Alert archive / Texas / Mesoscale Discussions in 2017

Mesoscale Discussion 787

May 19, 201717 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 19, 2017, 5:50 PM CDT for 17 counties in Texas. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued: May 19, 2017, 5:50 PM CDT (22:50 UTC)
Expired: May 19, 2017, 7:45 PM CDT
In force: 115 min
Issued by: the Storm Prediction Center

Counties Brown County, TX, Callahan County, TX, Coke County, TX, Coleman County, TX, Concho County, TX, Eastland County, TX, Fisher County, TX, Haskell County, TX, Jones County, TX, McCulloch County, TX, Nolan County, TX, Runnels County, TX, Shackelford County, TX, Stephens County, TX, Taylor County, TX, Throckmorton County, TX, Tom Green County, TX

The radar

The Dyess AFB radar (KDYX), 78 km from the middle of the area, began a volume at 22:49 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Tornado Watch 251May 19, 7:45 PM CDT

The nearest sounding before it

Fort Worth, TX (KFWD), launched 12:00Z, 10.8 hours before the alert went out and 258 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 1189 J/kg
Mixed-layer CIN: -285 J/kg
Mixed-layer LCL: 756 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 93 m²/s²
0-3 km storm-relative helicity: 75 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

978 
ACUS11 KWNS 192251
SWOMCD
SPC MCD 192250 
TXZ000-200045-

Mesoscale Discussion 0787
NWS Storm Prediction Center Norman OK
0550 PM CDT Fri May 19 2017

Areas affected...portions of central Texas

Concerning...Tornado Watch 246...

Valid 192250Z - 200045Z

The severe weather threat for Tornado Watch 246 continues.

SUMMARY...Severe/isolated tornado risk continues.

DISCUSSION...Latest radar loop shows several vigorous/rotating
storms across parts of the watch area, primarily within two small
clusters -- one between SJT and ABI, and the second northwest of
ABI.  With these storms ongoing within a moist/moderately unstable
airmass, expect the risk to continue over the next several hours.

One negative, with respect to tornado risk, is weakening low-level
flow with southwestward extent across the watch area.  Still, risk
for a tornado or two persists -- especially over northern portions
of the watch, along with risk for large hail and locally damaging
downdrafts.

..Goss.. 05/19/2017

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

ATTN...WFO...FWD...OUN...SJT...LUB...

LAT...LON   30920060 31790068 32740055 33330010 33569901 32319872
            31139887 30920060

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 18, 7:47 PM CDT	Severe Thunderstorm Watch	SPC	Archer, Baylor, Clay, Wichita	6 hr
May 18, 9:08 PM CDT	Mesoscale Discussion	SPC	Brown, Clay, Comanche, Cooke, Denton, Eastland and 10 more	37 min
May 19, 2:17 AM CDT	Mesoscale Discussion	SPC	Callahan, Coke, Crane, Ector, Fisher, Glasscock and 9 more	118 min
May 19, 2:44 AM CDT	Severe Thunderstorm Watch	SPC	Callahan, Coke, Fisher, Glasscock, Haskell, Howard and 13 more	6 hr
May 19, 7:03 AM CDT	Mesoscale Discussion	SPC	Callahan, Collin, Dallas, Denton, Eastland, Ellis and 15 more	117 min
May 19, 10:41 AM CDT	Mesoscale Discussion	SPC	Archer, Clay, Cooke, Fisher, Haskell, Jack and 9 more	94 min
May 19, 12:26 PM CDT	Tornado Watch	SPC	Brown, Callahan, Coke, Coleman, Comanche, Concho and 19 more	7 hr
May 19, 2:45 PM CDT	Mesoscale Discussion	SPC	Callahan, Coke, Coleman, Concho, Fisher, Irion and 10 more	60 min
May 19, 3:26 PM CDT	Tornado Watch	SPC	Archer, Baylor, Bosque, Clay, Collin, Comanche and 28 more	11 hr
May 19, 6:56 PM CDT	Mesoscale Discussion	SPC	Archer, Bosque, Brown, Clay, Collin, Comanche and 28 more	2 hr

Nearby

Mesoscale Discussions in Texas, 2017 Every mesoscale discussion in 2017

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.