Texas Spring 2020

[WacoWx]

Storms were headed right for me. Moved the cars in the garage, got .01. That’s it.

[EnnisTx]

Severe weather tonight with an Enhanced Risk for now. The SPC has mentioned a Westward shift of the Moderate is possible in later updates. May be a nasty night ahead of us.

Stay safe.

[Texas Snowman]

Denison is right on the western edge of today’s moderate risk. Don’t like that one bit.

 https://twitter.com/nwsspc/status/1255114098703888387

[EnnisTx]

Denison is right on the western edge of today’s moderate risk. Don’t like that one bit.https://twitter.com/nwsspc/status/1255114098703888387?s=21

Might be in the middle of it if they expand it Westward as talked about.

[EnnisTx]

Surprise storm this morning.

Long story short. The wife decided to clean up in the garage last night. Guess whose vehicle she forgot to put back in the garage??

Yep, mine! She said she was sorry, but followed that up with Happy Birthday!!! Now your truck looks a little bit like you, a little worse for wear...

[Ntxw]

The discussion from the SPC on the moderate risk. In line with the guidance it is for higher confidence in a strong squall line. Areas of highest coverage will be within the moderate risk. This is more akin to what we see in late May and early June than April. MCS season starting perhaps? There could be isolated tornadoes embedded within the squall but is probably not chaser type of risk day. The broader pattern is favoring NW flow a loft the next week or two with ridging to the desert southwest.

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0726 AM CDT Tue Apr 28 2020

Valid 281300Z - 291200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN OKLAHOMA...FAR WESTERN ARKANSAS AND NORTHEAST TEXAS...

...SUMMARY...
Widespread severe thunderstorms are expected to develop this
afternoon and evening across parts of the Ozarks into the southern
Plains. Damaging winds with gusts possibly exceeding 65 mph, very
large hail and a few tornadoes can be expected.

...Southern Plains/Arklatex/Ozarks/Mid to Upper Mississippi
Valley...
An upper-level trough will dig southeastward from the northern
Plains into the central Plains today. An associated mid-level jet
will dive southeastward into the central Plains. The leading edge of
the stronger mid-level flow associated with the jet will overspread
a corridor of maximized low-level moisture located from northeast
Texas north-northeastward into the Ozarks. Moisture advection ahead
of the system, will increase surface dewpoints into the 60s F across
most of Oklahoma, Arkansas and Missouri by afternoon. In response to
surface heating, the moisture will contribute to moderate
destabilization with MLCAPE values reaching the 2000 to 4000 J/kg
range across parts of the moist sector. Thunderstorms are forecast
to first initiate to the south of a surface low on the northern edge
of the moist airmass in eastern Iowa around midday. Thunderstorms
will then likely develop south-southwestward along a cold front from
northern Missouri into southeast Kansas during the afternoon. This
convection is forecast to grow upscale as a squall line organizes
and moves south-southeastward across the southern Plains and Ozarks.
The moisture and instability combined with strong deep-layer shear
will be favorable for severe thunderstorms across a widespread area.

RAP forecast soundings along the most unstable parts of the front
during the late afternoon increase MLCAPE into the 3000 to 4000 J/kg
range and show 0-6 km shear generally from 30 to 40 kt. This
environment will support supercells with large hail, especially
early in the event before the squall line becomes organized. The
potential for supercells with hailstones greater than 2 inches in
diameter is expected to be greatest from far southeast Kansas into
central Oklahoma and far northern Texas where instabilty is forecast
the strongest. Supercells early in the event may also be accompanied
by a tornado threat. The tornado threat is expected to be greatest
across eastern Oklahoma and far western Arkansas where a low-level
jet will strengthen during the late afternoon and early evening.
Forecast soundings in this area increase 0-3 km storm relative
helicities into the 250 to 400 m2/s2 range suggesting a more
substantial tornado threat will be possible. For this reason, have
added a 10 percent tornado probability contour across parts of the
moderate risk area.

Increasing low-level convergence during the early evening along the
front should gradually result in the development of a nearly
continuous squall line. This squall line is forecast to become more
organized as it moves southward across southwest Missouri, western
Arkansas and east-central Oklahoma. Wind damage will be likely along
the leading edge of the squall line. Wind gusts over 65 kt will be
possible ahead of the faster moving parts of the squall line. A few
tornadoes may also occur with rotating cells embedded in the line. A
widespread wind damage threat should continue into parts of
north-central and northeast Texas during the mid to late evening
before a gradual weakening takes place due to overnight decreasing
instability.

..Broyles/Guyer.. 04/28/2020

[vbhoutex]

Jeff Lindner's thoughts on today's possible severe weather in SE TX:

Severe weather threat for damaging winds tonight.

Significant moisture return has occurred in the last 12-18 hours priming the air mass over SE TX for a couple rounds of weather (one this afternoon) and the second (tonight).

This Afternoon:

A weak short wave will move across the region from the west and this coupled with increasing moisture and a very unstable afternoon air mass could produce a few strong to severe thunderstorms. Capping will have to be overcome, and expect the threat to be conditional to if any storm can break through the cap. Should that happen shear and instability in place would support a rapid growth of any storm to likely severe levels. Main threat for any strong o severe thunderstorms this afternoon will be northeast of a line from Conroe to Kingwood to Liberty, and most likely over San Jacinto, Polk, and Trinity Counties.

Tonight:

A southeast moving cold front will develop a large squall line over southern OK and N TX this evening. This feature will race southward overnight and across SE TX early Wednesday morning. Models are showing a pronounced bowing and bowing segments with this line indicating a potentially significant wind threat. A couple of the meso scale models are showing the formation of significant meso high pressure cell behind the squall line which yields a strong pressure gradient over the region.

Damaging winds of 50-70mph will be possible with this line across nearly the entire area. Highest risk will be inland from the coast as the line weakens as it nears the coast around sunrise Wednesday. Line should reach the College Station, Huntsville, Lake Livingston areas between midnight and 200am, I-10 between 200am-400am and the coast between 400-700am.

Secure all loose outdoors objects this evening. Additionally, strong winds can knock down trees and result in power outages.

[TarrantWx]

DFW was just upgraded to moderate in the latest SPC Day 1

[rwfromkansas]

A little surprised they were that aggressive. I figured it would go to Dallas only. Definitely shows increasing confidence in an impactful squall line going through much of the metro. But, that storm this morning was pretty strong and came out of nowhere.

[Brent]

DFW was just upgraded to moderate in the latest SPC Day 1

thats surprising

but so was the line this morning

[bubba hotep]

It seems like it's been a while since a really strong squall line moved through DFW? Over the last couple of yrs it has seemed like they all came in early morning and were in the process of weakening. Maybe I just don't have a good enough memory lol

[Brent]

I still don't really see much that sets off alarms on the hi-res models as far as like an extreme wind event maybe I'm missing something

It comes in around 11pm too not like it comes in at peak heating

[funster]

It doesn't look to really bow out until a few hours after passing n texas on the hrrr 15z

[WacoWx]

Including DFW allows TWC to get those population numbers affected up and really get that fear factor involved.

I know they have nothing to do with the Moderate expansion, but I KNOW they have to love it.

[wxman22]

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1126 AM CDT Tue Apr 28 2020

Valid 281630Z - 291200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
INTO TONIGHT FOR EASTERN OK...EXTREME WESTERN AR...AND NORTH
CENTRAL/NORTHEAST TX...

...SUMMARY...
Severe thunderstorms with widespread damaging winds, some greater
than 75 mph, large hail, and a few tornadoes are expected to develop
this afternoon and evening across parts of the Ozarks into the
southern Plains. The metropolitan areas of Tulsa and Oklahoma City
will be affected by these severe storms late this afternoon and this
evening, and Dallas-Fort Worth overnight.

...MO/KS/OK this afternoon into east TX/LA/MS overnight...
Rich low-level moisture is spreading northward from TX to OK and
southeast KS, south of a cold front moving into southeastward across
KS, and west of the morning convection from Texarkana southward
along the Sabine River. This moistening is occurring beneath a
plume of very steep midlevel lapse rates near 9 C/km. Surface
heating in advance of the front will boost MLCAPE into the 2500-3500
J/kg range from southwest MO into southeast KS and central/eastern
OK. Convective inhibition will weaken along the front by mid
afternoon, with rapid thunderstorm development expected near or just
after 21z from southern KS into MO.

The initial storms along the boundary will pose some threat for
tornadoes, given steep low-level lapse rates with large buoyancy and
vertical vorticity along the boundary. Fairly rapid upscale growth
into a line is expected by this evening, with storms back-building
into central OK. A mix of multicells/bowing segments and embedded
supercells is expected within the frontal squall line. Aside from a
few tornadoes with circulations within the line, the large
CAPE/steep lapse rate environment will favor both large hail
(especially with embedded supercells), and intense downbursts with
widespread damaging winds. Convection will likely surge
south-southeastward tonight across eastern OK/AR into east TX, with
the threat for fairly widespread damaging winds continuing. There
is some uncertainty regarding the eastern extent of the greater
severe threat toward the MS River late tonight, given the residual
influence of the ongoing Sabine River storms and possible
disruptions in destabilization.

...Upper/middle MS Valley region this afternoon/evening...
The primary synoptic cyclone will move eastward along the IA/MN
border toward southern WI today, in advance of a pronounced lead
shortwave trough likewise moving eastward over MN/IA. Low-level
moisture will be more limited compared to areas farther southwest,
but surface heating in cloud breaks and boundary-layer dewpoints of
56-60 F will support MLCAPE of 500-1000 J/kg this afternoon. Mass
response to cyclogenesis will maintain vertical shear/hodographs
favorable for supercells in advance of the cyclone and trailing cold
front, with an attendant threat for a couple of tornadoes, as well
as isolated large hail/damaging winds.

...East TX into southern LA today...
An ongoing, loosely organized cluster of storms near the Sabine
River may persist well into the afternoon, with a tendency for new
development on the south flank of the cluster as the low levels warm
and moisten from the south. Moderate-strong buoyancy will support
strong updrafts with marginal hail potential, though rather modest
vertical shear suggests that multicell clusters will be the main
convective mode. Likewise, occasional downburst winds will also be
possible through the afternoon.

...Central/eastern NE this afternoon/evening...
The primary synoptic front will be located east of this area this
afternoon with a lead shortwave trough. However, a secondary
frontal surge is expected across central/eastern NE this afternoon
in association with the primary amplifying midlevel trough (now over
the northern High Plains, as denoted by the band of rain now moving
into northwest NE). There will sufficient residual low-level
moisture for weak surface-based buoyancy this afternoon in advance
of the secondary frontal surge. Some low-topped convection will
accompany the front, where steep low-level lapse rates will favor
strong/isolated damaging outflow gusts this afternoon/evening.

..Thompson/Lyons.. 04/28/2020

[dhweather]

Interesting choice of words in an SPC product:


...Severe thunderstorms expected over parts of the southern Plains
later today and tonight...

* LOCATIONS...
Eastern Oklahoma
North central and northeast Texas
Extreme western Arkansas

* HAZARDS...
Widespread damaging winds, some hurricane force
A few tornadoes
Widespread large hail, some baseball size



https://www.spc.noaa.gov/products/outlook/pwo.html

[Quixotic]

I remember a similar situation back in the mid 90s. We had a bowing segment from the NW that produced 100 mph winds. I was at my parents and was awakened by the house groaning.

[Brent]

HRRR has a hole right over the airport

[cheezyWXguy]

HRRR has a hole right over the airport

https://i.ibb.co/Ltxxwj9/hrrr-apcpn-scus-13.png

The HRRR seems to be giving into its discrete storm bias. I don’t buy it. This should grow upscale into a pretty solid line like the NAM shows. That’s not to say a break in the line couldn’t occur, but seems the hrrr wants to keep it as single/multicell clusters as it passes the area, which doesn’t seem right.

[mcallum177]

Looking out the window the cumulus field over DFW is almost completely gone. Matches up with the visible imagery. Could this indicate dry air or is the energy lacking?