DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1247 AM CDT WED APR 01 2015 VALID 011200Z - 021200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM SRN MN SWWD INTO THE CNTRL PLAINS... ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER MIDWEST INTO THE SRN PLAINS SEWD INTO THE SERN U.S.... ...SUMMARY... ISOLATED TO SCATTERED SEVERE STORMS PRODUCING PRIMARILY LARGE HAIL AND DAMAGING WINDS ARE POSSIBLE FROM THE UPPER MIDWEST TO THE SOUTHERN GREAT PLAINS BEGINNING WEDNESDAY AFTERNOON. OTHER MARGINALLY SEVERE STORMS COULD EVOLVE FROM NORTHERN ARKANSAS TO NORTHERN FLORIDA. ...SYNOPSIS... A VIGOROUS SHORTWAVE TROUGH OVER THE NRN HIGH PLAINS/NRN ROCKIES WILL MOVE INTO THE NRN PLAINS BY THIS EVENING. A FRONTAL ZONE OVER NRN OK TUESDAY NIGHT WILL ADVANCE NWD AND TRANSPORT LOW-LEVEL MOISTURE POLEWARD BENEATH A PLUME OF STEEP MID-LEVEL LAPSE RATES OVER THE CNTRL-SRN PLAINS. THE PRIMARY SURFACE CYCLONE WILL DEVELOP NEWD FROM ND INTO SERN MANITOBA DURING THE DAY IN RESPONSE TO THE STRONGEST HEIGHT FALLS WHILE A COLD FRONT ARCS SWD THEN SWWD TO A SECONDARY LOW OVER NWRN KS. A DRYLINE/LEE TROUGH WILL EXTEND SWD FROM THE KS LOW THROUGH WRN KS AND INTO FAR WRN OK AND W TX. FARTHER E...A COMPOSITE CONVECTIVELY-REINFORCED FRONTAL ZONE WILL EXTEND FROM THE OZARKS SEWD INTO GA. ...SRN MN INTO THE MID MO VALLEY... IN WAKE OF TSTM ACTIVITY OVER OK EARLY WEDNESDAY MORNING...SLY LOW-LEVEL WINDS WILL ADVECT MOISTURE NWD THROUGH THE CNTRL PLAINS AND INTO THE UPPER MIDWEST DURING THE DAY. A COLD FRONT OVER THE ERN DAKOTAS WILL CONCURRENTLY PUSH ESEWD AND REACH SWRN MN SWWD INTO CNTRL NEB BY MID AFTERNOON. THE CAP WILL WEAKEN DURING THE DAY DUE IN PART TO STRONG HEATING AND DEWPOINTS RISING INTO 55-60 DEG F RANGE. FRONTAL LIFT AND UPPER ASCENT INCREASING FROM THE W WILL LIKELY LEAD TO SCATTERED STORMS PREFERENTIALLY DEVELOPING ALONG THE FRONT BY MID-LATE AFTERNOON. FORECAST SOUNDINGS SHOW MODERATE BUOYANCY /1000-2500 J PER KG MLCAPE/ WITH ADEQUATE DEEP-LAYER SHEAR FOR A MIXED MODE OF SUPERCELL AND ORGANIZED MULTICELLS. WHILE A 35-50 KT LLJ WILL BECOME FOCUSED OVER THE UPPER MS VALLEY DURING PEAK HEATING...THE TENDENCY FOR THE FRONT TO UNDERCUT STORMS THAT DEVELOP ON OR IMMEDIATELY AHEAD OF THE FRONT IS FORECAST TO OCCUR...ESPECIALLY WITH NWD EXTENT. AS A RESULT...UPSCALE GROWTH WILL FAVOR A TRANSITION TOWARDS PRIMARILY AN ISOLD HAIL/WIND THREAT. ...CNTRL KS SWD INTO W TX... THE SRN FRINGE OF MID-LEVEL HEIGHT FALLS WILL GLANCE KS DURING THE AFTERNOON/EVENING AS STRENGTHENING H5 FLOW OVERSPREADS THE WRN PORTION OF THE WARM SECTOR. STRONG HEATING INVOF THE LEE TROUGH/DRYLINE WILL WEAKEN THE CAP AND FOCUS ISOLD STORM DEVELOPMENT. STEEP LAPSE RATES AND 25-35 KT EFFECTIVE SHEAR WILL SUPPORT MARGINAL/TRANSIENT SUPERCELL STRUCTURES WITH THE STRONGEST STORMS AND THE POSSIBILITY FOR LARGE HAIL/SEVERE WINDS. THE ACTIVITY SHOULD DIMINISH DURING THE EVENING OWING TO INCREASING CINH AND A STABILIZING NEAR-SURFACE LAYER. ...AR SEWD INTO AL/GA... CONSIDERABLE UNCERTAINTY REMAINS REGARDING THE MESOSCALE DETAILS FOR TODAY BUT IT SEEMS ISOLD TO WIDELY SCATTERED STORMS MAY DEVELOP ALONG THE RESIDUAL FRONTAL SEGMENT AND/OR FROM REMNANT TSTM ACTIVITY PRIOR TO THE START OF THE PERIOD. MODEST BUT VEERING WINDS WITH HEIGHT AND STEEP MID-LEVEL LAPSE RATES WILL RESULT IN UPWARDS OF 1500-2500 J/KG MLCAPE. THE STRONGER CORES MAY YIELD AN ISOLD LARGE HAIL AND DMGG WIND RISK. ...NRN FL AND SRN GA... MODEL GUIDANCE DENOTES SLIGHTLY STRONGER NWLY DEEP-LAYER FLOW FIELDS AS A DISTURBANCE TRACKS SEWD FROM THE TN VALLEY TO THE GA/FL COAST DURING THE DAY. H5 TEMPS AROUND -15 DEG C COMBINED WITH FORECAST HIGH TEMPS BREACHING 80 DEG F AND DEWPOINTS NEAR 60 WILL PROBABLY YIELD MODERATE BUOYANCY /1000-1500 J PER KG SBCAPE/. THE ISOLD STORMS WILL POTENTIALLY BE CAPABLE OF AN ATTENDANT LARGE HAIL/DMGG WIND RISK.
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