make it heavy & then, like a bowling ball, make it crash to the ground, normally at the onset of the severe storm development, like at Crawfordsville.  LP supercells produce very large hail due to low freezing levels like we had in this event & hail up to 1.5″ diameter was reported.  Dew points or the relative humidity was low (dew points 50s) with this event, not your typically hot, humid regime that pops severe storms in our area.

Despite rotation in a few storms, no official tornadoes touched down.  The structural damage incurred in Tipton County, appears to be that of a macroburst.

TIPTON COUNTY: Several farm buildings damaged/destroyed with people trapped briefly.  First, it was classified as a tornado in the National Weather Service reports, but there was no official survey, nor confirmation of any tornado from the National Weather Service.  Further inspection revealed that a microburst was the likely cause, given the damage pattern.

The microburst was roughly 1.5 X 1.5 mile in diameter & occurred northeast of East Union in Cicero Township along County Road 450 to the intersection of County Road 500W & 500 S.  This location is about 5 miles northwest of Atlanta & 5 miles southwest of Tipton.

CARROLL COUNTY: Flora & southeast of Flora-Numerous reports of 1″ diameter hail.

Near Burlington-1″ diameter hail

BENTON COUNTY: Near Ambia-Trees down

Near Boswell-Trees down

Near Boswell-0.75″ diameter hail

HOWARD COUNTY: 3 Miles Northwest of Russiaville-1″ diameter hail.

Russiaville-0.75″ hail

FOUNTAIN COUNTY: Covington-1.25″ diameter hail

CLINTON COUNTY: West of Antioch-Strongly rotating mesocylone with lowering base, but no incipient tornado or funnel cloud.

MONTGOMERY COUNTY: Crawfordsville-Numerous 1-1.25″ diameter hail reports in city.  Trees were reportedly heavily de-foliated by the hailstorm.  It appears a microburst may have hit Crawfordsville, given the fact that there was a lack of sustained, straight-line, long-lasting, organized winds; only bursts of high winds being released & fanning out.  It did not make it down to Crawfordsville to check any of the damage out, however.

Crawfordsville-Numerous tree limbs, powerlines & trees were reported down

Crawfordsville-72 mph wind gust measured

1 mile northwest of Crawfordsville-70 mph winds estimated.

Jim Dieter caught this panorama shot of the sky as severe storms approached Carroll County.

Randy Rogers of Frankfort took these pics of the mesocyclone with the supercell in western & southern Clinton County.  Third pic has a faint rainbow visible on the left.  See how these storms resemble the Great Plains LP supercells?

If you look at the far right side of this pic from Bryan Kinslow, you can catch what appears to me a microburst/macroburst……notice how the falling rain curls upward after hitting the ground.  This is likely damaging wind in Clinton County…….GREAT shot of a dangerous weather phenomena from Bryan!  A quaint rainbow accompanied this image, showing the untamed strength & violence, yet breath-taking, calming beauty of nature.

Donna Wetzel caught this pic of the hailstorm in Rensselaer.

Phil Benson of Flora took this pic after the severe t’storm wreaked havoc with high winds & hail in central Carroll County.

Dena Flanagan took this great pic of a rainbow, rainshafts & a developing mesocyclone (wall cloud) in southern Tippecanoe County.  This storm had rotation markers with it & a tornado warning issued by the National Weather Service for it.

Dena also took this picture of rain shafts in a severe t’storm on the southside of Lafayette, which produced 0.75″ diameter hail.

…………………………………………………………………………………………………………………………………………………………………………………………………………………………..

EVENT #3:  May 15-16, 2009

LEWP or Line Echo Wave Pattern squall line passed….

Notice how there were no cells out in front of this well-formed, sharp line, indicating it had an uninterrupted supply of warm, juicy, robust inflow, unlike the previous event few days prior.  Thus, this line produced more in the way of severe weather with widespread swaths of 50-60 mph winds & cores of winds were there was significant winds damage up to 85 mph.

CARROLL COUNTY: 5 Miles West of Burlington-Numerous barns down in Cutler & toward Burlington-horses were trapped in one of the barns.

3 Miles Southwest of Burlington Near the Clinton County Line-Macroburst began  at Middle Fork Wildcat Creek near County Road 400E and 700 S removing southwest-facing roof of house.  13 other houses & outbuildings damaged further northeast to near 500E. Significant tree & powerline damage also occurred along this path.

Reportedly, a man was in a shed when the roof flew off in the storms.  I had no confirmation the man was injured, however.

TIPPECANOE COUNTY: Stockwell to Clarks Hill-A barn was destroyed & 4 other buildings damaged near County Road 700E & Route 28 near U.S. 52.  Significant tree & powerline damage occurred.  Apparent microburst with damage width of less than 2.5 miles.

These wind bursts literally occur out of NO WHERE & hit the ground like a bowling ball & are finished, making them EXTREMELY HAZARDOUS.  Often times, these severe storms will produce many belches of these wind bursts along their path, leading to very, very sporadic, but SIGNIFICANT wind damage. Contrastingly, straight-line winds are wide & often much-more consistent (damage-wise) across a large area.

What is a microburst????……..http://www.nwas.org/committees/avnwxcourse/teachl1.htm

Macroburst has a damage width of 2.5 miles or greater……….Microburst has a damage width of 2.5 miles or less……….

Microburst/macrobursts have a diverging or spreading-out damaging pattern from a central point.  Tornado shows damage in a converging pattern with debri largely pointing TOWARD a center along its path.  Straight-line wind damage has a pattern of everything facing one direction with no specific epicenter.

THESE IMAGES VIA NATIONAL WEATHER SERVICE LA CROSSE, WISCONSIN………THESE ARE MICRO/MACROBURSTS PICS (NOTICE DIVERGENT DAMAGE PATTERN [These pics are from Wisconsin, not here from recent event]):

.

Numerous reports of 1″ diameter hail in Lafayette & on the southside of Lafayette

WARREN COUNTY:  9 Miles West-Northwest of Williamsport-Trees down with debri over County Road 900W.

BENTON COUNTY: Tree down in Oxford

CLINTON COUNTY: 1 mile north of Michigantown trees down along Route 29

FOUNTAIN COUNTY: Tree down near Attica at County Road 170S

BOONE COUNTY: 5 Miles East-Northeast of Thorntown-Trees down along U.S. 52 just north of Route 47

Carroll County EMA pics of damage in the southern portion of the county via one or more macrobursts.  This first pic is a 100-year old barn blown totally off its foundation.  After storm after storm since 1909, this macroburst was powerful to move the entire structure.

…………………………………………………………………………………………………………………………………………………………………………………………………..

EVENT #2:  May 14, 2009

LEWP or Line Echo Wave Pattern squall line passed….a LEWP is a squall line with numerous “S”-shaped segments in it.  Each little mini-bough in the “S” is usually a core of damaging straight-line wind, whereas underneath the curled “S” shape is a higher tornado threat.

This LEWP was rather disorganized, however.  It had bowing segments, but many multi-cell t’storms formed out ahead of it, disrupting the line’s main source of food…..warm, moist inflow from the south & southeast.  The strongest, most organized line segment passed through Boone County.  Occasionally these cells in front of the line may spin up a brief, “weak” tornado when they gell with the squall line.  It appears this likely occurred in Whitley County, where the damage to several farms resembled that of EF1 damage, but no tornado was officially confirmed by the National Weather Service.

PULASKI COUNTY: Medaryville-Tree limbs down

BOONE COUNTY: Jamestown-4 trees down across town ranging in size from 6-12″ in diameter.

7 Miles North of Jamestown-Tree down near Route 75 & County Road 400S

2 Miles Northeast of Lebanon-Estimated wind gusts to 70 mph

5 Miles North of Jamestown-Measured 70 mph wind gusts

Scattered trees & limbs were blown down in Boone County.

……………………………………………………………………………………………………………………………………………………………………………………………………….

EVENT #1:  March 8, 2009

Slightly boughing segment of squall line passed through with widespread, damaging straight-line winds of 50-60 mph with few bursts of 75 mph winds.

Reports:

WHITE COUNTY: Reynolds-Fabric Cover of Building Blown Off.  Shingles Blown Off House

BENTON COUNTY: 2 Miles Southeast of Earl Park-Semi Truck Blown Over at U.S. 41 & U.S. 52

TIPPECANOE COUNTY: Lafayette-60 mph Wind Gust with Several Trees Down

West Lafayette-60 mph Wind Gust with Home Fence in Subdivision Blown Away Near U.S. 52

CLINTON COUNTY: Rossville-Powerlines Down

CARROLL COUNTY: Flora-Roof Off of Building, Trees & Powerlines Down

CASS COUNTY: 2 Miles East of Logansport-Back Half of Roof Ripped Off of a Business with No Injuries Reported

MIAMI COUNTY: 4 Miles South of Peru-Two Mobile Homes & a Block Building Suffered Heavy Damage with No Injuries Reported

Just West of Denver-Tree Down on Route 16

HOWARD COUNTY: 3 Miles South of Kokomo-Tree Down

Numerous trees were blown down with this event across Tippecanoe County.

…………………………………………………………………………………………………………………………………………………………………………………………………..

SATURDAY:

Cold front is speeding up for Saturday.

Most of the day is looking dry, but be prepared for scattered t’storms (50% coverage) by evening.

An isolated severe storm or two (wind/hail) cannot be ruled out given the dynamics aloft & reasonable instability.  However, at the present time, it appears the widespread severe threat will stay to our south & west…………….

STAY TUNED FOR ANY CHANGES………..

Rainfall potential looks to be confined Saturday evening-overnight with a lingering shower or two early Sunday morning.

SUNDAY:

Looks good with partly cloudy & 80-85.

Projected radar Saturday at 7 p.m.:

Projected Radar at 10 p.m.:

Orange = Above Normal Temperatures

Blue = Below Normal Temperatures

Green = Above Normal Precipitation

Tan = Below Normal Precipitation

EC = “Equal Chances” (No Specific Trend Observed, So Equal Chances of Above, Normal or Below Normal Temperatures or Precipitation)

If no “EC” is labeled in a specific area, then rainfall or temperatures will be near normal.

Fall 2009 Temperatures:

Fall 2009 Rainfall:

Winter 2009-2010 Temperatures:

Winter 2009-2010 Rainfall:

Spring 2010 Temperatures:

Spring 2010 Rainfall:

Summer 2010 Temperatures:

Summer 2010 Rainfall:

Orange = Above Normal Temperatures

Blue = Below Normal Temperatures

Green = Above Normal Precipitation

Tan = Below Normal Precipitation

EC = “Equal Chances” (No Specific Trend Observed, So Equal Chances of Above, Normal or Below Normal Temperatures or Precipitation)

If no “EC” is labeled in a specific area, then rainfall or temperatures will be near normal.

After the cool July, here is how August 2009 is looking:

(Data from NOAA’s Climate Prediction Center):

August 5-10 Temperatures:

(Average High/Low:  84/62)

August 5-10 Rainfall:

(Average Rainfall for This Period: 0.60″)

August 10-15 Temperatures:

(Average High/Low:  84/62)

August 10-15 Rainfall:

(Average Rainfall for This Period: 0.60″)

Overall August Temperatures:

(Overall Average: 84/62)

Overall August Rainfall:

(Overall Average August Rainfall: 3.68″)

WE ARE EXPERIENCING THE COOLEST JULY SINCE 1947 (FORMERLY SINCE 1869, 1924, 1909, BUT RECENT +80 TEMPS HAVE MITIGATED THE MAGNITUDE OF THE COOLNESS HERE AT LAFAYETTE).

ALL-TIME COOLEST JULY OVER MOST OF ILLINOIS, KENTUCKY, OHIO, INDIANA & MISSOURI!

WHERE’S THE HEAT????

OCEANS ARE THE HOTTEST ON RECORD WORLDWIDE……………..

EARTH-WIDE TEMPERATURES ARE SOME OF THE HOTTEST ON RECORD……………

ALL-TIME RECORDS ARE FALLING ACROSS THE NORTHWESTERN U.S & WESTERN CANADA…………..SEATTLE (BOEING FIELD) HIT 105 YESTERDAY WITH THE ALL-TIME AT 100!  TACOMA AIRPORT HIT 103.

ALASKA IS EXPERIENCING ONE OF THE WARMEST & DRIEST SUMMERS ON RECORD WITH 4 DAYS ABOVE 70 DEGREES IN JULY ON THE ARCTIC CIRCLE………..IT IS SO WARM THAT ALL OF THE TUNDRA IS THAWING!

FAIRBANKS, ALASKA HAS ONLY HAD 0.04″ RAIN ALL MONTH & SEATTLE HAS ONLY RECORDED 0.06″.

SIBERIA & CENTRAL ASIA HAVE ALSO BEEN ABNORMALLY WARM THIS SUMMER WITH RECORD HEAT & DROUGHT………………..

DESTRUCTIVE FLOODS IN EUROPE HAVE MITIGATED THE HOT, HOT SUMMER OCCURRING THERE………….BUT THEY ARE EXPERIENCING EXCEPTIONAL RAINS & T’STORMS………….

The heaviest, most widespread, soaking rains appear to be shifting north & south of the area today.

In fact, up to 3″………….even 4″ may fall with heavy rains/storms in the Tennessee & Lower Ohio Valley today.

As for us, few scattered t’showers with 35% peak in coverage this afternoon with a mix of clouds & sun, southerly breezes & highs around 80 degrees.

Projected rainfall for today via GFS model:

Movie of the Morning rains pulling away:

http://www.mmm.ucar.edu/imagearchive/

Rains have now moved southeastward into the Marion to Indianapolis to Vincennes areas……………..

Evening plans look fine with the sunshine & pleasant temperatures:

More showers & t’storms tomorrow (mainly after noon):

Projected radar for tomorrow:

Scattered showers continue with a few t’storms for the overnight:

At least scattered showers tomorrow & a t’storm or two with 50% rainfall coverage for the day.

The showers should really pull away by evening:

More widespread, potentially soaking rainfall is possible by Thursday:

Friday & Saturday look partly cloudy, dry & 80-87, while Sunday & Monday look wet.

From now through next Monday several rounds of showers & t’storms will bring the most widespread, soaking rains to the area since early-mid June.

Check out that band of white blobs from the central Pacific to the western U.S. leading up right into the WLFI area.  Also, notice the white blobs from the Gulf to our area.

All of this tropical moisture, specifically largely Pacific monsoonal moisture, is moving through the region & a cold front is wringing out the heavy t’storms:

Tropical rains of +2″ have prompted Flash Flood Warning for Benton County until 1 a.m. & a Flood Advisory for northern Warren County until 11:15 p.m.

Numerous scattered showers & t’storms will be the weather story for this evening-tonight.

If you have any plans (softball games, any other outdoor activities), you will be dodging these all evening, even if it does not rain at your house.

An isolated severe storm or two is not out of the question.

Heavy rainfall is possible as some of the cells train & dump +1″ rain.

There is a lot of rain to wring out of this tropical airmass with very high PWATs.  Up to 2″ rain/hour rates are possible in the heaviest cells this evening.

Storms have evolved into a bowing line over northern Illinois.

Surface instability continues to wane across this region & at least marginal capping (inhibition or CINH) continues.

Notice how there is little, if any surface instability (red lines)  in our area:

The storms appear to be continuing amidst increasing elevated instability above the marginal cap.

Notice the 1000-2000 J elevated CAPEs (instability) increasing in our area, promoting maintenance of that line of storms & even recent, new development from Bloomington, Illinois to Kankakee in the form of a few elevated showers.

This nice, potent instability above the cap is originating from the Plains & the bouyant, rapidly-rising parcels are being advected in & gliding over the top of the marginal lid.

There, clouds are bubbling up into elevated t’storms.

Notice the new shower development south of the line:

The cluster also appears to be aided by dynamics aloft……….in this case divergence at 300 mb (30,000′ up).  This split in a core of stronger upper-level winds literally sucks the air upward to fill the void left by the wind speed & jet split.

Check out the dramatic image of the storm cluster as the 300 mb divergence produces the classic “V”-notch shape of the cluster’s cold cloud tops:

That said, “Scattered T’Storms with 40% Coverage” for tonight’s & tomorrow morning’s forecast will do.

The eastern edge of that cluster of stronger storms may affect our western/southwestern counties overnight as a weakening line of t’storms.

Additional t’storms developing over Iowa & western Illinois will be around for the morning………….if we see the sun really break out, new development with a few severe storms is possible in the afternoon as the cold front approaches & decent dynamics overspread the front.