SINGING A SUMMERY SONG...
It's been 2 weeks since an 80 degree temperature was measured here in Cedar Rapids and it's looking like that streak will soon be coming to an end. The deep trough that's been delivering the sub-normal readings is beginning to break down (although it's just a temporary break).
The 500mb jet stream flow responsible for the cool conditions.
The resulting temperature departures the past 14 days. The Rockies and northern Plains have really taken the brunt of the chill.
Most places have had ample rain as well,
The short term pattern aloft shows the 500mb trough flattening for a few days later this week. This is Friday's projected storm track.
The more zonal flow finally allows some summer air to enter the Midwest. Come Friday highs are forecast to look like this on the GFS.
Along with the warmth will come the highest humidity levels of the year. Check out the dew points we're expecting on Friday. If we do get the 70s shown that will be the first time this year for moisture levels like that. Bottom line, it will be muggy!
Heat and humidity also create instability and that's measured in CAPE (convective available potential energy). WIth an active frontal zone in the central Midwest Thursday through Saturday scattered thunderstorms will become a factor to monitor. Here's the CAPE forecast for Friday. Easily the most potential energy for strong storms so far this year.
However, there's going to be some capping issues Friday with warm air aloft. But where storms do get going they will have the potential to push severe limits. Saturday probably has the greatest risk as a cold front advances on the region.
Between the time the rain threat gets going Thursday and ends Sunday the GFS shows many spots picking up .50 to 1.00" of new rain. Some locally higher amounts are possible in the stronger zones of convection.
Sunday another burst of cool air is progged into the Midwest and once again temperatures will take another healthy tumble. You can see the new surge of cool air coming in at jet stream level Monday.
The GFS has highs on Monday in the upper 50s. I'm pretty sure those numbers are 5-10 degrees too low. Even so, the trend will be back to cool dry weather more typical of April.
For now, that's the latest and greatest. Hope you enjoy your Wednesday. The afternoon hours should be picture perfect! Roll weather...TS