AREAS AFFECTED...NRN AND CNTRL IL INTO E CNTRL MO
CONCERNING...SEVERE THUNDERSTORM WATCH 401...402...
VALID 170058Z - 170230Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
401...402...CONTINUES.
SUMMARY...IT IS NOT CERTAIN THAT ANOTHER WW WILL BE NEEDED
SOUTH/EAST OF WWS 401 AND 402...BUT TRENDS WILL CONTINUE TO BE
MONITORED FOR THE POSSIBILITY OF A CONTINUING/INCREASING SEVERE
THREAT THAT MAY REQUIRE ONE.
DISCUSSION...AS A SURFACE CYCLONE DEEPENS OVER NORTHWEST
ONTARIO...MODEST SOUTHERLY 850 MB JET STRENGTHENING IS FORECAST
AHEAD OF A TRAILING SURFACE FRONT...WITH 30+ KTS BECOMING MORE
PROMINENT AS LEAST AS FAR SOUTH AS NORTHERN ILLINOIS. VARIABILITY
EXISTS AMONG THE MODEL GUIDANCE CONCERNING THE STRENGTH OF THE LOWER
FLOW FIELDS FARTHER SOUTH...INTO THE MIDDLE MISSISSIPPI VALLEY. AND
THIS WILL IMPACT THE EXTENT OF THE CONTINUING SEVERE RISK THIS
EVENING...AS THE BOUNDARY LAYER AHEAD OF THE STILL EVOLVING
MESOSCALE CONVECTIVE SYSTEM SLOWLY BEGINS TO STABILIZE WITH
RADIATIONAL SURFACE COOLING. BUT CLOUD TOPS HAVE BEEN COOLING WITH
CONSOLIDATING STORMS OVER CENTRAL MISSOURI...WHICH COULD BEGIN
IMPACTING THE ST. LOUIS METROPOLITAN AREA DURING THE 02-04Z TIME
FRAME.
..KERR.. 06/17/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LOT...ILX...LSX...DVN...SGF...
LAT...LON 38529206 38829174 39079099 40079013 40508989 40938951
41668915 41808786 41648751 40648775 39468819 38838869
38039027 37699162 38529206
