The CONUS continues to be characterized by an amplified pattern keeping the western half of the U.S. much drier than the East. This weather pattern is also contributing to the well-above average temperatures being experienced across the Great Plains and is expected to continue for at least the next 7 days. Let’s see what else is in store for the U.S. this upcoming week.
An area of high pressure at 500mb is situated near the Four Corners due to the ridging across the CONUS. Disturbances have been and will continue to traverse around the ridge, with one currently weakening and moving east-southeastward across the upper Midwest, eventually exiting the U.S. by Tuesday. A stronger disturbance/area of low pressure will trail behind it potentially causing severe weather and heavy rainfall across parts of the northern Plains, Midwest, and Great Lakes during Monday through Wednesday.
South/Central U.S. Heat
Uncomfortably hot temperatures in excess of 100F have been creeping their way into the southern Great Plains the past few days and are forecasted to continue well into next week. Above is the forecasted surface temperatures today at 4pm CT – it’s safe to say it is very hot across the CONUS with around 90-percent of the country expected to reach at least an 80 degree high temperature today.
It’s also important to consider the amount of moisture in the air, as the humidity can increase the heat index significantly. For example, a 90F temperature with a 70F dewpoint has nearly the same heat index (96F) as a 100F temperature with a 50F dewpoint. Additionally, humid heat can be more of a threat than dry heat, as your sweat cannot evaporate as quickly when it’s more humid, hindering you from cooling off as effectively. As the above image depicts, the eastern half of the U.S. will contain more moisture than the western half, so those hot temperatures further east could have a greater impact than they do in the West!
Upper Plains and Midwest Severe Weather
The above image is a forecast for the disturbance across the northern part of the U.S. early next week. I’ve highlighted the diffluent flow associated with it, which will be supportive of thunderstorms *if* they develop beneath this region. This upper-level diffluence is important for thunderstorms, especially supercells, because 1) it causes air at the surface to converge which creates lift and initiates thunderstorm development and 2) so that the storm can vent/breath instead of collapsing on itself like general pop-up thunderstorms do.
Because of the strong dynamics associated with this system, severe weather outlooks beyond day 3 have been issued in the northern portions of the Great Plains and Midwest. The exact locations of these risk areas will likely change in the coming days as we get closer to the event and confidence increases.
CONUS Rainfall
In terms of rainfall, the next 7 days will be dry for much of the west coast and western half of the U.S. with the exception of some monsoonal rainfall near the Four Corners. The Southeast will experience less rainfall overall compared to the last few days now that the Gulf disturbance has dissipated and the previous upper-level trough has since departed, meaning most rainfall will come from afternoon/evening pop-up thunderstorms with slightly higher amounts along the coasts where seabreeze fronts develop. Much of the Midwest and Northeast will accumulate rainfall over the next few days as the weakening shortwave in the first image moves eastward and off the coast of the U.S., otherwise have a good weekend everyone!
