SEVERE THUNDERSTORM OUTLOOK FOR TODAY

VALID 10 AM CDT TO 11 PM CDT TODAY 

*THIS IS NOT A FORECAST MAP FOR WHERE THUNDERSTORMS WILL FORM AND WHERE THEY WILL BE DURING THE VALID HOURS(10AM- 11PM CDT). THIS IS A FORECAST OF THE CHANCE OF THE STORMS BEING SEVERE.*


THE LATEST RAP FORECAST FROM 13Z SHOWS A BAND OF MODERATELY UNSTABLE AIR FROM SOUTHEASTERN NEBRASKA THROUGH SOUTHWESTERN TO NORTHEASTERN IOWA AND ENDING IN SOUTHEASTERN/CENTRAL WISCONSIN. THE  GREATEST INSTABILITY IS IN SOUTHEASTERN NEBRASKA, SOUTHWESTERN IOWA, AND SOUTHWESTERN WISCONSIN. THIS BAND OF INSTABILITY WILL GRADUALLY MOVE INTO SOUTHERN WISCONSIN, NORTHERN ILLINOIS, AND INTO NORTHERN INDIANA.


BY 10AM CDT, INSTABILITY IS GREATEST IN SOUTHERN WISCONSIN, NORTHERN ILLINOIS, AND EASTERN IOWA. YOU WOULD THINK WITH A LIFTING MECHANISM, A COOL FRONT, STORMS WOULD BE FORMING. THAT IS NOT THE CASE AT 10AM BECAUSE THERE IS WARM AIR ALOFT AT ABOUT 850-700MB, WHICH IS INHIBITING STORMS TO FORM. 


BY 11AM CDT, AREAS AT 10AM STILL HAVE THE GREATEST INSTABILITY. THERE ALSO IS STILL WARM AIR ALOFT, BUT IT IS STARTING TO COOL DOWN AND NOW IS FOUND AT 860-870MB. STORMS COULD INITIATE CLOSER TO THE HOUR OF 12PM, ONLY IF THE WARM AIR ALOFT HAS COOLED. IN SOUTHERN WISCONSIN THERE IS NOTHING INHIBITING THE STORMS EXCEPT THE WARM AIR ALOFT, EVEN CIN VALUES ARE VERY LOW.


BY 12PM, AREAS OF GREATEST INSTABILITY ARE STILL IN THE SAME AREAS, EXCEPT MOVED A BIT TO THE SOUTH IN NORTHERN ILLINOIS. THERE ALSO IS STILL WARM AIR ALOFT FROM 860-890MB, IT IS INCREASING IN SIZE WHICH INS'T GOOD FOR STORMS TO FORM. 


AT 1PM, IT IS THE SAME AS 12PM EXCEPT INSTABILITY HAS MOVED MORE SOUTH, EXTENDED MORE TOWARDS EASTERN IOWA.


BY 2PM, INSTABILITY AREAS ARE THE SAME EXCEPT EXTENDED MORE INTO NORTHERN INDIANA. THE WARM AIR ALOFT IS STILL IN PLACE(AT AROUND 860-880MB), BUT HAS WEAKENED. THIS WARM AIR ALOFT WAS VERY STABLE BUT NOW IT IS STABLE, BETTER STORM INITIATION CHANCES BUT IT ISN'T THE GREATEST CHANCE.    


AT 3PM GREATEST INSTABILITY AREAS ARE IN THE SAME LOCATIONS. THE WARM AIR ALOFT HAS DECREASED CONSIDERABLY FROM THE LAST HOUR(ONLY AT AROUND 860-870MB). WITH THIS COOLING, STORMS ARE MORE LIKELY TO FORM THAN PREVIOUS HOURS OF COOLING. SUPERCELLS ARE VERY UNLIKELY, BUT THERE ARE CONDITIONS FOR THEM TO HAPPEN.
         
AT 4PM, INSTABILITY IS IN THE SAME AREAS, EXCEPT SOUTHERN WISCONSIN IS LOSING ITS INSTABILITY. STORM INITIATION IS LIKELY BECAUSE THERE IS LITTLE WARM AIR ALOFT. AT THIS POINT OF TIME, SUPPERCELLS ARE POSSIBLE, BUT ARE NOT LIKELY. 


FROM 5-9PM THIS WILL REPEAT ITSELF UNTIL 9-10PM TONIGHT. THE STORMS WILL LOSE THEIR SUPERCELL STRUCTURE FROM 6-7PM.