2018-03-18 Event: TX

[Brian McKibben]

Just finished looking at 00z Convective Allowing Models (CAM) and they are all placing a potential storm between 380 and Red River. 18z 3km NAM showed this too and now 00z runs increase the confidence. Quick pick soundings show a volatile env with 0-1 shr wrll above 20 kts. Surface winds are SE or ESE. Mid 60 tds are leading to aoa 2000 CAPE.

I would target Denton right at I35 and 380. Ill likely arm chair chase this event to keep family apprised of changing conditions.

Sent from my SM-G920P using Stormtrack mobile app

 

[Brian McKibben]

I am looking at the data trying to find out what is the cause of this convection in N Texas. All models are showing it now. HRRR, HRRRx, 3km NAM, WRF(NSSL, ARM).

The main jet streak and shortwave don't really arrive until 06z.
[Broken External Image]:http://climate.cod.edu/data/forecast/NAM/2018031800/SGP/NAMSGP_500_spd_030.png

But the latest HRRR has this thing firing closer to 18-19z.
So what is the cause?

Here is the 500 hPa chart at 18z. It shows another jet moving over the N. Texas region prior to the primary jet. This jet came out of Mexico. The timing of this jet coincides with the development of convection. So my best guess is that the shortwave as seen on the 700 hPa map associated with this jet, which originated from a subtropical jet, is the cause for this convection. Moisture was already in place so we just need a firing mechanism. Lift associated with this jet seems to do the job. There is a pretty significant push of the dryline too throughout the day.

[Broken External Image]:http://climate.cod.edu/data/forecast/NAM/2018031800/US/NAMUS_500_spd_018.png

 

[Brian McKibben]

Still an uncertain scenario across N. Texas for this afternoon. The 12z CAM runs all dropped the storm development in this region. HRRR was first to get rid of it. Then the 3km NAM and WRFs all got rid of the convection too. And then the subsequent HRRR runs bring it back. Looking at GOES16 there are some cloud breaks west of I35 and south of the Red River.

Now it is the wait and see game. Tds near and south of I20 are aoa 65° F. I would still make a target along the 380 corridor and perhaps 50 miles west of I35. One this for sure is with the steep lapse rates and moisture we should see some large hail.

 

[Brandon Centeno]

I have very little reason to doubt CI this afternoon.