DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 121959
SWODY1
SPC AC 121957

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0157 PM CST SAT JAN 12 2013

VALID 122000Z - 131200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM FAR SERN OK AND THE
ARKLATEX INTO THE MID MS VALLEY...

...FAR SERN OK/NERN TX...
TRENDS IN LIGHTNING DATA SINCE THIS MORNING INDICATED STRIKES HAD
BEEN LOCATED PRIMARILY IN THE POST-FRONTAL ENVIRONMENT...THOUGH
TSTMS HAVE DEVELOPED RECENTLY INVOF THE FRONT FROM CENTRAL AR SWWD
INTO FAR SERN OK AND NERN TX. GIVEN THE LIKELIHOOD FOR SURFACE BASED
TSTMS TO BE PRIMARILY FOCUSED NEAR THE FRONT...THE SLIGHT RISK AND
SEVERE WIND AND TORNADO PROBABILITIES HAVE BEEN EXPANDED W/NWWD
ACROSS MORE OF NERN TX AND INCLUDES FAR SERN OK AND A LITTLE MORE OF
SWRN AR. OTHERWISE...THE 1630Z FORECAST SCENARIO REMAINS ON TRACK
AND FOR MESOSCALE DETAILS FROM THIS REGION NEWD ACROSS AR...REFER TO
MESOSCALE DISCUSSION NUMBER 15.

..PETERS.. 01/12/2013

.PREV DISCUSSION... /ISSUED 1022 AM CST SAT JAN 12 2013/

AN EXPANSIVE UPPER TROUGH IS PRESENT TODAY OVER THE WESTERN/CENTRAL
UNITED STATES...WITH DEEP AND STRONG SOUTHWESTERLY TROPOSPHERIC FLOW
STRETCHING FROM TX INTO THE GREAT LAKES REGION. SEVERAL WEAK
PERTURBATIONS ARE FORECAST TO TRACK NORTHEASTWARD ACROSS THE
ARKLATEX AND MID MS VALLEY REGIONS TODAY/TONIGHT...LEADING TO
SCATTERED SHOWERS AND THUNDERSTORMS.

MODEL SOLUTIONS TEND TO AGREE THAT PERSISTENT MID LEVEL HEIGHT FALLS
AND SLOWLY INCREASING LOW LEVEL WIND FIELDS WILL OCCUR ACROSS PARTS
OF EAST TX/AR/LA ALONG AND SOUTH OF THE SURFACE FRONT. A SURFACE
LOW WILL PROGRESS NORTHEASTWARD ALONG THE BOUNDARY AND THROUGH THESE
AREAS...FOCUSING LOW LEVEL CONVERGENCE AND SHEAR...AND PROMOTING
MORE ORGANIZED THUNDERSTORM DEVELOPMENT.

PRESENT INDICATIONS ARE THAT STORMS WILL INTENSIFY BY MID AFTERNOON
ALONG/IMMEDIATELY SOUTH OF THE BOUNDARY OVER NORTHEAST TX AND SPREAD
INTO ADJACENT PARTS OF NORTHERN LA/SOUTHERN AR. ACTIVITY SHOULD
BUILD/MOVE NORTHEASTWARD ACROSS CENTRAL AR AND INTO THE MID MS
VALLEY THROUGH THE EVENING. SURFACE DEWPOINTS IN THE MID/UPPER 60S
ARE EXPECTED ALONG THIS CORRIDOR BUT DAYTIME INSOLATION WILL BE VERY
LIMITED. THIS WILL YIELD MLCAPE VALUES OF ONLY 500-1000 J/KG.
GIVEN THE STRONG LOW/MID LEVEL WIND FIELDS...SUPERCELL/BOWING
STRUCTURES CAPABLE OF DAMAGING WINDS AND ISOLATED TORNADOES APPEAR
TO BE THE MAIN THREATS.

OVERNIGHT...COVERAGE OF STORMS IS EXPECTED TO INCREASE ALONG A
CORRIDOR FROM SOUTHEAST TX INTO WESTERN MS. WIND FIELDS WILL BE A
LITTLE WEAKER BY THIS TIME...SO ONLY LOW SEVERE PROBABILITIES ARE
INCLUDED AT THIS TIME. NEVERTHELESS...THIS AREA WILL BE
RE-EVALUATED IN LATER OUTLOOKS.

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