SPC 1730Z Day 2 Outlook
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
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day2otlk_1730.html
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