SPC 0600Z Day 2 Outlook
DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1257 AM CDT THU MAY 30 2013 VALID 311200Z - 011200Z ...THERE IS A SLGT RISK OF SVR TSTMS FOR OK AND ERN KS NEWD INTO THE SRN GREAT LAKES... ...SYNOPSIS... A DEEP-LAYER CYCLONE WILL REMAIN OVER THE UPPER MIDWEST THROUGH SATURDAY MORNING WHILE A BELT OF STRONG CYCLONIC FLOW WILL ARC THROUGH THE BASE OF THE MID-UPPER TROUGH OVER THE CNTRL PLAINS NEWD INTO THE GREAT LAKES. IN THE LOW LEVELS...AN OCCLUDED LOW/FRONT WILL DRAPE ITSELF OVER THE UPPER MS RIVER VALLEY WITH A COLD FRONT EXTENDING SWWD INTO THE CNTRL PLAINS WHERE A SECONDARY LEE CYCLONE OVER THE TX PANHANDLE WILL REMAIN QUASI-STATIONARY DURING THE DAY. A DRYLINE LINE WILL EXTEND SWD FROM WRN OK INTO TX. ...OK/KS AND OZARKS... HIGH QUALITY BOUNDARY LAYER MOISTURE --CHARACTERIZED BY 16 G/KG LOWEST 100 MB MEAN MIXING RATIO-- SAMPLED OVER THE TX COASTAL PLAIN ON WEDNESDAY EVENING WILL CONTINUE TO BE DRAWN NWD INTO MUCH OF OK...BENEATH A REINVIGORATED EML FORECAST TO OVERSPREAD OK/SRN KS DURING THE DAYTIME HOURS FRIDAY. DESPITE PROBABLE THURSDAY NIGHT/FRIDAY MORNING STORMS OVER A PORTION OF THIS REGION...A RELOADING OF STEEP MID LEVEL LAPSE RATES /IN EXCESS OF 8 DEG C PER KM H7-H5/ OVER THIS REGION FROM THE W IS LIKELY. ALTHOUGH THE DETAILS TO PRIOR STORM ACTIVITY ARE UNCERTAIN BOTH IN TERMS OF THE EXTENSIVENESS OF CONVECTIVE OVERTURNING AND PLACEMENT OF OUTFLOW BOUNDARIES...STRONG SURFACE HEATING SHOULD OCCUR IN ITS WAKE OVER AREAS TO THE S AND SW. A WEAKLY CAPPED AND VERY TO EXTREMELY UNSTABLE BOUNDARY LAYER IS FORECAST BY MID-LATE AFTERNOON OVER OK WITH MLCAPE RANGING FROM 3000-4500 J/KG...WITH DESTABILIZATION NOT QUITE AS STRONG FARTHER NE OVER WRN MO/SERN KS WHERE SOME AIRMASS RECOVERY IS FORECAST TO OCCUR. THE ORIENTATION OF THE N-S DRYLINE OVER OK/SRN KS NORMAL TO STRONG MID-HIGH LEVEL FLOW /NEUTRAL MID LEVEL HEIGHT FIELD/ WILL SUPPORT EXPLOSIVE DISCRETE SUPERCELL DEVELOPMENT GIVEN THE MAGNITUDE OF EXPECTED DEEP SHEAR/BUOYANCY. A LARGE TO PERHAPS EXTREMELY LARGE HAIL THREAT MAY DEVELOP WITH ANY INTENSE SUPERCELLS. MODELS DIFFER REGARDING THE LOW LEVEL MASS RESPONSE OVER OK/KS DURING THE AFTERNOON/EVENING...WHICH WILL HAVE AN INFLUENCE ON LOW LEVEL SHEAR AND TORNADO POTENTIAL/INTENSITY. SOME FORECAST SOUNDINGS SHOW A RATHER IMPRESSIVE INCREASE IN LOW LEVEL HODOGRAPH SIZE DURING THE AFTERNOON-EARLY EVENING PERIOD...WHILE OTHER FORECAST SOUNDINGS ARE MUTED IN THIS LOW LEVEL SHEAR DEPICTION. REGARDLESS...A LARGE HAIL/DMGG WIND/TORNADO THREAT WILL EXIST WITH SUPERCELLS THAT DEVELOP OVER THIS REGION. ATTM...WILL REFRAIN FROM A HIGHER CATEGORICAL RISK BUT ACKNOWLEDGE AN UPGRADE MAY BE REQUIRED IN LATER OUTLOOKS...ESPECIALLY FOR A PORTION OF OK. LATER IN THE EVENING...A STRENGTHENING SLY LLJ AND SWD ACCELERATING COLD FRONT OVER KS/NRN OK WILL LIKELY LEAD TO GREATER STORM COVERAGE...POSING A SEVERE THREAT WELL INTO THE EVENING/OVERNIGHT HOURS AS STORMS GROW UPSCALE FROM OK ENEWD INTO THE OZARKS. ...MO NEWD INTO THE GREAT LAKES... SEVERAL ROUNDS OF STORMS ARE POSSIBLE OVER THE LOWER MO RIVER VALLEY OWING TO BOTH LINGERING STORM ACTIVITY FROM THE MORNING AND DIURNALLY-DRIVEN STORMS LATER IN THE DAY ALONG THE FRONT. MODELS ARE IN FAIRLY GOOD AGREEMENT IN SHOWING A MOIST/MODERATELY UNSTABLE AIRMASS DEVELOPING OVER A LARGE PART OF THIS REGION WITH SCATTERED TO NUMEROUS STORMS EXPECTED TO DEVELOP. THE MAIN BELT OF STRONGER 1-3 KM SWLY FLOW WILL RESIDE OVER THIS REGION...ACTING TO SUPPORT ORGANIZED CLUSTERS OF STRONG-SEVERE STORMS IN THE FORM OF SUPERCELLS AND BOWING LINE SEGMENTS. IF SUBSTANTIAL DESTABILIZATION CAN OCCUR...STRONG FLOW FIELDS WOULD SUPPORT AN APPRECIABLE TORNADO THREAT --IN ADDITION TO HAIL/WIND-- AND PERHAPS HIGHER SEVERE PROBABILITIES THAN CURRENTLY FORECAST FOR A PORTION OF THIS AREA. EVENTUAL STORM MERGERS/CONSOLIDATION BY EVENING WOULD FAVOR THE GRADUAL TRANSITION TO MORE OF A STRAIGHT-LINE WIND THREAT THAT MAY PERSIST INTO SATURDAY MORNING. ..SMITH.. 05/30/2013
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day2otlk_0600.html
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