(11:50AM - 9/1/19) While relatively quiet weather is being seen across Illinois, most attention for the country has been focused on what is now Major Category 5 Hurricane Dorian.

Hurricane Dorian was upgraded to a category 5 hurricane earlier this morning. As of 11:50AM, Dorian currently features a minimum pressure of 911MB, sustained winds of 185MPH with gusts to 220MPH. Rapid intensification has been occurring this morning, as the eye of the hurricane approached the Bahamas.  As of this post, Hurricane Dorain has made landfall at Elbow Cay, Bahamas. This makes Dorain tied for the strongest hurricane on record (wind wise) to make a landfall in the Atlantic basin, as well as the 6th strongest hurricane on record pressure wise to make a landfall. Dorain is also among the strongest hurricanes on record for the Atlantic basin overall, now tied with three other storms for having the 2nd highest winds on record...as well as being just outside of the top 10 hurricanes with the strongest minimum pressure on record. The storm will make a direct hit to Abaco Island and Grand Bahama today, bringing a combination of 185MPH winds, storm surge of 18-23', waves of 20-30' and 12-24" of rain. This will lead to destructive and catastrophic damage for these areas.

Beyond the Bahamas, Dorian is expected to curve to the north and the northeast, as it runs along the periphery of the Florida, Georgia and South Carolina coast. Along this track, it will bring some significant impacts to the coastline including; high winds, high surge, high waves and heavy/flooding rains. Fortunately, the absence of a direct landfall across these areas will help prevent more catastrophic and destructive impacts. Towards the end of the week, it is possible Dorain could come close, if not make landfall, in South Carolina or Northern Carolina. This still far out, and changes are likely at this distance.

Below is the latest NHC forecast for Hurricane Dorain.

​JP

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What seems like a never-ending loop of poor weather for Illinois recently continues to get worse. While the main headlines for the past couple weeks have been the consistent severe weather, the rain from all these storms is causing historic flooding along the Mississippi and Illinois Rivers in parts of western and southwest Illinois. Along many points along the Mississippi River, the forecast crest is expecting to be the second highest crest in recorded history with most locations coming within 4 feet of the all-time crests and some as low as an inch! 

The Illinois River is also feeling the strain, specifically from Beardstown and points south. Valley City, IL is expecting to break the record crest in just a few days and locations such as Hardin and Meredosia are coming within 2' of their all-time crests.

Living in the area (Alton), I'm quite familiar with the devastation flooding can cause. In fact, today in West Alton, a levee has already breached and we still have close to 3 feet to go before the Mississippi River crests here. The impacts of these flood waters are going to be felt for months to come. Communities are scrambling to save their homes and businesses as noted by the rash of posts across social media calling for sandbaggers to do every thing they can to hold back the rising flood waters. That's not to mention the commutes these people will have just to get to work with the number of road closures occurring. 

If anyone in these communities needs volunteers to assist with sandbagging, please comment on this post on our Facebook so any of our followers in the area can see it and potentially come out to provide assistance. 

While the emphasis right now is on protecting our communities from the rising flood waters,  we must not forget about our farmers either. The exceptionally wet pattern we have been in has drastically reduced the amount of planting our they have been able to get done. As you can see in the graphics below (Midwest Ag Service), this year compared to the 5-year average shows we're still about 60% below where we should be for this week in terms of acres planted and with the recent rains, we will continue to fall behind until our fields can dry out. 

What we've been facing for a couple weeks now has been been a persistent ridge of high pressure in the southeast and a trough of low pressure over the west coast. This pattern (seen in the graphic below provided by Adam) allows Gulf moisture to surge north and provides an ideal track for systems to move and sometimes stall over our area resulting in round after round of severe weather and heavy rain. Sound familiar? Fortunately, it looks as though that may be moving off and we will enter a pattern where we get ridging over the southwest and central plains that will induce northwesterly flow over Illinois. While this can still bring heavy rain and severe weather, it isn't as conducive. For our farmers and the sake of these river communities, we certainly hope this upcoming pattern provides some relief.

As always, all of us here at ISC will be monitoring these conditions as we see them develop and we'll have forecasts and live severe weather coverage as needed. If there are any questions, feel free to message us! 

We appreciate your support! - Billy

This afternoon a unique visual and radar feature began migrating its way across the Chicagoland area - gravity waves. 

What are gravity waves? A gravity wave is vertical wave in the atmosphere. In order for gravity waves to develop, there must be something a triggering mechanism  to displace the parcel of air. A simple way to understand them is to envision a rock being tossed into a pond. In today's example, a round of showers and thundershowers moved through the area and displaced the stable parcel of air that was sitting in place over the Chicagoland area.

Gravity waves require stable air to be in place before the disturbance moves through. If the air was unstable, the air would continue to rise without creating a wave(s). When the parcel of air is displaced, it initially will rise but since the parcel is stable, it will then sink in an attempt to restore equilibrium. However, the momentum the initial displacement creates will cause the air to overshoot its equilibrium level in the vertical (both above and below). This is why you see the ripples. This rising and sinking motion will continue a certain distance away from the initial displacement until the air once again stabilizes and reaches equilibrium. 

It's also important to note that the upward motion in a gravity wave is the most favorable region for the development of clouds. Thanks to our community of followers, several images have already been shared with us of roll-type clouds giving us a great visual cue of the gravity waves traversing the area. Conversely, the sinking region of the gravity wave is not suitable for cloud development which is why we often see rows of clouds. ​

In the radar GIF above I have the typical reflectivity and velocity products displayed in order to easily see the gravity waves traversing the region. At the beginning of the loop you can see what is left of the triggering mechanism (the region of showers and thundershowers) as it moves off into Indiana. 

We've seen several reports of winds gusting over 35mph with these gravity waves as well. Just another interesting weather phenomenon to add to what has been a crazy week here in Illinois. 

History may have just been made in Illinois, and not the good kind of history either. Early reports are that around 12:30 this afternoon the official observation at Rock Island Arsenal recorded a river height of 22.64 ft - eclipsing the iconic record of 22.63 ft set on July 9th, 1993.

The record rains are a combination of heavy snow melt from a snowy winter across the northern and central plains and recent heavy spring rains. It is possible the levels could inch up just a little bit more and the official forecast calls for a crest at levels above the previous record. 

The good news for residents tired of battling these floodwaters is that dry weather is expected this weekend. Unfortunately, more heavy rains look to arrive early next week as the next weather system approaches the area. The residents along the Mississippi River undoubtedly have a long road ahead of them. 

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Southwest Illinois had a pretty neat little mesoscale feature pass through this morning - a wake low. Right before 3am we had a significant pressure drop of about 7mb over the course of 15 minutes with 5mb falling in 1 minute (which is highlighted in the graph below from my weather station). That was quickly followed by strong wind gusts - I peaked at 36mph here at the house but I've seen reports of 60mph just across the river in Missouri.

So what is a wake low and what caused it to happen? A wake low is an area of lower pressure that we typically see on the backside of a squall line or in stratiform rain (much like we got this morning as you can see in the radar screenshot below). It appears as though the rain-cooled air built up a small region of higher pressure (several millibars higher than the surrounding air) as it moved through the area creating a strong pressure gradient over a short distance. Since nature is always working to be in equilibrium, that sharp of a pressure gradient is unsustainable. Eventually, this pressure bubble 'burst' in and when it did, it sent out a rush of strong winds that prompted numerous damage and high wind reports across the St. Louis metro and southwestern IL. 

If you have any questions, inquiries or suggestions, feel free to shoot us a message! We'll be happy to help. - Billy​

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As of 5:30 p.m. we are still waiting the arrival of the CME (Coronal Mass Ejection) with currently no indications of its arrival. This isn’t surprising. Forecast guidance from the Space Weather Prediction Center were indicating a glancing blow as a best-case scenario with the bulk of the CME missing earth. So, we’re either looking at a complete miss or the CME has yet to arrive.

I have been monitoring the data streams all day today anticipating its arrival. As it stands, there has been no increase in low-energy protons which often occurs as a CME approaches. It’s a helpful tool to use as an indicator that an impact is imminent. There has also been no uptick in solar wind speed, solar wind density, or the interplanetary magnetic field – all of which are used to monitor space weather conditions.

So, as I was eluded to with yesterday’s post, I think the odds of Illinois (and even southern Wisconsin for those of you wanting to skip town and head north a bit), seeing the aurora are close to zero especially now that we have a blanket of clouds moving in from the west and southwest (seen below).
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As always, if you have any questions, shoot us a message and we’ll be happy to answer.

Yesterday morning the sun decided it wanted to wake up from a deep slumber when it launched a CME (coronal mass ejection) towards earth. This CME was associated with a C4 solar flare which typically isn’t even newsworthy. However, we’ve been deep in a solar minimum for quite some time now as the sun begins its transition towards Solar Cycle 25 so anything like this gets our attention. Especially for those of us who are aurora-starved and just looking for an excuse to get out and photograph the night sky.
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So, what are my thoughts on Illinois seeing the northern lights this weekend? Well, they probably aren’t what you all were hoping. A lot of things are going to be working against us here. First of all, a C4 flare and CME is nothing to write home about. As stated above, this generally isn’t newsworthy. After reviewing model data (below) of the CME, it looks as though the CME will arrive sometime during the day on Saturday. My initial guess tells me sometime between 8am and 6pm. Clearly, the latter would be much better for us here in Illinois since that is closer to sunset. CMEs are notoriously difficult to model, though, so that time window should be taken lightly. I will have to monitor space weather data from the DSCOVR satellite to determine when the CME arrives. 

Secondly, there is the possibility of cloud cover for parts of the state. Given it is still a couple days out and there are  chances of rain showers across portions of the state, I’ll hold off on issuing a cloud forecast until we get closer to the event and I can analyze satellite data to make a call. Nowcasting is very important when it comes to space weather.

Finally, we have to overcome the moon phase. We just had a full moon so the moon is still almost completely full in the night’s sky and unfortunately it will be rising close to 10:30 on Saturday night. While it isn’t impossible to see the aurora with a full moon, it does make it much more difficult. Especially down here in the middle latitudes where our aurora are often more faint and subdued in terms of color than those magical photos you often see from Norway, Iceland, Churchill or Alaska.
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So what can we actually expect? Personally, I don’t expect much. I think the G2 warning is likely overdone and I don’t think anyone in Illinois will be able to see the aurora with their naked eye due to the inhibiting factors listed above. That being said, the aurora tends to produce very well around the equinoxes due to a process called the Russel-McPherron Effect. While it is not well understood, the magnetic field lines that connect the sun and earth tend to align around the equinoxes. Because of this, even weak disturbances in space weather conditions can spark auroras. I believe that was taken into consideration when the SWPC made their G2 forecast. With that being said, I think we would need a stronger solar storm generated by a more potent CME– ideally G3 to G5 – with a new moon and the arrival of the CME timed where the peak of the storm is occurring around midnight in order to provide us with maximum darkness in order to see the northern lights in Illinois with our naked eyes. Oh, we also need the weather on earth to cooperate too and you would need to find a location away from city lights – sorry, Chicago. 

Assuming everything comes together, i.e. we get clear skies, the CME happens to arrive around 5pm or so and it peaks shortly after sunset, I will be monitoring conditions and post any updates as to whether the aurora can be seen on camera (possible) or if I think the aurora will be visible with the naked eye (unlikely).
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For those of you who want to risk it and test your luck regardless and want some viewing advice, it’s really pretty simple. Go out and find yourself a good, unobstructed view of the northern horizon. The aurora (if seen on camera or with the naked eye) will likely be low on the horizon. I also want to make sure to note that if you are lucky enough to see the northern lights with your naked eye, don’t be surprised if what you see is a dull gray or diffuse color rather than the rich, vibrant colors you often see in photos. This is because a camera can see a lot more than our eyes can. The photo I took below was when the aurora was clearly visible over Lake Superior but I saw no color. What I saw was a waving curtain rippling across the sky in a gray/dull white color. However, my camera picked up all the color you see here in the image. Hunting for the northern lights is a fickle hobby. If you like sitting and waiting this might be the thing for you! It’s worth it. But that’s about it for viewing tips. As I said, it’s really pretty easy. Just keep your fingers crossed for a substorm (a short-lived intensification in the aurora, to keep it basic) and you might get lucky! 

If anyone has any questions on camera settings, shoot us a message and I’ll be happy to answer them. I’ve photographed the aurora several times from my home down near St. Louis so it is possible to do. I’ve also seen them with my naked eye on the shores of Lake Superior and they are absolutely mesmerizing. It’s something I hope each and every one of you get to see at some point in your lives. 

​- Billy

As technology continues to advance, we are left with a question in regards to the aging technology of outdoor warning sirens. Are they worth it? According to Harvard, IL the answer is no. Harvard joins a growing number of communities across the nation that has recently chosen to no longer invest in the sirens. 

This all began back in February of 2019 when the sirens began sounding for no apparent reason - freaking people out. An investigation was launched and it was determined that the systems did not malfunction but rather someone gained access and then activated them. 

The official statement from the town is posted below, but in summary, the cost to upgrade and maintain the system does not justify the worth. The existing sirens don't even cover the entire town anyways. 

The decision to not continue with the use of sirens may sound surprising at first, but is actually a growing trend in recent years and brings up new debate. 

Outdoor warning sirens were first developed as a means to alert to possible enemy attacks back in the WW era. It wasn't until the 'Palm Sunday' outbreak in 1965 that the thought to use them for severe weather was first realized. Back then, communication - and overall knowledge about weather - was not what it is today. Weather radios didn't exist, the internet hadn't been invented, and smart phones certainly weren't around.

These days there is no excuse for someone to not be able to receive weather information right in the palm of their hands. Numerous apps exist to send alerts straight to your phone, and weather radios are more portable and affordable than ever. 

Sirens have their use (aside from cool audio in storm chaser video)  in alerting people who might not be paying attention outdoors, but they have limitations. They are not designed to be heard inside, and people who rely SOLEY on them will not be alerted. In many cases, they will not wake you up at night. The cost to maintain the systems is a burden for many jurisdictions.

The Harvard case highlights another issue. As technology continues to advance, individuals may have to  take on the responsibility of ensuring they can receive warning information as opposed to relying on someone else to activate the sirens - as more and more towns continue to phase them out. 

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(6:00PM - 3/9/19) It's that time of year again...Time to push the clocks forward 1 hour at 2AM tonight. Losing an hour of sleep tonight and having to get used to the time change can be hard for some, but the good news is that it will once again be staying light out later in the evening beginning tomorrow. It's also another sign spring in around the corner!

JP

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Remember the polar vortex back in late January? That was a fun one right? During that snap, there were - at the time - unofficial reports that the station in Mount Carroll, IL recorded a temperature of -38 degrees. If these were to be true that would beat out the previous record of -36 .

Well, the State Climate Extremes Committee (SCEC) unanimously voted to validate the -38 degrees reading observed on January 31st as the new official state record minimum temperature. This committee ensures that the observation is meteorologically possible, is within a range that the reporting instrument can detect, and that the instrument is in proper working order.

This beats out the previous record of -36 set in 1999 at Congerville. 

A complete review can be found here https://www.ncdc.noaa.gov/extremes/scec/reports

Pictured above is the observation site at Mt Carroll. So congratulations to everyone who lived and survived the event. The word historic often gets used when it doesn't need to when describing weather events. In this case, its absolutely warranted. Now, I don't know about you, but I am ok with that record holding for awhile.

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