May 7th-10th Severe Outbreaks

[cstrunk]

I'm very interested in the bulging dryline in west Texas.  I'd be sitting around Abilene give or take, watching satellite trends.  The environment doesn't look too bad south and west of DFW. 

 

The storm southwest of Fort Worth sure as an interesting shape on reflectivity, but that's probably about it for now anyways.

[tornadotony]

Brett's right, it's just too much.  The best tornado threat today may actually end up in the N TX 10% area.

[geddyweather]

 

MESOSCALE DISCUSSION 0564
NWS STORM PREDICTION CENTER NORMAN OK
1240 PM CDT SAT MAY 09 2015

AREAS AFFECTED...ERN CO/WRN KS

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 091740Z - 091845Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS
EASTERN CO AND WESTERN KS OVER THE NEXT FEW HOURS. LARGE
HAIL...TORNADOES...AND DAMAGING WINDS ARE LIKELY.

DISCUSSION...EXIT REGION OF STRONG MID-LEVEL SPEED MAX HAS ROTATED
INTO SERN CO AND ASCENT ASSOCIATED WITH THIS FEATURE IS EXPECTED TO
SPREAD NEWD INTO NWRN KS BY LATE AFTERNOON. STRONG BOUNDARY LAYER
HEATING ACROSS THE SRN HIGH PLAINS HAS CONTRIBUTED TO STEEPENING
LOW-LEVEL LAPSE RATES AND LATEST DIAGNOSTIC DATA SUGGESTS SFC-3KM
VALUES ARE APPROACHING 9 C/KM ALONG THE FRONT RANGE OF SERN CO/NERN
NM. VIS IMAGERY SUPPORTS THIS WITH AN EXPANDING/DEEPENING CU FIELD
ALONG THE SERN CO/NERN NM BORDER RIDGE...NWD ALONG THE SANGRE DE
CRISTO RANGE WEST OF PUB. OVER THE NEXT FEW HOURS...SUPERCELLS
SHOULD EVOLVE WITHIN FAVORABLY MOIST UPSLOPE REGIME AND TRACK NNEWD
AHEAD OF DEVELOPING/SURGING SFC LOW. LARGE HAIL WILL BE COMMON WITH
THIS ACTIVITY AND TORNADOES ARE ALSO EXPECTED WITH THE MOST
ORGANIZED SUPERCELLS.

..DARROW/CORFIDI.. 05/09/2015

 

Well Well Well....

[jojo762]

60/20 tornado probs on new watch over eastern CO/western KS.

[LocoAko]

TornadoTitans reported a wall cloud on the storm near Duncan. Central and SW Oklahoma being upgraded to Tor watch including OKC metro 

[jhamps10]

Watching cells begin to pop up just south of Abilene and near Stephenville, TX... keeping my eyes on those

[andyhb]

That, and the subtropical jet that has been juiced up by El Nino. Lots of badly-timed subtle southern stream impulses this year kicking up crapvection on the southern end of risk areas, which destroys destabilization to the north. I think Wed was the only day this year where crapvection was not present at 18Z, and guess how that turned out.

 

Given the massive WWB ongoing in the Pacific, I can't imagine southern stream issues disappearing anytime soon.

 

This will be less of an issue once systems start working their way north. There's a reason why El Nino years tend to start slow and pick up in May/June.

[andyhb]

Also worth noting that Central/E TX faces a potentially significant threat tomorrow (along with the more conditional triple point threat), with wind profiles that look much better as a southern vort rotates around the base of the trough.

[Memphis Weather]

DFW Metro placed in a Moderate Risk...per SPC

 

/1/ PORTIONS OF NORTH CENTRAL TEXAS INCLUDING THE DFW METROPLEX HAVE  
BEEN UPGRADED TO MODERATE RISK FOR AN INCREASED RISK OF  
TORNADOES...SOME POSSIBLY STRONG...FOR THIS AFTERNOON INTO THE  
EVENING. THE SPECIAL 19Z SOUNDING FROM FORT WORTH SAMPLES AROUND 8  
C/KM LAPSE RATES IN THE H7-H5 LAYER SURMOUNTING LOWER 70S DEWPOINTS  
SUPPORTING STRONG INSTABILITY. CONVECTION IS ALREADY DEVELOPING AT  
THE ERN EDGE OF THE STEEP LOW-LEVEL LAPSE RATE PLUME NOSING INTO SRN  
PARTS OF THE LOW ROLLING PLAINS...WITH DEEPENING CONVECTIVE TOWERS  
ALREADY NOTED IN THIS REGIME PER VIS IMAGERY AND RADAR TRENDS. THIS  
ACTIVITY IS EXPECTED TO FURTHER INTENSIFY WITH SUPERCELLS EXPECTED  
TO SPREAD EWD ACROSS THE MODERATE RISK AREA INTO THE EVENING. A  
VERTICALLY VEERING WIND PROFILE SAMPLED BY THIS RAOB IS SUPPORTING  
SUBSTANTIAL HODOGRAPH CURVATURE...YIELDING AROUND 325 M2/S2 OF  
EFFECTIVE SRH. THE PRESENCE OF A BACKGROUND BROAD OUTFLOW BOUNDARY  
ACROSS THIS REGION AND RELATED ENHANCED LOW-LEVEL SRH AND VERTICAL  
VORTICITY WILL FURTHER ENHANCE THIS RISK AMIDST RICH LOW-LEVEL  
MOISTURE. AND GIVE THE VERY LIMITED MAGNITUDE OF VERTICAL MOTION AT  
LARGER SCALES...A SUPERCELL MODE IS EXPECTED WITH THE RISK FOR  
TORNADOES -- SOME POSSIBLY STRONG. VERY LARGE HAIL IS ALSO EXPECTED.  

[1900hurricane]

Hatched 15% tornado for N TX.

Sent from my iPhone using Tapatalk

[Ian]

Cold pool crawling. That area between it and the dryline is ripe.

[KSWx]

Don't the probs on TW 150 seem a bit low now given the circumstances, or would you all still agree? Have they ever updated probs on a TW after it's been out; or could they perhaps create and separate a new watch for the mod area?

[jhamps10]

Cell SW of Putnam, TX starting to look a bit more interesting

[andyhb]

Don't the probs on TW 150 seem a bit low now given the circumstances, or would you all still agree? Have they ever updated probs on a TW after it's been out; or could they perhaps create and separate a new watch for the mod area?

 

They could add a new watch if things are looking ugly in the next few hours. DFW is obviously a very high impact target.

[Memphis Weather]

Here's the 19z FWD sounding FWIW. It terminated early so that impacts the thermodynamic numbers but otherwise a favorable look..as SPC implied.

 

[jhamps10]

They could add a new watch if things are looking ugly in the next few hours. DFW is obviously a very high impact target.

 

current watch out until 9, I wouldn't see an updated watch until evening if the threat is still there

[andyhb]

 

This visual shot just looks prime.

[Memphis Weather]

SUMMARY...LARGE HAIL AND TORNADO POTENTIAL IS EXPECTED TO STEADILY
INCREASE ACROSS NORTH-CENTRAL TX THROUGH EARLY EVENING...INITIALLY
IN AREAS JUST TO THE WEST OF THE DFW METROPLEX VICINITY. LOCALLY
DAMAGING WINDS/MARGINALLY SEVERE HAIL AND POSSIBLY SOME TORNADO RISK
WILL OTHERWISE CONTINUE ACROSS SOUTH-CENTRAL OK/FAR NORTHEAST TX.
TORNADO WATCH 150 CONTINUES UNTIL 02Z.

DISCUSSION...AN OUTFLOW BOUNDARY-RELATED EFFECTIVE WARM FRONT
EXTENDS ROUGHLY WEST-EAST ACROSS FAR NORTH TX ROUGHLY ALONG THE
NORTHERN EDGE OF THE METROPLEX AND THE ADJACENT NORTHERN TWO-TIERS
OF COUNTIES OF NORTH TX. STORMS SHOULD CONTINUE TO DEVELOP ALONG THE
I-20 CORRIDOR IN VICINITY OF BRECKENRIDGE/BROWNWOOD/STEPHENVILLE
VICINITIES NEAR A SURFACE LOW/DRYLINE THROUGH LATE AFTERNOON. AS AT
LEAST ISOLATED STORMS CONTINUE TO DEVELOP/MATURE AND SPREAD
NORTHEASTWARD...LARGE HAIL WILL BE POSSIBLE...AND TORNADOES
/INCLUDING A STRONG TORNADO RISK/ WOULD ESPECIALLY BE A CONCERN AS
STORMS ENCOUNTER A STRONGER CORRIDOR OF LOW-LEVEL SOUTHERLY WINDS TO
THE EAST AND/OR INTERACT WITH THE AFOREMENTIONED OUTFLOW BOUNDARY. A
SPECIAL 19Z OBSERVED SOUNDING FROM DALLAS-FORT WORTH SAMPLED A VERY
MOIST BOUNDARY LAYER /LOWER 70S F SURFACE DEWPOINTS/ WITH 300+ M2/S2
EFFECTIVE SRH.

FARTHER NORTH...THE PRIMARY SCENARIO WILL BE FOR CONTINUED STORM
MERGERS AHEAD OF SOUTHEASTWARD-PROPAGATING OUTFLOW CURRENTLY ACROSS
PORTIONS OF SOUTHWEST/SOUTH-CENTRAL OK. LOCALLY DAMAGING WINDS/SOME
HAIL WILL BE THE PRIMARY HAZARDS ACROSS SOUTH-CENTRAL OK.

[andyhb]

Impressive mid level lapse rates/low level shear on that sounding. The latter will increase further as the LLJ strengthens in response to the trough ejecting late this afternoon/evening.

[SouthernNJ]

The mentioned Putnam storm trying to get going,

threw off a left split already, and has strong winds

with it on the Base Velocity.

[andyhb]

Boy that CO cell INVOF Pueblo has a mean couplet.

[Indystorm]

Have to confess that developing string of pearls in north central Texas is making me nervous.  Today might end up fulfilling some of our original expectations.

[yoda]

PUBLIC SEVERE WEATHER OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0403 PM CDT SAT MAY 09 2015  
 
...SEVERE THUNDERSTORMS EXPECTED OVER PARTS OF THE SOUTHERN PLAINS  
THIS AFTERNOON AND EVENING...  
 
* LOCATIONS...  
NORTH CENTRAL TEXAS  
EXTREME SOUTHERN OKLAHOMA  
 
* HAZARDS...  
SEVERAL TORNADOES, A FEW INTENSE  
SCATTERED LARGE HAIL, SOME BASEBALL SIZE  
SCATTERED DAMAGING WINDS  
 
* SUMMARY...  
SEVERAL EPISODES OF SEVERE STORMS WILL OCCUR OVER PARTS OF THE  
CENTRAL AND SOUTHERN PLAINS THROUGH EARLY SUNDAY. THE AREAS AT  
GREATEST RISK FOR TORNADOES, SOME POSSIBLY STRONG, AND VERY  
LARGE HAIL WILL BE ACROSS NORTH CENTRAL TEXAS.  
 
PREPAREDNESS ACTIONS...  
 
REVIEW YOUR SEVERE WEATHER SAFETY PROCEDURES FOR THE POSSIBILITY  
OF DANGEROUS WEATHER TODAY. STAY TUNED TO NOAA WEATHER RADIO,  
WEATHER.GOV, OR OTHER MEDIA FOR WATCHES AND WARNINGS. A TORNADO  
WATCH MEANS THAT CONDITIONS ARE FAVORABLE FOR TORNADOES TO FORM  
DURING THE NEXT SEVERAL HOURS. IF A TORNADO WARNING IS ISSUED FOR  
YOUR AREA, MOVE TO A PLACE OF SAFETY, IDEALLY IN A BASEMENT OR  
INTERIOR ROOM ON THE LOWEST FLOOR OF A STURDY BUILDING.  
 

[jhamps10]

Have to confess that developing string of pearls in north central Texas is making me nervous.  Today might end up fulfilling some of our original expectations.

 

Have to agree with that, has my ears really peeled at this

[Ground Scouring]

Boy that CO cell INVOF Pueblo has a mean couplet.

I wonder if the gravity waves developing just E of that cell could offset the somewhat high LCLs. To me the tornado threat still looks conditional, maybe not worth the 15% (more worthy of the 10%), but maybe the cells need time to mature. One thing's certain: they're heading into the one area where very substantial instability remains (and will for a long period of time), with no back-veer-back anywhere. The good news is that the Pueblo (Callahan County, TX) cell really won't encounter high population densities for some time...until it gets to DFW.

[andyhb]

I wonder if the gravity waves developing just E of that cell could offset the somewhat high LCLs. To me the tornado threat still looks conditional, maybe not worth the 15% (more worthy of the 10%), but maybe the cells need time to mature. One thing's certain: they're heading into the one area where very substantial instability remains (and will for a long period of time), with no back-veer-back anywhere. The good news is that the Pueblo cell really won't encounter high population densities for some time...until it gets to DFW.

 

Good grief. You just don't stop do you? The storms initiated like 30 minutes ago, tornadoes don't just happen...

 

The storm east of Abilene already has tightening rotation aloft, and is pretty much as classic as it gets structure wise.

[rolltide_130]

I wonder if the gravity waves developing just E of that cell could offset the somewhat high LCLs. To me the tornado threat still looks conditional, maybe not worth the 15% (more worthy of the 10%), but maybe the cells need time to mature. One thing's certain: they're heading into the one area where very substantial instability remains (and will for a long period of time), with no back-veer-back anywhere. The good news is that the Pueblo cell really won't encounter high population densities for some time...until it gets to DFW.

 

Uh that cell is in Colorado.

[rolltide_130]

That cell near Putnam is going to be tracking pretty much right down I-20 for quite some time. Looks like it has the best rotation between the cells in Texas as well.

[andyhb]

Also, are you not familiar with Granbury/De Cordova 2013? There is plenty of population south and west of the DFW metro. My god, stop with this.

[Ground Scouring]

Also, are you not familiar with Granbury/De Cordova 2013? There is plenty of population south and west of the DFW metro. My god, stop with this.

This is north of Granbury on its current heading, which targets areas W and WSW of DFW--areas that are less densely populated than areas due SW of DFW. I consider the first major population center in its path (Weatherford) part of the DFW metro area. And on second thought, the distance between the cell and more back-veer-back profiles to the north isn't very great, which gives me more confidence that the tornado threat is conditional and might be even shorter-lived than I suspected. You can see how cells to the N of the southernmost one are struggling to maintain their isolation. UL winds might back even more over the next few hours as the UL trough approaches. Such would be good news for DFW and other, smaller population centers.