Alert archive / Texas / Mesoscale Discussions in 2013

Mesoscale Discussion 821

May 27, 201322 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 27, 2013, 3:34 PM CDT for 22 counties in Texas. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued: May 27, 2013, 3:34 PM CDT (20:34 UTC)
Expired: May 27, 2013, 4:30 PM CDT
In force: 56 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

All 22 counties

Borden County, TX, Childress County, TX, Cottle County, TX, Crane County, TX, Crosby County, TX, Dawson County, TX, Dickens County, TX, Ector County, TX, Garza County, TX, Glasscock County, TX, Howard County, TX, Kent County, TX, King County, TX, Martin County, TX, Midland County, TX, Mitchell County, TX, Motley County, TX, Pecos County, TX, Reagan County, TX, Scurry County, TX, Sterling County, TX, Upton County, TX

The radar

The Lubbock radar (KLBB), 95 km from the middle of the area, began a volume at 20:36 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.

Severe Thunderstorm Watch 230May 27, 3:50 PM CDT

The nearest sounding before it

Midland Regional, TX (KMAF), launched 12:00Z, 8.6 hours before the alert went out and 148 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: 989 J/kg
Mixed-layer CIN: -375 J/kg
Mixed-layer LCL: 1411 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 135 m²/s²
0-3 km storm-relative helicity: 213 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.

847 
ACUS11 KWNS 272035
SWOMCD
SPC MCD 272034 
TXZ000-272130-

MESOSCALE DISCUSSION 0821
NWS STORM PREDICTION CENTER NORMAN OK
0334 PM CDT MON MAY 27 2013

AREAS AFFECTED...SE TX PANHANDLE SWWD INTO SW TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 272034Z - 272130Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...SVR TSTMS ARE EXPECTED TO DEVELOP ALONG THE DRYLINE THIS
AFTERNOON. WW WILL LIKELY BE NEEDED.

DISCUSSION...VISIBLE SATELLITE IMAGERY HAS SHOWN A GRADUAL INCREASE
IN CU ALONG AND JUST W OF THE DRYLINE FROM THE SE TX PANHANDLE SWWD
INTO SW TX. RADAR IMAGERY SHOWS WEAK RETURNS IN THE DRY AIR JUST E
OF LBB IN CROSBY COUNTY. TEMPERATURES ALONG AND JUST WEST OF THE
DRYLINE ARE IN THE MID 90S TO 100 AT CDS WHILE IN THE UPPER 80S AND
LOW 90S EAST. DEWPOINTS ARE IN THE LOW TO MID 60S AHEAD OF THE
DRYLINE. ALTHOUGH SOME BACKING OF WINDS HAS BEEN
OBSERVED...CONVERGENCE ALONG THE DRYLINE IS WEAK OVERALL. DESPITE
THIS LACK OF CONVERGENCE AND ABSENCE OF ANY NOTABLE LARGE SCALE
FORCING...THE VERY WARM TEMPERATURES FAVOR CONVECTIVE INITIATION
SOON. THE OVERALL LACK OF FORCING SHOULD ACT TO KEEP STORMS
DISCRETE.

AN UNSTABLE ENVIRONMENT EXISTS AHEAD OF THE DRYLINE AS STEEP
MID-LEVEL LAPSE RATES EXIST ATOP A MOIST BOUNDARY LAYER. RUC-BASED
SURFACE ANALYSIS INDICATES MLCAPE IN EXCESS OF 2000 J/KG AND
EFFECTIVE SHEAR AROUND 30 TO 40 KT. AS A RESULT...ROTATING SVR
STORMS ARE LIKELY. THERE IS SOME POTENTIAL FOR SIGNIFICANT WINDS AND
HAIL GIVEN THE UNSTABLE ENVIRONMENT... STEEP LOW-LEVEL LAPSE
RATES...AND LARGE TEMPERATURE-DEWPOINT SPREADS.

..MOSIER/MEAD.. 05/27/2013

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

ATTN...WFO...OUN...SJT...LUB...MAF...

LAT...LON   34290062 34620011 34499987 34129985 31650104 30030272
            30550372 32740218 34290062

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 27, 3:47 PM CDT	Severe Thunderstorm Watch	SPC	Archer, Baylor, Borden, Brewster, Childress, Coke and 39 more	6 hr
May 27, 6:08 PM CDT	Mesoscale Discussion	SPC	Archer, Baylor, Borden, Childress, Coke, Cottle and 32 more	2 hr

Nearby

Mesoscale Discussions in Texas, 2013 Every mesoscale discussion in 2013

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.