8:00 AM CDT Updated SPC Outlook

The Storm Prediction Center extended the High risk to cover much of the Plains, as convection looks to be coming along easier than first thought.
The main risks remain tornadoes and large hail before storms turn more linear and it turns to a damaging wind threat.
Expect main convection to occur in the afternoon.

-Andrew

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

Significant Tornado Outbreak Likely Tomorrow

In the afternoon Day 2 update, the Storm Prediction Center added a high risk area for east Nebraska and west Iowa. A high risk remains in effect for north central Oklahoma and south central Kansas.

As of now, a deep trough is slowly moving northeast towards Nebraska. Eventually, a cold front will latch onto this system and pull up the dry line to initiate storms tomorrow evening. It can be expected that supercells will dominate the landscape tomorrow in northern Oklahoma and south central Kansas.

Here is my graphic for tomorrow.

As a raging jet stream carrying a strong storm system moves eastward, a strong storm system will pick up the frontal boundaries in place over west Texas and the Oklahoma panhandle. The dry line will move east, bumping into at least 2000 j/kg of instability combined with at least 70 knots of shearing will make for a supercell situation.
The exact coverage of severe weather is not known right now, but enough parameters are in place for a tornado outbreak to happen tomorrow.

Supercells will form in central Oklahoma and south east/south central Kansas, where the greatest tornadic risk is. As the cold front overcomes the dry line overnight, these storms will shift to a more linear threat, with squall lines and derechos possible.

Chase Spot: Enid, Oklahoma.

**Be warned that this situation is extremely dangerous and life threatening. Make all preparations now and do not wait until the last minute. Repeat: This is life threatening and very dangerous.**

Discussion on extreme severe weather at 4:00 pm CDT

Discussion will concern Saturday's threat.

**EXTREMELY DANGEROUS TORNADO OUTBREAK IN WORKS FOR SATURDAY**

A high risk has been issued for Day 2 (tomorrow) by the Storm Prediction Center. This has only happened 3 times before. Not even April 27, 2011 had a high risk on Day 2. That shows you just how bad things could get.

At this point in time, if you are in the high risk and have time, I would suggest you evacuate. This looks to be EXTREMELY DANGEROUS, and it is extremely possible that a super tornado outbreak occurs.

DO NOT take this lightly. 'High Risk' is the highest possible category for severe weather. Get your shelter ready now. Gather food and water supplies. I am sincerely concerned for the high threat of loss of life and property tomorrow in the High Risk.

To any amateur storm chasers: Do not chase tomorrow. This is high above what most chasers can chase.