4/21/2011 Chase

Well, had to pick up some nasonex for Ayden over in Benbrook and then I headed west on I-20.  Took 180 towards Mineral Wells and got there around 5:30.  Decent cu field began to disintigrate over the next hour.  The cap was just strong enough today.  The warm front became diffuse and the sfc convergence was not strong enough to get things going in N TX.  I thought that being a bit west might help if we received some subtle upper level support.  Didn't happen.  Decided to head home around 6:30. 

Taking a look at the FWD 00Z sounding:

Just enough cap today to keep storms from firing.  CIN of -51 J/kg.  Frustrating because it looked like a decent tornado chance today if storms were to fire along the warm front.  First cap bust of 2011!


A supercell did fire just west of Abilene though.  It was a beast and probably had a rain-wrapped tornado at one point.  Here is a screen grab from GRLevel3:

April 21, 2011 chase forecast

I noticed a couple days ago that there was some potential for storms along the retreating warm front on Thursday.  After coming back to school from a severe weather protocol session, I started musing over data.  I think there is potential for a few reports of tornadoes along the warm front today.  Right now, 20Z, the warm front is along a BWD-ACT-JSD line.  The warm front will continue north through the night and winds are backing up along the warm front.  The area north of the front has been socked in with clouds all day and temperature readings as of 20Z are in the mid 60's.  South of the front temps are running in the low 80's.  Low level shear should be enought to get some low level mesos going with any storm that becomes mature.  With the cap becoming negligible in the next hour or so and with convective temps being reached, I'm afraid that lots of storms will be competing at first.  A pretty robust cu field is moving north along the aforementioned line.  I will monitor trends over the next hour and probably make my way south to get out of the metroplex.  Whether I go east or west from there will be the next choice.

SPC's has 5% tornado probability over the area.

4/14/11 forecast

Well, tomorrow's forecast is a bit tricky.  The main components are set in place for a possible tornado outbreak over SE KS, NE OK, and E OK.  The NAM and GFS agree on a few things:

- negatively tilted H5 trough with westerly jet max nudging in at time of peak heating
- sfc moisture return into warm sector with low to mid 60's Td's nosing into NE OK by 00Z
- Dryline from triple point near KICT draped south along I-35 corridor with associated bulge in N OK
- Cape values aoa 2000 J/kg
- reduced CIN inv of dryline along I-35 corridor from KICT down to red river area
- both are closing off the H5 low.  The GFS the more active one
- Low LCL's aob 1250m

The GFS is closing the H5 low and this is causing veering flow patterns in the low levels along I-35.  This is not boding well for tornadic storms.   The better directional shear will be in the far eastern sections of the warm sector.  If the GFS does verify, storms will struggle to develop low level circulations until they move into better wind fields in E OK/W AR.

The NAM is not closing the H5 low as much and the low level wind fields look much better.  H85 winds are still southerly inv of dryline.  This is contributing to larger clockwise curved hodographs, especially as the llj strengthens into the early evening in E OK.  Sfc flow doesn't back as much along the dryline.  That's a little concerning but I think that if storms do fire along the dryline, they should mature and develop better rotation into the eastern section of the warm sector.

I'm hoping that the NAM doesn't continue to veer the low level winds as the GFS is doing.  I will probably head towards OKC tomorrow morning and reevaluate the mesoscale conditions around 18Z. 









Also, just checked the 00Z 4km WRF model and it looks quite enticing for supercells to form in C OK by 23-00Z and then into S OK a couple hours later. 


Simulated Radar Reflectivity



2-5km maximum updraft helicity