SWODY1
SPC AC 301233
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0733 AM CDT MON APR 30 2007
VALID 301300Z - 011200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF TX...
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS A SMALL PART OF THE NRN
MS RIVER VALLEY...
..CENTRAL/SRN TX...
MID/UPPER LOW CENTERED OVER SERN NM EARLY THIS MORNING WILL CONTINUE
MOVING SLOWLY ENEWD ACROSS THE WEST TX PLAINS AND INTO OK THROUGH
THE PERIOD. THIS SYSTEM WILL CONTINUE TO FOCUS NUMEROUS
THUNDERSTORMS IN THE FORM OF ONE OR MORE CONVECTIVE SYSTEMS THROUGH
THE PERIOD ACROSS THIS REGION. MCS WHICH WEAKENED AS IT MOVED INTO
GREATER STABILITY ACROSS CENTRAL TX PRIOR TO 10Z REINFORCED A
SURFACE OUTFLOW BOUNDARY...WITH TAIL END OF THIS BOUNDARY EXTENDING
ROUGHLY WSWWD BETWEEN SAT AND COT TO JUST SOUTH OF DRT AT 12Z. DEEP
ASCENT AND INFLUX OF STEEP MID LEVEL LAPSE RATES /EVIDENCED ON
EXTENSIVE DRY INTRUSION ON WV IMAGERY/ CONTINUES TO SUPPORT ELEVATED
THUNDERSTORM DEVELOPMENT JUST NORTH OF THIS BOUNDARY FROM THE BIG
BEND REGION INTO THE HILL COUNTRY THIS MORNING. DEEP LAYER SHEAR
REMAINS SUPPORTIVE OF SUPERCELLS...INCREASING THE POTENTIAL FOR
LARGE HAIL...AS AREA REMAINS FED WITH RICH BOUNDARY LAYER MOISTURE
IN PLACE OVER DEEP SOUTH TX.
SURFACE OUTFLOW BOUNDARY WILL LIKELY BECOME FOCUS OF MORE INTENSE
THUNDERSTORM DEVELOPMENT TODAY. APPEARS WARM SECTOR WILL BECOME
VERY UNSTABLE AS MAJORITY OF MORNING CLOUDS/PRECIPITATION ADVECT
NNEWD OVER COLD SIDE OF THE FORNT. MLCAPE EXCEEDING 2000 J/KG IS
EXPECTED BY THE MID AFTERNOON OVER SOUTH TX WHERE 30-40 KT MID LEVEL
WLYS WILL ENHANCE DEEP LAYER SHEAR. OVERALL PATTERN WILL BECOME
FAVORABLE FOR LONGER-LIVED SUPERCELLS IF STORMS DEVELOP NEAR THE
HIGHER TERRAIN WEST OF THE RIO GRANDE OR OVER SRN TX...AND TRACK
SLOWLY EWD ALONG THIS FRONT TODAY. IN ADDITION TO LARGE HAIL AND
DAMAGING WINDS...THE THREAT OF TORNADOES WILL ALSO ACCOMPANY THIS
ACTIVITY.
SEVERE THREAT WILL BE A BIT MORE DIFFICULT TO DISCERN FARTHER NORTH
INTO CENTRAL TX...WITH THREAT DEPENDING UPON PROPER
CLEARING/DESTABILIZATION IN WAKE OF EARLIER STORMS. MID LEVEL LAPSE
RATES AND MODEST SHEAR WOULD SUPPORT AT LEAST A LARGE HAIL THREAT
FOR MUCH OF THE PERIOD WITH STRONGER STORMS. AN AREA OF STRONGER
STORMS MIGHT DEVELOP INTO WRN TX/FAR SWRN OK NEARER THE MID/UPPER
LOW AND ASSOCIATED -14C TO -16C MID LEVEL COLD POCKET...WHERE DRY
SLOT MAY BOOST HEATING LATER TODAY. LARGE HAIL WOULD BE PRIMARY
THREAT WITH THIS ACTIVITY.
..NRN MS RIVER VALLEY...
SURFACE LOW IS FORECAST TO DEEPEN AS IT MOVES ACROSS SRN MN TODAY IN
RESPONSE OF FAST MOVING SHORTWAVE TROUGH MOVING RAPIDLY OVER THE NRN
PLAINS THIS MORNING. A WARM FRONT WILL BECOME BETTER DEFINED
EXTENDING EWD FROM THE LOW CENTER INTO THE TRI-STATE AREA OF
IA/WI/MN...WHICH WILL THEN EXTEND SEWD INTO NERN IND. MODELS HAVE
BEEN CONSISTENT IN DEVELOPING A SMALL AREA OF 60+ SURFACE DEW POINTS
JUST AHEAD OF THE SURFACE LOW...WHICH FORECAST SOUNDINGS INDICATE
WILL BOOST MLCAPE TO NEAR 1500 J/KG AND WEAKEN CINH. APPEARS
SUFFICIENT CONVERGENCE WILL DEVELOP BETWEEN 21Z-00Z FOR THUNDERSTORM
DEVELOPMENT NEAR THE TRI-STATE REGION...WITH ACTIVITY DEVELOPING
SEWD THROUGH THE EVENING. EFFECTIVE BULK SHEAR FROM 35-40 KT WILL
LIKELY SUPPORT A SUPERCELL OR TWO WITH STRONG LOW LEVEL SHEAR
INDICATING A THREAT OF TORNADOES WITH ANY SUSTAINED SUPERCELL NEAR
THE FRONT THROUGH THE EARLY EVENING.
..CENTRAL HIGH PLAINS...
OVERNIGHT MODELS CONTINUE TO INDICATE THUNDERSTORMS WILL DEVELOP
ALONG WRN END OF THE SURFACE FRONT MOVING ACROSS THE CENTRAL PLAINS
TODAY. THIS ACTIVITY WILL LIKELY FORM WITHIN UPSLOPE FLOW INTO
CENTRAL/SERN WY AND OVERSPREAD A MARGINALLY UNSTABLE AIR MASS OVER
THE HIGH PLAINS THIS EVENING. IN ADDITION TO HAIL...DEEPLY MIXED
BOUNDARY LAYER MAY SUPPORT STRONG GUSTS. DEEP MIXING AND
CONVERGENCE MAY ALSO AID IN ISOLATED THUNDERSTORM DEVELOPMENT ALONG
THE FRONT ACROSS THE CENTRAL PLAINS.
.EVANS/CROSBIE.. 04/30/2007
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