Friday, July 19, 2019

Heat Wave Peaks Today, Excessive Heat Warning in Effect

After such an unseasonably warm start to our Friday, highs are forecast to climb into the mid and even upper 90’s. And once you add the humidity into the equation, heat index values will make it very dangerous to be outside for prolonged periods of time. This will most likely end up being the warmest day of the year so far. In fact, today's high will be just a few degrees shy of the daily record high of 100° set back in not too long ago in 2011.
As of this morning, the National Weather Service added the rest of our viewing area, which includes Winnebago, Boone, McHenry, Green, Rock, and Walworth counties, to the Excessive Heat Warning. This warning is set to remain in effect until tomorrow evening around 7 PM CDT.

Excessive heat warnings are issued when maximum daytime heat index values are forecast to reach 110° or greater with overnight minimum heat index values of 75° or greater for at least 48 hours. Heat index values are suppose to eclipse the 100° mark by noontime and stay above 100° through the rest of the afternoon and into this evening. So if you have any outdoor activities or have to be outside for a prolonged period of time, please find ways to stay cool and hydrated.

For Rockford, the heat index could be as high as 112°. Overnight lows are once again expected to only fall into the upper 70’s to low 80’s throughout the area, meaning little relief from the oppressive heat will be felt. Similar to this morning, we will once again have an unseasonably warm start to the morning for our Saturday. Heat index values overnight are forecast to stay between 85° and 90° for a majority of the night. Saturday afternoon will feature more of the same in terms of hot and humid weather. This time, starting off the day with plenty of sunshine before we see increasing clouds during the afternoon as a cold front approaches the area.

Daytime highs will likely be a few degrees cooler, with most of the region topping out in the mid to upper 90’s. Heat index values will once again climb to between 105° and 110° by tomorrow afternoon. Once this potent cold front passes through Saturday night into Sunday, it will not only bring a good chance for thunderstorms, but also a cooler and much more comfortable air mass for the end of the weekend!

Thursday, July 18, 2019

Heavy Rainfall Possible Saturday Evening and Night

A cold front sweeping down from the North Saturday evening will bring an end to the heat and humidity, but also the chance for very heavy rainfall Saturday night.

The jet stream in the atmosphere will be running from west to east, nearly parallel with the cold front as it moves into southern Wisconsin.  This also means that storms will be moving in that same direction, as they typically tend to follow the flow in the mid-levels of the atmosphere.  This type of set-up, however, tends to lead to the possibility of 'training' thunderstorms - storms that move over the same area for a period of time.

Moisture in the atmosphere will be very high ahead of the front so any storm that does develop will have the potential to produce heavy rain.  Wind may also be a concern if storms were to develop earlier in the evening Saturday.  Storms will be possible into Sunday morning with drier conditions expected by the late afternoon.

Another Round of Storms Possible Thursday Night

Another complex of thunderstorms is expected to move through the Midwest Thursday night into Friday morning, possibly impact parts of the Stateline. Thunderstorms have already developed Thursday evening near the Iowa/Minnesota border with a few severe thunderstorm warnings being issued.

Storm motion in the atmosphere is more west to east but like with the storms we experienced
Thursday morning, a slight shift to the southeast is possible. If that were to occur, south-central Wisconsin and far northern Illinois would be in line for potentially more storms Friday morning. It's yet to be seen if the storms will make that shift south as the more favored area for development is across Wisconsin. However, a gradient in instability would allow storms to dive southeast from near Janesville to Rockford by morning. Greatest threats with the storms would be strong wind gusts and heavy rainfall once again. 

Much Needed Rain Thursday Morning

Heavy rain producing thunderstorms moved through southern Wisconsin and northern Illinois Thursday morning bringing anywhere from half an inch, up to nearly 3 inches of rain in some locations.  We needed the rain as the deficit for July had fallen to over an inch.

The thunderstorm activity also delayed temperatures from reaching the 90s, but did not limit the rise in humidity.  Dew point temperatures soared into the mid and upper 70s, pushing the heat index valued into the upper 90s and low 100s!

With the dew point temperature so high tonight, overnight lows will only fall into the mid 70s.  The warm start to Friday morning will help highs rise into the mid and upper 90s for tomorrow afternoon.  There will likely be thunderstorms that develop again Thursday evening and night, but the focus should be more to the north over Wisconsin.

A cold front will approach southern Wisconsin
and northern Illinois during the late afternoon and evening hours on Saturday, bringing rain and thunderstorms to the area.  Heavy rain will be the greatest concern with slow moving thunderstorms moving parallel to the cold front Saturday night.

Slightly cooler and drier air arrives Sunday bringing an end to the heat and humidity.  Temperatures next week will remain in the low to mid 80s, more seasonable for this time of year.

Morning Storms Will Give Way to Dangerous Heat

Northern Illinois and Southern Wisconsin has been impacted by several rounds of early morning storms. They really have packed a punch as a few places have recorded over an inch of rainfall including Rockford, Kirkland, Dekalb, and Galena. That should make many farmers out there happy, especially with how dry we have been lately. Once rain and storms come to an end, a pretty quick clearing trend will follow. This remains the big question mark in today's forecast.

There is quite a bit of uncertainty as to how quickly how quickly the clouds are able to clear out of the region. The longer the clouds stick around, the less likely we will be able to heat up to our full potential. Once the sun comes out and begins to heat the surface, temperatures will sky rocket into the mid-upper 90’s. And that doesn't take into account the humidity. Strong southwesterly flow at the surface will pump warm moist air into the region. This could allow heat index values for a few hours this afternoon to exceed 100° in numerous communities.

An Excessive Heat Warning continues to be in effect for Jo-Daviess, Stephenson, Carroll, Whiteside, Lee, Ogle and DeKalb counties. For the rest of the viewing area, which includes Green, Rock, Walworth, Winnebago, Boone and McHenry counties, a Heat Advisory continues to be in place. The Excessive Heat Warning expires Saturday evening at 7 PM while the Heat Advisory only stretches till 11 PM Friday night.

Tomorrow will not only be the hottest day of the year, but also the hottest day during this heat wave. Highs look to top out once again in the upper 90’s. For Rockford, we will be pretty close to the daily record high of 100° that was set back in 2011. And depending on how much sunshine the region will see, I got a hunch that somewhere in the viewing area will reach 100° for a high.

Outdoor activities will be dangerous later today and tomorrow, especially during prime time heating which is from 12 p.m. and 6 p.m., when the heat index is at its peak. Heat-related illnesses become likely if you spend a prolonged period of time outdoors, especially if you’re not taking those necessary precautions to stay cool or to stay hydrated. Once again, we urge that you feel any of these symptoms for heat exhaustion or heat stroke, please seek help immediately!

Wednesday, July 17, 2019

Hottest Weather Expected in Nearly 7 Years

Temperatures later this week are forecast to rise into the mid and upper 90s and would be the hottest weather we've felt in nearly 7 years, since the summer of 2012.  An Excessive Heat Warning has been issued for Jo Daviess, Stephenson, Carroll, Whiteside, Lee, Ogle and DeKalb counties while a Heat Advisory has been issued for Green, Rock, Walworth, Winnebago, Boone and McHenry counties.

Isolated thunderstorms developed east of Rockford Wednesday afternoon along a lake breeze but have been mostly focused over southeast Wisconsin and northeast Illinois.  To the west, a complex of thunderstorms over Iowa moved into Illinois with severe thunderstorms moving through west-central Illinois.  The northern edge of this complex weakened quite a bit to only showers in northwest Illinois.  Little relief from the warm and muggy air is expected Wednesday night.

Thunderstorms are forecast to develop over northern Iowa and southern Minnesota late Wednesday evening, moving east and southeast into Wisconsin.  While most of the activity will remain in Wisconsin, more

of a southward track is possible into southern Wisconsin and northern Illinois Thursday morning.  If this complex of storms develops and moves into the Stateline it could delay how quickly temperatures warm during the afternoon.  However, strong southwest winds are expected to develop during the afternoon and evening pushing temperatures into the low to mid 90s during the afternoon.  Peak heat index values could be as high as 105 degrees during the late afternoon.

Friday is the biggest day of concern with little opportunity for rain or thunderstorms.  Highs Friday afternoon will fall just shy of 100 degrees!  The heat index Friday could peak as high as 115 degrees in some locations.  The last time the high temperature was that high in Rockford was July 25th, 2012 when the mercury reached 99 degrees!

An approaching cold front will bring a chance for thunderstorms Saturday afternoon over Wisconsin and far northern Illinois, possibly tempering the heat some during the afternoon.  The front will pass Sunday bringing temperatures back down into the 80s for the end of the weekend and next week.

Tuesday, July 16, 2019

Dangerous Heat on the Way

Good morning everyone! After temperatures yesterday climbed up into the low 90s, today is going to still feel a little bit muggy but slightly cooler. Compared to Monday afternoon, there will be more cloud cover over the region which should limit high temperatures today to the mid to maybe upper 80s. We can definitely push for upper 80s if we can manage to get a few peeks of sun. On the other hand, heat index values will still be in the low 90’s throughout the day, so we technically won't be getting a “break” from the hot and humid weather. Especially with the dangerous heat and humidity levels that are about to move into the viewing area.

As of this moment, only 4 counties including Stephenson, Jo-Daviess, Carroll, and Whiteside, have been placed under a Excessive Heat Watch. This watch will go into effect starting tomorrow afternoon at 1 PM and stretch until 7 PM on Saturday. Heat indices during this time frame could be between 100° and 110°, meaning any outdoor activities can quickly become very dangerous. Especially if you do not limit your time outdoors during peak heating (12 PM to 6 PM) or keep yourself hydrated.

As for vehicle safety, it is essential that you "LOOK BEFORE YOU LOCK" your vehicle. It is quite easy to forget that you maybe brought a child or your pet with you. And during the summer, the temperature inside the car can quickly climb to deadly levels. In fact, if the temperature outside was 80°, the temperature inside the car can quickly heat up between 120 to 130° in just 15 to 20 minutes. With us being more than halfway through the year, 20 kids have already died from heatstroke by being left in a hot car. To prevent more deaths from happening, please make sure to look before you lock!