MESO: Mesoscale Discussion 0664

ACUS11 KWNS 031708
SWOMCD
SPC MCD 031708
TXZ000-031845-

MESOSCALE DISCUSSION 0664
NWS STORM PREDICTION CENTER NORMAN OK
1208 PM CDT THU MAY 03 2007

AREAS AFFECTED...PARTS OF CNTRL/NE TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 031708Z - 031845Z

TRENDS ARE BEING MONITORED FOR AN INCREASING SEVERE THREAT AND THE
POSSIBILITY OF A WW.

AS A SIGNIFICANT IMPULSE PIVOTS AROUND THE SOUTHERN PERIPHERY OF
LINGERING MID-LEVEL CIRCULATION CENTER NEAR WICHITA FALLS...A
SUBSTANTIAL INCREASE IN CONVECTIVE DEVELOPMENT IS UNDERWAY SOUTH
THROUGH EAST OF THE DALLAS/FORT WORTH METROPLEX. ONGOING ACTIVITY
IS BASED IN ZONE OF ISENTROPIC ASCENT ABOVE A WEAKENING SURFACE COLD
POOL...WHERE PARCELS ARE REACHING LEVELS OF FREE CONVECTION TO THE
NORTH OF WARMER MID-LEVEL ENVIRONMENT EXTENDING ACROSS MUCH OF
SOUTHERN/SOUTHEAST TEXAS. WEAK SHEAR WELL TO THE NORTH OF A 40-50
KT 500 MB JET STREAK AND LIMITED INSTABILITY ON THE ORDER OF
500-1000 J/KG SEEMS LIKELY TO MINIMIZE SEVERE POTENTIAL. BUT MOIST
ENVIRONMENT IS SUPPORTIVE OF LOCALLY HEAVY RAINFALL IN EXPANDING
CLUSTER ACROSS NORTHEAST TEXAS AND THE ARKLATEX THIS AFTERNOON.

PERHAPS OF GREATER CONCERN IN THE SHORT TERM...IS POTENTIAL FOR NEW
SURFACE BASED CONVECTIVE DEVELOPMENT SOUTH SOUTHWEST OF DALLAS/FORT
WORTH...IN NARROW WEDGE EAST OF WIND SHIFT ASSOCIATED WITH UPPER
IMPULSE...AND WEST OF RAIN COOLED AIR ASSOCIATED WITH ONGOING
STORMS. THIS IS WHERE SURFACE HEATING IS CONTRIBUTING TO MIXED
LAYER CAPE OF 1000-2000 J/KG...AND CAP IS WEAKENING WITH ONSET OF
MID-LEVEL COOLING. IN CLOSER PROXIMITY TO UPPER JET STREAK ACROSS
THE HILL COUNTRY...DEEP LAYER SHEAR IS SUFFICIENT FOR
SUPERCELLS...MAINLY WITH RISK FOR LARGE HAIL/ISOLATED DAMAGING WIND
GUSTS.

.KERR.. 05/03/2007

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

ATTN...WFO...FWD...EWX...SJT...

31249943 32059824 32529779 32499745 32139709 31329760
30749802 30529923

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