SWODY2
SPC AC 210559
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT TUE OCT 21 2008
VALID 221200Z - 231200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS E TX AND THE ARKLATEX
REGION...
...SYNOPSIS...
WHILE AN UPPER TROUGH OVER THE NORTHEAST CONTINUES DRIFTING SLOWLY
EWD...A MUCH STRONGER/MORE SIGNIFICANT FEATURE WILL CONTINUE TO DIG
SEWD ACROSS THE CENTRAL CONUS. BY THE END OF THE PERIOD...A DEEP
CLOSED LOW IS FORECAST...LIKELY CENTERED OVER THE CENTRAL PLAINS/WRN
MO REGION BY 23/12Z.
AT THE SURFACE...A LOW IS FORECAST TO LINGER INVOF ERN KS/NWRN
MO/SERN NEB/SWRN IA...OCCLUDING WITH TIME AS THE SURFACE FRONT
SURGES SEWD ACROSS THE SRN PLAINS. LATE IN THE PERIOD...THE FRONT
SHOULD CROSS THE MID MS VALLEY...WHILE PUSHING SEWD OFF THE TX COAST
INTO THE WRN GULF.
...E TX AND THE ARKLATEX REGION...
BOUNDARY LAYER MOISTENING IS FORECAST AHEAD OF THE SEWD-MOVING
FRONT...AS SLY WARM SECTOR FLOW ADVECTS GULF MOISTURE NWD. WHILE
GENERALLY WEAK LAPSE RATES WILL LIMIT THE POTENTIAL FOR
DESTABILIZATION...SOME HEATING AND THE MOISTENING BOUNDARY LAYER
SHOULD RESULT IN AFTERNOON MIXED-LAYER CAPE VALUES OF 250 TO 750
J/KG ACROSS E TX/WRN LA...AND AS FAR N AS THE ARKLATEX REGION.
SHOWERS AND SCATTERED THUNDERSTORMS SHOULD BE ONGOING AT THE START
OF THE PERIOD NEAR -- AND PARTICULARLY TO THE COOL SIDE -- OF THE
ADVANCING FRONT...WITH THIS TREND LIKELY TO CONTINUE THROUGH THE
PERIOD. HOWEVER...WARM-SECTOR DESTABILIZATION MAY SUPPORT THE
DEVELOPMENT OF SURFACE-BASED SHOWERS AND STORMS ALONG THE FRONT
THROUGH THE AFTERNOON...FROM SERN OK/THE ARKLATEX REGION INTO E TX.
ATTM...IT APPEARS THAT THE TENDENCY WILL BE FOR STORMS TO DEVELOP
AND THEN BE QUICKLY UNDERCUT BY THE ADVANCING FRONT -- PARTICULARLY
ACROSS E TX AND LA. PRESUMING THIS IS THE CASE...THE MAIN THREAT
ACROSS THIS REGION WOULD BE HAIL. THE GREATER THREAT FOR STORMS TO
REMAIN SURFACE-BASED APPEARS TO EXIST ACROSS AR...WHERE A MORE N-S
ALIGNMENT AND SLOWER ADVANCE OF THE FRONT IS EXPECTED. IF A CLUSTER
OF STORMS COULD ORGANIZE SUFFICIENTLY TO PRODUCE A SUBSTANTIAL COLD
POOL...THEN A SURGING GUST FRONT -- AIDED BY FAIRLY STRONG WLY FLOW
ABOVE THE SURFACE -- COULD BECOME THE EFFECTIVE FOCUS FOR NEW STORM
DEVELOPMENT IN THE WARM SECTOR. THIS WOULD SUPPORT A GREATER THREAT
FOR DAMAGING WINDS THAN IS FORECAST ATTM...BUT WITH WEAKER
INSTABILITY EXPECTED ACROSS AR...THIS SCENARIO APPEARS SOMEWHAT
UNLIKELY. WILL INTRODUCE 15% PROBABILITY/SLIGHT RISK THIS
FORECAST...MAINLY FOR THE POTENTIAL FOR HAIL...WITH DAMAGING WINDS
LIKELY TO REMAIN A LESSER THREAT. SEVERE POTENTIAL SHOULD DIMINISH
AFTER DARK...AS THE WARM SECTOR AIRMASS STABILIZES DIURNALLY.
..GOSS.. 10/21/2008
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