April 2021

General Weather Discussions and Analysis
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DoctorMu
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srainhoutx wrote: Fri Apr 23, 2021 1:47 pm 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
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don wrote: Fri Apr 23, 2021 1:42 pm 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?
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jasons2k
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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.
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don
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Areas south of I-10 may have to wait till tonight for any thunderstorms,assuming a squall line develops with the frontal passage.
BlueJay
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We got some rain! Maybe 1/4 inch.
Cpv17
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don wrote: Fri Apr 23, 2021 1:42 pm 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?
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DoctorMu
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jasons2k wrote: Fri Apr 23, 2021 2:16 pm 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. :lol:
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DoctorMu
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Cpv17 wrote: Fri Apr 23, 2021 3:07 pm
don wrote: Fri Apr 23, 2021 1:42 pm 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.
Last edited by DoctorMu on Fri Apr 23, 2021 3:45 pm, edited 2 times in total.
Cromagnum
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don wrote: Fri Apr 23, 2021 2:31 pm 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
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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.
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don
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Cpv17 wrote: Fri Apr 23, 2021 3:07 pm
don wrote: Fri Apr 23, 2021 1:42 pm 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?
It means the amount of shear is higher than the instability,and if the shear is sufficient enough and storms can tap into it, the high amount of shear can makeup for a lack of instability.And cause a supercell to form.

We need to watch the streamer cells moving into metro Houston from the west and south, as these individual cells can sometimes produce brief weak tornadoes.
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DoctorMu
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Got a few minutes of rain, but now in the hole in the middle of the storm.
Last edited by DoctorMu on Fri Apr 23, 2021 4:42 pm, edited 1 time in total.
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DoctorMu
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OK. NOW it's pouring. This would have been great day to break out the new electronic rain gauge that arrived in the mail yesterday (old one was a victim of the hail storm)...but that might have diverted the showers. ;)
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jasons2k
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Look towards Del Rio as that impulse swings through later tonight...
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jasons2k
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DoctorMu wrote: Fri Apr 23, 2021 4:18 pm OK. NOW it's pouring. This would have been great day to break out the new electronic rain gauge that arrived in the mail yesterday (old one was a victim of the hail storm)...but that might have diverted the showers. ;)
I would suggest a backup cylinder just in case :-) They are also super accurate.
Cpv17
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jasons2k wrote: Fri Apr 23, 2021 4:58 pm Look towards Del Rio as that impulse swings through later tonight...
I don’t see any model that shows anything of significance coming from that...
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jasons2k
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Cpv17 wrote: Fri Apr 23, 2021 5:18 pm
jasons2k wrote: Fri Apr 23, 2021 4:58 pm Look towards Del Rio as that impulse swings through later tonight...
I don’t see any model that shows anything of significance coming from that...
Famous last words :lol:

Justin Stapleton just mentioned it on KPRC...

Sometimes these mesoscale features are too fine for the models to resolve. It's probably a speed max that will help storms penetrate the cap later on. Something to monitor.
Cromagnum
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Unless something major comes through later this evening, it's another missed opportunity for meaningful rain towards the coast. It's getting really old.
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DoctorMu
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jasons2k wrote: Fri Apr 23, 2021 4:59 pm
DoctorMu wrote: Fri Apr 23, 2021 4:18 pm OK. NOW it's pouring. This would have been great day to break out the new electronic rain gauge that arrived in the mail yesterday (old one was a victim of the hail storm)...but that might have diverted the showers. ;)
I would suggest a backup cylinder just in case :-) They are also super accurate.
I love them, but they keep getting wrecked by hail, wind, heavy rain. :lol:

NWS radar, storm accumulation has us just over 2 inches...and no sign of hail. High shear and low CAPE FTW.
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djmike
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So is that it? Our grand finale Beaumont southward?
Was expecting a sprinkle or two or a rumble of thunder. All looks north and east. Is something supposed to develop later? A squall line or something?
Mike
Beaumont, TX
(IH-10 & College Street)
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