SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0747 AM CDT TUE MAY 28 2013 VALID 281300Z - 291200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE SRN PLNS AND CNTRL HIGH PLNS NEWD INTO THE LWR GRT LKS... ...SYNOPSIS... SLOWLY PROGRESSIVE...NEGATIVE-TILT GRT BASIN TROUGH WILL FURTHER AMPLIFY THIS PERIOD AS SHORTWAVE IMPULSE NOW IN NV CONTINUES ESE INTO CO/NM...AND UPSTREAM E PACIFIC SPEED MAX REACHES THE ORE CST. AHEAD OF THE AMPLIFYING TROUGH...SATELLITE SHOWS A SERIES OF SRN STREAM DISTURBANCES NOW EXTENDING FROM NW MEXICO TO THE SRN RCKYS THAT SHOULD SHEAR NEWD IN STRENGTHENING/BACKING MID/UPR-LVL FLOW OVER THE SRN/CNTRL PLNS LATER TODAY/TNGT. FARTHER E...HEIGHTS SHOULD RISE OVER THE OH VLY/MIDWEST...ESPECIALLY LATER IN THE PERIOD. IN THE MEAN TIME...EXPECT MODERATE WSW FLOW TO PERSIST FROM THE MID MS VLY TO THE LWR GRT LKS. AT THE SFC...KS LOW SHOULD RETREAT WWD INTO CO IN RESPONSE TO DEEPENING OF UPSTREAM TROUGH. AT THE SAME TIME...DIFFUSE STNRY/WARM FRONT EXTENDING E/NE FROM THE LOW SHOULD ADVANCE NWD AND NEWD INTO SRN MI AND THE LWR GRT LKS IN WAKE OF OVERNIGHT CONVECTIVE SYSTEMS. THE WARM/STNRY FRONT...A DRY LINE TRAILING S FROM THE KS/CO LOW...AND UPSLOPE FLOW TO THE N OF THE LOW WILL SERVE TO FOCUS SVR TSTM POTENTIAL TODAY THROUGH TNGT. ...KS/LWR MO VLY TO MID MS VLY TODAY/TNGT... AN AREA OF VERY STRONG SFC-BASED INSTABILITY...WITH SBCAPE AOA 3000 J/KG...WILL DEVELOP WITH SFC HEATING OVER CNTRL/ERN KS AND WRN MO TODAY...ALONG AND S OF DIFFUSE FRONT/RESIDUAL OUTFLOW BOUNDARIES. WHILE SFC LOW NOW IN KS WILL RETREAT WWD WITH TIME...EXPECT THAT LOW-LVL WIND FIELDS WILL REMAIN SUFFICIENTLY CONVERGENT TO SUPPORT STRONG STORM DEVELOPMENT NEAR THE BOUNDARIES BY LATE AFTN. GIVEN DEGREE OF BUOYANCY...40+ KT WSWLY DEEP SHEAR /LARGELY UNIDIRECTIONAL ABOVE THE BOUNDARY LAYER/ WILL PROMOTE STORM ORGANIZATION/SUSTENANCE...AND A RISK FOR VERY LARGE HAIL...HIGH WIND...AND PERHAPS A TORNADO OR TWO. THIS ACTIVITY COULD GROW UPSCALE INTO A SIZABLE CLUSTER THAT EXTENDS THE SVR THREAT E ACROSS THE NRN HALF OF MO AND PERHAPS ADJACENT PARTS OF SE NEB/SRN IA AND WRN IL INTO EARLY WED. ...CNTRL HI PLNS THIS AFTN/EVE... MOIST UPSLOPE FLOW N AND NW OF KS/CO SFC LOW...STEEP MID-LVL LAPSE RATES...AMPLE DEEP SHEAR...AND COOL/DIFFLUENT UPR FLOW SHOULD RESULT IN NUMEROUS STRONG TO SVR STORMS...INCLUDING SUPERCELLS...OVER NE CO...ERN WY...WRN NEB...AND SW SD THIS AFTN THROUGH EARLY TNGT. THESE WILL BE CAPABLE OF LARGE TO VERY LARGE HAIL AND A FEW TORNADOES...IN ADDITION TO LOCALLY DMGG WIND. THE MAIN FACTOR LIMITING THE POTENTIAL FOR A MORE WIDESPREAD OR INTENSE SVR RISK WILL BE THE RELATIVELY WEAK LOW-LVL FLOW. ...WRN PORTIONS OF THE SRN PLNS THIS AFTN INTO TNGT... SFC HEATING AND ASCENT ASSOCIATED WITH SRN STREAM DISTURBANCES EXPECTED TO PROMOTE SCTD STORMS ALONG LEE TROUGH/DRY LINE FROM SW KS THROUGH THE OK/TX PANHANDLES INTO SW TX LATER TODAY. GIVEN EXPECTED THERMODYNAMIC ENVIRONMENT...THESE STORMS COULD PRODUCE LARGE HAIL...DMGG WIND...AND POSSIBLY A TORNADO OR TWO. ONE OR TWO SMALL CONVECTIVE CLUSTERS MAY EVOLVE FROM THIS ACTIVITY BY EVE...EXTENDING THE RISK FOR SVR WEATHER /MAINLY INTO THE FORM OF DMGG WIND/...EWD INTO CNTRL OK/S CNTRL KS. ...MIDWEST/LWR GRT LKS THIS AFTN THROUGH TNGT... SATELLITE SUGGESTS THAT AT LEAST FILTERED SFC HEATING SHOULD OCCUR OVER PARTS OF IND...LWR MI...AND NRN OH TODAY...E OF REMNANT MCS NOW IN IL...AND INVOF DIFFUSE WARM FRONT ADVANCING NE ACROSS REGION. THIS CORRIDOR WILL LIE BENEATH A BELT OF 40+ KT WSWLY LWR TROPOSPHERIC FLOW ASSOCIATED WITH DISTURBANCE THAT CROSSED KS YESTERDAY. COUPLED WITH CONFLUENCE ALONG FRONT AND/OR ALONG OUTFLOW BOUNDARY FROM IL MCS...SETUP MAY YIELD BANDS OR SMALL CLUSTERS OF SUSTAINED STORMS/WEAK SUPERCELLS WITH BOWING SEGMENTS CAPABLE OF LOCALLY DMGG WIND AND POSSIBLY A TORNADO. MORE THAN ONE WAVE OF SUCH ACTIVITY MAY AFFECT THE REGION DURING THE PERIOD...WITH A CONDITIONAL SVR THREAT REACHING AS FAR E AS WRN NY/NW PA. ...MD/VA PIEDMONT THIS AFTN... ERN END OF DIFFUSE WARM FRONT WILL REDEVELOP NEWD INTO MD LATER TODAY...USHERING IN WARMER...WLY LOW-LVL FLOW INTO THE REGION. MOISTURE WILL BE RATHER MODEST /PW AROUND 1.25 INCHES AND SFC DEWPOINTS IN THE LOW 60S F/ BUT SUFFICIENT FOR STORMS GIVEN FAIRLY STEEP LOW TO MID-LVL LAPSE RATES. CONVERGENCE ALONG THE LEE TROUGH AND/OR ALONG THE BLUE RIDGE MAY FOSTER DEVELOPMENT OF A FEW AFTN PULSE STORMS WITH A LOW CONDITIONAL RISK FOR DMGG WIND/MARGINALLY SVR HAIL. ..CORFIDI/BOTHWELL.. 05/28/2013
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1300.html
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