HIGHER AND HIGHER...
Friday's rain event worked out as expected. Aside from a few small heavier pockets, amounts were generally under 3/10ths of an inch with the heavier totals (as expected) over the southwest half of the region. Here's rainfall totals from the Iowa Flood Center through late Friday afternoon.
You early risers Saturday may see some patchy fog as residual moisture and light winds allow dew points to fall close to the ambient temperatures. Fog or not, clouds are likely to be prevalent much of Saturday morning before breaks develop in the afternoon. Strengthening southerly flow and a slow moving warm front will begin to advect moisture into the region Saturday afternoon generating enough instability for scattered showers and storms. These look most likely in the northern half of the region. Highs will depend on how much sunshine can work its way into our skies but for the most part upper 70s to low 80s should cover it.
Saturday night and Sunday my region is on the northern edge of the heat dome that encompasses the Midwest early next week. That's an area that's not hot but one that is prime for thunderstorm development and potentially an MCS (mesoscale convective complex). Saturday night would be the most optimal time for such an event to occur. A strong storm or two is a possibility if the MCS materializes but the primary concern would be heavy rain. Models are not especially skilled at seeing this potential early or with much precision regarding location and amounts. It could be that it all adds up to be little more than a nothing burger. At the very least I expect scattered thunderstorms at some point Saturday night and perhaps a part of Sunday. Overall, there will be many dry hours so don't expect a long duration wash out. Highs Sunday should push into the 80s with dew points inching into the upper 60s making for a muggy day. Here's what the latest models are suggesting for rain totals Saturday through Sunday.
The EURO
THE GFS
The NBM (national blend of models)
The 12K NAM
The 3K NAM
THE HEAT IS ON...
Monday through Wednesday the long advertised heat is on. 500mb heights dramatically rise allowing a potent combination of heat and humidity to gain steam. Highs Monday through Wednesday will all be in the low to mid 90s. In the Quad Cities the NBM (national blend of models) shows this for temperatures. Notice that 98 Tuesday. Reaching the century mark would be a big deal. The last time it happened in the Quad Cities was nearly 10 years ago, July 6th, 2012.
The EURO shows 4 consecutive days in the 90s before a nice cool-down later next week. The highest it gets is 96 on Tuesday.
No matter how hot it gets, dew points in the 70s and temperatures in the low to mid 90s will get us oppressive conditions with heat index values of 100-105. Here's the NBM HX values Tuesday afternoon. It's very likely that headlines for heat related advisories or even warnings will be issued at some point.
The Weather Prediction Center does show the risk of excessive heat the 13th-16th in my counties east of the Mississippi. Personally, I see no reason why eastern Iowa would not be included. Unofficially, I say we are in!
The last issue to address is thunderstorms. Monday, Tuesday, and much of Wednesday a strong thunderstorm suppressing cap is in place. That means warm air aloft will thwart thunderstorm development. However, if by some chance the cap is released, Monday has huge severe weather potential with CAPE (instability) highly maximized and low level shear substantial. Chances the cap breaks are currently low but due to the potential unleashed if it did the situation needs to be watched as we get closer to that time frame. Here's the extreme CAPE depicted in the EURO late Monday,
Assuming we avoid storms through capping Monday and Tuesday, the next chance would be Wednesday when a front is expected to arrive from the north. Cooler air aloft and forcing from the cold front could be the trigger that sparks storm development. Timing will be a critical factor and we're too far out to accurately assess that situation but late afternoon and evening would be optimal when instability is maximized. With the front sinking south of the area the heat should abate Thursday, at the latest Friday. Some models see it coming back for next weekend, others hold it at bay with a big eastern trough keeping us in northwest flow aloft. That would keep us cooler but it could also mean a more active pattern if we are close to the ring of fire and the thunderstorms it's known to produce.
All right, I've taken enough of your time. Enjoy life, it's the only one you've got. Roll weather...TS
