Severe weather threat ramps up Friday night through Sunday morning

An area of low pressure is going to move out of the Rocky Mountains Friday evening.  Ahead of the low, several front will be passing through the Midwest providing areas of lift and shifting winds.

Scattered thunderstorms are expected to develop along a warm front that will lift through Indiana Friday night in to Saturday morning.  Along and ahead of the front some of the thunderstorms will have the capability of producing hail.

Computer model projection of radar imagery at 1 a.m. Saturday EDT.

Some data suggests there could be a period of time when ingredients in the atmosphere could allow thunderstorms to spin along the front.  The greatest threat for this appears to be between 10pm EDT Friday and 3am EDT Saturday and primarily confined to a corridor between southwest Indiana to Columbia, Missouri.

It should start to feel more "stormy" Saturday in the Midwest.  Temperatures will be higher with temperatures in the 60°s and 70°s.  It is also going to be much more humid as dew points climb to the upper 60°s.  This will all happen before a cold front passes through Missouri, Illinois and Indiana Saturday evening through Sunday morning.

While there could be scattered showers and thunderstorms late Saturday morning, there will be many dry hours.

Thunderstorms should begin to develop in eastern Iowa and eastern Missouri early Saturday afternoon as the cold front begins to move through central Iowa and central Missouri.  Because of the atmospheric environment the thunderstorms could rapidly intensify.

Computer model projection of radar imagery at 8 p.m. Saturday EDT.

A line of thunderstorms is projected to be moving east through western Illinois shortly after sunset.  The line will continue to move east through Indiana late Saturday night through early Sunday morning.

Early in the afternoon the greatest threat will be damaging wind and tornadoes in southeast Iowa and northwest Illinois, roughly from Cedar Rapids, Iowa to Galesburg, Illinois.  As the line of thunderstorms moves east the threat will be primarily damaging wind, but tornadoes and hail will be possible.  The tornado and hail threat should begin to diminish through the overnight as the line of storms moves east through Indiana and in to Ohio.

I again suggest making sure you have working batteries in your NOAA weather radios.  Also, be sure to keep your phones charged, especially Saturday evening in case there are power outages.  Some high resolution computer model data suggests there could be power outages in Indiana late Saturday night through Sunday morning.

Indianapolis 500 moved to August; Closer look at weather conditions for the race

If you have not already heard the Indianapolis 500 has been rescheduled for August 23, from its usual Memorial Day weekend, this year due to COVID19 concerns.

The first thought I had after hearing the news was, "It is going to miserably hot and humid for the race."  Many fans that attend the race will say that it is often hot for the race.  In fact, there have been six race days in which the temperature has reached 90°.  Interestingly, when looking back at weather records for August 23 in Indianapolis the temperature has reached 90° on 23 days.

The biggest impact to race fans attending the race will be the humidity.  My original thought was that it would be more humid in late August compared to late May.  After combing through the data it turns out that on average the dew point temperature (measure of moisture in the air) is higher in late August than in late May.

To come up with the numbers I looked at hourly dew point data collected between Noon and 5pm on August 23 and May 30 from 1980 to 2019.  (Yes, the race is not always run on the 30th, but that is the arbitrary date I selected.)  Here are the averages for each day.

AVERAGE DEW POINT
May 30:  58.8°
August 23:  62.3°

Typically once the dew point climbs above 60° it begins to feel uncomfortable.  Once the dew point reaches 70° it feels tropical and oppressive.  So lets look at how many years had an hourly dew point reading of 70°+.

May 30:  5 years
August 23:  9 years

Does this mean that this August 23 will be more humid?  No, not absolutely.  However, historically speaking, the odds are in favor of it being more humid.

7:30pm Update: Latest look at timing of tornado threat

Not much has changed in thinking for Thursday in regards to severe thunderstorms.

This is my attempt at giving some type of timeline for the evolution of storms throughout Thursday in to Friday morning.  The timing is highly subject to change as things begin to develop.

The main threat for southeast Missouri, southern Illinois, and western Kentucky will be Thursday evening.  The main threat for central Indiana will be Thursday evening through early Friday morning.

One thing to note.  A warm front will be passing through central Indiana during the day.  Much of the morning will be spent on the "cool" side of the front.  Once the front passes, temperatures will quickly climb in to the middle and upper 60°s.  Humidity will begin to increase as southerly winds increase (gusting to 40 mph) bringing in moisture.

Thunderstorms may develop on the north side of the warm front late morning/early afternoon.  Some of these will have the potential of producing large hail and an isolated tornado cannot be ruled out.

Computer models suggest damaging winds could be produced as storms roll through central Indiana Thursday night into Friday morning.  Data also suggests the potential for isolated power outages.

Power outage potential through Friday morning.

Due to the timing of storms, and the potential for power outages, make sure your NOAA weather radios have working batteries in case warnings are issued.

Update from Storm Prediction Center Concerning Thursday Storms

The Storm Prediction Center has published their afternoon "Day 2 Outlook".  The outlook covers the time between 8am EDT Thursday through 8am EDT Friday.

To note, the threat has shifted slightly further north according to SPC forecasters.

While I am not a fan of the "Enhanced" and "Marginal" outlook areas it is of interest to note the location of what I'd refer to as a "heightened" risk for severe storms.  In fact, the enhanced area lines up with the area I suggested of "greatest risk" earlier today.

Tornado Probability 8am EDT Thursday through 8am EDT Friday

The main threat continues to be damaging wind and tornadoes.

Computer model projection of power outages through Friday morning.

With damaging wind and tornadoes being a threat, the potential does exist for some power outages across central Indiana.

Storms in Missouri will likely occur the afternoon/early evening.  Storms in southern Illinois and western Kentucky will likely occur during the late afternoon/evening.  The window for storms in Indiana will be evening in to the night.

I'll post another update this evening as more data becomes available.

On a side note... I am considering providing live streaming coverage of storms Thursday evening/night.  Is that something you would watch?  Let me know by leaving a comment.

Severe Weather Threat Thursday in to Friday Morning

While most people's attention is on the current COVID19 situation impacting the country and the world, I don't want you to lose site of what is happening with weather in the Midwest.

An area of low pressure is projected to move out of the Rocky Mountains tonight and sweep across the central United States.  The low is going to bring energy, along with a couple fronts, allowing for thunderstorm development.  Some of these thunderstorms could be strong to severe Thursday in to early Friday morning.

The Storm Prediction Center has several states included in a "Slight Risk" for severe thunderstorms Thursday morning through Friday morning.

I've tried to narrow it down to an area that the latest data suggests has the "greatest" risk for severe storms between 3pm EDT Thursday and 5am EDT Friday.  The threat moves west to east over the time period.

Wind appears to be the main threat from storms that develop.  However, data suggests there is a tornado threat from storms.  I've highlighted (orange) an area where I think the highest chance for tornadoes to develop.  While the window is long - from Thursday morning through Friday morning - that window is not for the entire area.  Similar to the image above, the threat will begin Thursday morning in eastern Oklahoma and spread east with storms.

The threat transitions to late Thursday night in to Friday morning for southeast Illinois, southwest Indiana and northern Kentucky.  That means for some the threat will be overnight Thursday in to Friday.

I can't stress enough having a way to be alerted to severe weather warnings, especially late at night.  The best way is to have a working NOAA weather radio.  If you don't, it may be worthwhile to have someone stay up and keep an eye on the weather via television and wake up the family if a Tornado Warning is issued.

I'll post more updates and more data becomes available.

Severe Weather Preparedness Week: Tornado Warning vs Tornado Watch

Do you know the difference between a Tornado Warning and a Tornado Watch?  Many people do not.  It all comes down to “when to take action” and “when to prepare to take action”.  Here is an explanation of what each means and what you should do when one is issued.

TORNADO WARNING

A Tornado Warning is issued by your local National Weather Service office.  The warning is issued when either a tornado has been spotted or doppler radar indicates a tornado is imminent.  Most importantly, it is the time to TAKE ACTION.

Take shelter indoors immediately.  Go in to the location in your home, work, school, shopping mall or other building’s location designated as your tornado shelter.  Oftentimes it is a basement or an interior room (bathroom, closet, or hallway).  You want to stay away from windows and put as many walls between you and the outside as possible.  If you need help determining a good location, check out this page from FEMA.

Tornado Warnings are issued for individual storms, known as storm-based warnings or polygon warnings.  However, for most, the warning is displayed for counties.  Make sure you know which county you live, work, and frequent so when a warning is issued, you know if you are included in the warned area.

TORNADO WATCH

A Tornado Watch is issued by the Storm Prediction Center when conditions are favorable for the development of severe thunderstorms capable of producing tornadoes.  When a Tornado Watch is issued, it is often in effect for six hours.

There are times when conditions exist that could produce strong tornadoes.  In this event, the Storm Prediction Center can issue a Particularly Dangerous Situation (PDS) Tornado Watch.  These are issued a few times a year.

A Tornado Watch is your “heads up” alert.  Usually, there is not an immediate threat, however it is time to prepare in case a Tornado Warning is issued within the next couple of hours.

Right now is the time to come up with a plan of where to take shelter if a Tornado Warning is issued.  Once coming up with the plan make sure you go over it with your family.  Also take a few minutes to discuss where to go if at school, at work, at the mall, or at a park.  While you don't have to plan for every single location, get the idea of where it is safe to go so you can quickly figure it out wherever you area.

Work Week Forecast for Cape Girardeau

I'm going to start putting 7-day forecasts together for Cape Girardeau/southeast Missouri.  It has been a few years since I put specific numbers to that area, so it may take a little bit of time to re-calibrate my forecasting for that area, so bear with me.

Latest data suggests low clouds may obscure the sun for much of the day Sunday.  Showers return to the area Monday.  Then there is a nice warm-up coming for Tuesday with partly cloudy skies.  Rain chances return starting Wednesday, continuing until a cold front tries to pass through the area going in to the weekend.

Work Week Forecast for Indianapolis

I'm going to continue putting out 7-day outlooks for central Indiana.

Warmer temperatures move back in to the Hoosier state Sunday.  We'll start the day with clouds but we should have more sun by afternoon.

A few sprinkles will be possible Monday.  Then we turn breezy and warmer Tuesday.

Moisture returns to the state mid-week but it will fall as rain as temperatures will remain above freezing through the end of the work week.  A cold front is projected to move through the area sometime late Thursday or Friday afternoon.  That will cool things down going in to next weekend.

Announcement

You may have noticed different looking graphics on my social media accounts and if you live in central Indiana you may have noticed I was not on the CBS4 news last weekend. There is a reason for those things. After five years working at CBS4/FOX59 my last day was February 29.

I want to thank you for allowing me in to your homes on television and on your mobile screens. I also want to let you know the times I broke in to your your favorite shows was done in an effort to help keep you and your family safe in times of threatening weather. I will continue posting weather information for the various areas I have lived/worked around the country, as I have since the beginning of social media, on Twitter (www.twitter.com/johndissauer), on my Facebook page, and I will likely be posting more often here. What is next for me, I do not know. I am hoping to remain in the central Indiana area as this is home for me – a born and raised Hoosier – but am open to job opportunities. If you know of anything you think would be a good fit, let me know!

- John

Severe weather risk today identified

Those in southeast Missouri, southern Illinois and western Kentucky should keep an eye on the weather late afternoon through evening. Suspect a Tornado Watch will be issued.

Latest data suggests the greatest risk for severe weather today will be in southeast Missouri, southern Illinois, western Kentucky and southwest Indiana.  I'm looking at a window between 2pm CDT and 9pm CDT.

While damaging wind and large hail remain a threat from thunderstorms, there is also the potential for a few tornadoes in the highlighted area - some of which could be strong.

I suspect the Storm Prediction Center will issue a Tornado Watch this afternoon for part of the highlighted area.

Be sure to follow me on Twitter for further updates.

What to do when a Tornado Warning is issued

In light of Monday's storms and the fact that we are moving in to peak tornado season I thought it would be good to go over what you should do when a Tornado Warning is issued. Watching this 1min 45sec video could save your life!

Please share with family and friends.

One additional suggestion if you are in a car and a Tornado Warning is issued. First and foremost you should find a nearby sturdy building and go inside. The recommendation in the video is for situations where you don't have time for that and you can see the tornado.