11:30 AM CDT SPC Outlook Update

Overall severe weather threat

Risk of tornado within 25 miles of any point

In the most recent Storm Prediction Center outlook update, the 45% tornado risk area was pulled south, indicating a shift towards more tornadoes in Kansas.

This remains as dangerous a situation as ever, and I ask all of you to stay vigilant throughout the night.

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Particularly Dangerous Situation Tornado Watch #165

A Particularly Dangerous Situation, or PDS, tornado watch has been issued for north Oklahoma and central Kansas.

Probabilities in the above graphic indicate a 'High' likelihood of tornadoes, even a high likelihood of EF2+ tornadoes. Thunderstorms are erupting in central Kansas. With instability and rotation in place, expect these storms to go supercellular, if they are not already.

This watch expires at 6:00 PM CDT.

Repeat: This is a PDS Tornado Watch, meaning that these storms may threaten life and property. Plan accordingly.

Mesoscale Discussion #521

A mesoscale discussion has been issued by the Storm Prediction Center over North Texas, the Oklahoma panhandle, and southwest Kansas as towering cumulus clouds appear to be signaling the start of today's convection.
With the dryline only a little ways away from this mesoscale discussion, and dew points/instability rapidly rising in and to the east of this discussion, any convection that does start up will quickly become strong/severe and may have some rotation as a jet streak progresses eastward.

Andrew

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