SPC 0600Z Day 2 Outlook
DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1257 AM CDT MON APR 30 2012 VALID 011200Z - 021200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM A PORTION OF THE CNTRL AND NRN PLAINS INTO THE UPPER MS VALLEY AND GREAT LAKES... ...SYNOPSIS... UPPER PATTERN IS IN THE PROCESS OF DEAMPLIFYING AND WILL BECOME CHARACTERIZED BY A LOW AMPLITUDE BROAD CYCLONIC FLOW REGIME TUESDAY. UPPER JET AND ATTENDANT SHORTWAVE TROUGH APPROACHING THE PACIFIC NW AS OF EARLY MONDAY WILL REACH THE NRN PLAINS TUESDAY. THIS FEATURE WILL BE ACCOMPANIED BY A COLD FRONT THAT WILL MOVE SEWD THROUGH THE NRN/CNTRL PLAINS AND UPPER MS VALLEY. A DRYLINE WILL STRETCH FROM THE SRN THROUGH CNTRL HIGH PLAINS DURING THE DAY. WARM FRONT WILL LIFT NWD THROUGH THE UPPER MS AND OH VALLEYS AND GREAT LAKES. ...UPPER MS VALLEY THROUGH NRN AND CNTRL PLAINS REGIONS... LEE TROUGHING WILL HAVE BECOME ESTABLISHED OVER THE HIGH PLAINS WITHIN THE QUASI-ZONAL UPPER FLOW REGIME. AS THE WARM FRONT LIFTS NWD A BROAD...MOIST WARM SECTOR WILL ADVECT THROUGH ERN PORTIONS OF THE PLAINS AND UPPER MS VALLEY AND GREAT LAKES WITH UPPER 50S TO NEAR 60 DEWPOINTS AS FAR NORTH AS THE ERN DAKOTAS INTO MN AND LOW-MID 60S FARTHER EAST AND SOUTH. ZONE OF MODERATE TO STRONG INSTABILITY WILL DEVELOP IN THIS REGION AS PLUME OF STEEP LAPSE RATES ADVECT EWD ABOVE RETURNING MOIST AXIS AND AS THE BOUNDARY LAYER WARMS DURING THE AFTERNOON. MLCAPE SHOULD RANGE FROM 1500 TO 2000 J/KG OVER THE UPPER MS VALLEY TO NEAR 3000 J/KG OVER THE CNTRL PLAINS. AS LOW AMPLITUDE SHORTWAVE TROUGH APPROACHES FROM WEST...STORMS MAY DEVELOP WITHIN ZONE OF DEEPER FORCING ALONG AND EAST OF SEWD ADVANCING COLD FRONT ACROSS THE ERN DAKOTAS INTO NEB WITH MORE ISOLATED ACTIVITY POSSIBLE FARTHER SOUTH ALONG THE DRYLINE ACROSS KS. VERTICAL SHEAR FROM 35-45 KT WILL SUPPORT ORGANIZED STORMS INCLUDING SUPERCELLS AND BOWING SEGMENTS. LARGE HAIL AND DAMAGING WIND WILL BE THE MAIN THREATS...BUT 0-2 KM HODOGRAPHS WILL ALSO BE SUFFICIENT FOR ISOLATED TORNADOES. ACTIVITY WILL CONTINUE EAST INTO WRN PORTIONS OF THE GREAT LAKES AREA DURING THE EVENING WITH A CONTINUED SEVERE THREAT. ...SRN HIGH PLAINS... ISOLATED STORMS WILL BE POSSIBLE ALONG DRYLINE ACROSS THE SRN PLAINS AS WELL AS OVER THE HIGHER TERRAIN OF SWRN TX AS THE CAP WEAKENS DURING PEAK HEATING...BUT LACK OF FORCING FOR DEEP ASCENT AND A CAPPING EML SUGGEST COVERAGE WILL REMAIN SPARSE. VERTICAL SHEAR IN MUCH OF THIS REGION WILL BE WEAK. HOWEVER...A BELT OF SLIGHTLY STRONGER FLOW WITHIN THE SRN BRANCH OF THE WLYS WOULD PROMOTE SUPERCELLS SHOULD STORMS DEVELOP OVER SWRN TX. ISOLATED DAMAGING WIND AND HAIL WILL BE THE MAIN THREATS. ACTIVITY WILL LIKELY DIMINISH BY MID EVENING AS THE BOUNDARY LAYER STABILIZES. WILL MAINTAIN 5% SEVERE PROBABILITIES FOR NOW...BUT A PORTION OF THIS AREA MIGHT NEED TO BE INCLUDED IN A SLIGHT RISK ONCE CONFIDENCE IN WHERE STORMS ARE MORE LIKELY TO DEVELOP INCREASES. ...TN AND OH VALLEY REGION THROUGH MID ATLANTIC... SCATTERED STORMS WILL BE ONGOING OVER PORTIONS OF THE OH VALLEY WITHIN ZONE OF WEAK WARM ADVECTION AND IN ASSOCIATION WITH EJECTING IMPULSE. ACTIVITY WILL REMAIN EMBEDDED WITHIN MODEST VERTICAL SHEAR...BUT STRONGER STORMS MAY DEVELOP WHERE BOUNDARY LAYER WARMING OCCURS DURING THE AFTERNOON. PRIMARY THREAT WILL BE ISOLATED STRONG WIND GUSTS. AT THIS TIME...OVERALL THREAT APPEARS TOO MARGINAL FOR MORE THAN 5% PROBABILITIES. ..DIAL.. 04/30/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day2otlk_0600.html
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