SWODY1
SPC AC 121229
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0729 AM CDT THU APR 12 2007
VALID 121300Z - 131200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER WRN PARTS OF THE SRN
PLNS...
..SYNOPSIS...
DIFFLUENT...NEGATIVE TILT TROUGH NOW ENTERING THE WRN GRT BASIN
SHOULD FURTHER AMPLIFY AS IT CONTINUES SE INTO THE LWR CO VLY THIS
EVENING...AND THEN TURNS E TO REACH WRN NM AS A CLOSED LOW EARLY
FRIDAY. AHEAD OF THIS SYSTEM...SATELLITE AND VWP DATA SHOW A WEAKER
LEAD FEATURE NOW APPROACHING THE CA/AZ BORDER THAT SHOULD REACH FAR
ERN NM THIS EVENING. IN THE EAST...VIGOROUS DOWNSTREAM SYSTEM NOW
CENTERED OVER LWR MI EXPECTED TO ELONGATE E TOWARD UPSTATE NY/NRN
ENGLAND.
AT LWR LEVELS...PRESSURES HAVE JUST BEGUN TO FALL OVER ERN NM/FAR W
TX. THESE FALLS SHOULD INCREASE THROUGH TONIGHT AS LEE CYCLONE
DEVELOPS NEAR CVS...AND WARM FRONT GRADUALLY EVOLVES ESE TOWARD
HOU/GLS.
..FAR ERN NM INTO W TX...OK...AND SRN KS
SFC OBSERVATIONS AND SATELLITE DATA SHOW LEADING EDGE OF RICH GULF
MOISTURE /DEWPOINTS NEAR 70 F/ JUST BEGINNING TO EDGE NW INTO DEEP S
TX. MUCH DRIER AIR IS PRESENT N AND W OF THERE...WITH DEWPOINTS IN
THE 40S AND 30S OVER MUCH OF THE REMAINDER OF TX. STRENGTHENING LLJ
WILL ALLOW AT LEAST A NARROW RIBBON OF ENHANCED MOISTURE TO SPREAD
RAPIDLY NNW INTO W CNTRL TX AND THE SRN TX PANHANDLE BY
EVENING...WHERE DEWPOINTS SHOULD INCREASE TO AROUND 50. A MORE
SUBSTANTIAL MOISTURE INCREASE LIKELY WILL OCCUR TONIGHT...WITH
READINGS AROUND 60 POSSIBLE NWD TO VICINITY OF DEVELOPING WARM FRONT
NEAR CDS BY 12Z FRIDAY.
COMBINATION OF STRONG SFC HEATING...INCREASING MOISTURE...
CONVERGENCE INVOF STRENGTHENING LEE CYCLONE/TROUGH...AND
FAVORABLY-TIMED LARGE SCALE ASCENT PROVIDED BY LEAD UPR IMPULSE
EXPECTED TO SUPPORT DEVELOPMENT OF HIGH-BASED TSTMS BY LATE THIS
AFTERNOON IN NE NM AND THE WRN TX PANHANDLE. ADDITIONAL SOMEWHAT
MORE SUBSTANTIAL ACTIVITY LIKELY WILL APPEAR A BIT LATER FARTHER S
OR SE ACROSS W CNTRL TX...WHERE MLCAPE SHOULD FROM 500 TO 1000 J/KG.
50-60 KT WSWLY 500 MB FLOW ATOP 40+ KT SLY LLJ WILL MAINTAIN DEEP
SHEAR FAVORABLE FOR SUPERCELLS GIVEN STEEP LOW TO MID LEVEL LAPSE
RATES. WHILE LARGE HAIL AND POSSIBLY DAMAGING WIND SHOULD BE THE
INITIAL SEVERE THREATS...POTENTIAL WILL INCREASE FOR A BRIEF TORNADO
OR TWO THROUGH MID EVENING AS LLJ STRENGTHENS AND MOISTENS.
LATER TONIGHT...ARRIVAL OF RICHER MOISTURE AND INCREASING WARM
ADVECTION LIKELY WILL RESULT IN INCREASED STORM COVERAGE ALONG AND
EVEN WELL N OF DEVELOPING WARM FRONT. STRENGTH AND BREADTH OF LLJ
..AND APPROACH OF MAIN UPR SYSTEM...SUGGEST THAT THIS ACTIVITY WILL
EVOLVE INTO ONE OR MORE OVERNIGHT MCSS. THESE SYSTEMS SHOULD
MOVE/DEVELOP E/NE ACROSS NW TX...MUCH OF OK AND SRN KS...POSING A
THREAT FOR LARGE HAIL AND...IN TX...ALSO PERHAPS DAMAGING WIND.
..MD/DE/PA/NJ...
DRY SLOT ASSOCIATED WITH DEEP GRT LKS UPR LOW WILL SWEEP ENE ACROSS
THE MID ATLANTIC REGION TODAY...WHERE IT WILL OVERSPREAD NARROW AXIS
OF LOW LEVEL MOISTURE OVER THE UPR CHESAPEAKE BAY/LOWER
SUSQUEHANNA/DELAWARE VLYS AROUND MAX HEATING. RELATIVELY STEEP LOW
TO MID LEVEL LAPSE RATES AND MODERATE TO STRONG WSWLY FLOW APPEAR
FAVORABLE FOR DEVELOPMENT OF ONE OR TWO SHORT LINES OF SUSTAINED
STORMS THAT COULD YIELD MARGINALLY SEVERE HAIL.
..SE FL...
TSTMS NOW OVER SW FL AND OFF THE SW FL CST APPEAR TO HAVE FORMED IN
RESPONSE TO INCREASED WARM ADVECTION ATOP SHALLOW COLD DOME LEFT
FROM YESTERDAY'S ACTIVITY. THE STORMS SHOULD MOVE/DEVELOP GENERALLY
E ACROSS THE REMAINDER OF S FL THROUGH MIDDAY. MODEST SWLY LOW TO
MID LEVEL FLOW WILL MINIMIZE UPDRAFT LONGEVITY/ ORGANIZATION. BUT
PRESENCE OF 60 KT JET LEVEL WINDS... UNIDIRECTIONAL NATURE OF DEEP
FLOW...AND ONSET OF DAYTIME HEATING IN FAIRLY UNSTABLE ENVIRONMENT
/SBCAPE TO 2000 J PER KG/ SUGGEST POTENTIAL FOR A FEW SPOTS OF
LOCALLY DAMAGING WIND AND HAIL /REF MCD #470/.
.CORFIDI/CROSBIE.. 04/12/2007
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