Severe Thunderstorm Watch #588

The Storm Prediction Center has issued Severe Thunderstorm Watch #588 for eastern Missouri and south central Illinois. The watch is in effect until 8:00pm CT Sunday.


A few of the communities included in the watch include: Missouri: Chesterfield, Columbua, Farmington, O'Fallon, St. Louis, Ste. Genevieve; Illinois: Belleville, Centralia, Du Quoin, Edwardsville, Effingham, Flora and Mt. Vernon.

Thunderstorms are beginning to flare up in the watch area along a weak front. Heating of the day is allowing the atmosphere to become unstable. Combine the instability and a lifting mechanism (the front) and you can get several strong thunderstorms.

The main severe weather threat will be hail. The storms will also be capable of producing heavy downpours. A few of the thunderstorms could produce some strong winds as storms collapse.

The thunderstorms are expected to move east at 25-30 mph.

Remember that you can check out the radar and the latest warnings by using the tabs at the top of my page.

8:00am Storm Update

It appears likely that an outbreak or two of severe weather will happen over the next 36-45 hours for parts of the country.

There is a lot of data to go over so this will be somewhat short and to the point. There is still a chance for strong to severe storms around southeast Missouri, southern Illinois, western Kentucky, northwest Tennessee, and northeast Arkansas today through Saturday.

Here is the latest from the Storm Prediction Center (SPC). This covers now through 7am CT Saturday.


Southeast Missouri and southern Illinois are included in the "Slight Risk" area. Northeast Arkansas and parts of the Missouri bootheel are included in the "Moderate Risk" area.

Tornado Probabilities*:


Hail Probabilities*:


Damaging Wind Probabilities*:


*Probabilities indicate the percentage that any given point in the area will see that type of weather. It doesn't mean there is a xx% chance of that weather for the entire area.

Here is a look at the severe weather outlook from SPC for Saturday. The outlook covers from 7am CT Saturday through 7am CT Sunday.


Here is a look at the overall probabilities of severe weather.


My thoughts are still pretty much what I said two posts ago (see below).

• First, we will see the possibility of thunderstorms developing along a warm front passes through the area (southwest to northeast) today. However, most of the storms should fire once the front is north of the area. The main threat from these storms would be large hail.
  

• Decaying storms will move in to the area overnight tonight/early Saturday morning (before sunrise). This line will come from a line of storms from western Missouri/northeast Akansas (if they develop). The main threat from these storms would be damaging wind.
  

• Thunderstorms will "pop"/initiate over the top of us Saturday. This could start as early as late Saturday morning. As a surface low develops over the top of the KFVS viewing area, there will be a threat for tornadoes on the east side of the low. This would be mainly confined to Tennessee and Kentucky. The main threat with these storms would be large hail, damaging wind, and tornadoes (east of Mississippi).
  

Note that the biggest concentration will be to the south/southeast of the KFVS viewing area. However, we should still be on the lookout for storms firing Saturday late morning/afternoon.

Spring is here!

I'm back from vacation and my batteries are recharged. I'll post some pics from the trip a little later (I'm still trying to unpack).

I did want to make everyone aware of the threat of thunderstorms for Sunday. I just sat down and took a look at the Storm Prediction Center's website and noticed that Missouri, Illinois, Kentucky, Tennessee, Arkansas, and Indiana are highlighted with a "Slight Risk" area.

The above graphic is the Day 3 Outlook from SPC. It covers the time period 7am Sunday - 7am Monday. The current forecast discussion from the meteorologists at SPC state that the main threat from thunderstorms will be large hail and damaging wind.

By the way, welcome to spring! Meteorological spring begins March 1.

If you are out and about this weekend, it might be a good idea to pick-up a new battery for your NOAA weather radio. If you don't have one, it would be a perfect time to purchase one.

Caught in the Middle

We're back to weather for today. This time not about winter storms, but instead spring storms in the winter.

It appears that we might have two rounds of thunderstorms this coming week. The first round will come Monday. These shouldn't be too bad. The second round will come Tuesday evening and last through the first half of Wednesday.

The Storm Prediction Center, the meteorologists that issue Severe Thunderstorm/Tornado Watches, have put the area in a "Slight Risk" of severe weather for Tuesday evening. (See image below. You can click on the image to see a larger version.)


Looking at SPC's probabilities of severe weather leads me to believe that we could see an upgrade to a moderate risk for parts of Arkansas. (See the image below.)

When you see the probabilities from the SPC, it does not mean that there is a 30% chance of severe weather. It means that there is a 30% chance of having one or more severe events occurring within 25 miles of any point inside of the area.

Right now it looks as though storms will fire up across eastern Oklahoma, eastern Texas, and western Arkansas. They would then move to the east. They wouldn't arrive in to southeast Missouri until later Tuesday evening if not early Wednesday morning (overnight). Most likely the storms would form in to a line with the main threat being damaging winds.

Normally you would think that would be the end of the storms. That won't be the case this time. There is still a upper level low pressure that will be slowly moving to the east. It will continue to send waves (or as I sometimes call it "chunks") of energy our way. Take a look at the upper-level wind graphic below. It might be a little confusing at first, but I will describe what you are seeing.

This is a view of winds at 500mb or approximately 18,000 feet. You are seeing lots of colors on the map. The colors represent the wind speed. For instance, the brighter yellow areas represent winds 65 knots to 70 knots or 75 mph to 80 mph.

Notice the reds and even purple out over southern New Mexico/western Texas. Just to the north of those strong winds is the upper-level low pressure center. When looking at upper-level charts you can see the waves of energy spitting out of the storm. Typically, you will see storms develop on the leading edge of the upper-level winds. The map above is for 6pm CT Tuesday.

Now take a look at the chart below which is for 12pm CT Wednesday.

See how the winds start to swing around the area of low pressure? By the way, the strongest winds at this point are right over the top of southeast Missouri, southern Illinois, western Kentucky, and northwest Tennessee. The storms that come through early Wednesday morning will have some upper-level support to keep going, but there won't be as much energy/juice (from heating and moisture) to work with. So when the storms come through here, they should be weakening. Think about it as a marathon runner runs their race, towards the end they can keep going, but they don't have as much in the tank to go as hard as they could towards the beginning.

Since the winds are right over the top of the Heartland around noon Wednesday, the next round of afternoon thunderstorms should develop just to the east of the viewing area. The SPC concurs with that thinking. Take a look at their Day 4 outlook. (The SPC does not issue slight, moderate, or high risk outlooks beyond Day 3.)


We will have to see how this pans out as it is still a couple of days away. But right now, it appears southeast Missouri, southern Illinois, western Kentucky, and northwest Tennessee are Caught in the Middle. Which can be a good thing in these situations. That being said, it does not mean that we will not see some watches/warnings out of this, but it does not look to be as bad as it could.

This is still a couple days away. We will have to keep monitoring the situation and see if things shift east or west a little.

By the way, this shouldn't be the first you are hearing about this as I have been talking about the chance of seeing some strong "spring-like" storms around the area since Wednesday.