After a few pleasant days, more heat, humidity… and storms likely

Tuesday has been a mostly pleasant June day across Minnesota. It began with thunderstorms with isolated damaging hail across the southern part of the state very early in the day. Remnant clouds have been slow to break up above the metro area and southeastern Minnesota.  Afternoon temperatures have risen into the 70s. And dew points have remained comfortable.

Here is the look from the a weather satellite:

Visible satellite image showing puffy cumulus clouds. (Source:NOAA)

While the afternoon has been storm-free across Minnesota, the country has some active areas and the lightning display shows us where they are:

Lightning by 4 p.m. CDT. (Source:Vaisala)

The usual clusters of thunderstorms with abundant lightning have grown from east Texas to Florida to the Carolinas. Farther north, scattered- to- broken lines of thunderstorms have developed along a front from Massachusetts to Kansas, and along a trough from North Carolina through Virginia to Delmarva.

But take a look farther west. Mountains in the mid latitudes are excellent generators of thunderstorms in summer. They not only heat up during the day to cause rising air, but also deflect the wind upslope. This happens all along the Rocky Mountains from Montana to New Mexico but the most reliable location is Colorado.  That is where the Rockies are their highest and the mountains are far enough south that the sun can cause significant heating.  Skies can go from clear to thunderstormy in a remarkably short amount of time.  So hiking above treeline in those areas is best done in the morning before the cumulonimbus clouds blow up.

Rocky Mountain National Park has a website with a link to several webcams of the mountains.  Click on the thumbnails to see the big picture, and note how rapidly the mountaintop weather changes from morning to early afternoon.  Here is a view from one of their cams:

Low-topped thunderstorm in the Rocky Mountains. (Source:Rocky Mountain national Park)

Getting back to Minnesota,  Wednesday will be a third delightful day for most of us, although a scattering of thunderstorms is likely in the northern and western parts in the afternoon. High temperatures will be in the 70s to low 80s.  Then the heat and humidity will increase as we go through Thursday and especially Friday when the dew points will climb into the 60s.

Look for periods of showers and thunderstorms from Wednesday night through the weekend and possibly on Monday. In addition, there is a chance of severe storms on Thursday.

Weather forecast map for Thursday with a risk of severe weather for Minnesota. (Source:NWS/Weather Prediction Center)

The weekend is too far away to nail down the forecast but the models indicate an unsettled period from Friday through the weekend. Strong to severe storms and some heavy rains could be in the mix.