DOING THE MONSTER MASH...
Fantastic late summer weather prevailed Thursday with delightful temperatures and turquois skies. The chamber of commerce weather is already on its way out as summer takes another run at the region. In fact, we'll be doing the monster mash on this cool air as readings warm 40-45 degrees from Thursday's low to Saturday's highs! Here's a sampling of lows around the region Thursday morning. Vinton, Iowa went all the way down to 45! Cedar Rapids fell to 48 and in Davenport a 49 was posted.
With high pressure off to the east and low pressure over the Plains, a strengthening pressure gradient develops for the start of the weekend. It will serve to drive a brisk SW wind that rapidly tugs in a burst of late summer heat.
At 500mb you can see the heat dome expanding out of the SW towards Iowa Saturday afternoon.
The GFS goes hard core with the heat sending highs of 95-100 into a large portion of Iowa, Missouri, and northern Illinois Saturday afternoon.
The EURO is 5-7 degrees lower. Personally I like a compromise in my area which leaves us with readings of 90-94
The saving grace will be dew points that remain in the mid 60s. That should see to it that heat index values are only a couple degrees above the actual temperature. Throw in a nice breeze and it will be hot but nothing as bad as what we saw earlier in the summer with dew points of 75-80.
From the looks of things, a front that could provide relief is likely to get hung up over my central counties Sunday before inching north as a warm front Monday. That implies very warm readings will remain over my central and southern counties Sunday-Tuesday. Highs in this area could very well remain in the upper 80s to low 90s all three days. The northern third or so of my area should fair a little better, especially Sunday with some clouds and at least a slight chance of a shower or storm near and north of the boundary. I see highs more in the low 80s up in the area around HWY 20. Even there, readings are likely to go back up Monday and Tuesday with the passage of the warm front.
As for rain chances, there are a couple of opportunities. The first is Sunday night and essentially involves the northern half to one third of my area. Near and north of a stationary boundary showers and thunderstorms are possible on the nose of the heat and the nocturnal jet. I could see some good rains out of this if indeed storms fire. The issues that need to be resolved are the exact position of the front, the extent of the forcing, and mesoscale influences that can't be seen at this distance. I do think there will be some activity somewhere in the north.
With the warm front off to the north Monday and most of Tuesday, some very warm temperatures aloft will likely establish a cap suppressing storm development those days. The exception may be in the far north where a few storms could bleed south from time to time (not overly likely though). Late Tuesday and Tuesday night a cold front is anticipated that could be the trigger for more widespread showers and storms. The timing of the front will be a critical factor regarding coverage and intensity. As it stands now, here are the rainfall totals indicated by the EURO and GFS Sunday through Tuesday night. The GFS is clearly the most optimistic on amounts and overall coverage.
After the front readings will cool to more typical levels the middle and end of next week. However, before then you will all be aware that summer is alive and well and doing the monster mash. Roll weather...TS