MESO: Mesoscale Discussion 0642

ACUS11 KWNS 150055
SWOMCD
SPC MCD 150055
TXZ000-150300-

MESOSCALE DISCUSSION 0642
NWS STORM PREDICTION CENTER NORMAN OK
0755 PM CDT TUE MAY 14 2013

AREAS AFFECTED...SRN PART OF THE EDWARDS PLATEAU INTO PORTIONS OF
SOUTH AND SOUTH CENTRAL TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 150055Z - 150300Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...ONGOING TSTMS LOCATED OVER NRN CHIHUAHUA TO ALONG AND JUST
N OF THE INTERNATIONAL BORDER IN SRN BREWSTER/ADJACENT TERRELL
COUNTIES ARE EXPECTED TO SPREAD ENEWD THIS EVENING...AFFECTING THE
SRN PART OF THE EDWARDS PLATEAU AND PORTIONS OF SOUTH AND SOUTH
CENTRAL TX. SOME OF THIS ACTIVITY SHOULD BE OR BECOME CAPABLE OF
PRODUCING SEVERE HAIL AND DAMAGING WIND GUSTS. THIS POTENTIAL
SEVERE WEATHER WILL CONTINUE TO BE MONITORED WITH WATCH ISSUANCE
POSSIBLE YET THIS EVENING.

DISCUSSION...AT 0030Z...REGIONAL RADAR IMAGERY...LIGHTNING DATA AND
COOLING CLOUD TOPS PER IR IMAGERY SHOWED A CLUSTER OF TSTMS
EXTENDING FROM NRN CHIHUAHUA MEXICO NWD INTO THE ADJACENT PORTIONS
OF BREWSTER/TERRELL COUNTIES. THE DOWNSTREAM ENVIRONMENT ACROSS THE
EDWARDS PLATEAU INTO THE LOWER RIO GRANDE VALLEY IS MODERATELY
UNSTABLE GIVEN PRECIPITABLE WATER VALUES EXCEEDING 1-1.5 INCHES AND
STEEP LAPSE RATES /7.5-8 C/KM AT MIDLEVELS PER 00Z DRT SOUNDING/.
DESPITE THE LOSS OF DAY TIME HEATING THROUGH THE
EVENING...MOISTENING PER A STRENGTHENING SLY LLJ ACROSS THE
DISCUSSION AREA WILL AID IN DESTABILIZATION BENEATH THE STEEP
MIDLEVEL LAPSE RATES TO AT LEAST SUSTAIN MODERATE INSTABILITY AFTER
SUNSET.

MEANWHILE...THE HRRR /INCLUDING RUNS SINCE 21Z/ HAS INDICATED ONE OR
TWO CLUSTERS OF TSTMS WILL AFFECT THE SRN EDWARDS PLATEAU INTO PARTS
OF SOUTH AND SOUTH CENTRAL TX THIS EVENING...BUT OVERALL COVERAGE OF
STRONGER/SEVERE STORMS REMAINS UNCERTAIN. FORCING FOR ASCENT
ATTENDANT TO A MIDLEVEL IMPULSE TRACKING NEWD FROM NRN MEXICO INTO
TX SHOULD SUPPORT THE ONGOING NRN MEXICO TSTM CLUSTER AND NEW TSTM
ACTIVITY INTO THE DISCUSSION AREA THIS EVENING. 40-50 KT SWLY
MIDLEVEL WINDS ACCOMPANYING THE IMPULSE AND 30-40 KT SLY LLJ WILL
RESULT IN STRENGTHENING EFFECTIVE BULK SHEAR FOR STORM ORGANIZATION.
GIVEN THE ENVIRONMENT ACROSS THE DISCUSSION AREA EXPECTED TO BE
SUPPORTIVE FOR SEVERE STORMS...REGIONAL RADAR TRENDS WILL BE
MONITORED AS ONGOING STORMS PROGRESS EWD FROM NRN MEXICO WITH THE
POTENTIAL FOR WATCH ISSUANCE YET THIS EVENING.

..PETERS/HART.. 05/15/2013

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

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

LAT...LON 29890178 30430151 30509975 30229902 29539878 28249852
27579886 27429940 28190026 29220095 29670168 29890178

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