RAIN, RAIN GO AWAY...
Congratulations Cedar Rapids, you just set the record for consecutive days with rainfall. That's right, 11 straight days rain has bee been observed tying the record previously set in 2007 and 1990.
What's really interesting though is that late spring patterns featuring long stretches of wet weather usually are ones with well above normal amounts. In the record years of 2007 and 1990, amounts over the 11 days were more than 2.50 inches above the norm. This year though, amounts are about .66 inches below what typically would have fallen during that period. That's odd, just a bunch of light rain events. The most that fell on any given day was 0.19" on the 18th.
If things follow the script, there's a good chance 2021 in Cedar Rapids claims the record all to itself Tuesday as rain is anticipated at some point before midnight. This is what the GFS shows for the calendar day ending at midnight.
The front that brings the rain threat could also bring a couple of strong storms late Tuesday afternoon or evening but that will be conditional on heating and how much instability can be achieved. It does appear that there's a decent chance of scattered thunderstorms with the potential to create at least scattered pockets of heavy rain. The severe threat would be limited to some gusty winds in any of the stronger updrafts.
Once the front passes by daybreak dry weather is indicated Wednesday with a significant drop in humidity. Dew points are projected to go from the mid 60s Tuesday to the low 50s Wednesday. Here's the comparison on the EURO.
Dew points Tuesday (muggy)
Dew points Wednesday (comfortable)
As for temperatures, Tuesday will be another warm sticky day with highs near 80. However, without the humidity Wednesday, highs will be seasonable in the mid to upper 70s for a far more comfortable day.
Rain chances quickly return on Thursday as a wave of low pressure rides the front situated just south of the Iowa border. With a nice thermal gradient, decent forcing, and water vapor increasing to 1.3 to 1.7" the stage is set for widespread rain, some of it could be heavy. The EURO projects this for water vapor Thursday afternoon.
Here's what the GFS and EURO show for rain totals from the two systems combined later Tuesday and again Thursday.
The GFS
The EURO
Depending on how far north the boundary can get Thursday, some strong storms are possible in my far southern counties, generally HWY 34 south. The front will also divide temperatures in the low 50s north to ones in the low 70s in the extreme south.
That leads us into the holiday weekend and by all accounts it won't be a banner one. Some lingering light passing showers are still possible Friday, especially in the morning. Otherwise it looks like we'll be battling east winds much of the holiday period and boy is that going to change temperatures. Sunshine is also problematic with the potential for periods of low clouds to rule much of Friday-Monday. At this point, chances for sunshine appear greatest on Saturday. Getting to the point, highs may struggle to get out of the low to mid 50s Friday and remain no better than the 60s Saturday through Memorial Day. I don't see any rain Saturday or Sunday but it looks like it will be back in the picture again by Monday afternoon.
This return to cooler weather is tied to the MJO (Madden Julien Oscillation) and its push out of the warm May phase of 6 into the cool June phase of 7. It looks like our summery conditions will be back in the shelf after Tuesday. Here's the 5 day temperature departures for the period Thursday through Memorial Day. Ugh!
That's the nuts and bolts of this post. Sorry for the lack of good news with the advent of this wet and eventually cooler period. We'll have to make the most of it. Roll weather...TS
