April 2021

General Weather Discussions and Analysis
txsnowmaker
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jasons2k wrote: Wed Apr 21, 2021 5:35 pm NWS is already mentioning the "C" word for next week's system.

Hoping for some decent rains this Friday.
What is the “c” word?
davidiowx
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txsnowmaker wrote: Wed Apr 21, 2021 7:10 pm
jasons2k wrote: Wed Apr 21, 2021 5:35 pm NWS is already mentioning the "C" word for next week's system.

Hoping for some decent rains this Friday.
What is the “c” word?
That would be “cap”. Strong SW flow at it again. It’s still a way out so things can and will change
Cromagnum
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txsnowmaker wrote: Wed Apr 21, 2021 7:10 pm
jasons2k wrote: Wed Apr 21, 2021 5:35 pm NWS is already mentioning the "C" word for next week's system.

Hoping for some decent rains this Friday.
What is the “c” word?
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don
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12z NAM still showing discreet supercells over the area.
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Screenshot_2021-04-22 Models NAM 3km CONUS — Pivotal Weather(1).png
Screenshot_2021-04-22 Models NAM 3km CONUS — Pivotal Weather(2).png
txbear
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HGX including wording that cap may limit rain for tomorrow, now too. Super dry SW flow that davidiowx alluded to for next week's system as well.

I think i'm looking at the HRRR model correctly for tomorrow, and it doesn't look promising for rain with SW winds aloft and a big drop in the dew point. But please correct me if I'm wrong.
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don
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Yes,there's a chance especially south of I-10 that the cap may struggle to break.But looking at a few of the 12z mesoscale models and global models most show the cap breaking.But things may be more conditional for the coastal tier of counties.
Cpv17
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I’m not sure what y’all are seeing saying we won’t be getting much rain over the next week or so. Models are showing 2-4” for most of us over the next 10 days.
txbear
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Thanks, don.

Cpv - just looking at HRRR and what's available currently for WRF compared to what HGX is saying in their discussions. It seems to my amateur eye on the forecast sounding for my general area on the west side has it looking close to a capped situation for tomorrow. I've been pegged the past couple of chances of having anywhere from 1-2", but the cap has limited to that to maybe a 0.1 at its very best. Lucy and the football.

Not saying I'm geared up for an outbreak, but rain sure would help take the ease of the sprinklers. Pines around are also looking a bit parched in color.
Cpv17
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txbear wrote: Thu Apr 22, 2021 11:50 am Thanks, don.

Cpv - just looking at HRRR and what's available currently for WRF compared to what HGX is saying in their discussions. It seems to my amateur eye on the forecast sounding for my general area on the west side has it looking close to a capped situation for tomorrow. I've been pegged the past couple of chances of having anywhere from 1-2", but the cap has limited to that to maybe a 0.1 at its very best. Lucy and the football.

Not saying I'm geared up for an outbreak, but rain sure would help take the ease of the sprinklers. Pines around are also looking a bit parched in color.
I think we’ll get our fair share of rain over the next few weeks. Things are looking pretty promising from what I see. Best they’ve looked in a while.
Cpv17
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Latest Euro run is quite interesting.
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jasons2k
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Ruh roh - best I could draw on my phone
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Houstonkid
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Appears NWS removed Severe wording from the forecast for us in Harris Co.. Pretty sure I saw it there this morning.
unome
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Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
321 PM EDT Thu Apr 22 2021
...

Day 2
Valid 12Z Fri Apr 23 2021 - 12Z Sat Apr 24 2021

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS THE LOWER
MISSISSIPPI VALLEY AND THE GULF STATES...

There continues to be a strong signal for a heavy rainfall event
developing over eastern Texas and Oklahoma that spreads east
across the Lower Mississippi Valley and the central Gulf Coast
states. PW values build to 1.5"+ (nearing 2 standard deviations
above normal for late April) along the Gulf Coast while continuing
to transport northward into the central U.S.
A low pressure system exiting the Rockies will track across the
southern tier states, lifting a warm front up the Mississippi
Valley while a cold front sweeps in a few hours later. The upper
level jet will be passing overhead and provide divergence
aloft/enhanced vertical motion in the low/mid levels of the
atmosphere. Low-level inflow rises to 40-60 knots (with effective
bulk shear to match), close to the value of the mean 850-400 hPa
wind. Instability will be increasing across the Southern Plains
ahead of the cold front with CAPE values of 1500+ J/Kg supporting
periods of heavy rainfall.

There is some degree of spread on where the maximum values will
occur, but the overall consensus suggests a fairly large area
where 2-4 inches will fall with very isolated maximums of 5-6
inches possible. Although some locations have had several days to
recover from recent soaking rains, rain of this magnitude may
quickly become problematic, thus increasing the threat for flash
flooding. The Slight Risk area was slightly reshaped for this
update, but remains about the same. The Marginal Risk area spans
from eastern Texas to Alabama and from central Oklahoma into the
Midwest. The LCH/Lake Charles LA, SHV/Shreveport LA, and
LIX/Slidell LA forecast offices were consulted in this update.

Roth/Campbell


I'll be happy with 1/2"
fill_94qwbg - Copy.gif
txbear
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jasons2k wrote: Thu Apr 22, 2021 2:42 pm Ruh roh - best I could draw on my phone
jason - those are some decently high SigTor probabilities. the ingredients seem like they'll definitely be there for things to get a bit sporty if/when capping can be overcome especially with the amount of shear that will be in place. think SPC will upgrade the outlook to have a small bullseye of moderate risk a day out?

i'm hoping that we can get some good rumbles of thunder and a good soaking, with the severe roaming about in rural areas avoiding folks.
Cromagnum
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unome wrote: Thu Apr 22, 2021 3:05 pm Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
321 PM EDT Thu Apr 22 2021
...

Day 2
Valid 12Z Fri Apr 23 2021 - 12Z Sat Apr 24 2021

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS THE LOWER
MISSISSIPPI VALLEY AND THE GULF STATES...

There continues to be a strong signal for a heavy rainfall event
developing over eastern Texas and Oklahoma that spreads east
across the Lower Mississippi Valley and the central Gulf Coast
states. PW values build to 1.5"+ (nearing 2 standard deviations
above normal for late April) along the Gulf Coast while continuing
to transport northward into the central U.S.
A low pressure system exiting the Rockies will track across the
southern tier states, lifting a warm front up the Mississippi
Valley while a cold front sweeps in a few hours later. The upper
level jet will be passing overhead and provide divergence
aloft/enhanced vertical motion in the low/mid levels of the
atmosphere. Low-level inflow rises to 40-60 knots (with effective
bulk shear to match), close to the value of the mean 850-400 hPa
wind. Instability will be increasing across the Southern Plains
ahead of the cold front with CAPE values of 1500+ J/Kg supporting
periods of heavy rainfall.

There is some degree of spread on where the maximum values will
occur, but the overall consensus suggests a fairly large area
where 2-4 inches will fall with very isolated maximums of 5-6
inches possible. Although some locations have had several days to
recover from recent soaking rains, rain of this magnitude may
quickly become problematic, thus increasing the threat for flash
flooding. The Slight Risk area was slightly reshaped for this
update, but remains about the same. The Marginal Risk area spans
from eastern Texas to Alabama and from central Oklahoma into the
Midwest. The LCH/Lake Charles LA, SHV/Shreveport LA, and
LIX/Slidell LA forecast offices were consulted in this update.

Roth/Campbell


I'll be happy with 1/2"

fill_94qwbg - Copy.gif
If it does that, I'll be dragging the hose around again on Saturday.
cperk
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Cpv17 wrote: Thu Apr 22, 2021 11:42 am I’m not sure what y’all are seeing saying we won’t be getting much rain over the next week or so. Models are showing 2-4” for most of us over the next 10 days.
I sure hope that’s the case I’ve sent two back breaking days filling in low spots in my yard with bank sand.
Cpv17
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Dew points better start rising. It sure doesn’t feel like any severe weather is coming anytime soon.
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jasons2k
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My dew point has risen 20 degrees since this morning...the airmass is definitely modifying with the return flow in place now.
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Katdaddy
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Hopefully just some more well needed rainfall in NW Galveston County without any excitement.
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DoctorMu
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jasons2k wrote: Thu Apr 22, 2021 5:51 pm My dew point has risen 20 degrees since this morning...the airmass is definitely modifying with the return flow in place now.
Same here. I'm going out walking/running with the dog before it gets too humid!
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