Alert archive / Texas / Mesoscale Discussions in 2015

Mesoscale Discussion 421

April 22, 201514 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 22, 2015, 5:48 PM CDT for 14 counties in Texas. It was in force for 117 min.

The area

The outline as issued.

The facts

Issued: Apr 22, 2015, 5:48 PM CDT (22:48 UTC)
Expired: Apr 22, 2015, 7:45 PM CDT
In force: 117 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

Counties Bosque County, TX, Comanche County, TX, Coryell County, TX, Ellis County, TX, Erath County, TX, Hamilton County, TX, Henderson County, TX, Hill County, TX, Hood County, TX, Johnson County, TX, Kaufman County, TX, McLennan County, TX, Navarro County, TX, Somervell County, TX

The radar

The Dallas/Ft Worth radar (KFWS), 46 km from the middle of the area, began a volume at 22:48 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 nearest sounding before it

Fort Worth, TX (KFWD), launched 12:00Z, 10.8 hours before the alert went out and 73 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: 311 J/kg
Mixed-layer CIN: -327 J/kg
Mixed-layer LCL: 760 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 126 m²/s²
0-3 km storm-relative helicity: 118 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

056 
ACUS11 KWNS 222248
SWOMCD
SPC MCD 222248 
TXZ000-230045-

MESOSCALE DISCUSSION 0421
NWS STORM PREDICTION CENTER NORMAN OK
0548 PM CDT WED APR 22 2015

AREAS AFFECTED...CNTRL AND NCNTRL TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 222248Z - 230045Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...CLUSTER OF STORMS OVER CNTRL TX JUST WEST OF WACO MAY
CONTINUE TO POSE A THREAT FOR LARGE HAIL...DAMAGING WIND AND PERHAPS
A TORNADO. STORMS APPEAR ONLY LOOSELY ORGANIZED WITH SPARSE
COVERAGE...SO ANY WW ISSUANCE WILL DEPEND ON CONVECTIVE TRENDS.

DISCUSSION...STORMS THAT DEVELOPED ALONG WHAT APPEARS TO BE A
CONVECTIVELY ENHANCED BOUNDARY CONTINUE OVER CNTRL TX WEST OF THE
WACO AREA. THIS ACTIVITY HAS EXHIBITED MARGINAL HP SUPERCELL
CHARACTERISTICS BUT OVERALL THE STORM APPEARS TO BE ONLY LOOSELY
ORGANIZED. VWP DATA INDICATE STRONG EFFECTIVE SHEAR THROUGH A DEEP
LAYER DUE TO LOW-LEVEL VEERING AND STRONG WINDS ALOFT...BUT WINDS IN
THE 0-2 KM LAYER REMAIN MODEST /GENERALLY AOB 20 KT/ WHICH IS
LIMITING THE SIZE OF LOW-LEVEL HODOGRAPHS. BACKGROUND LARGE SCALE
PATTERN IS DOMINATED BY A LOW-AMPLITUDE RIDGE...BUT WITH EMBEDDED
WEAK PERTURBATIONS. RAP SOUNDINGS ALSO INDICATE AN INVERSION AROUND
700 MB WHICH /ALTHOUGH NOT SUFFICIENT TO PREVENT INITIATION ALONG
THE BOUNDARIES/ MAY ALSO BE LIMITING UPDRAFT STRENGTH TO SOME DEGREE
WITHIN THE LOWER HALF OF THE STORMS. GIVEN THESE LIMITING
FACTORS...ONSET OF NOCTURNAL COOLING WITHIN THE NEXT COUPLE HOURS
AND ONLY A MODEST INCREASE IN THE LLJ...IT REMAINS UNCERTAIN WHETHER
OR NOT STORMS WILL BECOME ORGANIZED SUFFICIENTLY FOR WW ISSUANCE.
NEVERTHELESS THE ENVIRONMENT REMAINS SUFFICIENT FOR AT LEAST A FEW
INSTANCES OF LARGE HAIL...DAMAGING WIND AND PERHAPS A TORNADO.

..DIAL/THOMPSON.. 04/22/2015

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FWD...

LAT...LON   32649839 32759735 32799590 32079583 31509700 31259833
            31939881 32649839

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 22, 2:55 AM CDT	Mesoscale Discussion	SPC	Hemphill, Wheeler	3 hr
Apr 22, 10:43 AM CDT	Mesoscale Discussion	SPC	Aransas, Atascosa, Austin, Bandera, Bastrop, Bee and 36 more	2 hr
Apr 22, 11:13 AM CDT	Tornado Watch	SPC	Aransas, Bee, Calhoun, Duval, Goliad, Jim Wells and 7 more	7 hr
Apr 22, 12:07 PM CDT	Mesoscale Discussion	SPC	Jim Wells, Nueces	83 min
Apr 22, 1:43 PM CDT	Mesoscale Discussion	SPC	Atascosa, Austin, Bandera, Bastrop, Bexar, Caldwell and 15 more	92 min
Apr 22, 2:07 PM CDT	Mesoscale Discussion	SPC	Archer, Armstrong, Baylor, Briscoe, Castro, Childress and 25 more	2 hr
Apr 22, 2:29 PM CDT	Mesoscale Discussion	SPC	Aransas, Bee, Calhoun, Duval, Goliad, Jim Wells and 5 more	61 min
Apr 22, 2:56 PM CDT	Tornado Watch	SPC	Archer, Armstrong, Bailey, Baylor, Briscoe, Callahan and 36 more	9 hr
Apr 22, 6:45 PM CDT	Mesoscale Discussion	SPC	Archer, Armstrong, Baylor, Briscoe, Carson, Castro and 29 more	2 hr

Nearby

Mesoscale Discussions in Texas, 2015 Every mesoscale discussion in 2015

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.