COOL AND WET, A RADICAL CHANGE?
June is off to a toasty start all across the Midwest. Temperatures as you can see are running 5-8 degrees above normal the first 19 days of the month.
Here in Cedar Rapids we're running nearly 6 degrees above average per day. We've also had 7-90 degree days which is 3 times the monthly norm.
After the steam of last week it was a real shock the last couple of mornings to walk out and feel the change engineered by the weekend cold front. Those dew points have shrunk to the 50s and highs have returned to the 70s. Here's the big trough and its associated pool of pleasantly cool air at 500mb.
Just looking at the overall pattern it sure seems to me like the rest of the month is going to be far cooler than the first 19 days. After a quick warm-up Wednesday and Thursday with a 500mb flow that goes zonal like like this.
The pattern quickly buckles again and another burst of cool air overtakes the eastern 2/3 of the nation.
Here's a new and rather stout trough getting established again for the weekend.
The GFS has this for temperature anomalies days 0-5. Cool but not unusual.
In the day 5-10 period, the departures do get out of line. Now this is a bit unusual.
The CFSv2 sees the big cool-down coming and locks it in for the remainder of the month. It has this for departures the rest of June. Wow, that's some turn around!
Another contributing factor to the cooler weather might be rain and associated clouds. The GFS has this for rain in the coming 16 days. It shows a broad area area of well above normal amounts right through the central and upper Midwest.
This tighter view centered on Iowa shows some amounts over 5". Moist...
The new EURO weeklies are also indicating a wet period ahead. It's new 32 day control run has excessive rains over the next 4+ weeks. Some parts of NW Missouri are shown with amounts over a foot!