SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0751 AM CDT SUN MAY 06 2012 VALID 061300Z - 071200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID MS VLY SSW INTO PARTS OF THE SRN PLNS... ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE SERN STATES... ...SYNOPSIS... SRN SK UPR LOW EXPECTED TO TRACK SLOWLY E INTO SRN MB THIS PERIOD AS TRAILING...POSITIVE TILT TROUGH EDGES MORE SLOWLY E ACROSS THE GRT BASIN. THE EWD ADVANCE OF THE LOW/TROUGH...AND THAT OF WEAKER DISTURBANCES TO THEIR E...WILL SERVE TO DEPRESS HEIGHTS FROM THE N CNTRL STATES INTO THE UPR GRT LKS. LESSER HEIGHT FALLS WILL PREVAIL OVER THE SRN PLNS AND OVER THE TN VLY/GULF CST STATES IN CONJUNCTION WITH RESPECTIVE SRN BRANCH DISTURBANCES MOVING NEWD FROM NM AND SEWD INTO MS/AL. AT LWR LVLS...SSW-NNE COLD FRONT ASSOCIATED WITH MB/GRT BASIN SYSTEM WILL ADVANCE E/SE FROM THE LWR MO VLY/CNTRL PLNS THIS MORNING INTO THE MID MS VLY/SRN PLNS BY EVE. THE SRN PART OF THE FRONT WILL OVERTAKE THE DRYLINE IN WRN OK...WITH THE DRYLINE CONTINUING S/SW FROM THERE ACROSS WRN PARTS OF THE TX HILL COUNTRY TO THE TX BIG BEND. FARTHER NE...FRONT ATTM EXTENDING FROM CNTRL IA TO SRN IND EXPECTED TO ADVANCE SLOWLY NEWD TODAY...WITH MOVEMENT IN IA LIKELY OFFSET BY OUTFLOW FROM ONGOING TSTMS. WHILE LARGE SCALE FORCING FOR ASCENT WILL REMAIN WEAK...SFC HEATING OF SEASONABLY MOIST/BUOYANT AIR ALONG AND AHEAD OF COLD FRONT/DRYLINE...AND ALONG WARM FRONT...WILL YIELD A FAIRLY LARGE AREA SUBJECT TO A CONDITIONAL THREAT FOR SVR TSTMS. ...MID MS VLY SSW INTO PARTS OF THE SRN PLNS TODAY/TNGT... CNTRL/SW IA SQLN EXPECTED TO CONTINUE SLOWLY E/SE THROUGH THIS MORNING. WHILE STRONGER STORMS WITHIN THIS BAND REMAINED ISOLD THROUGH THE OVERNIGHT...UPDRAFTS MAY INTENSIFY/BECOME SUSTAINED LATER THIS MORNING AS SFC HEATING DESTABILIZES INFLOW. ALTHOUGH FCST WIND PROFILES AND THE ORIENTATION OF THE CONVECTIVE SYSTEM RELATIVE TO MEAN SW TO WSWLY MID LVL FLOW DO NOT APPEAR OPTIMAL FOR INTENSE DEVELOPMENT...SUFFICIENT SHEAR AND INSTABILITY LIKELY WILL EXIST FOR EMBEDDED STORMS WITH SVR WIND/HAIL. A FEW STORMS MAY FORM AHEAD OF THE MCS INVOF DIFFUSE WARM/STNRY FRONT IN IL. THESE MAY YIELD SVR HAIL AND...POSSIBLY...A WEAK TORNADO OR TWO GIVEN MOIST/BACKED LOW LVL FLOW. ADDITIONAL TSTMS/STORM CLUSTERS SHOULD FORM THIS AFTN ALONG COLD FRONT AND RESIDUAL OUTFLOW BOUNDARIES FROM NW MO/NE KS SSW INTO OK. A BIT LATER IN THE DAY...STORMS ALSO MAY FORM ALONG THE DRYLINE IN TX. STRONG WARM SECTOR INSTABILITY /SBCAPE TO 4000 J PER KG/ SUGGESTS THE POSSIBILITY FOR SVR HAIL AND WIND. HOWEVER...MODEST /20-30 KT/ DEEP SWLY SHEAR SHOULD LIMIT UPDRAFT SUSTENANCE/ ORGANIZATION...WITH COMPLEX STORM MODES/SLOWLY-MOVING MULTICELL CLUSTERS...AND MARGINAL/TRANSIENT SUPERCELLS EXPECTED. CORRIDORS OF GREATEST SVR RISK WILL BE DETERMINED BY STORM-SCALE INTERACTIONS GIVEN ABSENCE OF STRONG SHEAR. LOOSELY-ORGANIZED BANDS/CLUSTERS OF STORMS MAY PERSIST INTO TNGT E/SE INTO PARTS OF IL...IND...MO...AND AR...BUT WITH A GRADUALLY DIMINISHING/MORE EPISODIC SVR THREAT. ...SERN STATES TODAY... SMALL...LOOSELY-ORGANIZED MCS NOW IN NRN AL HAS EVOLVED FROM SIMILAR OVERNIGHT ACTIVITY THAT EXTENDING UPSTREAM INTO WRN TN. STORMS SHOULD INCREASE IN COVERAGE AND POSSIBLY STRENGTH TODAY IN RESPONSE TO STRONG SFC HEATING AND WEAK ASCENT ASSOCIATED WITH AFOREMENTIONED UPR IMPULSE. WIND FIELD WILL REMAIN WEAK. BUT MODEST MEAN NNWLY FLOW PARALLEL TO SYSTEM OUTFLOW BOUNDARY...PRESENCE OF EML...AND HIGH PWS SUGGEST THE POSSIBILITY FOR STORMS TO ORGANIZE INTO FORWARD-PROPAGATING BANDS BY AFTN...WITH AN ACCOMPANYING RISK FOR DMG WIND/MARGINALLY SVR HAIL. ..CORFIDI/GARNER.. 05/06/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1300.html
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