Discussion (May 18-19-20-21) Moore Tornado EF-5 from NWS

[CrazyC83]

We have one more day of these severe threats to get through. Ark-la-tex into North Texas greatest risk.

[artist]

9 are children

[WeatherGuesser]

Again, casualty numbers will vary for the next few days. No reason to focus on them now.

[WeatherGuesser]

Only active warning for the moment is an SVR for an area of OK outside the Risk Areas.

[CrazyC83]

Tornado Watch just issued. Here we go again...mentions of strong tornadoes in the watch.

[cheezyWXguy]

looks like things are about to get started. Looks like the first cell has already become established north of the abilene area, and seems to be developing a bit of a tail...

[Ntxw]

looks like things are about to get started. Looks like the first cell has already become established north of the abilene area, and seems to be developing a bit of a tail...

Velocity on radar is getting its act together, wouldn't be surprised to see a tor warn for that cell soon.

[WeatherGuesser]

New SVR Watch just popped up.

[cheezyWXguy]

new outlook, mdt encompasses even more of dfw now. looking really ominous today

[apocalypt-flyer]

Yeah I don't particularly like the look of things. The DFW metroplex is sitting really close to the area where jet will probably be the strongest today in the afternoon.

[artist]

press conference coming up soon -
http://www.koco.com/news/oklahomanews/w ... index.html

also storms headed in there in about 30 minutes

[Ntxw]

One thing that is different today is that the cold front is getting a push from the MCS to the north. Most of the storms so far are being undercut by cooler air. Still think areas to the east ahead of the boundary is capable of super-cell initiation, just a silver lining I noticed.

[EF-5bigj]

It looks like Dallas is under the gun.

[cheezyWXguy]

One thing that is different today is that the cold front is getting a push from the MCS to the north. Most of the storms so far are being undercut by cooler air. Still think areas to the east ahead of the boundary is capable of super-cell initiation, just a silver lining I noticed.

That is true, but this may explain why the spc's outlook has lower tornado probabilities out to the west than further east. It looks like probabilities ramp up right along denton to parker county line.

[Ntxw]

One thing that is different today is that the cold front is getting a push from the MCS to the north. Most of the storms so far are being undercut by cooler air. Still think areas to the east ahead of the boundary is capable of super-cell initiation, just a silver lining I noticed.

That is true, but this may explain why the spc's outlook has lower tornado probabilities out to the west than further east. It looks like probabilities ramp up right along denton to parker county line.

The best/max supercell composite and sigtor values are currently in far NE Texas along I-30 to Texarkana from SPC Meso analysis. I would watch this area closely as short range guidance keeps sending some big storms through this region that may get their birth in the counties you referenced.

[gboudx]

Update from jeff:

SPC has issued a large tornado watch for much of N and portions of C TX until 700pm.

Outflow boundary from S OK convection is surging southward over N TX while at the same time the dry line/cold front combo is approaching from the west. The air mass over N and C TX is becoming very unstable with CAPE values of 3000-4000 J/kg along the I-35 corridor. With continued surface heating, expect supercells to develop within the next few hours from NW of Fort Worth SSW along the dry line deep into C TX. Backed low level winds near the incoming outflow boundary from the NW may help to enhance the tornado threat near/around Fort Worth over the next several hours.

Southern flank supercells that fire along the dry line west of Austin/Waco will have a high end tornado threat along with a very large hail threat (greater than 2.0 inches in diameter). Storms will congeal into a forward fast moving line by this evening with a very significant wind damage threat (frequent speeds to hurricane force) spreading across much of NTX into our northern counties. Short term high resolution models continue to suggest a bow echo evolving over N TX with southern flank supercells with a tornado threat across central TX. Think the biggest tornado threat will reside NW of a line from Austin to near College Station to Lufkin and ahead of the main squall line.

Meso models continue to trend toward bring an MCS/bow echo into and possibly even through much of SE TX overnight. Still some questions on the cap intensity with the same models showing a building cap after sunset from deep south TX into the coastal bend so even though the meso models are wanting to bring storms all the way to the coast, the thermodynamic profile may not be very favorable south of I-10.

[artist]

237 injuries they know of. Death numbers are not confirmed. Some bodies may have been taken to funeral homes, rather than the medical examiner.

[cheezyWXguy]

One thing I am curious about is the fact that there is very little if any discrete supercellular development atm along or ahead of that boundary. Is this playing out as expected, or is this becoming more specifically a wind threat above all else?

[gboudx]

One thing I am curious about is the fact that there is very little if any discrete supercellular development atm along or ahead of that boundary. Is this playing out as expected, or is this becoming more specifically a wind threat above all else?

jeff's update implies that supercell initiation may occur within the next few hours.

[Ntxw]

Latest info from FW. Cap so far is holding off storms away from the line. IF they don't fire this will mostly be a hail and damaging wind threat from that complex by afternoon. So far the boundary/weak cold front seem to be racing southward ahead of these storms.

***
NATIONAL WEATHER SERVICE FORT WORTH TX
1242 PM CDT TUE MAY 21 2013

.AVIATION...
THE FIRST 6 HOURS OF THIS TAF PACKAGE WILL BE THE MOST CRITICAL
WITH THUNDERSTORMS EXPECTED TO IMPACT ALL TAF SITES. THE
THUNDERSTORMS WILL CONTINUE TO ORGANIZE ALONG A SOUTHWARD MOVING
COLD FRONT. THE MAIN LINE OF STORMS SHOULD REACH THE METROPLEX TAF
SITES BETWEEN 19 AND 21Z AND WACO BETWEEN 21 AND 22Z. ALTHOUGH
ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE AHEAD OF THE MAIN LINE
OF STORMS THROUGH THE AFTERNOON...COVERAGE WILL BE LIMITED.
INCOMING 18Z SOUNDING DATA SHOWS A SMALL CAP STILL IN PLACE.
HOWEVER...IN A COUPLE OF HOURS THAT CAP SHOULD DISAPPEAR WITH
CONTINUED HEATING AND INCREASING LARGE SCALE LIFT. ANY STORM THAT
IMPACTS ANY OF THE TAF SITES WILL HAVE A POTENTIAL FOR DAMAGING
WINDS AND LARGE HAIL. STORMS SHOULD END AT THE METROPLEX TAF SITES
BY 00Z AND WACO BY 02Z. AFTER STORMS END...CEILINGS WILL LIFT AND
EVENTUALLY CLEAR OUT.
***