DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 281245
SWODY1
SPC AC 281244

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0744 AM CDT FRI MAR 28 2014

VALID 281300Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL TX TO
MID-SOUTH REGION AND GULF COAST STATES...

...SYNOPSIS...
DOWNSTREAM FROM LARGE NERN PAC CYCLONE...PROGRESSIVE/QUASI-ZONAL
FLOW WILL PERSIST ACROSS CONUS. SHORTWAVE TROUGH ASSOCIATED WITH
CONVECTION OVER MO/IA YESTERDAY IS MOVING ENEWD ACROSS UPPER GREAT
LAKES ATTM...AND WILL CONTINUE TO WEAKEN AS IT ACCELERATES EWD OVER
SRN ONT...SRN QUE AND NEW ENGLAND. MEANWHILE...SHORTWAVE TROUGHS
NOW OVER BLACK HILLS AND SRN HIGH PLAINS ARE SEPARATE BUT MOVING
NEARLY IN STEP WITH EACH OTHER. BY 00Z...THESE PERTURBATIONS SHOULD
REACH FSD-OMA AND DFW-VCT CORRIDORS...RESPECTIVELY. SRN-STREAM
TROUGH SHOULD EJECT NEWD ACROSS TN VALLEY REGION BY DAYBREAK
TOMORROW MORNING...AS INITIALLY WEAK/INTERMEDIARY TROUGH AMPLIFIES
OVER OZARKS. MOISTURE-CHANNEL IMAGERY ALSO INDICATES PRECURSORY
SHORTWAVE TROUGH HAS DEVELOPED IN ASSOCIATION WITH -- AND PROBABLY
RESULTING FROM -- PERSISTENT/DISORGANIZED MCS OVER LA/MS/AL. THIS
FEATURE SHOULD TRACK EWD ACROSS CENTRAL-ERN GULF COASTAL PLAIN AND
GA THROUGH REMAINDER PERIOD.

AT SFC...FRONTAL ZONE ASSOCIATED WITH DEPARTING NRN-STREAM TROUGH
HAS STALLED ACROSS SWRN AR...SERN OK...N-CENTRAL TX BETWEEN
METROPLEX AND RED RIVER AND NW TX...TO WEAK SFC CYCLONE CENTERED
BETWEEN ABI-SPS-CDS. AS MID-UPPER LEVEL WAVE MOVES OVER CENTRAL
TX...COLD FRONT WILL MOVE SWD OVER THAT REGION WHILE SFC LOW
MIGRATES ESEWD TO E-CENTRAL/SE TX. OVERNIGHT...LOW SHOULD
SHIFT/REDEVELOP ENEWD OVER NRN MS...DEEPENING AND REACHING
MIDDLE-ERN TN BY 12Z. AT THAT TIME...COLD FRONT SHOULD EXTEND SWWD
THROUGH WRN AL..SERN MS...SERN LA AND NWRN GULF.
DRYLINE...CURRENTLY ANALYZED FROM NRN COAHUILA NEWD ACROSS BWD
AREA...SHOULD MIX EWD BY MID-LATE AFTN TO I-35/US-77 CORRIDOR BEFORE
BEING OVERTAKEN FROM N-S BY COLD FRONT.

...CENTRAL TX TO MID-SOUTH REGION AND GULF COAST STATES...
BROAD...MESSY AND SOMEWHAT CONDITIONAL SVR THREAT IS EVIDENT OVER
THIS REGION. BIG 15%/SLGT AREA ACTUALLY IS AGGREGATED FROM THREE
SOMEWHAT DISTINCT THREATS THAT OVERLAP SPATIALLY...

1. LOWER DELTA TO SRN AL AND FL PANHANDLE TODAY --
ONGOING/PERSISTENT MCS OVER THIS REGION IS EXPECTED TO TRANSLATE
SLOWLY EWD...OFFERING RISK OF SPORADIC DAMAGING DOWNDRAFTS...MAINLY
FROM OUTFLOW DRIVEN BY PRECIP LOADING IN SMALL BOWS. HAIL THREAT
APPEARS MRGL AND TIED TO ANY SUSTAINED SUPERCELL STRUCTURES...GIVEN
WEAK AMBIENT LAPSE RATES. TORNADO POTENTIAL FROM ANY
EMBEDDED/TRANSIENT SUPERCELLS CANNOT BE RULED OUT BUT IS VERY
DEPENDENT ON MESO-BETA TO STORM-SCALE EFFECTS.

2. S TX TO ARKLATEX AND MID-SOUTH...MORNING THROUGH EVENING --
SCATTERED...INITIALLY ELEVATED TSTMS HAVE DEVELOPED BETWEEN SJT-MWL
IN REGIME OF LOW-LEVEL WAA AND MOISTURE TRANSPORT ABOVE STG
INVERSION LAYER EVIDENT IN 12Z FWD/DRT RAOBS. THIS OR MORE LIKELY
SUBSEQUENT/AFTN CONVECTION NEAR DRYLINE SHOULD MOVE EWD INTO
DIABATICALLY DESTABILIZING AIR MASS. TIMING...DURATION...COVERAGE
AND EVOLUTION OF CONVECTION ACROSS THIS AREA REMAINS VERY UNCERTAIN.
AS SUCH...PROBABILITIES IN THIS AREA ARE ADJUSTED LITTLE FROM PRIOR
OUTLOOK.

VERY STEEP MIDLEVEL LAPSE RATES ARE LIKELY...SUCH THAT MAX
CLOUD-LAYER LI OF -13 TO -16 AND 2000-3000 J/KG MLCAPES ARE POSSIBLE
EVEN WITH REDUCTION IN SFC DEW POINTS DUE TO BOUNDARY-LAYER MIXING.
THAT MIXING WILL PRODUCE INVERTED-V THERMODYNAMIC PROFILES SUITABLE
FOR DAMAGING GUSTS AS WELL AS FOR MAINTENANCE TO SFC OF LARGE HAIL
GENERATED ALOFT. FORECAST SOUNDINGS INDICATE SUPERCELL-SUPPORTIVE
LOW-MIDDLE LEVEL WIND PROFILES...AND PRESENCE OF LARGE CAPE ALOFT IN
IDEAL HAIL-GENERATION ZONES. AS SUCH...SIGNIFICANT/DAMAGING HAIL IS
QUITE POSSIBLE FROM ANY SUSTAINED/DISCRETE STORMS. ACTIVITY MAY
UNDERGO COLD-POOL-DRIVEN AGGREGATION INTO ONE OR MORE BANDS OR ARCS
MOVING ENEWD TO EWD OVER THIS AREA WITH DAMAGING WINDS AND LARGE
HAIL POSSIBLE.

3. MS DELTA REGION TONIGHT --
ANOTHER ROUND OF TSTMS MAY DEVELOP INVOF SFC COLD FRONT...OFFERING
DAMAGING WINDS AND ISOLATED HAIL. ANY SUCH ACTIVITY WOULD MOVE EWD
OVER AIR MASS THAT...BY THEN...SHOULD HAVE RECOVERED SUFFICIENTLY
FROM CURRENT MCS ACTIVITY TO SUPPORT RENEWED SVR POTENTIAL.
MEANWHILE DEEP SHEAR AND LARGE-SCALE ASCENT EACH WILL BE ENHANCED BY
APCH OF SHORTWAVE TROUGH...AMIDST SFC DEW POINTS MID-60S F.

..EDWARDS/SMITH.. 03/28/2014

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