Tour 1 has started

This weekend the first ‘Cloud 9’ tour of 2016 started. Unfortunately (from a chasing point of view) the plains are really quiet at the moment when it comes to weather. They have headed out to San Antonio were we also spend a few days at the end of our trip in 2014.

Next Saturday a new system is forecast to move across the plains, though at this point the positively tilted closed off upper low does not seem to interact very well with the low level moisture it should give them at least something to chase.

500wh.conus

An historic day

Today

First outlook for later today shows a large area with a 10% chance for tornadoes over Oklahoma, Kansas, Nebraska and a tiny bit of Texas. The chance for EF2 or stronger tornadoes is also 10%.

day1probotlk_20160426_1200_torn_prtThis amounts to an Enhanced Risk for tornadoes. The same area however has a 45% probability for large hail (>1 inch) and a 10% chance for hail of 2 inches or larger, leading to an overal Moderate Risk.

5 years ago

Back in 2011 the Super Outbreak had started. The night before four people had been killed when a wedge tornado struck Vilonia in Arkansas. SPC had issued a High Risk for April 26, driven by a 30% chance for (significant) tornadoes in the corners of Oklahoma, Texas and Arkansas. The day did bring many tornadoes, with the storm system continuing into the night. Overnight it turned into a line with strong wind gusts and tornadoes killing several people in Mississippi and causing widespread power outages.

25 years ago

This all comes on the 25th anniversary of the Andover, Kansas F5 tornado. Andover is just east of Wichita and pretty much in the center of today’s severe area. The Andover F5 was the last F5 tornado in Kansas, 16 laters the Greensburg, Kansas tornado was the first EF5.

The 2011 Super Outbreak – 2

Before continuing a look at the events of 5 years ago I must mention the current outlooks.

Several models have been consistently depicting a serious severe weather setup for next Tuesday. SPC has been highlighting the area with a 30% risk area since yesterday. There will be several days with severe storms possible but the main focus at the moment is on Tuesday April 26… the 25th anniversary of the Andover, Kansas F5 tornado. At this moment Oklahoma City (and Moore and Norman), Tulsa and Wichita are in the area with the highest risk.

Five years ago — the wording in the D4-8 outlook wasn’t actually too alarming. While areas for April 25 and 26 were depicted and tornadoes were mentioned, no special attention was given to April 27. The expected events of the days before made the predictions too uncertain.

Also the current day required plenty of attention as April 22 would get an event of it’s own. SPC upgraded it’s risk from Slight to Moderate in the course of the day, mainly for very large hail but they also identified an area with a 10% tornado chance. In the evening a tornado formed near St. Louis and tracked directly over the international airport with many people trapped inside airplanes. Miraculously the tornado, that was rated EF4, caused no casualties. It did force the airport to close for 24 hours though.

The long term outlook of the next day was the first in which April 27 was specifically mentioned:

   AMPLY UNSTABLE AIRMASS COMBINED WITH THE 
   STRENGTH OF THE UPPER SYSTEM AND
   ASSOCIATED FLOW FIELD SUGGESTS WIDESPREAD 
   SEVERE WEATHER CAN BE EXPECTED...
   INCLUDING THE POTENTIAL FOR TORNADOES.