DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 251730
SWODY2
SPC AC 251729

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CDT THU APR 25 2013

VALID 261200Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS FAR SOUTHERN OK/NORTH TX
TO THE ARKLATEX...

...SYNOPSIS...
MODELS MAINTAIN A PROGRESSIVE/SPLIT FLOW PATTERN THROUGH DAY 2 WITH
STRONGEST WLY MID-UPPER LEVEL WINDS REMAINING NORTH OF THE
U.S./CANADA BORDER. MEANWHILE...A MIGRATORY SRN STREAM SHORTWAVE
TROUGH WILL PROGRESS ENEWD FROM THE CENTRAL/SRN ROCKIES...REACHING
THE LOWER MO VALLEY TO OZARKS REGION BY 12Z SAT. GIVEN RELATIVELY
WEAK UPPER FORCING WITH THE SRN STREAM SYSTEM...THE MODELS ARE
DIFFERING WITH THE TRACK OF AN ATTENDANT SURFACE LOW ACROSS KS OR OK
FRI...WITH THIS FEATURE REACHING CENTRAL OR SRN MO BY THE END OF THE
PERIOD. A WARM FRONT...DELINEATING THE NWD RETURN OF MOISTURE
WITHIN THE WRN PERIPHERY OF A DEPARTING SURFACE RIDGE...WILL ADVANCE
NNEWD ACROSS THE ERN HALF OF TX AND LA AND SHOULD EXTEND FROM THE
RED RIVER ALONG THE OK/TX BORDER INTO CENTRAL/NRN LA BY 27/00Z.
THIS BOUNDARY WILL MAKE FURTHER NWD PROGRESS FRI NIGHT INTO AR/MID
SOUTH...WHILE A WEAK COLD FRONT MOVES ACROSS OK EXTENDING TO KMAF BY
12Z SAT.

...SRN PLAINS TO ARKLATEX...
ELEVATED STORMS...LIKELY ROOTED AROUND 850 MB...WITHIN A LOW LEVEL
WAA REGIME SHOULD BE ONGOING AT THE START OF DAY 2 FROM PARTS OF FAR
CONVECTIVE DETAILS...WITH ELEVATED CONVECTION/TSTMS EXPECTED TO
PERSIST E/NEWD FRI/FRI NIGHT IN STRONG LOW LEVEL WAA. THE GREATEST
POTENTIAL FOR A MARGINALLY SEVERE HAIL THREAT WITH THIS WAA ACTIVITY
SHOULD BE ACROSS AR. THIS AREA WILL BE CLOSER TO THE INFLUX OF
GREATER LOW LEVEL MOISTURE/INSTABILITY AND ALONG THE ERN EXTENT OF
STEEPER MIDLEVEL LAPSE RATES.

DESPITE THE PRESENCE OF AN EML/STEEP MIDLEVEL LAPSE RATES ACROSS
MUCH OF THE SRN PLAINS AT THE START OF DAY2...GREATER NWD MOISTURE
RETURN NOT OCCURRING UNTIL FRI SUGGESTS DESTABILIZATION COULD BE
TEMPERED. HOWEVER...IT APPEARS RELATIVELY STRONGER SURFACE HEATING
ACROSS THE WARM SECTOR IN N-NE TX...WHERE A DIFFERENTIAL HEATING
BOUNDARY COULD BECOME ESTABLISHED ALONG THE SRN PERIPHERY OF THE
AFOREMENTIONED ONGOING ELEVATED STORMS...COULD PROVE SUFFICIENT FOR
WEAKENING SURFACE BASED INHIBITION. THE LACK OF STRONGER FORCING FOR
ASCENT ALOFT ACROSS SRN OK/N TX TO THE ARKLATEX AND WEAK LOW LEVEL
CONVERGENCE WITH WWD EXTENT ALONG THE RED RIVER SUGGEST THE BEST
POTENTIAL FOR SURFACE BASED STORMS WOULD BE ACROSS NERN TX AS
DEPICTED IN THE SEVERE PROBABILITIES WITH GREATER SWD EXTENSION. A
50 KT WSWLY MIDLEVEL JET EXPECTED ACROSS THE SLIGHT RISK AREA FRI
AFTERNOON AND A SWLY LLJ INTO NORTH CENTRAL-NE TX WILL AID IN
EFFECTIVE BULK SHEAR OF 40-50 KT. THIS COMBINED WITH MODERATE
INSTABILITY WILL SUPPORT ORGANIZED STORMS/SUPERCELLS...IF STORMS CAN
BECOME SURFACE BASED...WITH ALL FACETS OF SEVERE WEATHER POSSIBLE.
A TORNADO THREAT SHOULD BE CONFINED TO NERN TX...GIVEN GREATER LOW
LEVEL MOISTURE RETURN INTO THIS AREA.

TSTMS...SOME SEVERE...SHOULD PERSIST EWD INTO THE EVENING/OVERNIGHT
WITHIN A WAA REGIME ALONG A VEERING LOW LEVEL JET.

FARTHER WEST...STORMS MAY DEVELOP MAINLY N OF THE SWD MOVING COLD
FRONT...BUT THE LACK OF STRONGER INSTABILITY SUGGESTS MUCH OF THIS
ACTIVITY SHOULD BE SUB-SEVERE.

..PETERS.. 04/25/2013

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