SPC 2000Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0252 PM CDT THU MAY 03 2012 VALID 032000Z - 041200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL PLAINS...MID TO UPPER MS VALLEY...OH VALLEY AND SRN GREAT LAKES... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SOUTHWEST TX... SEVERAL CHANGES HAVE BEEN MADE TO THE OUTLOOK AT 20Z. THE FIRST CHANGE IS TO REMOVE THE SLIGHT RISK AREA ACROSS CNTRL WI AND NRN LOWER MI WHERE INSTABILITY IS WEAK. THE SECOND CHANGE IS TO MAKE THE SIGNIFICANT HAIL THREAT AREA SMALLER LOCATED ACROSS FAR NERN KS...NRN MO...SE IA AND FAR WRN IL WHERE STRONG INSTABILITY IS ANALYZED AND THE DEEP LAYER SHEAR SHOULD BE ADEQUATE FOR SUPERCELL DEVELOPMENT. THE MORE DOMINANT SUPERCELLS COULD PRODUCE HAILSTONES OF GREATER THAN 2 INCHES IN DIAMETER. ALSO...THE 5 PERCENT WIND DAMAGE PROBABILITY IS MOVED NWD ACROSS NRN IA INTO FAR SE MN WHERE STRONG TO SEVERE THUNDERSTORMS ARE DEVELOPING. ANOTHER CHANGE IS TO REMOVE THUNDER FROM PARTS OF NCNTRL MN...ERN ND AND NE SD WHERE INSTABILITY IS MINIMAL. ALSO...REMOVED THUNDER FROM SRN MT AND NW WY WHERE MODEL FORECASTS FAIL TO DEVELOP CONVECTION LATE THIS AFTERNOON. FINALLY...REMOVED THUNDER FROM WRN MS WHERE WATER VAPOR IMAGERY SHOWS SIGNIFICANT DRYING TAKING PLACE FROM THE WEST. ..BROYLES.. 05/03/2012 .PREV DISCUSSION... /ISSUED 1126 AM CDT THU MAY 03 2012/ ...MN/WI EAST TO NRN LOWER MI... A COMPLEX SURFACE PATTERN PRESENTS ITSELF THIS MORNING WITH ONGOING DEEP CONVECTION FOCUSED NEAR WEAK FRONTAL WAVES IN SRN MN AND CNTRL/ERN WI. SUFFICIENT INSTABILITY AND FORCING EXIST NEAR THE LOW CENTERS...AND ALONG/NORTH OF THE FRONTAL ZONE EXTENDING FROM MN TO NRN LOWER MI...TO SUSTAIN CLUSTERS OF STORMS...OCCASIONALLY PRODUCING SEVERE HAIL...AMIDST EFFECTIVE SHEAR VALUES OF 30-40KT. RELATIVELY WIDESPREAD CONVECTIVE OVERTURNING OVER THE PAST SEVERAL HOURS ACROSS MN AND WI WAS LIKELY LIMITING GREATER STORM INTENSITY AT THIS TIME. HOWEVER...SOME LARGE SCALE SUPPORT FOR CONTINUING ASCENT WITHIN THIS CORRIDOR SHOULD BE PROVIDED BY THE LOW AMPLITUDE CONVECTIVELY-INDUCED SHORT WAVE TROUGH NOW OVER IA/MN. AS DOWNSTREAM AIRMASS ALONG THE FRONT OVER MI CONTINUES TO DESTABILIZE...EXPECT MORE ROBUST STORM UPDRAFTS TO DEVELOP WITH THE THREAT FOR LARGE HAIL AND HIGH WINDS INCREASING THROUGH THE AFTERNOON. REFER TO SWOMCD 674 FOR ADDITIONAL DETAILS AND WATCH PROGNOSIS. ...IA/MO EAST ACROSS NRN IL... A VERY MOIST AND WARMING AIRMASS PRECEDES A WELL-DEFINED OUTFLOW BOUNDARY ACROSS NRN/NERN MO AND AN UNPERTURBED WARM AND UNSTABLE REGIME WAS IN PLACE EAST OF THE MS RIVER...ACROSS MUCH OF THE MIDWEST...WHERE MLCAPE VALUES HAVE ALREADY CLIMBED TO AROUND 2000 J/KG. AIRMASS RECOVERY WAS ALSO WELL UNDERWAY IN THE WAKE OF THE EARLIER MCS OVER IA. WHILE THIS ENTIRE ZONE IS FORECAST TO REMAIN SOMEWHAT REMOVED FROM THE STRONGER DEEP-LAYER SHEAR AND FORCING...THE CONTINUATION OF STRONG DESTABILIZATION COINCIDENT WITH FOCUSED MESOSCALE FORCING NEAR RESIDUAL OUTFLOWS SHOULD CONTRIBUTE TO STORM DEVELOPMENT AND SEVERE POTENTIAL LATER THIS AFTERNOON AND INTO THE EVENING. RESULTING ACTIVITY MAY EXHIBIT UPSCALE GROWTH INTO ONE OR MORE FORWARD PROPAGATING SYSTEMS WITH LARGE HAIL AND WIND DAMAGE THREAT SPREADING EAST FROM IA/MO TO IL...AND PERHAPS AS FAR EAST AS IND/NWRN OH THROUGH LATE EVENING. ...TX... ASCENT ACROSS THE DRYLINE MAY BE ENHANCED COINCIDENT WITH MAX HEATING AS A WEAK SHORT WAVE TROUGH TRACKS NEWD FROM MEXICO INTO ERN NM. MAJORITY OF MODEL GUIDANCE INDICATES AT LEAST ISOLD STORM DEVELOPMENT COULD OCCUR BY LATE AFTERNOON FROM THE RIO GRANDE NORTH ALONG THE EDWARDS PLATEAU. MAGNITUDE OF INSTABILITY AND VERY WARM SURFACE TEMPS IN THE 90S COULD CONTRIBUTE TO DOWNBURST AND LARGE HAIL POTENTIAL WITH ANY DEEP CONVECTION THAT DEVELOPS.
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_2000.html
Be First to Comment