THE AUGUST SPECIAL CONTINUES

Thunderstorms over Illinois taken while on a Southwest flight inbound to Chicago's Midway Airport.

I sit here back in the Midwest for the weekend (Chicago) in the midst of what August has to offer - hot and humid conditions with low-confidence but high-intensity thunderstorms. This time of year is certainly a challenge to forecast beyond the "scattered storms" and "hot and humid conditions." Quite frankly, it's a lot more challenging than a February blizzard or a tornado outbreak mainly because we have a good idea on the what, but not a very good idea on the where.

Case in point, Saturday night thunderstorms were producing heavy rain and a flash flood threat in northeast Iowa, far northwest Illinois and southwest Wisconsin. A week ago we had a pretty good idea on the triple-digit heat indices and the threat of heavy rain that would be taking place this weekend, but the exact placement of the heaviest rain is a situation where the boundaries have to set up in the right spots. Pattern recognition can get us close, but the small details are so critical in the final hours.

Sunday afternoon and evening, we once again anticipate showers and storms to develop in the region capable of very heavy rain. Model guidance is coming into agreement the hot spots will likely be across northern Iowa, southern Minnesota and southwest Wisconsin - similar areas hit Saturday and Saturday night.

Blended models keep the bulk of the rain north of the Quad Cities region on Sunday with some areas potentially picking up another 1-2" of moisture. The consistency of this active pattern since early July is simply remarkable.

The entire state of Iowa, and nearly all of Minnesota and Wisconsin, are drought free as of Aug. 12. Despite a few rounds of severe weather overall much of this rainfall came without destructive storms. Crop impacts by severe storms in particular has been quite limited with some of the best conditions in recent years for corn and soybeans in the region.

According to USDA crop status reports across the region, the corn and soybeans considered to be in Good and Excellent condition is in the upper tier of records for numerous states. Indiana and Illinois the percentages are a little less favorable, but Iowa and Missouri are in the top five years of record since 1986.

Looking longer term, it is starting to look like the active weather pattern may come to an end, or at least a pause. Ensembles and analogs are indicating a trend towards below-normal rainfall for the second half of August once we get past Monday. The signal is actually rather high for much of Iowa and western Illinois.

Analogs are equally showing the below-normal trend in precipitation heading into late August, albeit the signal isn't as strong locally. There are higher trends for drier conditions in the northeast and Ohio River Valley.

Looking at how analogs are interpreting the upper air pattern this would support drier conditions certainly in the central CONUS. Strong ridging in the west will allow northwest flow of drier air across the Midwest. This will put some limit on the moisture availability. This will also likely limit some heat potential thankfully as well (out west is a much different story).

Coming back to the short-term forecast, the heat is still on for the next two days (Sunday/Monday) before we begin to see moderating in temperatures. Highs longer term towards late August are looking more comfortable with highs back in the 70s which correlates with the northwest flow discussed above. We just need to get through the next two days then we are well on our way to the first snowflakes of the season.

SUNDAY

MONDAY

The thoughts of shoveling snow probably sound quite nice with Sunday and Monday heat indices right back in the triple digits. However, a rather strong cold front late Monday will bring relief Tuesday and beyond.

Stay cool, friends!

-Meteorologist Nick Stewart