DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 151251
SWODY1
SPC AC 151249

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0749 AM CDT SAT MAR 15 2014

VALID 151300Z - 161200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL TX/ARKLATEX TO
LOWER DELTA REGION AND MS COAST...

...SYNOPSIS...
UPPER-AIR PATTERN WILL BE DOMINATED THIS PERIOD BY HIGH-AMPLITUDE
BUT PROGRESSIVE RIDGING...MOVING EWD FROM W COAST...AND LARGE
CYCLONIC GYRE COVERING MUCH OF ERN CANADA AND CENTERED OVER HUDSON
BAY. E OF THAT RIDGE--TWO SHORTWAVE TROUGHS WILL SERVE AS PRIMARY
MID-UPPER INFLUENCES ON CONVECTIVE POTENTIAL DAY-1...
1. SRN-STREAM PERTURBATION NOW EVIDENT IN MOISTURE-CHANNEL IMAGERY
OVER ERN NM...FAR W TX AND CHIHUAHUA. THIS TROUGH WILL LOSE
AMPLITUDE AS EMBEDDED 500-MB VORTICITY MAX/WEAK CIRCULATION EJECTS
ENEWD ACROSS N-CENTRAL TX/EXTREME S-CENTRAL OK AROUND 00Z...REACHING
SERN OK/SWRN AR/NE TX BY END OF PERIOD.
2. NRN-STREAM TROUGH CURRENTLY MOVING SEWD ACROSS PORTIONS SRN
MT...WRN WY AND ERN UT. THIS FEATURE WILL TURN SSEWD ACROSS SRN
ROCKIES AND INTENSIFY CONSIDERABLY BY 12Z...REACHING LOWER-MIDDLE
PECOS VALLEY AND PORTIONS N-CENTRAL MEX.

CYCLONIC FLOW ASSOCIATED WITH THESE FEATURES WILL BROADEN ACROSS SRN
PLAINS AND NRN MEX...WITH HEIGHT FALLS INTENSIFYING AND SHIFTING
SLOWLY EWD ACROSS THESE REGIONS AND NWRN GULF BY END OF PERIOD.

AT SFC...11Z ANALYSIS SHOWED WAVY/QUASISTATIONARY FRONTAL ZONE FROM
MO BOOTHEEL REGION WSWWD ACROSS ERN/SWRN OK...NW TX...BETWEEN
LBB-MAF...AND OVER SERN NM. WARM FRONTOGENESIS WAS EVIDENT FROM
BETWEEN DYS-CDS EWD ACROSS TXK AREA AND SRN AR. BOTH OF THESE
BOUNDARIES ARE EXPECTED TO BECOME ILL-DEFINED TODAY AS RETURN FLOW
OCCURS AHEAD OF SEPARATE COLD FRONT MOVING SEWD ACROSS CENTRAL HIGH
PLAINS...AND PERHAPS MORE IMPORTANTLY...GROWING AREAS OF
CLOUDS...PRECIP AND TSTMS OVER TX AND OK RECONFIGURE BOUNDARY-LAYER
BAROCLINICITY CONSIDERABLY ON MESOSCALE.

...SRN PLAINS...MORNING THROUGH EVENING...
MESSY SCENARIO EVIDENT WITH SCATTERED-NUMEROUS SHOWERS AND TSTMS
EXPECTED TO DEVELOP THROUGH REMAINDER MORNING/EARLY-AFTN HOURS
ACROSS PORTIONS W-CENTRAL/NW/N-CENTRAL TX AND MUCH OF OK...OFFERING
MRGL WIND/HAIL RISK. ADDITIONAL TSTMS SHOULD FORM THROUGH AFTN OVER
CENTRAL TX AND MOVE/SPREAD ENEWD....THESE HAVING BETTER-ORGANIZED
SVR THREAT. THIS PROCESS WILL OCCUR AS LARGE-SCALE ASCENT
ALOFT...IMMEDIATELY PRECEDING MID-UPPER TROUGH...BECOMES
INCREASINGLY JUXTAPOSED WITH FAVORABLE LOW-LEVEL THETAE ADVECTION.

MOISTURE TRANSPORT/ADVECTION ALREADY UNDERWAY ABOVE SFC WILL BE
MANIFEST IN PRECONVECTIVE SFC ENVIRONMENT BY NWD SPREAD OF 60S F SFC
DEW POINTS NOW IN CENTRAL/S TX TOWARD RED RIVER...AND 50S THAT HAVE
REACHED SRN OK. THICK MIDDLE-HIGH CLOUDS WILL PRECLUDE STG SFC
DIABATIC HEATING ACROSS MUCH OF THIS AREA...HOWEVER...COMBINATION OF
DIFFUSE INSOLATION AND WAA WILL BOOST MLCAPE AND REDUCE MLCINH
THROUGHOUT MIDDAY INTO AFTN IN PRECONVECTIVE AIR MASS. TSTM
COVERAGE SHOULD EXTEND AND SHIFT EWD ACROSS NRN/CENTRAL TX THROUGH
AFTN AND INTO EVE...AS INFLOW-LAYER AIR MASS MOISTENS.

BUOYANCY WILL DEPEND STRONGLY ON AVAILABILITY OF LOCALIZED POCKETS
OF ENHANCED/SUSTAINED INSOLATION OVER CENTRAL TX...AND ABSENCE OF
PRECIP/OUTFLOW FARTHER N...NEAR AND N OF I-20. ALTHOUGH LOW-LEVEL
WINDS WILL REMAIN WEAK THROUGH MUCH OF AFTN...LIMITING HODOGRAPH
SIZE...WRN RIM OF LLJ WILL ENLARGE HODOGRAPHS AROUND 00Z AND
THEREAFTER FOR ANY SFC-BASED TSTMS DEVELOPING AND MOVING EWD/ENEWD
FROM CENTRAL TO E-CENTRAL/NE TX. THIS CORRIDOR REPRESENTS MOST
PROBABLE JUXTAPOSITION OF FAVORABLE BUOYANCY/SHEAR FROM LATE AFTN
INTO EVENING. FARTHER S INTO S TX...THOUGH CAPE WILL BE
GREATER...SO WILL CINH...AND FOCI FOR CONVECTIVE-SCALE LIFT BECOME
MORE UNCLEAR.

...SE TX TO MS DELTA/COAST REGIONS...TONIGHT...
ATTM IT STILL IS UNCERTAIN WHETHER TX CONVECTIVE REGIME WILL
1. RUN CONTINUOUSLY INTO LA/MS. SOME SWD BACKBUILDING IS PSBL INTO
SE TX AND SWRN LA...THOUGH DEAMPLIFICATION OF UPPER WAVE FARTHER N
AND RELATED LACK OF LARGE-SCALE ASCENT EXTENDING SWD ACROSS SABINE
RIVER AREA MAY DISFAVOR THAT IDEA.
2. AS MOST CONVECTION-PERMITTING HIGH-RES MODELS SUGGEST...DEVELOP
AS SEPARATE AREA OF TSTMS AND BECOME SFC-BASED CLOSER TO GULF COAST
OVER LA/MS. FCST SOUNDINGS SUGGEST ACCOMPANYING/WEAKLY CAPPED
LOW-LEVEL WAA ZONE THAT WILL BE ACCOMPANIED BY
LARGE...SUPERCELL-FAVORING LOW-LEVEL HODOGRAPHS AND STRENGTHENING
DEEP SHEAR--E.G. EFFECTIVE SRH EXCEEDING 400 J/KG AND EFFECTIVE
SHEAR MAGNITUDES 45-60 KT. THOUGH MID-60S DEW POINTS ARE
FCST...LAPSE RATES WILL BE WEAKER THAN FARTHER W...KEEPING
MLCAPE/MUCAPE AROUND 1000 J/KG OR LESS. WEAK LOW-LEVEL LAPSE RATES
DURING OVERNIGHT HOURS MAY LIMIT VIGOR OF MANY UPDRAFTS...DESPITE
TECHNICALLY SFC-BASED CHARACTER OF EFFECTIVE-INFLOW PARCELS IN FCST
SOUNDINGS.

...NRN OK/EXTREME SRN KS...
SOME MOIST ADVECTION ALSO MAY EXTEND OUT FROM BENEATH CLOUD SHIELD
AND INTO BETTER-HEATED AREAS ACROSS PORTIONS NRN OK/SRN KS...AHEAD
OF HIGH-PLAINS COLD FRONT. THIS COULD FOSTER
CONDITIONAL/SHORT-LIVED POTENTIAL FOR A FEW STG-MRGL SVR TSTMS IN
THAT AREA. MID-UPPER SUPPORT WILL DIMINISH WITH NWD
EXTENT...LOW-LEVEL FLOW/SHEAR WILL BE WEAK...AND LOW-LEVEL LIFT IS
IN QUESTION GIVEN LACK OF BOUNDARIES OTHER THAN DIFFERENTIAL-HEATING
ZONES AND DECAYING/DIFFUSE FRONT. STILL...STEEP DEEP-LAYER LAPSE
RATES...MLCAPE 1000-1500 J/KG...AND ENOUGH HEATING TO REMOVE CINH
ARE ANTICIPATED...SUGGESTING ISOLATED GUSTS/HAIL NEAR SVR LIMITS MAY
OCCUR. MRGL SVR PROBABILITIES ACCORDINGLY HAVE BEEN EXTENDED NWD
INTO THIS REGION. ISOLATED TSTMS NEAR SVR LEVELS ALSO MAY FORM
ALONG COLD FRONT AFTER DARK AS IT ENCOUNTERS RESIDUAL/MRGLLY
FAVORABLE LOW-LEVEL MOISTURE/INSTABILITY.

..EDWARDS/MOSIER.. 03/15/2014

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