More July weather in May

Update at 2 p.m. Tuesday

Strong thunderstorms have been developing on this hot and sticky afternoon. The Storm Prediction Center has issued a severe thunderstorm watch for much of central and southern Minnesota, including the Twin Cities metro area, until 8 p.m.

From this morning:

While the rest of the world has adopted the Celsius temperature scale with zero and 100 degrees representing the freezing and boiling points of water, respectively, I am kind of partial to our Fahrenheit scale for everyday use.

Subzero Fahrenheit temperatures in winter clearly inform you that it is cold outside. And rare triple-digit readings, like when some areas hit 100 degrees on Memorial Day, really scream that it is indeed hot enough for you out there. The Celsius equivalent of 100 degrees F, 37.8 degrees C, fails to excite.

And what a Memorial Day it was!

The Twin Cities' high of 100 was:

• a record high temperature for the day

• a record hottest Memorial Day

• a record for the earliest 100-degree day of record

• our fifth consecutive day of 90 degrees or hotter, setting a record for our longest string of such days in May

The strong and severe thunderstorms that blew across the area definitely were hit-and-miss. While flash flooding and hail broke out across northern parts of the metro area, Minneapolis-St. Paul International Airport measured just one hundredth of an inch of rain. My rain gauge in Minneapolis picked up eight hundredths of an inch plus some wind-blown tree debris.

Sweaty Tuesday likely becoming thundery

For most of us, Tuesday will be slightly less hot than yesterday but more humid. High temperatures should be mainly from the mid 80s to mid 90s, but cooler near Lake Superior.

Coupling the hot temperatures reaching the mid 90s with the stickier dew points means that the National Weather Service has posted a heat advisory for the Twin Cities metro area from 11 a.m. until 7 p.m.

The advice always is to drink plenty of fluids during hot weather, and it is wise to remain hydrated, but it is even more important to stay out of the sun and heat if possible. Air conditioning is your good friend on these toasty days.

Air quality alert

Sunny, hot, humid weather can lead to the formation of ozone, a molecule of three oxygen atoms, in the lowest layer of the atmosphere. While an ozone layer high aloft protects us from most incoming ultraviolet radiation, ozone near the surface can affect sensitive individuals and aggravate lung conditions such as asthma, emphysema and COPD.

The Minnesota Pollution Control Agency (MPCA) has posted an air quality alert for east central and southeastern Minnesota where ozone is expected to reach unsafe levels from noon until 8 p.m. today.

Thunderstorms are likely to rev up in the heating of this afternoon and become widespread this evening. Some storms might become strong or severe, especially north of the Twin Cities.

As of 8 a.m., the Storm Prediction Center has expanded the slight risk area to cover most of Minnesota including the Twin Cities area, Rochester, St. Cloud and Bemidji. The remainder of the state, in green below, is in a marginal risk.

End of the 90s

Tomorrow should bring us cooler weather with high temperatures from the mid 70s to low 80. Showers and some non-severe thunderstorms will remain likely, however.

Dry Thursday and Friday; rain Saturday?

The last two days of the work week are expected to be mostly dry and rather comfortable.

Saturday might treat our lawns and gardens to showers and thunderstorms.

Alberto update

What is left of former subtropical storm Alberto will continue to drop considerable rainfalls as it weakens and tracks generally north from Alabama toward the Ohio River Valley and then Michigan.