Mesoscale Discussion 621

Issued

Apr 28, 2009, 7:23 PM CDT (00:23 UTC)

Expired

Apr 28, 2009, 10:00 PM CDT

In force

3 hr

Issued by

the Storm Prediction Center

The Lubbock radar (KLBB), 93 km from the middle of the area, began a volume at 00:24 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.

• Severe Thunderstorm Watch 206Apr 28, 9:25 PM CDT
• Severe Thunderstorm Watch 207Apr 28, 11:00 PM CDT

000 
ACUS11 KWNS 290023
SWOMCD
SPC MCD 290023 
TXZ000-290300-

MESOSCALE DISCUSSION 0621
NWS STORM PREDICTION CENTER NORMAN OK
0723 PM CDT TUE APR 28 2009

AREAS AFFECTED...PORTIONS W-CENTRAL-NW TX...PANHANDLE THROUGH
SOUTH-PLAINS...LOW ROLLING PLAINS AND PERMIAN BASIN REGIONS.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 290023Z - 290300Z

WW MAY BE REQUIRED FOR PORTIONS OF THIS REGION ANY TIME THROUGH LATE
EVENING. SVR POTENTIAL SHOULD INCREASE THROUGH REMAINDER LATE
AFTERNOON/EVENING ACROSS AREAS E OF WW 205...AND IN SOMEWHAT
SEPARATE REGIME FROM THAT PRIMARILY DRIVING THAT WW.

SFC MESOANALYSIS SHOWS VERY DIFFUSE WARM FRONTAL ZONE FROM LOWEST
PORTION PECOS VALLEY ENEWD OVER EDWARDS PLATEAU AND SRN HILL COUNTRY
-- BETWEEN JCT-SJT AND N OF AUS -- THEN EWD TO AREAS BETWEEN
CLL-TPL.  THIS FRONT SHOULD LIFT NWD ERRATICALLY THROUGH
EVENING...BENEATH BROAD AND INCREASINGLY MOIST SELY LLJ.  PRIND LLJ
WILL STRENGTHEN TO 35-45 KT RANGE AFTER ABOUT 02Z AND VEER
SOMEWHAT...WITH STG/ELEVATED WAA AND MOISTURE TRANSPORT OVER
DISCUSSION AREA.  THIS PROCESS SHOULD BOOST BOTH LOW LEVEL THETAE
AND LOW-MIDLEVEL LAPSE RATES...INCREASING MUCAPE FROM ROUGHLY 1000
J/KG OVER PANHANDLE AND SOUTH-PLAINS REGION TO NEAR 2000 J/KG WHILE
MAINTAINING AT LEAST 2000 J/KG MUCAPE SWD INTO PORTIONS CONCHO
VALLEY AND LOW ROLLING PLAINS.  EVEN AFTER ADJUSTING FOR APPARENT
THERMAL SENSOR ERROR IN LOW LEVELS OF MAF RAOB THAT ARTIFICIALLY
BOOSTS BUOYANCY...MAF RAOB STILL SHOWS ML/MUCAPE IN 2000-2500 RANGE.


CONDITIONAL/SFC-BASED SUPERCELL POTENTIAL EXISTS ACROSS LATTER AREAS
BEFORE DUSK.  ALTHOUGH LOW LEVEL CONVERGENCE APPEARS WEAK...SO IS
SBCINH...AND ANY TSTMS THAT CAN DEVELOP AND STAY ROOTED WITHIN WARM
FRONTAL ZONE BEFORE DARK MAY EVOLVE INTO SFC-BASED SUPERCELLS.  MORE
PROBABLE SCENARIO IS FOR GRADUAL INCREASE IN TSTMS ELEVATED ABOVE
RELATIVELY COOL/STABLE LAYER FATHER NW ON EITHER SIDE OF CAPROCK
INTO PANHANDLE.  PROFILER DATA AND MODIFIED RUC SOUNDINGS SUGGEST
EFFECTIVE SHEAR MAGNITUDES APCHG 50 KT FOR ANY SUCH
ACTIVITY...SUPPORTING ROTATION ALOFT AND THREAT FOR LARGE HAIL.

..EDWARDS.. 04/29/2009

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

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

LAT...LON   30660172 31070211 31330272 32080272 32070305 35720297
            36420203 36080045 34710030 33559987 32329932 31099890
            30660172

Mesoscale Discussions in Texas, 2009Every mesoscale discussion in 2009

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.