Late afternoon Saturday, a stormy low pressure area will blow up right over Iowa and spread a legacy of rain through here during the evening. There may be some rain showers or a thunderstorm even earlier in the day leading up to this, but a window for possible severe weather and/or heavy rainfall will certainly be open Saturday evening – 7:00pm to 1:00am as it seems now; 10:00pm to midnight most specifically. It is a forecast worth staying up-to-date with, particularly if you have outdoor work or pleasure plans for the upcoming weekend.
Severe weather Saturday?
Saturday, winds will strengthen and shift from south to west with increasing height in the atmosphere – that’s wind shear, and whether it’s May or October, it’s typical of severe weather episodes.
If we have plenty of cloud cover and/or periodic rain showers in the morning and afternoon, the threat for severe weather Saturday evening will go way down. If we have some decent breaks in cloudiness, and Saturday is a more sunny proposition, our chances for a severe weather evening go up quite a bit. It’s convoluted as to how that very important dynamic will play out.
Severe weather would be most apt to include large hail and damaging winds with any initial supercell thunderstorm and later damaging straight-line winds as the main line of storms along the cold front comes through. The plots of highest rainfall totals and ugliest weather are currently shown both to the immediate north and immediate south of us – a pattern we have seen many times with this type of event – but just too early to know for sure.
Temperatures will be in the mid 70s to 80 – again depending on how persistent cloud cover is for the day. Rainfall totals seem to be in the 1-inch to 1.5-inch range for Saturday’s weather, although isolated spots could get several inches of rain and possible flash flooding with this event.
Sunday looks partly to mostly sunny and cooler behind the strong cold front from Saturday evening’s weather. Low to mid 60s for highs may be optimistic. The morning could conceivably be riddled with a few rain showers – but I’m currently expecting a faster moving front that would equate to a dry Sunday.