AREAS AFFECTED...SERN IA/NRN IL/FAR SRN WI
CONCERNING...SEVERE THUNDERSTORM WATCH 557...
VALID 041809Z - 041915Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 557
CONTINUES.
SUMMARY...A LINE OF TSTMS WILL CONTINUE PROGRESSING EWD ACROSS SERN
IA INTO NRN IL. PRIMARY SEVERE THREAT OF DAMAGING WINDS WITH THE LOW
PROBABILITY OF A FEW SEVERE HAIL REPORTS WILL EXIST AS LINE
CONTINUES EWD. A DOWNSTREAM WW WILL LIKELY BE NEEDED WITHIN THE NEXT
HOUR OR TWO.
DISCUSSION...RECENT DVN RADAR TRENDS HAVE SHOWN IMPROVED CONVECTIVE
STRUCTURE WITH INCREASED ORGANIZATION OVER THE PAST HOUR. DVN BASE
VELOCITY DATA HAS ALSO SHOWN AN INCREASING TREND WITH MAX WINDS
LOCATED ACROSS CEDAR COUNTY IA. ADDITIONALLY...RECENT SURFACE
OBSERVATIONS DEPICT A WELL-DEFINED RISE-FALL-RISE PRESSURE TREND
ALONG AND JUST BEHIND THE LINE...FURTHER VERIFYING THE
STRENGTH/MATURITY OF THE MCS. MLCAPE AOA 2000 J/KG...SUPPORTED BY
MOSTLY CLEAR SKIES...TEMPERATURES IN THE UPPER 80S/LOW 90S...AND
DEWPOINT VALUES IN THE UPPER 60S/LOW 70S...EXISTS DOWNSTREAM OF THE
LINE. LATEST MESOANALYSIS ALSO SUGGEST EFFECTIVE SHEAR VALUES IN
EXCESS OF 35 KTS ACROSS NRN IL. GIVEN THIS ENVIRONMENT...THE LINE IS
EXPECTED TO CONTINUE PROGRESSING EWD WITH A CONTINUED THREAT OF
DAMAGING WINDS AND SEVERE HAIL. CURRENT STORM MOTION IS ESTIMATED AT
250/45 WITH SOME DISCRETE PROPAGATION NOTED ACROSS CEDAR AND JONES
COUNTIES. THE LINE WILL LIKELY MOVE OUTSIDE OF WW 557 AND A
DOWNSTREAM WW WILL LIKELY BE NEEDED WITHIN THE NEXT HOUR OR TWO.
..MOSIER.. 08/04/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LOT...ILX...MKX...DVN...ARX...
LAT...LON 40138938 40179031 40239129 40319182 40679203 41429218
42299203 42859179 42859060 42548841 41798800 41118805
40628826 40138938
