MD 1812 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR SERN IA / NERN MO / W-CNTRL IL
MESOSCALE DISCUSSION 1812 NWS STORM PREDICTION CENTER NORMAN OK 0754 PM CDT THU SEP 17 2015 AREAS AFFECTED...SERN IA / NERN MO / W-CNTRL IL CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY VALID 180054Z - 180200Z PROBABILITY OF WATCH ISSUANCE...20 PERCENT SUMMARY...AN ISOLD LARGE-HAIL THREAT MAY DEVELOP TO THE EAST OF SEVERE THUNDERSTORM WATCH 511. CURRENT THINKING IS THE SEVERE RISK WILL REMAIN ISOLD ENOUGH TO NOT WARRANT AN ADDITIONAL WATCH. TRENDS WILL BE MONITORED. DISCUSSION...RADAR MOSAIC SHOWS A LEFT AND RIGHT SUPERCELL SPLIT STRADDLING THE MO/IA BORDER AND MRMS MESH DATA INDICATE SEVERE HAIL IS OCCURRING WITH THIS PAIR OF STORMS. THE ACTIVITY LIKELY DEVELOPED FROM MID-LEVEL CONVECTION AND BECAME SURFACE-BASED OVER THE PAST FEW HOURS. COOLING DUE TO THE LOSS OF DAYTIME HEATING OVER THE NEXT 1-3 HOURS WILL PROBABLY LEAD TO A DECOUPLING OF THE BOUNDARY LAYER AND SERVE TO SLOWLY WEAKEN THE EXISTING ACTIVITY. NONETHELESS...A FEED OF STEEP LAPSE RATES FROM THE WEST IN THE -10 TO -30 DEG C LAYER /REFERENCE THE 18/00Z TOP RAOB/ AND SUFFICIENT SHEAR FOR ORGANIZED STORMS WILL LEND SOME POTENTIAL FOR A LARGE-HAIL RISK MOVING BEYOND THE EASTERN BOUND OF SEVERE THUNDERSTORM WATCH 511. WHILE AN ADDITIONAL SEVERE THUNDERSTORM WATCH APPEARS UNLIKELY...WILL MONITOR OBSERVATIONAL TRENDS OVER THE NEXT 1-3 HOURS. ..SMITH/EDWARDS.. 09/18/2015 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...LSX...DVN... LAT...LON 40029226 41149197 41349126 41139097 40149137 39899186 40029226
from SPC Mesoscale Discussions http://1.usa.gov/1OAMUDf
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