Saturday, April 14, 2012

Significant Tornado Outbreak Expected Today

Overall Outlook

Chance of a tornado within 25 miles of any point
There is a 45% chance of tornadoes within any given point today in central and eastern Nebraska as a strong storm system's winds combine with the wind field of a warm front to initiate tornadic thunderstorms and supercells. Further south, there remains a 30% chance for tornadoes, just slightly lower, but still very high where tornadoes can be anticipated.

The latest sounding from OUN (Norman, Oklahoma) indicates some pretty stunning things. First, we have over 3000 j/kg of instability- a lot of instability to work with. The Supercell index is over 16, which is very high. Even more concerning is in the bottom right, where analogues to previous soundings are matched against this one. From that, 9 other soundings matched up with this one, two of them described as 'Significant' supercells. Using the bottom pink wording, one can deduce that there would theoretically be a 62% chance for a tornado if the sounding could predict the future.

A strong, amplified 300mb jet stream will be pushing eastward, adding a lot of energy to the system responsible for this event. The system will be up near Nebraska. Increasing the system strength increases the surrounding wind field, thus increasing rotation and instability potentials. The storms will begin when the dryline begins to shift east to try and escape the oncoming cold front from the west (which will not happen). With up to 3000 j/kg of instability and over 3 on the EHI index, expect storms that form to quickly become tornadic.

Initiation, or the initial occurrence, of these storms has been sort of a gray area in recent days. Here is the latest initiation graphic from the National Severe Storms Laboratory (NSSL)'s personal WRF model.


I have circled the area where the strongest storms are expected to be at 7:00 PM CDT tonight. Now, this is what I see as the initialization of strong to severe storms. But see below's actual initiation graphic.

Actual initialization is expected in west or central Oklahoma around 4-5 PM CDT, as the dryline edges east and the cold front moves even faster east than the dry line is.
Here is my tornado graphic.
Blue: Low risk for tornadoes
Dark blue: Moderate risk- a few weak tornadoes
Purple: Substantial risk- many weak-moderate tornadoes
Green: Dangerous risk- several strong tornadoes expected
Andrew

11 comments:

Aran said...

I know for a fact that we will have many deaths if they don't hear the tornado warning.A PDS tornado watch will probably be issued.We will be seeing a lot of those new tornado warnings.

ERN WX said...

The new tornado warnings hopefully will be taken more seriously. Let's hope that people have heeded the warnings about this dangerous situation.

ERN WX said...

A very large high risk area is in place. I expect a very catastrophic outbreak. There will be tornadoes that will completely destroy WHOLE towns. In addition to tornadoes, expect very large hail (baseball sized and larger), winds in excess of 80 mph, and dangerous cloud-to-ground lightning. The high risk area is huge.

Anonymous said...

Hey Andrew, it's that waiting-to-be spotter from Wichita. Now the seperate high risks are congealed but the 45% hasn't been stretched. Bad news is the 30% stretches from Norman to that 45% and also I don't think March 2 had a 45%. I am salvaging in my home for supplies of course to prepare. This outlook has been been difficult however compared to March 2. Still better to be safe than dead (sorry is out of equation when life is in the balance). I am very optimistic about people in the worst case scenario because the Plains people have many awareness advantages against storms that people elsewhere may not have. I will be fine!

ERN WX said...

Anonymous, take care of yourself!!! This is one nasty outbreak. I think they only went with a 30% risk of tornadoes with the March outbreak. I have been out in your area storm chasing before. Most of the people prepare well ahead of impending danger.

ERN WX said...

I sometimes wonder why I don't move to the Midwest. The East Coast has been so boring this year.

Anonymous said...

Hello...i know this will be a deadly outbreak?i been living the southern plains for 6 years now....im still not used to tornados...they are so scary and the tornados sirens freak me out.........being from louisiana we rarely see them...everybody be safe and prepared...

ERN WX said...

Mesoscale Discussion for the Texas panhandle, the Oklahoma panhandle, and western Kansas. A tornado watch is likely. Storm initiation might be going on.

Anonymous said...

Thanks ERN WX! It's 10:10 AM and the sun is trying to come out. The sun is the trigger and key.

ERN WX said...

Starting at 11 central, turn on your NOAA weather radios.

ERN WX said...

Instability rising.