SWODY1
SPC AC 081919
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0219 PM CDT SAT OCT 08 2011
VALID 082000Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF S-CNTRL AND
SWRN TX...
...FL...
HAVE LOWERED SEVERE PROBABILITIES ACROSS SRN FL. SCATTERED STORMS
WILL CONTINUE THROUGH THE PERIOD...EMBEDDED WITHIN A STRONG ELY
GRADIENT FLOW REGIME. HOWEVER...MID TO UPPER LEVEL WINDS REMAIN
WEAK...AND WILL BE A DETRIMENT TO ORGANIZATION OR UPSCALE GROWTH.
ALSO...WIDESPREAD NATURE OF RAIN WILL HELP TO STABILIZE THE
ATMOSPHERE SOMEWHAT. SOME EMBEDDED ROTATION MAY EXIST WITH 0-1 KM
SRH ON THE ORDER OF 50-100 M2/S2...BUT POOR LAPSE RATE ENVIRONMENT
AND WEAK FLOW ALOFT SHOULD HELP TO MINIMIZE ANY TORNADO THREAT.
...OK INTO TX...
TRIMMED LOW END TORNADO PROBABILITIES TO SOUTH OF THE RED RIVER AS
OUTFLOW CONTINUES EWD ACROSS MUCH OF OK WHICH WILL REDUCE SURFACE
BASED INSTABILITY.
FARTHER S...ANOTHER OUTFLOW BOUNDARY WAS SAGGING SWD FROM SAN ANGELO
TO THE BIG BEND. A CONTINUOUS FEED OF MOIST AND UNSTABLE AIR WILL
KEEP THE THREAT OF STRONG TO SEVERE STORMS OVER MUCH S CNTRL/SW TX.
DEEP LAYER SHEAR IS NOT STRONG...BUT SUFFICIENT FOR A FEW BOWING
STRUCTURES CAPABLE OF DAMAGING WIND GUSTS...ALONG WITH HAIL
ESPECIALLY WITH THE MORE CELLULAR STORM STRUCTURES.
..JEWELL.. 10/08/2011
.PREV DISCUSSION... /ISSUED 1126 AM CDT SAT OCT 08 2011/
...SWRN AND S-CNTRL TX...
SURFACE OBSERVATIONS AND SATELLITE-DERIVED PW IMAGERY INDICATE THE
PRESENCE OF AN MT AIR MASS OVER THE LOWER RIO GRANDE VALLEY AND
CNTRL TX WHERE DEWPOINTS ARE IN THE UPPER 60S-LOWER 70S WITH PW
VALUES OF 1.50-1.75 INCHES. THIS MOISTURE WILL COMBINE WITH DAYTIME
HEATING TO YIELD A MODERATELY UNSTABLE AIR MASS BY AFTERNOON WITH
MLCAPE VALUES INCREASING TO 1500-2500 J/KG. CONVERGENCE ALONG
PRE-EXISTING OUTFLOW BOUNDARIES...UPSLOPE FLOW...AND ASCENDING
BRANCH OF AGEOSTROPHIC CIRCULATION ATTENDANT TO COUPLED UPPER-LEVEL
JET STRUCTURE ALL WILL CONTRIBUTE TO AN INCREASE IN TSTMS TODAY OVER
THE EDWARDS PLATEAU REGION. THOUGH DEEP-LAYER WIND FIELD WILL
REMAIN MARGINALLY SUPPORTIVE OF ORGANIZED STORM MODES...VERTICALLY
VEERING WIND PROFILES COUPLED WITH THE HIGH PW ENVIRONMENT MAY
FOSTER EVOLUTION OF ONE OR MORE CONVECTIVE SYSTEMS WITH AN ATTENDANT
RISK FOR DAMAGING WINDS AND PERHAPS SOME HAIL.
ADDITIONAL STORMS CAPABLE OF MARGINALLY SEVERE HAIL MAY DEVELOP
OVERNIGHT ACROSS THE TRANS-PECOS REGION IN RESPONSE TO APPROACH OF
UPSTREAM VORTICITY MAXIMUM ROTATING THROUGH THE BASE OF LARGE-SCALE
TROUGH.
...S FL...
A GRADUAL STRENGTHENING OF LOW-LEVEL GRADIENT FLOW IS FORECAST TODAY
INTO TONIGHT ALONG SRN FRINGE OF MID ATLANTIC ANTICYCLONE IN
RESPONSE TO DEVELOPING LOW PRESSURE OVER THE SERN GULF OF MEXICO.
THIS WILL RESULT IN ENLARGING LOW-LEVEL HODOGRAPHS WITHIN A
MOIST/MODERATELY UNSTABLE ENVIRONMENT WITH MLCAPE OF 1000-2000 J/KG.
AS SUCH...SOME POTENTIAL WILL EXIST FOR ORGANIZED STORM
MODES...INCLUDING SHALLOW SUPERCELLS AND BOWING STRUCTURES WITH THE
PRIMARY HAZARD BEING DAMAGING WIND GUSTS.
...CNTRL OK INTO NRN TX...
RECENT TRENDS IN REGIONAL RADAR IMAGERY SHOW A GRADUAL INCREASE IN
TSTM INTENSITY ALONG LEADING EDGE OF RESIDUAL COLD POOL OVER SWRN
OK. WHILE LARGE-SCALE FORCING FOR ASCENT WILL REMAIN NEGLIGIBLE
THROUGH THE REMAINDER OF THE DIURNAL HEATING CYCLE...GUSTY...SELY
SURFACE WINDS WILL ENHANCE INFLOW OF A RELATIVELY MOIST AND MODESTLY
UNSTABLE AIR MASS INTO ONGOING ACTIVITY. GIVEN THE RELATIVELY STRONG
LOW- AND DEEP-LAYER SHEAR IN PLACE...A LOW PROBABILITY RISK FOR
DAMAGING WINDS AND PERHAPS A BRIEF SPIN-UP ALONG CONVECTIVE GUST
FRONT WILL BE POSSIBLE.
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