SWODY2
SPC AC 231729
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CDT SAT OCT 23 2010
VALID 241200Z - 251200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS ERN PARTS OF THE SRN
PLAINS TO THE LOWER MS VALLEY AND SRN MO...
...SYNOPSIS...
MODELS ARE IN GENERAL AGREEMENT WITH THE LARGE SCALE PATTERN FOR DAY
2. THE COMPLEX UPPER LOW CURRENTLY OVER THE CENTRAL PLAINS IS
FORECAST TO WEAKEN AND GRADUALLY EJECT EWD ACROSS THE UPPER MS VLY
AS AN OPEN WAVE ON SUNDAY. MEANWHILE...ADDITIONAL JET ENERGY AND
SRN EXTENT OF A TROUGH...NOW MOVING INTO THE GREAT BASIN...WILL
CARVE OUT A SHORTWAVE OVER THE SRN PLAINS BY SUNDAY AFTERNOON. THIS
FEATURE WILL REACH THE MID SOUTH SUNDAY NIGHT AS AN EVEN STRONGER
TROUGH TRANSLATES INTO THE CNTRL/NRN ROCKIES AIDING THE EVOLUTION OF
A BROAD LARGE SCALE LONG WAVE TROUGH ACROSS MUCH OF THE CONUS BY 12Z
MONDAY.
...ERN PARTS OF SRN PLAINS TO THE LOWER MS VALLEY/MID SOUTH...
LOW-LEVEL MOISTURE CHARACTERIZED BY LOWER/MID 60S SURFACE DEWPOINTS
WILL BE MAINTAINED/TRANSPORTED THROUGH ERN PARTS OF THE SRN
PLAINS/LOWER MS VALLEY THROUGH SUNDAY. MOISTURE TRANSPORT AND
GLANCING INFLUENCE OF THE AFOREMENTIONED WEAKENING LEAD WAVE WILL
CONTRIBUTE TO ELEVATED BANDS OF CONVECTION IN THE ARKLATEX/ OZARKS
REGION EARLY SUNDAY.
SVR PROBABILITIES WILL RAMP-UP SUNDAY AFTERNOON FARTHER W AS THE
NEXT UPPER TROUGH ARRIVES ACROSS OK/TX. ZONE OF PROBABLE DIABATIC
HEATING...MODESTLY MOIST BOUNDARY LAYER AND COOLING/MOISTENING
PROFILES ATTENDANT WITH THE PV-ANOMALY WILL BE FOR FAVORABLE STORM
INITIATION ALONG THE SURGING DRYLINE IN ERN OK AND NERN TX BY
MID-AFTERNOON SUNDAY...AND ALSO EWD ACROSS AR/NRN LA. DISCRETE
SUPERCELLS WITH LARGE HAIL AND PERHAPS A TORNADO OR TWO WILL BE
LIKELY AS ROUGHLY 50 KTS OF WLY DEEP LAYER SHEAR BECOMES ORIENTED
LARGELY NORMAL TO DRYLINE. STRONG UVV...HOWEVER...SHOULD
EVENTUALLY LEAD TO COMPLEX LINES WITH EMBEDDED ROTATING STRUCTURES
WITH AN ADDED THREAT FOR EVENING SVR WINDS.
MOST OF THE DIURNAL ACTIVITY WILL MOVE ENE TOWARD THE MID-SOUTH/SRN
MO OVERNIGHT WITH SEVERE PROBABILITIES GRADUALLY DECREASING WHERE
CLOUDS/PRECIPITATION MITIGATE EARLY DAY HEATING.
NONETHELESS...STRONG SHEAR AND FAVORABLE LAPSE RATES COULD SUPPORT
NOCTURNAL HAIL/GUSTY WINDS.
...CENTRAL GULF COAST REGION...
MODELS SUGGEST CONVECTION WILL BE POSSIBLE ALONG THE CENTRAL GULF
COAST FROM PARTS OF SRN LA/SRN MS TO SRN AL/FAR WRN FL PANHANDLE BY
SUNDAY AFTERNOON...WITHIN A MOISTENING/DESTABILIZING AIR MASS ALONG
WRN EDGE OF RETREATING CP AIR MASS. FORECAST SOUNDINGS SHOW A
MIDLEVEL INVERSION /AROUND 700 MB/ THAT MAY TEND TO MAINTAIN A MORE
SHALLOW NATURE TO THE INITIAL CONVECTION. WEAK HEIGHT FALLS ARE
EXPECTED INTO THIS REGION SUNDAY AFTERNOON WITH THE APPROACH OF THE
SRN HIGH PLAINS TROUGH AND SOME FORCING FOR ASCENT IS POSSIBLE ALONG
SRN EXTENT OF A LEADING MIDLEVEL IMPULSE LIFTING NEWD FROM THE MID
MS/LOWER TN VALLEYS. THIS COMBINED WITH SURFACE HEATING AND
DEWPOINTS INTO THE MID-UPPER 60S MAY PROVE SUFFICIENT IN WEAKENING
THE CAP FOR TSTM DEVELOPMENT BY MID-LATE SUNDAY AFTERNOON. MODERATE
INSTABILITY AND EFFECTIVE BULK SHEAR WILL BE SUFFICIENT FOR
ORGANIZED STORMS...INCLUDING SUPERCELLS.
A SECOND PEAK IN TSTM DEVELOPMENT...AND POTENTIALLY GREATER SEVERE
WEATHER THREAT...IS SUGGESTED BY THE MODELS FOR THE SECOND HALF OF
THE FORECAST PERIOD AS STRONGER HEIGHT FALLS SPREAD INTO THE MID
SOUTH. WARMING DEWPOINTS AMIDST INCREASING LOW-LEVEL SRH CONTINUES
TO BOOST CONCERNS FOR TORNADOES AND GUSTY WINDS OVERNIGHT
SUNDAY/EARLY MONDAY.
...CENTRAL MO/MID MS VLY...
SLIGHT RISK AREA HAS BEEN EXPANDED NNEWD INTO CENTRAL/EAST CENTRAL
MO FOR PRIMARILY A SEVERE WEATHER THREAT SUNDAY AFTERNOON/EARLY
EVENING. THIS REGION RESIDES BETWEEN TWO SHORTWAVE TROUGHS SUNDAY
AFTERNOON WITH NEUTRAL TO AT BEST WEAK HEIGHT FALLS AHEAD OF THE SRN
PLAINS TROUGH SHOULD SUPPORT SURFACE BASED CONVECTION AS THE AIR
MASS DESTABILIZES IN THE WAKE OF ANY ONGOING TSTMS SUNDAY MORNING.
MODELS SUGGEST AT LEAST MODERATE INSTABILITY SHOULD DEVELOP INTO
CENTRAL/EAST CENTRAL MO WITH A CORRIDOR OF EFFECTIVE BULK SHEAR
/30-35 KT/ SUPPORTING STORM ORGANIZATION/ATTENDANT SEVERE WEATHER
THREAT.
..PETERS.. 10/23/2010
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