Chase Day Updates

9:12pm: Well, three hours later and at best all we found was about 30 second of good lightning footage.  So it goes with the majority of severe weather chases.  The storms window of severity was, as expected, small.  But it turned out to be much smaller than we anticipated.  While a threat remains for portions of eastern Iowa, I am ready to throw in the towel.  I am writing this as we drive back to Cedar Rapids from Bremer County.  For now we will piece together a bit of weather video for the KCRG-TV 9 News at 10 and head home for a good night’s sleep.  Better luck Sunday!

6:15pm: Thunderstorms warning aplenty in the Mason City area.  Early reports are of mainly hail.  Expect winds to increase in some storms as the complex gains a little more forward motion.  Currently moving at a modest 30mph.

untitled4:40pm: Getting first indication of returns on NEXRAD in Des Moines.  Further weakening of the cap also evident by thunderstorm development in southeast Minnesota.  Still some capping out there so not sure how widespread this will grow and when/if it will become severe…

Expect the Storm Prediction Center to soon issue a watch relatively soon.  Not sure when the line will take shape and move into eastern Iowa.


4:25pm: Evidence beginning to show a weakening of the cap in north central Iowa.  If this continues, rapid and explosive thunderstorm development would be possible in areas west of Mason City.  There is a line of cloud development along the wave in that area that could trigger a line of thunderstorms.  Supercells are a possibility during the first 1-3 hours of convection.  A faster moving line of wind and hail producing thunderstorms could then become a long term threat through the evening hours.  Expect a watch to be issued soon…

Area under consideration for a watch

3:25pm: Storm Prediction Center considers watch for portions of eastern Iowa, details can be found here.

1:50pm: Currently the forecast is unchanged from this morning.  My best guess is we could see initiation in northcentral Iowa sometime after 4pm.  Whether storms get organized will depend on the cap setting up over much of the state.  Strong cape values of 2000+ are already evident so there’s plenty of moisture and energy out there for storms if convection fires up.

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