Archive for the ‘Weather’ Category

Fog risk forecast returning

Posted: 2017/09/11 in Weather

As the colder weather months approaches, the fog risk forecast is returning as the prime time for river fog and eventually inversion type fog will return.  In recent weeks there have been posts on Facebook on nights where there were favorable conditions for such development, and almost every morning those posts were confirmed.

The reason why risk forecasts are posted from September through May starting last season was a good reason: river fog during the fall, winter, and spring months has the potential for a AM peak disaster.  The risk falls under a few categories and other weather conditions may play in a role in the risk.

Low – the conditions for fog to develop are not favorable

Medium – favorable conditions exist but not likely to cause the NWS to release Dense Fog Advisories

High – favorable conditions exist AND the NWS is likely to release Dense Fog Advisories


Fog risk forecasts are only posted via the Facebook page, likely on Sunday evenings.  The forecasts for early week are more likely going to be accurate than late in the week so there will be time that Thursday/Friday risk will be deferred.  Unless otherwise noted the risk will only be valid from 05:00 to 09:00.

Why is River Fog so dangerous?

Some of the biggest epic fails during the fall and winter months came on mornings that conditions for river fog to develop were favorable – which is warm days, cool nights, and a lack of a wind.  River fog only develops late at night or first thing in the morning around or near sunrise, and is much more likely to develop over or near a body of water.  It tends to dissipate late in the morning. From October through April, the temperatures in the morning can flirt with the freezing point and that can turn fog into ice.

What is Inversion Fog?

Inversion fog is more likely to occur during this time of the year and it can occur at any time of the day.  It is essentially warm air trapped over cold ground with a lack of wind.  The main difference is that it can last 24/7 and it is not limited to the river valleys.  It too can occur when the temperatures are at or below freezing.  Unlike River Fog that can happen on a sunny day, inversion fog usually occurs on a cloudy or rainy day, but there are times it can occur on a clear day when there is snow on the ground.


While the potential of the heavy traffic from this weather event has been ignored by the admins due to other more pressing reasons (thanks to IDOT that decides to load the entire month of August so far with a lot of lane closures on 270 including the weekend before the eclipse), the fact this is such a rare weather event people will be making the trip to this area.

While this section of 270 is essentially on the fringes of totality (it will not be at 100% path but it has to be very close to 99%), its clear that IDOT and MoDOT been posting stuff on social media.

Find a safe spot to pull over and wait out the event.  Don’t forget the appropriate glasses.  Most of the influx of traffic the day before has been near the SIU campus for an unrelated reason.  Most of the traffic congestion is right before and shortly after the eclipse begins, as the majority of the people from out of state have opted to use campgrounds.  Still there will be heavier than normal traffic for the time of day, especially in South County where that section of 270 is in the path of 100%.

The NWS has set this area to Moderate Risk for severe weather as the main event is expected to roll through this area late this afternoon.  While this section of 270 is on the fringes of the Moderate Risk threat, the main threat of this outbreak being strong winds is a concern for the truckers that are using this road during the holiday weekend.

The admins think the worst will happen to the south and especially the southwest of here.  There is a preceding line forming that could affect the potency of the severe storms later this afternoon.

While a tornado watch is now out, it does not include this section of 270 at the time:

However, a severe storm watch was issued as the admins were writing this post:

Please stay weather aware this afternoon.

Today the NWS gave us bad news and confirmed that the Mississippi River at Alton will go past the 29 foot threshold as early as Monday.  The bad news when the river hits that point is that the southbound lanes of 367 just south of the Clark Bridge start to flood and that usually renders the southbound direction of the Clark Bridge off limits.alton-apr30at1700

The projected crest is on Wednesday at or around the 33 foot mark.

Based on an recent MoDOT press conference held this evening, the NB lanes of 367 will be converted into two-way traffic and that will help with the heavier than normal traffic on this section of 270. However, this also means that there will be delays in both the AM and PM peak starting Monday afternoon and lasting likely through the end of the week. Either way, traffic on 270 will be heavier than normal for a few days, the canal bridge area is a known choke point, and plan on delays on both the Clark Bridge and the Chain of Rocks.

While the NWS DOES NOT have Winter Weather Advisories in effect for this area (but they do have in effect in the counties along and north of I-72), snow is expected to come just before the Monday morning peak:

While the ground temperatures are above freezing, an recent cold snap and the fact nobody has seen the white stuff for two months may mean very slick roads. (There has been more severe weather outbreaks than inches of snow this season to put this in perspective.) With that in mind combined with a recent run of terrible form when it comes to the North County drive (with last week AM peak fatal MVA on WB 270 in consideration), the admins made the decision to put the AM peak at HIGH risk. (It is also a full moon out there as well so people may be driving much more crazier than normal.)

While not a lot of snow is expected (the worst is expected to remain to the north), the timing can cause big problems as it does not take a lot of snow to cause gridlock, given that 270 up in North County is hilly and the 1-3 inch range is where people often get complacent when it comes to snow.

Although some of the previous models have put this section of 270 on the fringes of the severe weather threat, some of the latest model runs this morning is pointing to an enhanced threat.  While the TORCON is set at 4, the biggest risk is an outbreak consistent with an derecho:

This is the second possible severe weather outbreak in a week, and the first one the threat just missed to the east with the hail while the worst was about 75 miles south.

The risk forecast for Tuesday morning has been upgraded to medium as is may affect the morning peak. Stay weather aware as conditions may change in an instant.

UPDATE 2/28/17 at 11:30 – the NWS has upgraded the risk to medium

While the winter has been a flop in one term (not even 2 inches of snow for the entire season and maybe a total of four winter weather events – and the last one was over six weeks ago), the anything goes mentality means that severe weather can be a threat.  The NWS has put this area in the enhanced risk for Tuesday evening/Wednesday morning time window, and while that threat is still subject to change it is the first major weather threat since mid January.  Fearing weather complacency and the recent run on very poor form when it comes to that Clark Bridge commute (three major incidents in the past two weeks), the admins are somewhat concerned and has hit the peak periods for Tuesday afternoon/Wednesday morning as HIGH RISK.

The bottom line is that people need to remain weather aware on Tuesday evening/Wednesday morning time window.  While the admins do not expect a direct hit during the peak periods there could be a isolated shower popping in time for the Tuesday evening peak and leftover rain for Wednesday morning.

For the first time in just over 10 years an ice storm warning has been put in effect.  The winter weather event that hit an month ago was just a dry run compared to what this storm is bringing and as such all the schools along 270 in North County and the Riverbend have called off classes for tomorrow.

To add to the misery, tomorrow is Friday the 13rh which is a day known to superstition as either good luck or bad luck.  With the past history with ice events along 270 we know it will likely bring bad luck out there so please stay off the roads.  A state of emergency has been issued for Missouri.  The worst will likely happen just to the southwest, but the storm could very well come in time for the morning peak.  The morning peak is going to be very questionable and the evening peak will likely be like this:


The bottom line is stay home if possible because your kids are already home from school on what turned out to be a 4 day weekend for them.

If you must head out please note the crews will be out and treating the roads.  Earlier this afternoon they were out prepping the bridges:


The NWS has issued the Ice Storm Warning for the area until Sunday, when the temperatures are expected to be warm enough to turn all the freezing rain into plain liquid rain and the conditions will slowly improve for the remainder of the event.

Remember, when there is ice, it takes very little to cause massive problems.

Poor timing snow event for 1/5

Posted: 2017/01/04 in IDOT, MoDOT, Weather
Tags: , ,


The NWS has predicted up to 4 inches of the white stuff for Thursday – and projected the stuff to fall in time for the morning peak:

Earlier this evening, MoDOT goes out and their #2 man in the district declares in a press conference to the local media there will be no pretreating of the roads prior to the event.

Instead they have urged the people to stay off the roads and likewise the Illinois State Police has issued a travel advisory for the I-64 and I-70 corridors:

With the lights on the river bridge out and the poor timing of the event, the admins decided to upgrade the risk factor to HIGH. The hilly 270 mainline up in North County is likely going to be terrible, and in the last winter event that hill east of 157 proved its ugly head like no other. Since the admins have honestly lost count of how many incidents that happened on that hilly mainline in recent years (it seems like it happens every season), anyone that has to go out in this stuff due to essential reasons needs to allow extra time and be prepared to be stuck. Temperatures in this event is expected to be in the teens and low 20s, which can make rock salt rather ineffective.

Just for good measure, the past snow events at poor times have yielded big problems so please lets not make a repeat of this mess:

OR this mess the last time MoDOT didn’t pretreat the roads, or for good measure the epic twitter feed:

Whatever happens tomorrow please allow a lot of extra time or just stay home. The evening peak will likely be just as dicey depending on when the snow exits.

Although the admins cannot make up the determination on what type of precipitation that this quick hit could bring, crews had been out earlier today pretreating bridges and the temperatures for Friday morning are expected to be borderline. Regardless of what could fall, the admins decided this morning to upgrade the risk to medium and set same risk for the rest of the weekend. The weather forecast for the entire weekend is not favorable and while the temperatures are expected to be above freezing for the majority of the weekend, rain is also in the forecast.

What happens for Saturday and Sunday, however, is none of the concern right now. The main concern is the morning peak Friday. While this morning peak is expected to be lighter than normal with most of the employers and schools on Christmas break, there will be a lot of truckers making the jaunt through here either to avoid the blizzard that is expected well to the north or to get in hot loads at the nearby distribution centers. Why the Friday morning concern? On an normal Friday, the timing of the precipitation is expected to hit during the morning peak. With projected lows expected to be at or below freezing (as this post was being written, the temperature at Alton was at 32), the poor timing of the nasty weather can lead to problems.

It was a night to largely forget last week.
That bad weather led to big problems in the St. Louis area when it hit at a poor time one week, and while this section of 270 didn’t have the major problems compared to the rest of the region, it was very shitty once you got east of 255. While the admins do not have the details on what allegedly happened on the hill east of 255 (one of them that normally goes through at that time of the day didn’t do the usual trip that evening due to a prior commitment), there were some horror stories of delays going over 3 hours. (Rest of the 270/70 Mainline from 255 to Effingham was a nightmare, with at least 4 different locations were blocked at some point Friday evening due to tractor-trailers failing to navigate hills and various minor incidents.) The following day brought a fatality incident on 255 at 270, and there were several incidents on the exit ramps between 367 and Riverview. All that drama came from freezing drizzle and some inversion fog – which emphasizes that it takes very little ice to cause big problems when it happens at the worst time of the day.  (Speaking of that 255/270 interchange, it was the second fatality incident in a month.)

That was a common sight on the ramps – and there is a brand new dent on the cable rails just east of 203 that wasn’t there just a week ago.

That was a total lie. Dunn Road was shit all night long, and there were a few incidents on the hilly mainline in North County the entire weekend.

While the admins hope that tomorrow morning does not bring a repeat performance of the peak period a week ago, keep in mind that last weekend forecast by the majority of the TV meteorologists in the St. Louis area was an horrible bust.