July 2021

[Cpv17]

Yeah based on some of the latest data I’m seeing I think Brazoria, Galveston, & Wharton counties could possibly be added to the FFW.

[don]

0z GFS has shifted the heaviest axis of moisture further northeast. Offshore and along the middle and upper Texas coastal counties.

[Stratton20]

Interesting, definitely will see if the flood watch geta extended further Northeast

[don]

0z Canadian has some excessive qpf amounts in the southwestern counties and coastal bend area.

[Stratton20]

Don yep saw that as well, interesting next couple pf days

[Scott747]

Hi-Res euro almost spins up a depression just off Corpus today before moving towards Laredo, but everything is pointing towards it staying in the mid levels.

Almost doesn't matter as the results will be similar to a truly low level tropical system and there is potential for a nocturnal event over the next few days.

[don]

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
427 AM EDT Wed Jul 07 2021

Day 1
Valid 0350Z Wed Jul 07 2021 - 12Z Wed Jul 07 2021

...THERE IS A HIGH RISK OF EXCESSIVE RAINFALL ACROSS THE LOWER TO
MIDDLE TEXAS COAST...

...Lower to Middle Texas Coast...
Potentially considerable to life-threatening flash flooding setup
unfolding across the South Texas coast with the introduction of a
High Risk in the Day 1 Excessive Rainfall Outlook. The synoptic
setup characterized by a mid/upper level weakness over South Texas
with a surface trough/weak low centered over extreme South Texas
has provided deep southeasterly inflow, sustaining the anomalously
high moisture airmass. The latest blended TPW products show PWs in
excess of 2.2-2.3" along the coast with 20-30 kts of inflow in the
lower levels. There was a noted QPF increase in the 00Z hi-res
guidance with the potential for extreme rain rates associated with
convection developing along the coast. The HREF probabilities of
exceeding 3"+/hr reach 30-35 percent at times this morning and
again tonight/early Thursday morning while the probabilities of
exceeding 5" for the period are above 90 percent. Some of the
deterministic hi-res models show totals in excess of 10" in what
will likely be a couple rounds of slow moving, persistent
thunderstorms. Finally, the 100 year ARI exceedance probability is
up to 30 percent from the 00Z HREF. With that said, there remains
some 'bust' potential if some of the deeper convection holds just
offshore, tied to where the better instability may end up. This
could limit the inland extent of any deeper convection or keep it
just offshore. But driving the potential higher end flash flood
threat is the very wet soils and antecedent conditions. Previous
heavy rainfall over the area (6" to locally 10") has primed the
soils and the latest FFG is very low. The 7-14 day anomalies are
400 to 600 percent of normal and the latest NASA SPoRT soil
moisture shows 70-90 percent soil saturation in the 0-100 cm
layer. Going with an ingredients based approach combined with the
latest antecedent conditions, after coordinating with affected
WFOs, a High Risk was introduced along the immediate Lower to
Middle Texas Coast.

[don]

Looking at radar and satellite this morning the system is definitely getting that "tropical look". I'm assuming someone's watching it just incase. Because a GOES satellite floater was put over the system.

[Cpv17]

Looks like the rain is having a hard time trying to push north.

[don]

Yep things may be more of the popcorn variety of showers north of 59 today.Tomorrow when the low is further inland is when inland areas may see more widespread coverage.Like Scott mentioned im a little concerned about a core rain event setup Thursday night into Friday.

[Stratton20]

Yeah im just watching it just in case the Low decides to shift into the Gulf, definitely has a good spin to it

[djmike]

Flooded in and around Beaumont by this one band.
Man these bands this summer pack a punch!

[Stratton20]

at least on my radar, it looks to me like the Low is farther north than where models currently have it at

[snowman65]

Clearly has a center of circulation. Bands of rain all day it looks like. Hopefully it wont be a days long event.

[don]

Eric Webb
https://twitter.com/webberweather/statu ... 6621656068

[Stratton20]

I honestly think this could develop, its close enough to a large water source just like what Eric Webb says plus it had the characteristics, I know the NHC probably wont jump the gun on this, but this already looks pike a depression to me

[don]

Looks like the friction of the coast may be helping it to try to wrap up,seems like its almost a depression. But it will probably not get organized enough for any TC designation.The reason why the rain is having a hard time moving past the coastal counties, is because the low is tightening up, thus pulling the moisture around itself.That is expected to change though over the next couple of days and my concern is that the system is going to sit there stalled for a few days, and as the area of low pressure broadens out heavy rain bands will move inland and train over the area.

[Stratton20]

Don how would land friction help this low organize? And how long do you think this Low could meander around for?

[mcheer23]

12Z GFS is a little more aggressive with rainfall totals.

SGR 4.45
GLS 8.12

Bullseye of 12.36 right by chocolate bay

[don]

12Z GFS agreeing with some of the mesoscale models showing a core rain event starting tomorrow night.12Z Canadian also has it but further west around the coastal bend region.