AREAS AFFECTED...ERN IA/NRN AND CENTRAL IL
CONCERNING...SEVERE THUNDERSTORM WATCH 368...
VALID 260832Z - 261000Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 368
CONTINUES.
SUMMARY...A RECENT INCREASE IN THE THREAT FOR DAMAGING WINDS APPEARS
TO HAVE DEVELOPED OVER EAST CENTRAL IA...WITH THIS THREAT EXPECTED
TO PROGRESS SSEWD AND SEWD THROUGH EAST CENTRAL-SERN IA AND INTO
NWRN IL EARLY THIS MORNING.
IF A FORWARD PROPAGATING LINE/BOWING STRUCTURE IS SUSTAINED THROUGH
10Z...THEN A NEW SVR TSTM WATCH COULD BE WARRANTED TO THE NORTH OF
WW 371.
DISCUSSION...SINCE 07Z...A SSEWD SURGE OCCURRED WITHIN THE CLUSTER
OF TSTMS LOCATED OVER NERN-EAST CENTRAL IA...FROM BLACK
HAWK/BUCHANAN COUNTIES INTO ERN BENTON/LINN COUNTIES WITH STRONG
WIND GUSTS/TREES DOWN NEAR KCID AT 0745Z. FORCING FOR ASCENT
ATTENDANT TO A MIDLEVEL IMPULSE AND THE EXIT REGION OF AN
ACCOMPANYING WNWLY 40-50 KT MIDLEVEL JET...AND LOW LEVEL WAA INTO
ERN IA ARE SUPPORTING THIS CLUSTER OF STORMS. THE LARGE SCALE ASCENT
AND WEAKER LOW LEVEL WAA APPEARS TO BE RESULTING IN ADDITIONAL
DOWNSTREAM STORMS OVER FAR NRN IL INTO SRN WI...WITH THIS ACTIVITY
LOCATED NEAR AND N OF A WARM FRONT WHICH EXTENDED FROM SERN MN
THROUGH FAR SWRN WI TO NRN IL...AND THEN EWD INTO FAR NRN IND.
MODERATE INSTABILITY AND BULK SHEAR UP TO 35 KT FROM SERN IA INTO
CENTRAL IL COMBINED WITH FURTHER COLD POOL DEVELOPMENT WITH THE
DEVELOPING BOW STRUCTURE IN EAST CENTRAL IA SUGGEST AT LEAST A SHORT
TERM DAMAGING WIND THREAT EXISTS. BY 10Z...IF THE BOWING STRUCTURE
MAINTAINS ITS EXISTENCE...THEN THE BOW SHOULD EXTEND FROM HENDERSON
TO KNOX TO BUREAU COUNTIES IN NWRN IL. TRENDS WILL BE MONITORED FOR
THE POTENTIAL NEED OF A DOWNSTREAM SVR TSTM WATCH.
MEANWHILE...GIVEN THE PROXIMITY TO THE CENTER OF THE MIDLEVEL
IMPULSE OVER IA...BULK SHEAR IS GENERALLY AOB 30 KT INTO NRN IL
SUGGESTING THE STORMS NEAR THE WARM FRONT WILL BE LESS
ORGANIZED...POSING A LOWER RISK FOR SVR STORMS.
..PETERS/HART.. 06/26/2013
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LOT...ILX...MKX...LSX...DVN...ARX...DMX...
LAT...LON 42409248 42869224 42979103 42838933 42578879 42148803
41798804 41078820 40798843 40898941 40289017 40259049
40219123 40249169 40459224 40759210 41289222 41889238
42409248
