Indian summer fever: multiple warm waves ahead

Attention Minnesota corporate HR departments. A "sick call" tsunami may be imminent.

An outbreak of Indian summer fever spreads like wildfire across the Upper Midwest this week. Sunshine, temps in the 60s to near 70 degrees and a fresh October air mass bring some of the most delightful weather of the year. Temps peak Thursday afternoon, when the Twin Cities has a 50/50 shot at one more 70 degree reading.

News flash: The latest upper air charts seem to favor another short of unseasonably mild air next week.

And another mild shot the weekend of Oct. 25?

The European Centre for Medium-Range Weather Forecasts model has locked in on the notion of a second Indian summer next week.

Yes, it now appears Minnesota could see at least two bouts of Indian summer, as this October goes out with a mild bias.

Here's the National Oceanic and Atmospheric Administration's Global Forecast System 16-day temp output, which cranks out a string of late October temps in the mid and upper 60s.

A spectacular final weekend in October this year? Place your bets.

Stay tuned as we track the potential for a second Indian summer next week, and enjoy part one now.

Soaking rains on the plains

Minnesota rode the edge of a major fall soaker early this week. Southeast Minnesota got in on the much needed soaker with over an inch at Rochester. More than 2 inches fell at La Crosse, Wisconsin. Iowa picked up several inches as heavier rains fell all the way south to the Gulf Coast along the Mississippi.

Here's the impressive rainfall swath from NOAA's Advanced Hydrologic Prediction Service.

Winter snowfall forecast? Past results do not guarantee future performance

Yes, predicting winter snowfall in Minnesota is about as skillful as predicting where the stock market will be next April. You'll hear a lot of winter forecasts out there in the coming weeks. Enjoy them, with a shaker of salt.

Here's the data on past winter snowfall and the lack of a discernible pattern from the Twin Cities National Weather Service.

It may be a good time to look at the Snowfall by Season and try to determine what the upcoming Winter 2014-15 will bring. Does the past predict the future?

The last two Snowfall Seasons have been well above normal at Minneapolis /St Paul, MN (MSP). Does that mean this winter will have less snow than usual?

Hurricane Ana a threat to Hawaii?

It's been an active Pacific hurricane season. Ana, the next storm that may graze Hawaii, is moving west on a general path toward the Big Island.

Madden-Julian Oscillation aiding hurricane development?

It's not your imagination. Hurricane activity is on the uptick in recent weeks. A phenomenon called the Madden-Julian Oscillation may be the trigger for the recent increase in hurricane development.

Climate Central's Andrea Thompson has more on the "MJO."

And what’s the Madden-Julian Oscillation, you may ask? Essentially it’s a wave of enhanced and then suppressed thunderstorm activity that works its way eastward across the tropics over about 30 to 50 days. (This same phenomenon is also playing a role in the tropical storm that could hit Hawaii, but more on that in a minute.)

During the climatological peak of the hurricane season, the basin was in “the quiet part of that wave,” Blake told Climate Central. Those suppressive conditions were superimposed on an atmospheric setup already hostile to storm formation.

“In general the climate conditions have not been that favorable at all” for hurricanes to form, Blake said. Part of this has been due to the burgeoning El Niño, that even though it has yet to fully emerge is creating more stable, subsiding air over the Atlantic and decreasing the wind shear that can rip apart a budding storm.

So a sort-of El Niño plus a suppressive MJO phase equaled a quiet September.

But now, the enhanced phase of the MJO has come into the area, and it’s been a particularly strong one, Blake said.

“We’ve seen this type of thing happen before, it’s just rare,” he said.

The boost from the MJO has helped give storms a friendlier atmospheric environment in which to form, while ocean temperatures are still warm enough.

“It’s still October, and October's a pretty busy month for hurricanes, and the Atlantic’s still plenty warm,” Blake said, though he added that the busiest October pales in comparison to the busiest September.