TS Bertha

[kayman]

I do wonder if the low-level circulation is reforming further south near the mid-level circulation in Bertha.

[Chinook]

what a weird tropical storm

surface low by Louisiana

convective storm far south

 

 

 

 

[vortex95]

6 hours ago, Chinook said:

what a weird tropical storm

surface low by Louisiana

convective storm far south

 

 

 

 

You can see the mid-level center spin on radar near CRP currently.  Talk about a tilted vortex sfc to mid-levels!  This one of the most "disconnected" TCs I think I have ever seen.  Great case study.

The ECWMF handled this evolution very well.  Compare its 925 mb RH/streamlines to its 500 mb RH streamlines, and the disconnect was fcst very well.

This is about as far as you can get from a classic TC structure, but they exist on a *spectrum*.  You can't use textbook examples all the time for what actually occurs in the real world.

So both Arthur and Bertha  were odd ducks, and even for sheared TC, more atypical for this variant of a TC.  It also shows how the models still struggle w/ initial TC genesis for systems like this.  Pre-Bertha was a non-tropical low that appeared it would remain broad and cold core, and strong shear was factor.  Not that the models can't handle non-tropical to tropical transition, but the overall environment was not favorable, so that likely influenced the models.  Yet the system still managed to form a large, solid LLCC in the mid 990s. 
 

[GaWx]

Parts of Houston metro received significantly more rainfall from Bertha than models had with up to ~5” vs mist progs of ~0.75”. Here’s the final advisory:

BULLETIN
Remnants Of Bertha Advisory Number 19
NWS National Hurricane Center Miami FL AL022026
1000 PM CDT Thu Jul 23 2026

...BERTHA HAS DEGENERATED INTO A TROUGH...
...THIS IS THE LAST ADVISORY...


SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...30.0N 96.0W
ABOUT 40 MI...65 KM WNW OF HOUSTON TEXAS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES


Remnants Of Bertha Discussion Number 19
NWS National Hurricane Center Miami FL AL022026
1000 PM CDT Thu Jul 23 2026

Surface observations over eastern Texas indicate that Bertha no
longer has a well-defined circulation, and has opened up into a
trough. Therefore, the system has dissipated, and this will be the
last advisory.

Bertha's remnants will likely continue to produce some locally heavy
rainfall over portions of eastern and southern Texas, where isolated
flash flooding is possible overnight.

FORECAST POSITIONS AND MAX WINDS

INIT 24/0300Z 30.0N 96.0W 30 KT 35 MPH...REMNANTS
12H 24/1200Z...DISSIPATED

$$
Forecaster Pasch

[Stx_Thunder]

Having more sheared and faster moving TCs in EN summers is always more of a common thing at least over the northern Gulf. Likely due to typically more intense ridging nearby.

The weirdest thing to me was the north-easterly upper shear from the subtrop mid-upper High that was parked north of TS Bertha. Instead of the usual south-westerly shear which commonly keeps most convection on the northern/eastern quadrants.

Bertha's convection was mainly in the southern quadrant. The only other time I remember seeing that was TS Don, back in 2011. Which also went into TX. Its LL and ML circulations were also displaced, but both came into South TX. And not as much as Bertha's were.

 

On 7/23/2026 at 6:10 PM, vortex95 said:

Pre-Bertha was a non-tropical low that appeared it would remain broad and cold core, and strong shear was factor.  Not that the models can't handle non-tropical to tropical transition, but the overall environment was not favorable, so that likely influenced the models.  Yet the system still managed to form a large, solid LLCC in the mid 990s. 

I figured Bertha was not necessarily a fully tropical TC. As the ML circulation deep convection from what I recall on lightning data was showing some more frequent and intense (+)CG lightning over the Gulf, than normal in most TCs.

A "colder" ML core would've had to been the culprit. By contributing to steeper mid-level lapse rates. Which typically results in more frequent and intense +CG strikes in any deep convection. Especially when ML or 700Mb - 500Mb lapse rate gets down to -7 and lower.