Saturday, June 24, 2017

Lingering Low Brings Storms; Cooler end to the Weekend

That occluded low to the northeast has lingered, and since the jet stream is nearby it allowed for a trough to develop to the northwest of us.  Thunderstorms and showers have developed along the trough, and is tracking in our direction.  The storms aren't severe, but they may produce some gusty winds.  Luckily the storms have been dying down, but the rain has remained.  Even though the storms are dying down, we may still hear a few rumbles of thunder along the stateline while the storms continue to die down.  The line will mainly move through our northern counties: Green, Rock, and Walworth.  However, we can't rule the line dipping down into the counties just south of the Stateline quite yet.  The trough will move out a little after 10pm, where we'll stay mostly clear afterwards.

Once that high pressure system to the northwest tracks closer, which will happen tomorrow night, it'll push that low to the east and keep pop-up showers and storms away from our area.  We'll see cloudy skies on Sunday and Monday, but more sunshine is expected on Tuesday when that high moves directly over our area.  Another low moves in on Wednesday, which will bring back warmer temperatures and thunderstorms.  We'll warm back up into the 80°s by the end of the week, but thunderstorms will stay with us from Wednesday to Friday.  However, the storms are expected to clear out for next Saturday.

Friday, June 23, 2017

Cooling Off

We had a bit of a rough start this morning with the thunderstorms moving through, but since then the weather has stayed fairly nice! That low pressure system that brought us the thunderstorms has been pulling northerly air into our area.  It hasn't done much to our temperatures yet, but it has lowered our humidity quite a bit and has also been clearing the skies.  The skies will continue clearing during the evening, where temperatures will be in the 70°s.  That northerly air will start to impact our temperatures after sunset, cooling us down into the mid 50°s during the overnight tonight. 

A high pressure system will move in from the west tomorrow morning, and will continue that inflow of northerly air into our area.  This will shift the jet stream south of our area, which means we'll see cooler and drier weather, while everyone that's south of the jet stream continues to see the heat and humidity that we've dealt with the past couple of weeks.  Even though our temperatures will be cooler, and it may not necessarily be summertime pool weather, our humidity values will stay low and we'll get to enjoy plenty of sunshine. 

The cool inflow will end on Wednesday when that high pressure system tracks east and another low moves in.  This will bring back the warmth and humidity, but it'll also increase our storm chances.  A cold front will move through late Wednesday night, keeping thunderstorms with us during the overnight.  We'll see some lingering rain on Thursday before the storms return on Friday, where another cold front will move through.  Temperatures are expected to warm back up into the low 80°s by the end of next week.

Weekend Weather

You might have woken up to the thunderstorms overnight, but as we look into the weekend it will feature fairly dry and comfortable conditions. Today will still be warm with highs near 80°, despite the cold front south of the area. The cooler air will lag, which it typically does with summer time fronts, but arrives tomorrow bringing high temperatures into the low 70's and upper 60's through the weekend.

Drier air will advect in behind the front, so humidity will drop quite a bit through the weekend and into next week. Overall you can expect a dry weekend, but there are a few spotty rain chances through Sunday. An upper level trough will dig in over the Midwest and Great Lakes, and will tug with it cooler air. But, there will also be a few disturbances that ride along the trough that could squeeze out what little moisture we'll have overhead. Both this evening and Saturday evening feature isolated shower chances. A strong wave passes through Sunday and this will bring slightly higher chances for showers, and maybe even a rumble of thunder Sunday evening. Right now, that chance is still relatively low, but we'll keep you posted if that changes in forecast updates!

Friday Morning Storms

5am Update: Heaviest rain pushing into #Chicago suburbs - drying out west of Rockford. Moderate rain over Winnebago, Ogle, Lee, Boone, DeKalb, & McHenry

 Line of strong storms from near Capron to Oregon - moving SE at 25 mph. Heavy rain and wind gusts up to 50 mph.

Heavy rain and lightning over Roscoe. 

Heavy rain and strong gusty winds moving into west Rockford. Visibility will drop quickly, storms moving SE at 35mph with wind gusts up to  40mph.

Thursday, June 22, 2017

Thursday Evening Storm Threat

11:25pm Update: Heavy rainfall is becoming more likely over northeast Iowa and southwest Wisconsin.  There have been a few stronger thunderstorms over northeast Iowa, but those have since fallen below severe limits.  Thunderstorms are expected to move in closer between midnight and 2am. 

10:00pm Update: Showers and thunderstorms are beginning to increase in coverage late Thursday evening.  The overall severe threat will remain low, however, an isolated strong wind gust can't be ruled out.  Of greater threat may be the heavy rain potential.  Moisture values in the atmosphere are over one inch.  This means thunderstorms will be very efficient at producing heavy rainfall.  Individual thunderstorms west over Iowa have had a hail and wind threat associated with them, but as they move that will shift to heavy rainfall.

An isolated thunderstorm or two is possible through sunset, but the majority of the evening will remain dry.  A cold front draped over Wisconsin will begin to sink south Thursday night and early Friday morning, not completely passing northern Illinois until after sunrise Friday.

Non-severe showers and thunderstorms have been developing along and ahead of the front in Wisconsin Thursday afternoon.  As the front sinks south, our storm threat will gradually increase roughly after 9pm/10pm this evening.  Heavy rainfall and gusty winds remain the primary threats, but a hail threat will persist initially with storms that develop to the north.

Cold front passes by Friday morning, ending the chance for rain.  It'll still feel muggy during the morning, but drier air arrives after 10am and should make Friday afternoon and evening feel much more comfortable.

Falling Temperatures this Weekend

After a brief return to summer like heat and humidity this afternoon, comfortable temperatures will great us this weekend.

High temperatures this afternoon will climb to about 90°, but higher humidity will bring the heat index near 95°. This will fuel showers and storms this evening, with a threat for heavy rain and strong winds. There is still a 'slight risk' over the area with storms this evening. Storm threat goes up around sunset tonight with an incoming cold front.

High temperatures Friday will be about 10° cooler for the afternoon, compared to today. The cold air will lag a bit behind the front, and we will notice the coolest air arrive this weekend. Along with the temperature drop tomorrow, we will notice a drop in the humidity as well. It will feel much better this weekend high high temperatures about 10° below average. We'll sit in the low 70's through this weekend and into the start of next week. Enjoy!

Wednesday, June 21, 2017

Climbing Heat and Humidity Thursday

Temperatures over the central Plains and parts of the Midwest warmed into the 90's Wednesday afternoon.  A warm front passing Wednesday night will bring a slight chance for showers and thunderstorms, but a significant warm up for Thursday afternoon.

Highs Thursday will warm into the upper 80's, possibly low 90's, over northern Illinois and southern Wisconsin.  With the warmth, a rise in humidity will also be felt as the heat index reaches the mid 90's for many.  Other than a chance for an isolated shower/storm Thursday morning, it looks like most of the afternoon should remain dry - just hot.  As a cold front moves down the Midwest from Minnesota and Wisconsin, thunderstorms will quickly develop in the warm and unstable air mass.  A line of thunderstorms will be possible up north in Wisconsin during the late afternoon and evening.  As the front sinks south, a wind threat could develop over southern Wisconsin and northern Illinois by late Thursday evening.

The Stateline is under a slight risk for strong to severe thunderstorms late Thursday and Thursday night, primarily for damaging winds.  Make sure you stay updated with the forecast Thursday.  Heavy rainfall is also likely north over Wisconsin where anywhere from two, to three inches of rain could fall.

Stormy Nights Ahead

Currently watching storms that have developed in northwest Iowa march east this morning. The complex is holding together enough, that we will have to watch for a few showers and storms this afternoon. The complex will be on the weakening side of things this afternoon. Temperatures for the first day of summer, will be near average at 82° this afternoon.

A higher chance for storms arrives this evening with an incoming warm front. The Storm Prediction Center has highlighted portions of northern Illinois and southern Wisconsin under a slight risk for strong to severe storms. Storms will develop west ahead of the warm front and will head east. A strong low level jet will develop tonight and will focus the heaviest rain north into southern Wisconsin.

There could be a few showers and storms lingering into Thursday morning, before the warm front passes north into central Wisconsin. Thursday we will be under the warm sector of the system, and this will bring hot and humid conditions with highs in the upper 80's and heat index values climbing into the low to mid 90's. Another round of storms arrive Thursday night into Friday with the system's cold front diving southeast. Again there is a slight risk for severe storms Thursday night into Friday. Threats would include hail and strong winds, along with heavy rain. The front will pass Friday
afternoon and the rest of the day will end of being dry, but it will be much cooler behind the front. We'll be sitting in the 70's through the weekend.

Monday, June 19, 2017

Southwest Sizzles while the Midwest Cools

A change in the jet stream pattern brings almost a daily rain threat with it this week.  The first came this afternoon, with the second arriving Tuesday.

High pressure will build over the southwest causing temperatures to soar well past 100 degrees in many locations from California all the way to west Texas.  Excessive Heat Warnings and Heat Advisories have been issued - some of which last all week long!  Further north over the center of the country the flow within the jet stream will move more west to east - or what meteorologists call 'zonal' flow.  This will keep the extreme heat from making it this far northward, but also allow several upper level disturbances to move through the Midwest and Great Lakes.  And as each wave of energy passes through, the threat for rain will increase.  Right now it looks like the greatest chance for rain - some of which could be quite heavy - arrives Thursday afternoon into Friday.  A cold front will come down from the northwest during the day on Thursday.  This front will then stall because the winds within the jet stream will be running parallel to the cold front.  This won't allow the front to move much during this time and could bring heavy rainfall to *parts of the Stateline.  Best case scenario would be for the front to shift south Friday morning, taking any of the rainfall with it.  A few forecast models do offer up that solution.

By the end of the week temperatures are expected to cool into the 70's, with the low 70's expected for the weekend.  It does look like June may end slightly cooler than where our average highs should be, which are in the low 80's.  A far cry from how the beginning of the month started.

Early Start to the Hurricane Season

Tropical Storm Bret formed off the east coast of Venezuela Monday afternoon, but isn't expected to strengthen much further than its current state.  According to the National Hurricane Center, an Air Force WC-130 found a well-defined closed circulation - well west of where it was initially thought.  The storm has quickly strengthened, but with its expected landfall near Venezuela and moving into an environment with a little more wind shear, intensification is not expected.  This storm is not expected to have an impact on the United States, but will likely bring quite a bit of rain along the coast of Venezuela and Columbia.

Of greater concern for the United States is Potential Tropical Cyclone 3 forming in the Gulf of Mexico. 

New this year is the option of the National Weather Service to issue advisories, watches and warnings for low pressure systems that have not yet reached tropical storm or hurricane status yet, but could pose a threat to land within 48 hours.  Current forecasts from the National Hurricane Center have Potential Tropical Cyclone 3 reaching Tropical Storm status as early as Tuesday late morning or early afternoon.  The exact track of this system is a little uncertain at the moment, but it's likely to make landfall somewhere along the Gulf coast from near
Galveston, TX to Louisiana.  Biggest threat for these areas along the coast will be heavy rainfall.  Current rainfall forecasts through Thursday evening have nearly five inches of rain, with isolated rainfall totals nearing ten inches!

Monday Afternoon Weather Update

6:30pm Update: Radar upstream still showing a few more isolated showers, but looking a little less active.

5:20pm Update: Thunderstorms have become a little more scattered late this afternoon.  Brief, heavy downpours will be the biggest threats.  Storms will last until a little after sunset this evening, with skies turning partly cloudy overnight.

Widely scattered thunderstorms will continue to develop Monday afternoon as an upper level low moves across the Great Lakes.  Severe weather is not expected with these storms, however, some may grow just enough to produce a few locally strong wind gusts and hail up to quarter sized.  The storm threat will last through sunset.

Another Round of Storms for Monday

The severe weather threat is low to kick off the work week, but you'll still need to keep an eye to the radar with scattered showers and storms arriving in the mid to late morning, and continuing into the early evening.

A few scattered ripples or waves of energy will ride through the northwest flow currently in place in the upper levels of the atmosphere. The ripples will act as a lifting mechanism needed for showers and storms, and the instability needed will come by way of a cold pocket of air. At the 500mb level of the atmosphere, a pocket, or area, of very cold air will arrive overhead from the northern plains. The cold air will bring steeper lapse rates in the atmosphere which will generate some instability.

Timing of the waves will be in the mid to late morning, which will bring initial showers and storms this morning and that will continue through the early evening.  Some small hail will be possible in these storms, as the freezing line drops closer to the surface with the arrival of the cold pocket. This allows for a better chance for small hail, even though cloud tops won't be very high, they will be tall enough to tap into that chilly air.

Once the sun sets this evening, the threat for storms goes down. Another chance for rain and thunder arrives Tuesday.

Sunday, June 18, 2017

Nicer Weather Ahead

We've had a beautiful day here in the Stateline, and you can't ask for better weather than this on Father's Day, especially after the strong storms that moved through our area last night.  We reached the upper 70°s today despite those clouds, but we still got to see a good amount of sunshine.  Clouds will decrease as we move through the evening tonight, and we'll hang on to the low 70°s before cooling to the low 60°s during the overnight.  Clouds will build back up tomorrow as that low to the northeast will still have a small influence on our area, with a chance for some light rain showers up north. A high pressure system will move in on Tuesday to replace it and bring us more sunshine to go along with those temperatures in the mid 70°s.

Another low will move in Wednesday and bring us some storms during the overnight, but it'll stall through Thursday due to the jet stream having a more meridional flow, meaning non-linear.  Since the low will stall, we'll have a chance for storms during the afternoon on Thursday.  The storms are not expected to be severe.  However, the upper level jet will return to being zonal, or linear, by Thursday evening and the low will clear out of our area.  Once that happens, we'll see more sunshine for the rest of the week and maintain those temperatures in the 70°s

Saturday, June 17, 2017

Severe Weather Threat Update

More thunderstorms are continuing to move in from the southwest, where most of these storms have formed from the high instability.  We've seen some hail with these thunderstorms as they've moved through our area, along with gusty winds upwards of 40 mph.  A funnel cloud was reported in Rock County, but never reached the ground and fizzled out.  The storms will continue until about 1am, when most of them are supposed to die down

Storms this Evening with Nicer Weather On the Way

We had a decent start to the day with a few breaks in the clouds that allowed for some sunshine, but unfortunately those breaks in the clouds got our temperatures to heat up a little bit more and develop some isolated storms and showers.  Our instability has increased since 4pm as an upper-level trough has dipped just west of us, increasing lift over our area.  This is why we're seeing more thunderstorms developing, and is also why we're under a Slight Risk for severe weather.  The only county not under a Slight risk is Jo Daviess, which is just under a Marginal Risk.  The Enhanced risk was shifted to the south into central Illinois, where large hail and tornadoes are likely.  Any storms that form down there will track northeast, and will avoid the Stateline.

 The storms moving through our area aren't severe, but with our increasing instability we can't rule out the chance for a little bit of hail to be seen with these storms, and some gusty winds.  The storms are expected to die down between 1-4am, when the frontal boundary moves southeast.   Afterwards we'll stay fairly cloudy for the rest of the overnight.

Father's Day is looking to be a beautiful day!  We'll have temperatures in the upper 70°s with partly cloudy skies, so be sure to get out and enjoy the nice weather.  Some clouds will build up on Monday with an approaching low, but a high will move in on Tuesday to clear them all out.  Another low pressure system will move in Wednesday, bringing us a chance for storm during the evening, with a third low pressure system bringing rain during the overnight Thursday night.  The third low will also bring us a rain chance during Friday afternoon, before bringing a storm chance during the overnight Saturday night.  Despite the couple of storms and showers next week, temperatures will be back in the 80°s by Wednesday, climbing to the mid 80°s by next Saturday.

Friday, June 16, 2017

Severe Weather Threat Tomorrow

We are under a Marginal Risk for severe weather, the main reason being that the stronger storms are forming in Iowa and tracking towards our area.  The main threat from these storms has been hail, but luckily these storms have died down as they've gotten closer to our area.  However, we can't rule out the chance for a few more thunderstorms developing and possibly tracking into our area during the evening and the late-night hours. 

Tomorrow will be the bigger event, as we're under an ENHANCED risk for severe weather.  That low pressure system out west, which formed the storms in Iowa today, will track towards our area and strengthen tomorrow.  It will increase our heat and moisture inflow, allowing a chance for a few isolated storms in the morning, but in the afternoon it'll bring a cold front through.  The front will increase wind shear and allow for stronger storms to develop.  The main threats are large hail and strong winds, but our tornado threat is low.  The isolated storm chance in the morning plays a crucial role for the severe weather in the afternoon.  If we see isolated storms in the morning, the rain from them will cool our temperatures, which could impede severe weather development later on.  If no storms form though, our severe weather threat will remain.

As of now it looks like the isolated storms will start to form around noon, which would give plenty of time to cool off and stabilize the atmosphere before the stronger storms get a chance to develop between 3-4pm.  If the severe weather does form, it'll stay with us until around 1am.

The good news is that we clear up for Father's Day!  We'll see temperatures in the upper 70°s with plenty of sunshine, and also hang on to the nice weather for Monday.  We do have a chance for some thunderstorms for Tuesday evening and Wednesday evening, but Thursday will be another nice day with temperatures getting back into the 80°s to go along with the sunshine.  We maintain the 80°s afterwards, with more thunderstorms on Friday.

Changing jet stream pattern brings severe threat for the weekend

Upper level winds, or our jet stream winds will change from an amplified ridge ( which brought our 6 straight days of 90's) to flattened zonal flow. Zonal flow essentially means winds flows from west to east. Oftentimes showers and storms develop in this type of pattern when you get multiple disturbances that ride along that same flow. A zonal pattern is taking shape today, and a few different impulses or disturbances that move along it will bring scattered chances for showers and storms through the weekend. The first of those will arrive this evening, and will prompt a few showers and storms in the evening. The severe threat stays west of the area, though we could get a couple gustier storms in the evening. The best chance for showers or storms will be after 7pm this evening.

The threat for severe weather goes up Saturday for a few reasons. First we will have more CAPE or energy available for the storms to feed off of. Also the impulse or vorticity will be stronger then the one arriving this evening. We also have more of something called, directional shear. Shear basically equates to winds that change direction with respect to height. So winds aloft are coming in from the west, while our surface winds will arrive from the south. This will give storms the the potential to form and become severe.

Threats for Saturday include mainly large hail, strong damaging winds, and heavy rain. The tornado threat is low, but not zero.

One big question for severe weather on Saturday will be what happens with storms Saturday morning. If the atmosphere is able to recharge essentially then storms will be likely into the afternoon. Storms could arrive as early as 3/4pm.

Severe weather is not set in stone for Saturday, but the threat is definitely there, so make sure you stay weather aware this weekend!

Thursday, June 15, 2017

Storms out west could move through northern Illinois Thursday night

10:05pm Update: Line of strong thunderstorms moving into Ogle and Lee counties.  Dime sized hail and wind gusts to 50 mph are possible.  Heads up for the cities highlighted.

9:45pm Update: Thunderstorms with frequent lightning moving in from the west from Monroe to Lanark.  Small hail and a few stronger wind gusts are possible, but overall severe threat remains low.

9:10pm Update: Severe thunderstorms continue to move into northeast Iowa, but are moving more southeast than east.  This is where better instability is located.  Storms a bit further north will still pose a hail threat as they become elevated, but overall severe threat for northern Illinois and southern Wisconsin will remain low.

Despite a cold front passing Thursday afternoon, high temperatures still made it into the upper 80's and low 90's.  It wasn't as humid, but it was still very hot! 

With the front to the south the majority of the afternoon and evening will be very quiet.  Big thunderstorms are developing over the central Plains, closer tied to an area of low pressure.  But thunderstorms developing over northeast Iowa bare some watching as they are likely to move into northern Illinois after 9pm tonight.

The image on the left is a 'simulated radar' image of what the radar may look like (future radar) around Midnight.  The storms will weaken a little as they move into Illinois due to loss of daytime heating, but there will still be quite a bit of instability in the atmosphere during the overnight.  This may help overcome the loss of heating and keep a few stronger storms around that would be capable of producing large hail and wind gusts to 60 mph.  The storm threat will last through roughly 2am/3am Friday morning.

Additional thunderstorms - some likely severe - are possible going into the weekend.  I'll have more on that coming up in a later post.

Storm Threat Ramps up Friday and Saturday.

Summer activities in full swing this weekend, and if you are planning on heading out to any of them you'll want to keep your eyes on the radar.

By Friday, a series of upper level waves will be pushing through Illinois, and bring with them the threat for storms. Hail, wind, and heavy rain will all be of concern Friday, with ample moisture and instability present. A few strong storms will be possible, and there is an isolated severe threat. However, the higher chance is highlighted under the yellow 'slight risk' for Friday just west of Illinois, through Iowa, northern Missouri, and eastern Nebraska.

Saturday will be of bigger concern, as an area of low pressure deepens as it moves into the area. The system's front also moves overhead, which would provide low level shear, or spin, in the atmosphere. Along with that, there will be ample CAPE (energy) and deep layer shear, that will bring a threat for all types of severe weather possible. Models are still not in agreement on timing of the storm development, though at the moment the best time frame would be early evening. The Storm Prediction Center has the area under a slight risk for severe storms on Saturday.

We'll make sure to keep updating you as more information comes out, but for now make sure to enjoy our sunny Thursday!

Wednesday, June 14, 2017

Severe Thunderstorm Watch - Wednesday

6:45pm Update: All Severe Thunderstorm Watches have been allowed to expire for northern Illinois and southern Wisconsin.  Light to moderate rain continues to fall over McHenry, eastern Boone and DeKalb counties.

A Flood Warning has been issued for southern Boone, McHenry and northern DeKalb counties until 11:45pm.  Radar estimates of 2 to 4 inches of rain has occurred in this area.

6:10pm Update: The Severe Thunderstorm Watch has been cancelled for Green, Rock, Stephenson, Jo Daviess, Carroll and Whiteside counties but continues for Winnebago, Boone, McHenry, Ogle, Lee and DeKalb counties until 8pm.

The majority of the severe weather has moved in towards Chicago, but additional thunderstorms are developing back to the west and southwest - with on Severe Thunderstorm Warning for Dubuque County in Northeast Iowa.  We may see isolated thunderstorms through 8pm - especially moving into northwest Illinois.  These storms are forming ahead of the main cold front that will pass through the overnight.

3:40pm Update:  A Flood Advisory has been issued for Northwest DeKalb County until 6:45pm Wednesday evening.  There has been very little movement in thunderstorms over the past hour from Fairdale to just north of Genoa - where very heavy rain has been occurring.  Rainfall estimates of 1" to 2" have occurred. 

These storms are very slow moving with winds in the upper part of the atmosphere very weak.  Additional thunderstorms over west-central Illinois do need watching as those are expected to pull northeast - mostly east of I-39 - before 6pm.  Strong winds would be the primary concern should those storms hold together and make it to the northeast.

Check out how tall these storms are! Approaching 50,00ft! Large hail is possible in these storms.

Severe storm warning for Rock Co until 1:45. 1" hail and 60mph winds possible along with heavy rain. 

A Severe thunderstorm watch is in place for the entire Stateline until 8pm. Heavy rain, large hail, and strong winds are biggest threats. 

Strong Storms Possible Wednesday

It has been a very muggy morning, it's not even noon and dew points are currently in the low 70's for many! This is a very tropical like air mass, something that is more typical of the late summer across our neck of the woods. High dew point numbers today are once again already bringing heat index values into the 90's. And we can expect heat index as high as 100° this afternoon, however any storms we get will drop temperatures this afternoon.

Along with the sticky feel, high dew points will also lead to heavy rain producing thunderstorms. Storms will be efficient rain producers because of the high amounts of moisture available, along with their slow moving nature.

Storms will develop midday as a couple features come into play. First features will be a few mid-level impulses that will be moving through northern Illinois today, ahead of our next cold front. As clouds are clearing, we are able to generate more and more instability in the atmosphere that will help to be 'fuel' for thunderstorms. This moist and unstable environment will be key to storm development.

Along with a few 'disturbances' or impulses(energy) moving into the area, we also have an old outflow boundary nearby. Like yesterday, this boundary will be a focal point for storms to develop today.

With high moisture, instability, and even some wind shear; strong to severe storms will be possible today. The storm prediction center shows the Stateline and much of the Midwest under a 'slight risk' for severe storms this afternoon. Biggest threats would be heavy rain, hail, and strong winds. The tornado threat is low, but not zero today.

The best timing is midday to late afternoon, as this time is when we are under peak heating from the sun, and are able to generate a lot of instability to fuel storms. We are just waiting for those energy waves which will be the 'spark' for storms. Storms should begin to fade this evening as we lose the energy.

A cold front passes early Thursday, which will bring back more sunshine. It won't feel any cooler behind the front, we will still be near 90°, but drier air advects in. This means it will be less humid and feel much more comfortable.

Make sure to check back for updates regarding storm potential today.

Tuesday, June 13, 2017

Thunderstorms Tuesday evening

6:40pm Update:  Thunderstorms will continue to fizzle as an old outflow boundary continues to move west - away from the Stateline.  One storm near Amboy will still produce heavy rainfall, but the overall coverage of storms will continue to decrease through sunset.

Isolated severe thunderstorms developed southeast and east of Rockford along an old outflow boundary Tuesday afternoon.  Reports of dime to nickel sized hail came in from Fairdale to Belvidere.  There were even a few reports of pea sized hail southeast of Rockford.

Outflow boundaries from those storms have allowed new thunderstorms to develop over Stephenson, Ogle and Lee counties.  These are not severe, but will likely produce very heavy rainfall and small hail.  We'll lose *some* of the instability once the sun sets, but with lingering outflow boundaries it's possible additional thunderstorms could occur overnight.