DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 231731
SWODY2
SPC AC 231730

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT WED MAY 23 2012

VALID 241200Z - 251200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR THE UPPER/MID-MS VALLEY...

...SYNOPSIS...
STRONG MID-LEVEL SPEED MAX CURRENTLY FROM NRN CA TO THE GREAT BASIN
WILL EJECT ACROSS THE CNTRL HIGH PLAINS TOWARDS THE UPPER MS VALLEY
ON THU. COUPLED UPPER-LEVEL JET STRUCTURE SHOULD RESULT IN FAVORABLE
DIVERGENCE RESULTING IN A DEEPENING SHORT WAVE IMPULSE AND SURFACE
CYCLONE FROM THE MID-MO TO THE UPPER MS VALLEYS. ATTENDANT SURFACE
COLD FRONT WILL ACCELERATE EWD ACROSS THE UPPER MS VALLEY TOWARDS
THE UPPER GREAT LAKES THU AFTERNOON/NIGHT. TRAILING PORTION OF THE
FRONT SHOULD BECOME QUASI-STATIONARY IN WRN MO AND KS BY EARLY FRI.

...UPPER MS VALLEY...
POTENT SYNOPTIC PATTERN SETUP SHOULD UNFOLD THU
AFTERNOON/EVENING...PERHAPS YIELDING A MODERATE RISK IN LATER
OUTLOOKS. ALTHOUGH GUIDANCE IS CONSISTENT IN DEPICTING
CYCLOGENESIS...THE NAM IS THE MOST AGGRESSIVE WITH INTENSE S/SWLY
MID-LEVEL FLOW FIELDS /100 KT AT 500 MB AND 80 KT AT 700 MB/
DEVELOPING ALONG THE COLD FRONT AROUND 25/00Z. ALTHOUGH THIS IS AN
OUTLIER...THIS AMPLITUDE OF DEEPENING APPEARS PLAUSIBLE GIVEN THE
STRENGTH OF THE UPPER-LEVEL JET OVER THE WRN CONUS.

MORE UNCERTAINTY EXISTS IN THE POTENTIAL EFFECTS OF D1 CONVECTION ON
SUBSEQUENT DESTABILIZATION ALONG THE FRONT...AS WELL AS THE DEGREE
OF LOW-LEVEL MOISTENING AHEAD OF THE BOUNDARY. MOST GUIDANCE HAS
BEEN TOO AGGRESSIVE WITH BOUNDARY LAYER MOISTURE RETURN IN THE CNTRL
STATES OVER THE PAST SEVERAL DAYS. BUT THE CURRENT PRESENCE OF
MIDDLE TO UPPER 60S SURFACE DEW POINTS IN SERN TX AND LA RENDERS
GREATER CONFIDENCE THAT LOWER 60S SURFACE DEW POINTS SHOULD BECOME
ESTABLISHED WITHIN A RELATIVELY NARROW CORRIDOR AHEAD OF THE FRONT
IN THE UPPER MS VALLEY. GUIDANCE IS GENERALLY ONLY MODERATELY
UNSTABLE WITH MLCAPE EXPECTED TO BE AROUND 750-1500 J/KG.
STILL...GIVEN THE STRENGTH OF THE INTENSIFYING KINEMATIC FIELDS AND
FLOW NEARLY PARALLELING THE FRONT...THIS SHOULD RESULT IN ROBUST
TSTM DEVELOPMENT DURING THE AFTERNOON WHERE LARGE/ELONGATED
LOW-LEVEL HODOGRAPHS WILL BE FAVORABLE FOR SUPERCELLS AND TORNADOES.
CONVECTION SHOULD GROW QUICKLY UPSCALE INTO A QLCS...WITH THE
LIKELIHOOD FOR BOWING SEGMENTS AND EMBEDDED SUPERCELL STRUCTURES
YIELDING RISKS OF DAMAGING WINDS AND ISOLATED TORNADOES /EITHER OF
WHICH COULD BE SIGNIFICANT/.

...KS/MID-MS VALLEY...
THE SRN EXTENT OF DIURNAL TSTM DEVELOPMENT ALONG THE FRONT IN THE
MID-MS VALLEY WILL BE CONDITIONAL ON SUFFICIENT CONVERGENCE TO BREAK
A PRONOUNCED CAPPING INVERSION. IF CONVECTION FORMS...SUPERCELL WIND
PROFILES WILL SUPPORT A RISK FOR ISOLATED SEVERE STORMS.

FARTHER W...LOW-LEVEL WARM/MOIST ADVECTION WILL INTENSIFY THU NIGHT
ALONG THE STALLED PORTION OF THE COLD FRONT. DEEP-LAYER SHEAR WILL
BE RATHER STRONG AND WITH MODERATE ELEVATED INSTABILITY...IT MAY
YIELD ELEVATED SUPERCELLS FORMING TOWARDS 12Z/FRI. BUT WITH
MID-LEVEL HEIGHT RISES...COVERAGE OF STORMS IS UNCERTAIN AND WILL
DEFER TO LATER OUTLOOKS FOR POSSIBLE SLIGHT RISK DELINEATION.

...LOWER MID-ATLANTIC/CAROLINAS...
A REMNANT OF THE WEAK UPPER-LEVEL IMPULSE IS PROGGED TO PERSIST IN
THE LEE OF THE SRN APPALACHIANS THROUGH TOMORROW. A BELT OF 20-25 KT
MID-LEVEL SWLYS SHOULD BE MAINTAINED AND WOULD BE SUFFICIENT FOR
MULTICELL STORMS DURING THE AFTERNOON WITH RISKS OF MARGINALLY
SEVERE HAIL/LOCALLY DAMAGING WIND.

..GRAMS/BUNTING.. 05/23/2012

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