SWODY1
SPC AC 221955
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0155 PM CST TUE DEC 22 2009
VALID 222000Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...ERN OK/WRN AR INTO CNTRL/ERN TX...
TRENDS IN REGIONAL VWP/PROFILER DATA INDICATE A GRADUAL BACKING AND
INTENSIFICATION OF LLJ ACROSS CNTRL AND ERN PARTS OF TX...LIKELY IN
RESPONSE TO APPROACH OF LEAD VORTICITY MAXIMUM TOWARD THE SRN
ROCKIES. THIS LOW-LEVEL MASS ADJUSTMENT IS SERVING TO ENHANCE THE
NWD/NEWD FLUX OF A MODIFIED CONTINENTAL AIR MASS THROUGH LOWER
ELEVATIONS OF THE SRN PLAINS WITH LOWER/MID 50S DEWPOINTS AS FAR N
AS THE RED RIVER AS OF 19Z.
RADAR/SATELLITE IMAGERY ARE SHOWING A GRADUAL DEEPENING OF CUMULUS
CONVECTION WITHIN MOISTENING AIR MASS W OF HOU WHERE RUC OBJECTIVE
FIELDS SUGGEST THAT ENVIRONMENT HAS BECOME WEAKLY UNSTABLE WITH
SBCAPE OF AROUND 500 J/KG. GIVEN THE PERSISTENT LOW-LEVEL WAA
FORECAST AND STRENGTHENING DEEP LAYER WIND FIELD...THERE IS SOME
QUESTION AS TO WHETHER ANY SEVERE THREAT WILL DEVELOP THROUGH THE
REMAINDER OF THE DIURNAL HEATING CYCLE. LATEST SHORT TERM MODEL
GUIDANCE SUGGESTS THAT CAPPING ASSOCIATED WITH AN EML /REF 12Z DRT
SOUNDING/ WILL SPREAD EWD TODAY IN ASSOCIATION WITH STRENGTHENING
WLY/SWLY FLOW ABOVE THE BOUNDARY LAYER. THIS MAY TEND TO LIMIT THE
VERTICAL GROWTH OF ABOVE-MENTIONED MOIST CONVECTION AND THE
POTENTIAL FOR STRONGER/MORE PERSISTENT UPDRAFTS. AS SUCH...ONLY LOW
SEVERE PROBABILITIES WILL BE MAINTAINED.
OTHERWISE...CURRENT SCENARIO ESTABLISHED IN PRIOR OUTLOOKS FOR
TONIGHT APPEARS ON TRACK WITH ONLY SMALL CHANGES MADE TO THE AREAL
LOCATION OF PROBABILITY AND GENERAL THUNDER LINES.
..MEAD.. 12/22/2009
.PREV DISCUSSION... /ISSUED 1030 AM CST TUE DEC 22 2009/
...SYNOPSIS...
ORE UPR LOW EXPECTED TO CONTINUE SE INTO NV THIS EVE BEFORE TURNING
ESE TOWARD THE FOUR CORNERS REGION EARLY WED. AT THE SAME
TIME...LEAD IMPULSE NOW OVER THE LWR CO VLY EXPECTED TO REACH THE
AZ/NM BORDER THIS EVE BEFORE CONTINUING NE TO THE TX PANHANDLE BY
12Z WED.
AT THE SFC...WEAK LEE CYCLONE ALREADY PRESENT OVER THE SRN HI PLNS
SHOULD GRADUALLY STRENGTHEN IN PLACE. ASSOCIATED LLJ ALSO SHOULD
PERSIST AND PERHAPS SLIGHTLY BACK AS LEAD UPR IMPULSE APPROACHES
FROM THE WEST.
...CNTRL/E TX INTO E OK TONIGHT...
MODEST LOW LVL MOISTURE RETURN WILL ACCOMPANY LLJ OVER E CNTRL AND E
TX INTO ERN OK THROUGH WED. ATOP THE MOISTENING BOUNDARY
LAYER...MID LVL LAPSE RATES WILL STEEPEN TO AROUND 7 DEG C/KM IN
PERSISTENT SWLY MID LVL FLOW. THIS SHOULD CONTRIBUTE TO THE
DEVELOPMENT OF WEAK INSTABILITY /MLCAPE AROUND 500 J/KG/ OVER REGION
TONIGHT/EARLY WED. OVERALL INSTABILITY...HOWEVER...LIKELY WILL BE
LIMITED BY RELATIVELY COOL SFC TEMPERATURES/TIME OF DAY. IN
ADDITION...LARGE SCALE FORCING FOR ASCENT /OUTSIDE OF WAA/ WILL
REMAIN WEAK. NONETHELESS... COMBINATION OF INCREASING MOISTURE WITH
SUFFICIENTLY COOL MID LVL TEMPERATURES SHOULD SUPPORT STORM
DEVELOPMENT ALONG WRN/NRN FRINGE OF LLJ TONIGHT THROUGH EARLY WED.
CIN WILL BE WEAK AND STORMS SHOULD BE ROOTED AT OR VERY NEAR THE
SFC. COUPLED WITH SRH OF 250-350 M2/S2...AND 35-40 KT BULK
SHEAR...SETUP COULD SUPPORT ONE OR TWO SUPERCELLS WITH MARGINALLY
SVR HAIL...STRONG GUSTS...AND POSSIBLY A WEAK TORNADO. HOWEVER...
BOTH SATELLITE DERIVED PW DATA AND SFC OBSERVATIONS SUGGEST THAT
MOISTURE AVAILABILITY WILL REMAIN LIMITED...WITH AIR MASS BEING
PARTIALLY MODIFIED POLAR IN ORIGIN. THUS ONLY LOW SVR STORM
PROBABILITIES APPEAR WARRANTED ATTM.
FARTHER SE...AN AREA OF PERSISTENT CONVECTION EXPECTED TO DEVELOP
LATER TODAY THROUGH WED MORNING FROM SE TX INTO WRN/NRN LA...ON ERN
FRINGE OF LLJ THIS ACTIVITY SHOULD REMAIN CAPPED BENEATH EML
SPREADING NEWD FROM S TX. THE CONVECTION SHOULD GRADUALLY DEEPEN
WITH TIME...AND MAY EVOLVE INTO TSTMS...AS THE SUPPORTING MOIST
LAYER SLOWLY MOISTENS/DEEPENS. BUT LIMITED MOISTURE AVAILABILITY
AND SLIGHTLY ELEVATED NATURE OF THE CONVECTION SHOULD PRECLUDE ANY
SUSTAINED SVR THREAT.
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