100 degree heat index Sunday, late July heat wave

Get ready for the hottest stretch of weather so far this summer.

A steamy July hot front gurgles north into Minnesota this weekend. The atmospheric mechanics of advancing summer warm fronts? The typical forecast sequence goes like this.

High wispy cirrus clouds arrive. Dew points climb into the 60s. Scattered, often overnight and early morning thunderstorms bubble up. The warm front kicks north and we break into a steamy, hazy air mass as temperatures push 90 degrees.

The weather maps scream July, and next week looks like the warmest week so far this year. We likely sweat through two to three days of 90-plus degrees heat in the next week. Dew points hit a the tropically sweaty 70 degree mark by Sunday. The (still dicey) longer range GFS cranks out 100 degree temps around July 24th. We may be transitioning into a sweltering late July to remember.

Anatomy of a hot front

Rounded red bumps on a red line on the weather map. That's the warm front pushing into southern Minnesota Sunday. Scattered storms bubble up ahead of the front Saturday.

The most likely timing for storms around the metro favors early Saturday and Sunday night. The front kicks north Sunday putting the highest storm coverage in northern Minnesota as the Twin Cities busts into a hot hazy humid air mass.

The long range guidance from the National Oceanic and Atmospheric Administration's Global Forecast System continues to crank out temps above 90 Sunday and Monday for the Twin Cities.

I won't be shocked to see some bank thermometers around the metro flashing 93-plus degrees Sunday and Monday afternoon.

Temps moderate a little, but only back into the mid and upper 80s next week. We may see more 90s by next weekend.

It's not the heat, it's the dew point.

The actual air temperature may be academic Sunday and Monday. The inbound air mas is rich with Gulf moisture. Dew points climb into the 70s Sunday. You'll feel the effect on your body as it works harder to cool you because evaporational cooling from sweat is less efficient.

With temps in the low 90s and dew points above 70 the heat index will push 100 to 105 in southern Minnesota Sunday and Monday. That's the edge of danger for overexertion. Minnesotans handle the cold well, but some of us can become overheated in summer. Take it easy and hydrate.

Smoke image of the day

The Smoky Summer of 2015 continues to create interesting sky art across Minnesota. Friday's feature shows the ribbon of smoke that drifted south Thursday coming back north as winds aloft turn southerly. NASA's MODIS Terra 1,000 meter resolution shot clearly shows how the smoke band suppresses cumulus formation underneath, while a field of cumulus bubble up in the surrounding air mass.

The smoke layer limits heating of the ground below suppressing updrafts which are able to form cumulus clouds in the surrounding air mass.

Seeley: Typhoons and heavy rains.

Mark Seeley talks about Pacific typhoons and fire weather incident meteorologists in this week's Weather Talk.

Two powerful Typhoons were churning this week in the Western Pacific Ocean.  Typhoon Chan-Hom was packing wind gusts up to 140 mph and producing sea waves from 35-40 feet as it headed across the East China Sea towards the Chinese coastline near Shanghai.  Farther out to sea and well south of Japan, Super Typhoon Nangka was producing wind gusts up to 175 mph and sea wave heights of 40-45 feet.  It was expected to remain out to sea between Guam and Japan.

NOAA reports this week that several Incident Meteorologists have been deployed to Alaska to assist firefighters there.  Alaska is having one of its worst wildfire seasons with over 600 fires reported so far and more than 300 structures burned.  The Incident Meteorologists provide up to the minute local weather forecasts related to wind, humidity, temperatures, and rainfall chance.  All of this information helps firefighters in more effective deployment of resources to control these wildfires.  Official speculate that it will be a long wildfire season in Alaska this year.  You can read more at...

http://www.dnr.state.mn.us/climate/journal/150705_06_heavy_rain.html

100 degrees on the horizon?

It's still way early to bite in this, but the GFS is cranking out a major heat wave with 100 degrees by around July 24.

Stay cool and classy Minnesota.