HOT DRY TIME IN THE CORNBELT

I noticed on Monday evening's sounding that the 500mb height contour in Minnneapolis reached 6,010 meters, which according to unofficial IEM archives is the highest height on record for the Twin Cities. It beat the 5988 meter reading that was achieved August 22nd of 2023. An extrememly warm lower atmosphere like we've seen this week will vertically "push" the height of a pressure surface further away from the ground, in this case all the way to the jet stream. Meteorologists consider a height of 6 kilometers as a very impressive height for the 500 hPa pressure to be found, especially in Minnesota.

This impressive upper level ridge (heat dome) has been in firm control of our weather the past few days with hardly a cloud in the sky let alone a drop of rain. Unfortunately, very hot and dry air extends in Minnesota and Canada where numerous wildfires have occured over northern Minnesota and into Canada. The hi-res GOES satellite shows the smoke plume blanketing much of northern Minnesota, Wisconsin, and Michigan. Some fair weather cumulus can be seen over much of Iowa where strong subsidence (sinking air) under the heat dome has kept us high, dry, and hot. Some smoke is likely to return this weekend leading to hazy skies and poor air quality.

For many of us, Thursday was the 12 consecutive day without rain. That is a dramatic change from the wet "ring of fire" pattern that prevailed through most of June and early July. Below you can see the rain totals for the period June 1st to July 4th. Many spots from central Iowa through northern Illinois saw amounts of 10-15 inches, which is 200-300 percent more than average. It pretty much erased our drought.

However, if you look at the last 3.5 months, the trend has been for dry weather. 88 of the past 107 days in the Quad Cities have seen no more than .18 hundredths of an inch of rain on any single day, (most amounts were a 10th of an inch or less). 68 of the past 107 in the Quad Cities rain amounts have been a trace or less. (in other words, 63 percent of our days since April 1st have seen no measurable rain). This graphic showing daily rainfall totals in the Quad Cities tells the tale.

The next couple of days there will be just enough instability for some widely scattered showers and storms to occur, especially in the afternoon and evening. It will remain very steamy through Saturday with Friday looking especially uncomfortable with highs 90-94 with heat index values again close to 100. Any storms Friday and Saturday should be very much hit and miss with coverge 30 percent or less. With very weak steering currents, those lucky enough to get under a storm could see some isolated downpours. These look to be few and far between and it would not be surprising for most of the area to stay dry.

Next week NW flow sharpens and after a hot muggy start to the week, some cooler air and a boundary should settle in from the north midweek. Not only will this take the edge off the heat. It has the potential to increase the chances of scattered showers and storms. The determining factor for rain will be the position of the baroclinic boundary. The EURO shows it running though the region resulting in 2 week rain totals that are above normal in most areas, some by as much as 2 inches.

The GFS keeps a more diffuse boundary with no real focus on forcing locally. That does not bode as well for rain. As you can see the GFS has 2 week totals that in most of the Midwest are below normal, some by as much as an inch.

No doubt there is a hint of hope for a wetter (certainly cooler) weather pattern in a week or so, but until there is better agreement on models and the placement of the strorm track, all we can do is speculate and wait.

Friday it's back to the heat and humidity that's prevailed all week. Stay cool and roll weather...TS