SPC 1200Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1245 AM CDT SUN JUL 29 2012 VALID 291200Z - 301200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM ND THROUGH NRN MN... ...SYNOPSIS... SUMMER BLOCKING PATTERN WITH UPPER RIDGE CENTERED OVER THE SRN PLAINS FLANKED BY MEAN TROUGHS OVER THE ERN STATES AND WRN U.S. COAST WILL PERSIST SUNDAY. SMALLER SCALE FEATURES OF INTEREST EMBEDDED IN THIS REGIME INCLUDE A VORT MAX OVER SRN SASKATCHEWAN. THIS FEATURE WILL CREST UPPER RIDGE AND TURN SEWD...REACHING NRN MN THIS EVENING. VORT MAX NOW MOVING INTO THE UPPER MS VALLEY WILL CONTINUE SEWD INTO IL THIS AFTERNOON. AT THE SFC A COLD FRONT WILL ACCOMPANY THE SHORTWAVE TROUGH MOVING THROUGH SRN CANADA. THIS BOUNDARY WILL ADVANCE THROUGH ND DURING THE DAY...REACHING NRN MN SUNDAY NIGHT. FARTHER SOUTH A FRONT WILL PERSIST FROM THE ERN CAROLINAS WWD INTO THE SERN STATES THEN NWWD AS A WARM FRONT THROUGH THE MID MS VALLEY REGION. WEAK SFC LOW MAY DEVELOP ALONG THIS BOUNDARY OVER MO/IL IN ASSOCIATION WITH THE SEWD ADVANCING VORT MAX. A SFC TROUGH WILL EXTEND WWD FROM THE LOW THROUGH MO AND KS. ...ND THROUGH NRN MN... UPPER 50S TO LOW 60S BOUNDARY LAYER DEWPOINTS WILL CHARACTERIZE THE PRE-FRONTAL WARM SECTOR FROM ND INTO NRN MN. THE ATMOSPHERE WILL DESTABILIZE DURING THE DAY PROMOTED BY STRONG SFC HEATING AND EWD ADVECTION OF STEEP LAPSE RATES PLUME SUPPORTING 1500-2000 J/KG MLCAPE. SURFACE BASED THUNDERSTORM INITIATION WILL LIKELY BE DELAYED UNTIL MID-LATE AFTERNOON WHEN DIABATIC WARMING AND DEEPER ASCENT WITH PROGRESSIVE VORT MAX AND FRONTAL CIRCULATION WILL WEAKEN THE CAP. MID LEVEL JET ATTENDING THE IMPULSE WILL RESULT IN SUFFICIENT EFFECTIVE UNIDIRECTIONAL SHEAR FOR SOME STORMS TO DEVELOP SUPERCELL STRUCTURES. ACTIVITY WILL BE RELATIVELY HIGH BASED WITH ISOLATED DAMAGING WIND AND LARGE HAIL THE MAIN THREATS. STORMS MAY EVENTUALLY CONSOLIDATE INTO AN MCS OVER NRN MN SUNDAY NIGHT SUPPORTED BY STRENGTHENING LLJ. ...ERN KS THROUGH MID MS VALLEY REGION... WSWLY LLJ WILL PERSIST OVER THE MID MS VALLEY IN ASSOCIATION WITH SEWD ADVANCING SHORTWAVE TROUGH. THIS FEATURE WILL MAINTAIN ISENTROPIC ASCENT AND ELEVATED STORMS EAST OF NW-SE ORIENTED WARM FRONT. PRIMARY THREAT WILL BE MARGINALLY SEVERE HAIL AS ACTIVITY SHIFTS SEWD THROUGH ERN MO AND IL. FARTHER WEST FROM CNTRL MO TO ERN KS...DIABATIC WARMING AND MIXING SHOULD WEAKEN CAP ENOUGH FOR STORMS TO DEVELOP ALONG E-W TROUGH AXIS. VEERING WINDS WITH 35-40 KT EFFECTIVE SHEAR WILL SUPPORT POTENTIAL FOR A FEW STORMS TO DEVELOP UPDRAFT ROTATION OVER MO...WITH MULTICELL MODES FARTHER WEST INTO KS WHERE WEAKER SHEAR WILL EXIST. PRIMARY THREATS WILL BE ISOLATED DAMAGING WIND AND LARGE HAIL. THIS AREA WILL BE MONITORED FOR A POSSIBLE SLIGHT RISK IN LATER UPDATES. ...SERN STATES... MULTICELL STORMS WILL LIKELY ONCE AGAIN DEVELOP SOUTH OF FRONT FROM THE GULF COASTAL STATES INTO THE ERN CAROLINAS. DIABATIC WARMING WILL STEEPEN LOW LEVEL LAPSE RATES...AND A FEW STORMS MAY BECOME CAPABLE OF PRODUCING STRONG WIND GUSTS. ..DIAL/SMITH.. 07/29/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1200.html
Comments are closed.