Alert archive / Texas / Mesoscale Discussions in 2012

Mesoscale Discussion 650

May 1, 201211 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 1, 2012, 5:43 PM CDT for 11 counties in Texas. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
May 1, 2012, 5:43 PM CDT (22:43 UTC)
Expired
May 1, 2012, 8:15 PM CDT
In force
3 hr
Issued by
the Storm Prediction Center
Chance of a watch
20%

Counties Brewster County, TX, Crane County, TX, Crockett County, TX, Edwards County, TX, Kinney County, TX, Maverick County, TX, Pecos County, TX, Reeves County, TX, Terrell County, TX, Val Verde County, TX, Ward County, TX

The radar

The Laughlin AFB radar (KDFX), 180 km from the middle of the area, began a volume at 22:45 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

Del Rio, TX (KDRT), launched 12:00Z, 10.7 hours before the alert went out and 125 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-pSkew-T log-p diagram, Del Rio, TX at 12:00Z on 2012-05-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1484 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Del Rio, TX at 12:00Z on 2012-05-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 102 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
1484 J/kg
Mixed-layer CIN
-199 J/kg
Mixed-layer LCL
620 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
102 m²/s²
0-3 km storm-relative helicity
284 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.1

Open this sounding in Storm Lab

The text

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

446 
ACUS11 KWNS 012243
SWOMCD
SPC MCD 012243 
TXZ000-020115-

MESOSCALE DISCUSSION 0650
NWS STORM PREDICTION CENTER NORMAN OK
0543 PM CDT TUE MAY 01 2012

AREAS AFFECTED...PORTIONS SW TX -- TRANS-PECOS AND BIG BEND REGIONS
SEWD ALONG MIDDLE RIO GRANDE VALLEY.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 012243Z - 020115Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...WIDELY SCATTERED TSTMS MAY MOVE ACROSS BIG BEND AREA AND
OFF DAVIS MOUNTAINS WITH POTENTIAL FOR ISOLATED DAMAGING GUSTS OR
LARGE HAIL.  ADDITIONAL TSTMS OVER SERRANIAS DEL BURRO MOUNTAINS OF
NRN COAHUILA MAY CROSS RIO GRANDE WITH SPORADIC WIND/HAIL THREAT AS
WELL...EITHER FROM LEFT-MOVERS HEADED NWD OR FROM LATER AGGREGATION
OF FORWARD-PROPAGATING/COLD-POOL DRIVEN CONVECTION MOVING EWD TOWARD
DRT AREA.

DISCUSSION...22Z SFC MESOANALYSIS SHOWED DRYLINE FROM SWRN CORNER OF
OK SWWD BETWEEN SNK-BPG...THEN SSWWD JUST W OF 6R6 AND INTO NWRN
SLOPES OF MEX MOUNTAINS E OF BIG BEND.  VIS IMAGERY SHOWED TCU AND
YOUNG CBS W OF DRYLINE...OVER HIGHER TERRAIN FROM BIG BEND NATIONAL
PARK NWD PAST MRF...ALL MOVING NEWD.  CONVECTION BEHIND DRYLINE WILL
MOVE OVER HOT...DEEPLY MIXED BOUNDARY LAYER CHARACTERIZED BY TEMPS
90S F AND 45-60 DEG F DEW POINT DEPRESSIONS...BEFORE DRYLINE BACKS
INTO REGION.  EVEN IN DRY AIR...MLCAPE 500-1200 J/KG IS EVIDENT FROM
MODIFIED RR AND ETA-KF SOUNDINGS...ATOP DCAPE 1000-2000 J/KG. 
EFFECTIVE SHEAR MAGNITUDES 30-40 KT MAY AID STORM ORGANIZATION IN
SUPPORT OF PRIMARY SVR GUST THREAT...WITH HAIL ALSO POSSIBLE.

AIR MASS E OF DRYLINE...OVER LOWER ELEVATIONS...IS CHARACTERIZED BY
SFC DEW POINTS MID-UPPER 60S F AND STEEP MIDLEVEL LAPSE RATES
ASSOCIATED WITH ELEVATED MIXED LAYER.  RESULT IS EXTREME BUOYANCY
FOR ANY TSTMS THAT CAN MOVE OFF HIGHER TERRAIN INTO VALLEY...WITH
PEAK MLCAPE APCHG 5000 J/KG. TRANSIENT SUPERCELL STRUCTURES ALSO ARE
POSSIBLE...BUT MAINLY OVER MEX...BEFORE STORM MODES POTENTIALLY GET
MESSIER AROUND RIO GRANDE. ANY LEFT-MOVERS OR RELATIVELY DISCRETE
RIGHT MOVING SUPERCELLS THAT DO REACH TX CAN PRODUCE DAMAGING HAIL
AND GUSTS...BUT THREAT IS VERY CONDITIONAL.  SOME POTENTIAL ALSO
EXISTS FOR UPSCALE COLD-POOL GROWTH WITH MEX CONVECTION THAT COULD
SEND FORWARD-PROPAGATING TSTM CLUSTER EWD ACROSS RIO GRANDE WITH
POTENTIAL FOR STG-SVR GUSTS.

..EDWARDS/CORFIDI.. 05/01/2012

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

ATTN...WFO...CRP...EWX...SJT...MAF...

LAT...LON   29320403 30440422 31160388 31490356 31570283 31220174
            29900008 28339979 27799987 27909991 28140006 28260032
            29090067 29170080 29220081 29500127 29770143 29780207
            29870230 29720234 29740264 29350283 29310288 29220286
            29170296 29080303 29060309 28970308 28970323 29060341
            29320403

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 30, 8:55 PM CDTMesoscale DiscussionSPCCollingsworth, Donley, Hemphill, Wheeler65 min
Apr 30, 9:37 PM CDTMesoscale DiscussionSPCBandera, Baylor, Brown, Callahan, Coke, Coleman and 33 more113 min
Apr 30, 9:51 PM CDTTornado WatchSPCClay, Wichita, Wilbarger4 hr
Apr 30, 11:28 PM CDTMesoscale DiscussionSPCWichita, Wilbarger92 min

Nearby

Mesoscale Discussions in Texas, 2012Every mesoscale discussion in 2012

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.