April 2021

[Katdaddy]

Looking interesting for SE TX this afternoon and evening with the main concern N and NE of Houston and ETX.

[jasons2k]

Mesoscale Discussion 0407
NWS Storm Prediction Center Norman OK
1243 PM CDT Fri Apr 23 2021

Areas affected...portions of east/southeast Texas into western
Louisiana

Concerning...Severe potential...Tornado Watch likely

Valid 231743Z - 231945Z
Probability of Watch Issuance...95 percent

SUMMARY...Severe thunderstorms capable of producing tornadoes,
damaging gusts and hail are expected this afternoon and evening
across parts of eastern Texas into western Louisiana.

DISCUSSION...A strong low-level warm advection regime continues
across east Texas into western LA early this afternoon. A warm front
is draped northwest-to-southeast from central TX into southwest LA
per 17z surface analysis. This front should continue to gradually
lift northward over the next several hours. Dewpoints will increase
to the mid 60s to low 70s F near and south of the front,
contributing to increasing low-level instability. Forecasts
currently increase 0-3 km CAPE to around 100-150 J/kg after 20z in a
corridor near the warm front, with mixing ratios around 15-16 g/kg.
Additionally, the front will further augment already favorable
low-level wind profiles suitable for tornadoes. As a
south/southwesterly low-level jet increases to 50+ kt toward 00z,
some upscale growth into one or more bowing segments is possible.
This could increase damaging wind potential. Even as storm mode
evolves, low-level hodographs will remain favorable for mesovortex
formation and a continuation of a tornado threat with eastward
extent into western LA.

[jasons2k]

.70" hail report near New Braunfels.

Cap is busting.

[Stormlover2020]

Hrr is struggling

[unome]

https://twitter.com/NWSSevereTstorm

Severe Thunderstorm Warning including Lockhart TX, Redwood TX, Martindale TX until 2:15 PM CDT

[don]

This setup doesn't happen too often around here, this would kind of be considered a high shear low cape setup,usually its the other way around here locally .With most severe weather events being high cape but low shear events.

[srainhoutx]

Special balloon launch from College Station...

[unome]

Special balloon launch from College Station...

will you interpret for us soundings-challenged weather-boardsters

[srainhoutx]

Special balloon launch from College Station...

will you interpret for us soundings-challenged weather-boardsters

The Cap is razor thin. Looks like enough veering with height for rotating updraft. Hail production Looks possible as well. Stay weather wise this afternoon everyone!

[txbear]

I know this is for NWS Fort Worth's AOR, but it does pan out to our NW reaches just to get some perspective. It'd be nice if HGX had something similar. Experimental as it may be, still interesting to keep an eye on.

https://www.weather.gov/fwd/convectiveparameters

Srain, would you mind helping explain a little of what's in that Skew-T? Am I seeing a cap with high shear and decent CAPE?

ETA: Thanks unome for also asking similar question and srain responding.

[DoctorMu]

Special balloon launch from College Station...

It’s raining in Bryan, but not in College Station. Very juicy but paranoid about either bust or hail.

Never a happy medium!

[Cromagnum]

This setup doesn't happen too often around here, this would kind of be considered a high shear low cape setup,usually its the other way around here locally .With most severe weather events being high cape but low shear events.

How does that translate when you have variable winds with height, but low thunderstorm energy? Does that mean lots of weak tornadoes?

[jasons2k]

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 99
NWS Storm Prediction Center Norman OK
155 PM CDT Fri Apr 23 2021

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of
Central and Western Louisiana
Southeast Texas
Coastal Waters

* Effective this Friday afternoon and evening from 155 PM until
900 PM CDT.

* Primary threats include...
A few tornadoes possible
Scattered damaging wind gusts to 70 mph likely
Scattered large hail and isolated very large hail events to 2
inches in diameter possible

SUMMARY...Thunderstorms will increase in coverage and intensity this
afternoon across the region. A few supercell storms are
expected,capable of damaging winds, tornadoes, and large hail.

The tornado watch area is approximately along and 65 statute miles
north and south of a line from 35 miles south southwest of College
Station TX to 30 miles east of Alexandria LA. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU9).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.

[don]

Areas south of I-10 may have to wait till tonight for any thunderstorms,assuming a squall line develops with the frontal passage.

[BlueJay]

We got some rain! Maybe 1/4 inch.

[Cpv17]

This setup doesn't happen too often around here, this would kind of be considered a high shear low cape setup,usually its the other way around here locally .With most severe weather events being high cape but low shear events.

I don’t understand what any of this means? Could someone explain?

[DoctorMu]

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 99
NWS Storm Prediction Center Norman OK
155 PM CDT Fri Apr 23 2021

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of
Central and Western Louisiana
Southeast Texas
Coastal Waters

* Effective this Friday afternoon and evening from 155 PM until
900 PM CDT.

* Primary threats include...
A few tornadoes possible
Scattered damaging wind gusts to 70 mph likely
Scattered large hail and isolated very large hail events to 2
inches in diameter possible

SUMMARY...Thunderstorms will increase in coverage and intensity this
afternoon across the region. A few supercell storms are
expected,capable of damaging winds, tornadoes, and large hail.

The tornado watch area is approximately along and 65 statute miles
north and south of a line from 35 miles south southwest of College
Station TX to 30 miles east of Alexandria LA. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU9).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.

Starting to look like feast instead of famine. But tornado and/or hail.

We were up and Bryan an hour ago and there was definitely shear upon in the clouds. Classic SE wind low and SW winds aloft.

It has still barely rained IMBY...but the boom could be lowered very soon.

[DoctorMu]

This setup doesn't happen too often around here, this would kind of be considered a high shear low cape setup,usually its the other way around here locally .With most severe weather events being high cape but low shear events.

I don’t understand what any of this means? Could someone explain?

More like the SE rather than the great plains.

https://www.weather.gov/gsp/21Feb97SevereWx

https://www.theweatherprediction.com/we ... index.html


Cape = instability (energy) marker

Shear - difference in wind direction vertically upwards.

Combine high CAPE + shear = bad tornado outbreak. Shear would roll the cloud horizontally, and updraft from the storm would give the tube or funnel vertically.

Under a high shear, low CAPE environment thunderheads are not as high and with lower updrafts tornadoes occur but are weaker. Lower risk of large hail.


High Cape, low shear (Houston) would yield tall t-storms with high updraft.

High CAPE, high shear - College Station through Oklahoma and Kansas = potential for large hail, F3+ tornadoes.

[Cromagnum]

Areas south of I-10 may have to wait till tonight for any thunderstorms,assuming a squall line develops with the frontal passage.

I know this story. A squall does develop but fizzles out as it crosses the southern area. Already seen that several times.

[txbear]

Well it's still somewhat early, and SPC did mention that thinks will really get cranking this evening, but.....looking at HRRR, it just doesn't look like we'll get through the cap along I-10 (I'm sure it's worse further south you go). Was at least wanting a good soak, but not sure that'll happen.

Certainly not crying wolf, just an observation. Looks like DoctorMu certainly lucked out with the rain thus far.