Live Chasing!

Wednesday, April 25, 2012

April 3, 2012 chase

This was definitely a surprise chase day for me. 

Synoptic environment:
A compact upper level low was spinning over NM by 12Z and the associated 500mb low was progged to move slowly NE throughout the day. 

A 60kt jet streak was located at the base of the 500mb low and was forecast to move over the N TX area during the early afternoon. 
Note the SW 55kt flow at DFW.

The upper level low moved N throughout the day and we actually had southerly 55 kt flow by 00Z. 

850mb flow was southerly and around 25-30 kts. 

At the surface, there was appreciable moisture with dewpoints in the upper 60's.  Winds were ESE at around 5-10 kts. 

There was a definite outflow boundary from previous night's convection in OK that was making it's way south.  Notice the easterly and northeasterly winds running roughly along a line from DFW area to Texarkana.  I noticed this in the morning and it was plain as day on vis satellite.  I didn't know at the time that this would help to contribute to the mini-tornado outbreak that I was to commence later in the afternoon.

A line of elevated storms had already developed along the dryline in western North Texas and was making a slow progression to the east.  I decided, after getting back from the doctor's office, that I would go out west and do a test run with the video stream.  Although there were some breaks in the cloud cover to the east of the line of storms, I didn't think that discrete convection would fire around the metroplex so I headed west to Weatherford.  I set up at a truck stop along I-20 and started streaming the rotating, yet elevated, storm that was moving into that area.  I messed around with that storm for about 15 minutes until I noticed a cell developing south of the metroplex and ahead of the main line.  I quickly jetted east on I-20 and by the time I had reached western parts of Fort Worth, the storm became tornado warned.  I figured that I would be able to intercept somewhere east of I-35 and eventually made my way into the strong winds and heavy rain of the FFD around the Kennedale area.  I knew that the meso had to be to my south because of the northerly winds.  When I got into the clearing in the bear's cage, I turned off onto Little Rd near the I-20/287 interchange.  As I made my way down the road I caught the first glimpse of the tornado.

I headed to the on ramp of 287 and stopped to set up.  The tornado was less than a mile to my SW and I was able to get out and make a quick judgement call that the tornado was going to move just to my south. 

What commenced was the best footage of my life:




The tornado passed 1/2 mile to my south and displayed varying shapes (cone/stovepipe, multi-vortex, no condensation funnel, ragged tube) as it moved to the northeast.  This is the first time that I have seen multiple vortices up close and personal.  Pretty interesting how it did that while on the highway.  I couldn't believe cars weren't bailing out of there.  I don't think some of them knew what was actually going on or didn't realize the situation until it was upon them.

The descending RFD was a pretty dramatic sight.  When you get this close you really lose sight of the massive wall cloud over your head.  After losing sight of the tornado, I quickly drove down to the place where the tornado crossed and turned around.  I snapped a few photos of the damage.


 The tornado continued into the Arlington area causing EF-2 damage.

I drove back to I-20 and headed east to see the tornado roping out. 


I was quite worried because my wife was working at a nursing home in the Euless/Bedford area and the meso was heading in her direction and still showing strong rotation.  After calling and warning her about the incoming storm, I headed east and then north to reposition on the storm.  I wasn't able to get another good vantage point of the base of the wall cloud, but I did get a few structure shots of the meso with a beautiful RFD cut. 



Called it a day to the east of DFW airport at around 2:00 pm.  This was the earliest that I had returned home from a successful intercept! 

Here are the storm reports for that day:

Radar image of supercell at approximate time of my footage:
Kennedale/Arlington Tornado
www.srh.noaa.gov/fwd





Monday, April 2, 2012

4/2/12

I've been watching this system evolve over the past couple days and haven't posted about it.  The closed 500mb low is currently over NM and an attendant 90kt jet streak is rounding the base of the low.  The position of the low is far west of the dryline placement today, which is located roughly from Canadian-Childress-SW TX with a slight bulging near the Red River.  This morning the WRF 4km models were showing CI occurring around 23-0Z from far Western OK down to just a couple counties west of Fort Worth.  The HRRR was also showing CI closer to the SPS area.  The problem I'm seeing right now is that it looks like the thin layer of moisture (around 100mb deep) is being mixed out ahead of the dryline south of Childress.  This could make it harder for CU to break through the cap to the west of Fort Worth.  Now, the HRRR is only showing CI in Western OK closer to the surface low. 
abi METAR plot

If storms can fire, they will become severe very quickly with MLCAPE values AOA 3000 J/kg.  If storms can remain discrete, I believe that as the upper level support increases from the west and bulk shear values increase AOA 40kt, then we can get some massive HP supercells with few reports of weak tornadoes.  If I were positioning today, I would be parked in Altus, OK (where a cu field is developing) and watch to see which storm becomes dominant.  The slow storm speeds today should make for easy viewing of the storms.  Structure shots will be a premium today! 

I will be sitting at home tonight watching KU try for another basketball championship.  GO JAYHAWKS!!