Severe WX May 18th - May 27th Severe Weather Threat (2 Viewers)


Bevo

Member
Messages
144
Location
Dallas, TX
New Day 1 Outlook is out (8 AM CST/9 AM EST)

SPC AC 221253

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 AM CDT Fri May 22 2020

Valid 221300Z - 231200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PORTIONS
OF NORTH-CENTRAL/NORTHEAST TEXAS AND SOUTHEASTERN OKLAHOMA...

...SUMMARY...
Severe storms are expected today from north Texas into the Ozarks.

...Synopsis...
In mid/upper levels, a longwave trough will persist over the western
CONUS, while a blocking pattern breaks down in the East. The latter
will be related to height falls across the Great Plains states,
shifting to the Mississippi Valley, contributing to the
northeastward ejection of a formerly cut-off low now near CVG. The
associated cyclone will fill gradually as it moves northeastward up
the Ohio valley, past PIT around 06Z, then eastward over the
southern PA/MD area.

To the west, as a cyclone over central AB weakens and shifts
northeastward, a strong shortwave trough now over the interior
Northwest will dig east-southeastward. This perturbation should
become a closed cyclone over southern ID and northwestern UT around
the end of the period. A shortwave trough -- now evident in
moisture-channel imagery over the central/southern High Plains --
will move east-northeastward across KS and northern OK, phasing with
MCVs produced by an ongoing MCS over portions of OK/KS. The
combined perturbation may develop a closed 500-mb low over IA by 12Z
tomorrow.

At the surface, a low was analyzed over sotuhern VA, with weak,
slow-moving cold front over eastern NC and coastal SC, becoming
quasistationary over central GA. This part of the boundary should
become more diffuse and retreat northward over GA and the Carolinas
through the day. The warm-frontal segment -- analyzed across
central AL, northern MS, southern AR and eastern OK, will be
overtaken over much of its OK extent (and perhaps some of AR) by an
extensive outflow boundary from an MCS now mostly covering southern/
eastern OK. A dryline -- analyzed initially from the TX Big Bend
region north-northeastward to just west of CDS, will mix eastward
today to parts of northwest/west-central TX, to northern Coahuila.
The dryline and outflow boundary may intersect this afternoon near
the Red River over northwest TX.

...North TX/Arklatex/Ozarks...
Except for an initially separate multicellular cluster over south-
central OK, near its southern flank, an extensive MCS that has
produced several measured severe gusts in central/northern OK
appears to be undergoing a general weakening trend while moving
east-southeastward astride the warm-frontal zone. See SPC watch 201
and related mesoscale discussions for near-term details.

The major influence on the convective/severe potential today will be
the MCS' outflow boundary. This complex has progressed farther/
faster than indicated by most progs used for the previous outlook
cycle, and it still bears a substantial pressure/theta-e
perturbation. This introduces more uncertainty regarding the
ultimate stalling position of the boundary, and therefore associated
severe probabilities, which still may need more shifting as
mesoscale trends warrant. Nonetheless, the boundary still should
focus the bulk of afternoon severe convective development, even if
more likely farther south near the Red River in north TX and
southeastern OK. This repositioning would displace the most robust
convection farther from stronger midlevel westerlies related to the
shortwave trough, in turn marginalizing deep shear somewhat.

Scattered thunderstorms are expected to form this afternoon along
the boundary, perhaps very rapidly, given the strong instability
expected on its south side. Convection should be isolated to widely
scattered farther southwest near the dryline. The moist sector
across southern OK, north-central/northeast TX, and AR south of the
warm front will be characterized largely by surface dew points in
the upper 60s to low 70s F. Where these preconvective conditions
persist, steep midlevel lapse rates and a deep troposphere will
contribute to peak afternoon MLCAPE in the 3500-4500 J/kg, locally
higher. The thermodynamic profiles favoring very intense updrafts,
combined with effective-shear magnitudes around 30-35 kt and
localized boundary-layer vorticity enhancement along the boundary,
indicate a mix of multicell and heavy-precip supercell modes, with
at least broken quasi-linear clustering ultimately occurring. Until
the mode gets too messy, considerable hail is likely, some of it
significant/ destructive in nature, along with severe gusts.
Storm-scale and boundary interactions still support a threat for a
few tornadoes as well. Isolated severe hail and gusts also will be
possible from convection near the dryline.

Pockets of somewhat drier and more readily mixed, lower-buoyancy air
may linger over portions of southern OK and western north TX,
advected from a convectively processed air mass now southwest
through west of the Metroplex, where mid-50s to low-60s F surface
dew points have been observed for a few hours. If maintained, this
air mass may affect severe potential over parts of northwest/north-
central TX, by making convection more high-based and outflow-
dominant.

...GA/Carolinas/eastern TN...
Isolated severe gusts and hail are possible across the outlook area
through this afternoon. An MCV and associated midlevel shortwave
trough -- currently associated with nonsevere convection across
portions of the Mid-South region into northern AL and mid TN, will
move eastward today. The associated field of large-scale ascent
will impinge on a boundary layer that will be destabilizing from
south-north across the outlook area, from a combination of diabatic
heating and theta-e advection. Scattered thunderstorms should move
eastward from the higher terrain of southeastern TN/northern GA,
into an airmass with around 1000-1500 J/kg MLCAPE. Additional
development may occur in a weakly capped warm sector over southern
parts of the outlook area. Deep shear should increase as the
mid/upper low pivots northeastward and the MCV/shortwave approaches,
with effective-shear magnitudes in the 30-40 kt range. A mix of
multicell and at least isolated supercell modes are possible.

..Edwards/Smith.. 05/22/2020
The major update to this outlook is to remove the 10% hatched tornado risk across N.TX and OK. Let's hope it stays that way! (sorry chasers)
Screen Shot 2020-05-22 at 8.07.15.png
The second big adjustment to the new outlook is to expand and enhance the sig.severe hail threat. It now encompasses a much wider area, which reflects the more widespread hail sizes on the model soundings.
Screen Shot 2020-05-22 at 8.07.36.png
Wind risk is like "hey guys I'm still here"
Screen Shot 2020-05-22 at 8.07.31.png
 

MichelleH

Member
Messages
374
Location
Hanceville, AL
I've seen this event unfold before.(Hopefully and we shouldn't have a widespread tornado outbreak.) (Easter Outbreak.)
The Easter tornado outbreak was being talked about a week in advance and most of us knew it was going to be very bad. Actually, as bad as that day was, some of us expected it to be a lot worse.
 

Bevo

Member
Messages
144
Location
Dallas, TX
The Easter tornado outbreak was being talked about a week in advance and most of us knew it was going to be very bad. Actually, as bad as that day was, some of us expected it to be a lot worse.
I expected that day to go high risk to be honest.
It doesn't look like there's a risk area for the time period discussed earlier at this moment anyway, just Day 2 and 3 currently.
Day 4-8:
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 220758
SPC AC 220758

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 AM CDT Fri May 22 2020

Valid 251200Z - 301200Z

...DISCUSSION...
Some timing difference exist but medium-range guidance is in
relatively good agreement that the upper flow splits as the trough
moves into the Plains on D5/Tuesday or D6/Wednesday. The northern
stream will retreat to the US/Canada border while a closed cyclone
develops over the southern Plains, flanked by two strong
anticyclones over the western and eastern CONUS. This pattern will
likely result in a large area of high precipitation totals across
the southern and central Plains by the end of the week. However,
with the stronger westerlies displaced north of the better low-level
moisture/instability, any severe potential will depend primarily on
mesoscale factors and a organized severe event appears unlikely.

..Mosier.. 05/22/2020
 

Brice

Member
Messages
182
Location
Virginia
The Easter tornado outbreak was being talked about a week in advance and most of us knew it was going to be very bad. Actually, as bad as that day was, some of us expected it to be a lot worse.

Yes, I understand it could've been a lot worse, we didn't have much data when the outlook came out for each day, until the event actually occurred. That was because we didn't have much models from airports and some others. But also, I wouldn't want to listen to the mob media who thought the event will rival or top the 2011 Super Outbreak of this millennium.
 

Bevo

Member
Messages
144
Location
Dallas, TX
Sounds like the town of Bowie, TX sustained significant damage tonight. Hearing reports of considerable structural damage and multiple mobile homes destroyed in town as a result of a likely tornado.
Yeah I think Bowie, Burkburnett, and towns north of Witchita Falls who saw the first explosive cell got the brunt of the threat last night. There was near constant rotation on the Bowie cell during its entire life cycle while I was tracking it before it collapsed west of Denton county. A LOT of flooding out that way too because of the slow, sometimes almost stationary movement of some cells. 7”+ in some areas!
Here’s some potentially record size hail from Burkburnett:

EDIT: NWS concluded Bowie did have a tornado, EF1. @buckeye05
 
Last edited:

Bevo

Member
Messages
144
Location
Dallas, TX
I went ahead and edited the thread to account for the next few days of severe weather development that are forecast (since things are generally quiet otherwise).

Today's threat seems to be pretty widespread across 3 different regions.
Screen Shot 2020-05-23 at 13.13.46.png
My greatest concern at this time is with what is beginning to unfold in the Illinois/Wisconsin/Iowa vicinity, where a 10% (non-hatched) corridor exists for tornadoes. There is already a tornado watch in place in this area with some pretty high confidence that tornadoes of some kind will occur. The watch DOES include the Chicago metro, Milwaukee, Cedar Rapids, and other populated areas.
In fact, there are already several tornado warnings in progress right now (1:20 PM CST) in Iowa and just crossing into the Illinois state line.
7FD6A827-741C-41E0-9D59-DFA1FA3987C6.png
Screen Shot 2020-05-23 at 13.14.28.png

Screen Shot 2020-05-23 at 13.17.25.png
Screen Shot 2020-05-23 at 13.17.52.png
The other significant risk outlined at this time involves large hail, with a sig.severe probability in the high plains and in Texas (again).
Screen Shot 2020-05-23 at 13.18.24.png
There are 15% risk areas for high winds in the slight regions as well, but no sig.severe or higher probabilities at this time.
 
Last edited:

Bevo

Member
Messages
144
Location
Dallas, TX
Yikes, this is headed toward Joliet and tor warned. Struggling a bit with rotation but if it wraps up this will be trouble. Headed on a track toward south Chicago suburbs.
D6F09FEE-ADF5-4B24-AF23-A543E37264F0.png
8072D805-1FA9-4AD2-A629-6C7D53D6E9AB.png
4:03 PM - Has transitioned to severe warned with ping pong ball hail and 60mph wind.
 
Last edited:

Bevo

Member
Messages
144
Location
Dallas, TX
Okay...well here's a PDS Tornado Warning in Texas at the moment.

Reflect/Velocity:


This cell as of 7:09 PM is CONTINUING to cycle and produce, 3 hours later, in nearly the same exact location--major flash flooding is happening.
Reed is actually still on this one, not very many other photos/videos floating around as of right now.

 
Last edited:

Bevo

Member
Messages
144
Location
Dallas, TX
Hello everyone,
Sorry for the spotty updates--I've been interviewing like crazy trying to get a teaching job in the fall.
Anyway, some amendments. I edited the thread date range once again to reflect the next couple of days of severe weather.
Let's look at today's threat:
Today we have our eyes on Iowa, Wisconsin, and Minnesota for a tornado-driven slight risk, with a 5% chance of a tornado occurring within 25 miles of any point in the slight yellow risk area.
Screen Shot 2020-05-26 at 13.29.27.png
Screen Shot 2020-05-26 at 13.29.10.png
A tornado watch has been put into place across a large portion of Iowa. I could perhaps see additional watches being added northward into Minnesota or Wisconsin later on depending on what happens in Iowa first.

I'm having some difficulties attaching the probability graphic but you can check it out here.
-Probs of 2 or more tornadoes (40%)
-Probs of 1 or more strong tornadoes (20%)

Tomorrow's (5/27) setup seems to have come out of left field...if you can call it that, given that it's still May. Equally as untimely considering the day it falls on as the anniversary of the Jarrell monster, though that setup was much more of a "one in a million" type case and does not look like tomorrow's. SPC has decided to upgrade the risk tomorrow to enhanced for central Texas, including the Austin metro in the bullseye. As the threat evolves, I will update the thread.
Screen Shot 2020-05-26 at 13.34.42.png
Screen Shot 2020-05-26 at 13.34.49.png WIND PROBS
Screen Shot 2020-05-26 at 13.34.53.pngLARGE HAIL PROBS
Screen Shot 2020-05-26 at 13.36.40.pngTORNADO PROBS (literally includes 3 of the 5 biggest metros in the state but Austin is definitely the one to watch closely)

Mississippi valley area and Carolinas are included in a marginal risk currently, and aside from Texas, the Carolinas are the only other area to be denoted in a tornado risk (2%).

2:47 PM CST update: 2 active tornado warning areas
ABDAD498-BE83-4987-A4BE-CB0BE719D680.png
 
Last edited:

Bevo

Member
Messages
144
Location
Dallas, TX
That one looks like it touched the ground, a lot of other pics coming in on Twitter have houses and trees blocking so it's difficult to tell.

May is determined to go out with a bang I guess.
 

Bevo

Member
Messages
144
Location
Dallas, TX
Good morning everyone,
It appears that SPC has maintained an enhanced risk for central Texas as of now, but the most significant update was to add a hatched sig.severe area for wind to the enhanced region.

Screen Shot 2020-05-27 at 9.27.36.png
Tornado risk. This has constantly been trimmed/adjusted. The 5% area has been narrowed NE of San Antonio slightly as of last update.
Screen Shot 2020-05-27 at 9.27.24.png
Sig.severe hail risk in the hatched region. Soundings were indicating giant hail is possible, 3"+.
Screen Shot 2020-05-27 at 9.27.33.png
Sig.severe wind risk in the hatched region.

Another notable update is that the tornado risk for the Carolinas has expanded inland. Previously it was confined to more of the coastal area.
Screen Shot 2020-05-27 at 9.30.29.png
 

KoD

Moderator
Staff member
Moderator
2020 Supporter
PerryW Project Supporter
Messages
1,063
Location
Huntsville, AL
Got some 74dB returns on that, I bet the hail is turning the ground white.
 

Bevo

Member
Messages
144
Location
Dallas, TX

Oh my gosh, look at that sky. :eek: It is 1 PM.

1:28 PM CST Severe Thunderstorm Watch now in effect for a large swatch of central and SE Texas. DOES include both Austin and Houston metros as well as College Station for any Aggies out there.
Pretty high confidence in severe winds and hail (80%+). Tornado threat is lower (20% for 2 or more tornadoes, 5% for strong) but don't discount it with the mesoscale features in play today.
E32C7742-3BD4-4E8B-9FBD-4548D048132D.png
3:20 PM CST Initiation is beginning around Abilene. Supercells are currently somewhat discrete and some are starting to split. These are not yet producing monster hail, but as they move SE into a better environment they may begin to.
First Texas tornado warning of the day NW of Houston metro.
 
Last edited:

KoD

Moderator
Staff member
Moderator
2020 Supporter
PerryW Project Supporter
Messages
1,063
Location
Huntsville, AL
Man I hate that I goofed this one up... I recorded a timelapse too quick and lost valuable frames. I was trying to capture some pre-convective waves and instead was treated to a beautiful vortex. I assume it was an outflow/updraft interaction because it appeared to be spinning and lifting at the same time prior to heavy rainfall.

Regardless, here's the short video. I recommend watching it at 0.5x speed in the video settings.

I'll get a great one some day..
 

Users Who Are Viewing This Thread (Users: 0, Guests: 2)

Top