APRIL 2019: Warm & Muggy WX to End The Month

[Belmer]

Potential expansion of a new Tornado Watch for our far western counties later this morning.

Mesoscale Discussion 0317
NWS Storm Prediction Center Norman OK
0711 AM CDT Sat Apr 13 2019

Areas affected...portions of west-central into central Texas

Concerning...Tornado Watch 49...

Valid 131211Z - 131415Z

The severe weather threat for Tornado Watch 49 continues.

SUMMARY...The severe threat continues across much of Tornado Watch
#49. A replacement watch may eventually be needed pending
convective trends.

DISCUSSION...The ongoing MCS currently near Sutton/Val Verde
counties in Texas continues to mature and develop farther southward
than most models/CAMS suggest. Additionally, a mature supercell
continues across Uvalde County despite progressively moving toward
increased convective inhibition east of the area. Tornado Watch 49
currently has an expiration time of 14Z, although the current
progression of the MCS suggests convection will persist within the
watch through at least 16Z - assuming the MCS can maintain its
current intensity.

Assuming ongoing convection does persist, instability/shear profiles
support a continued threat of all modes of severe - especially near
the warm frontal zone where low-level shear will be maximized and
storms can ingest near-surface-based parcels. With these
considerations in mind, WW 49 may need to be replaced with a new
Tornado Watch in the 13-14Z timeframe - with the new watch possibly
covering the Austin/San Antonio areas and points slightly east.

..Cook/Edwards.. 04/13/2019

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...HGX...FWD...EWX...SJT...

[Belmer]

This is more of a 'now-cast' event than relying on what models spit out. I think it's pretty clear that a significant severe weather episode with strong tornadoes not out of the question in parts of NE/E Texas and into Louisiana. While we aren't expecting quite the severe event down here in SETX, we'll need to closely watch the radar heading into this afternoon.
While it is only one run, the latest 11z HRRR has definitely come in a bit more aggressive for potential supercell development near our area today.

[srainhoutx]

Day 1 Convective Outlook shifts the Enhanced Risk further West to include potions of SE Texas mainly along and N of HYW 105. The Slight Risk has also shifted further West to include areas near and N of San Antonio/Austin mainly along and N of I-10. The risk for large and damaging hail has increased across our area mainly N of the I-10 Corridor as well. The greatest Tornado threat still remains across portions of East Texas into Central Louisiana and Western Mississippi.

[Andrew]

HRRR is doing a rather poor job with how far south the line has developed so far. Looking at 12z soundings across the gulf coast indicate if there is any cap present, it is rather shallow and should be pretty easy to erode. Currently, most of the convection over central and SE Texas isn't surface based so no severe weather is expected with that, but over the next couple of hours that will change as caping erodes, and convective temperatures are met. I do think areas around college station are in a pretty good location to see some severe weather with the overall line. It's going to be close further south around the Houston area. The main event will be to our northeast though as the LLJ ramps up later this evening from weak cyclogenesis. Some of the forecast hodographs in Louisiana are very ominous, with the only limiting factor keeping this from being a high risk is the limited energy available. Busy day ahead for a lot of people Good news though, temperatures will be cooler for Sunday into the beginning of next week.

[Andrew]

TAMU KCLL special 12z sounding. Notice the inversion (cap) at ~800mb. The wind profile shows weak cold air advection at that level which will help to erode it. The key here is how much available energy (CAPE) will be present if we break the cap. The hodograph looks messy and I don't expect that to change much, limiting the tornado threat. The main thing here will likely be hail and maybe wind.

Also, take into consideration College Station is right behind the warm front.

[srainhoutx]

NWS Austin/San Antonio‏Verified account @NWSSanAntonio · 1m1 minute ago
A severe thunderstorm watch has been issued for parts of Texas until 3 PM CDT

[unome]

2 experimental Twitter accounts of NWS, used to auto-post severe thunderstorm and tornado warning impact graphics - love these

https://twitter.com/NWSSevereTstorm

https://twitter.com/NWStornado

it goes without saying, pay attention to your local NWS & area emergency partners

[Belmer]

Severe weather threat on the increase this morning. Initially the threat should be focused over the western areas but will shift eastward throughout the morning and afternoon.

[Andrew]

Large hail north of San Antonio

[unome]

Meso 1 over TX/LA/etc

https://weather.msfc.nasa.gov/cgi-bin/s ... CloudPhase

http://rammb-slider.cira.colostate.edu/ ... 000&y=1000

[unome]

Mesoscale Discussion 0318
NWS Storm Prediction Center Norman OK
0940 AM CDT Sat Apr 13 2019

Areas affected...South central Texas

Concerning...Severe Thunderstorm Watch 50...51...

Valid 131440Z - 131615Z

The severe weather threat for Severe Thunderstorm Watch 50, 51
continues.

SUMMARY...Some risk for severe hail will continue, with damaging
wind potential also increasing in association with an upscale
growing convective system through early afternoon.

DISCUSSION...Narrow squall line is advancing east of the Edwards
Plateau region at around 30 kt, largely supported by forcing on the
leading edge of stronger mid-level cooling, to the north of a 50-70
kt 500 mb jet streak nosing south of the Big Bend region into the
lower Rio Grande Valley. This activity appears likely to gradually
overtake more discrete ongoing thunderstorm develop near the
Interstate 35 corridor of south central Texas during the next few
hours.

Stronger southerly 850 mb flow associated with the developing
cyclone over south central Texas is forecast to remain focused off
the western Gulf of Mexico into areas near/east of the Sabine
Valley, and low-level forcing for ascent may remain relatively
modest to weak across much of south central into eastern Texas.
However, weak/broad low-level warm advection to the immediate north
of a stalled/slowly northward advancing front now north of Houston
into the San Antonio area may provide the focus for an increasingly
organized mesoscale convective system.

The evolving convective system appears likely to be supported by
inflow of increasingly moist and moderately unstable air (with CAPE
of 1000-2000 J/kg) now present to the south/east of the frontal
zone. And with intensification/upscale growth, potential for
strong, damaging wind gusts may increase through the 16-17Z time
frame. The evolution of mesovortices with locally enhanced wind (or
perhaps a tornado) potential may not be out of the question.

..Kerr.. 04/13/2019

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...HGX...FWD...EWX...

LAT...LON 31109826 31469743 31689556 30639525 29979689 29319818
29269918 29629902 30899843 31109826

[srainhoutx]

Watch likely...

Mesoscale Discussion 0319
NWS Storm Prediction Center Norman OK
0949 AM CDT Sat Apr 13 2019

Areas affected...Remainder of northeast Texas into northwest
Louisiana

Concerning...Severe potential...Watch likely

Valid 131449Z - 131545Z

Probability of Watch Issuance...80 percent

SUMMARY...Increasing thunderstorms through midday may be accompanied
by a risk for severe hail, with the potential for damaging wind
gusts also increasing by afternoon.

DISCUSSION...A strengthening southerly low-level jet associated with
the developing cyclone over south central Texas is contributing to
increasing large-scale ascent and associated thunderstorm
development to the north of a stalled/slowly northward advancing
surface front. This activity may continue to strengthen in the
presence of steep mid-level lapse rates, moderate CAPE, and strong
shear in the cloud bearing layer, while an evolving upstream
mesoscale convective system (now advancing east of the Edwards
Plateau/Hill Country) continues to approach the region through early
afternoon.

..Kerr/Grams.. 04/13/2019

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LCH...SHV...HGX...FWD...

[Andrew]

Looks like storms are becoming more surface based over Central Texas. Could see our first tornado warning here with cell south of Rockdale.

[srainhoutx]

Look for the possibility of larger Watch a bit later this morning into the early afternoon encompassing more of the SE Texas Region...

NWS Houston‏Verified account @NWSHouston · 2m2 minutes ago
A severe thunderstorm watch has been issued for parts of Arkansas, Louisiana and Texas until 3 PM CDT

[javakah]

Looks like storms are becoming more surface based over Central Texas. Could see our first tornado warning here with cell south of Rockdale.

That cell that produced that hail signature near SA had previously been tornado warned.

[srainhoutx]

GOES 16 Mesoscale Floater now up for those interested.

[Belmer]

Storms getting closer and the atmosphere is destabilizing. Threat for severe weather will increase quickly in the next few hours.

[unome]

https://twitter.com/hylandwx/status/1117079717843218433
Pat Hyland
‏ @hylandwx

Gentle bump for using the @NOAANSSL mPING app today to do some citizen science to report weather that you’re seeing in your area! Those reports are incredibly important verification for forecasters and researchers! #okwx #txwx #lawx #mswx #arwx #alwx #tnwx #mping

[Andrew]

Cell near Hearne

[Belmer]

Correlation Coefficient is indicating debris with this tornado warned storm. Meaning there is a good possibility there is a large tornado on the ground. This should pass north of Hearne and just south of Calvert heading toward Franklin.

Edit to add: Getting reports that there IS a confirmed tornado on the ground moving toward Highway 6.