Air conditioning optional

Well, this comes as quite a shock to the system: another day of cooler than average weather. Frowns at the neighborhood swimming pool (which begs the question: is it wrong to dress in layers going off the high dive?) July had no 90s to speak of, from the St. Cloud and the Twin Cities east to Chicago, Boston, New York. All this while the west sizzled, Alaska baked, the Yukon simmered – and meteorologists shrugged until their shoulders hurt.

Normally weather falls into an occasional rut that may linger a week, possibly two at the outside. But a month-long spell of aberrant weather, temperatures 15, 20, even 25 degrees removed from “normal”….whatever that is. We’re still not really sure why a cold, polar low did the twist high above Hudson Bay, Canada for the better part of July, sending little darts – cool zingers – south of the border week after week after week. Sunspots, volcanic eruptions, a floundering El Nino? Or just Mother Nature reminding us who’s really in control?

Forecast for 7 pm today. Last night’s weak cool front will reach Detroit and St. Louis with showers and storms, a bubble of high pressure approaching from the Red River Valley treating us to cool, dry, lukewarm weather.

QPF, Quantitative Precipitation Forecast through 7 pm this evening, showing a bullseye of rainfall over northern Missouri, showery weather over Florida, and a dry sky stretched across Wisconsin and Minnesota. For your own 24 hour probability of rain click here.

Dew Point Temperatures last night. Dew point is an ABSOLUTE measure of how much water is in the air, the higher the number, the more uncomfortable it feels. Unlike relative humidity, which is dependent on temperature, dew point is a bit easier to grasp. For example, a relative humidity of 90% sounds awful, but if the temperature outside is 65 degrees it won’t feel bad at all. However, a relative humidity of 60% on a day when it’s 95 outside will feel hideous – horrific! A doubling of dew point means there is roughly twice as much water in the air (ie. driving from northern Minnesota into Iowa, where dew points are 15-25 degrees higher, means there is TWICE as much water in the air over Iowa as over the North Woods of Minnesota.

The pattern is (finally) breaking down – the swirl of rude, summer chill loitering over eastern Canada is finally lifting north and east, toward the arctic (where it belongs the first week of August). Jet stream winds are shifting from west/northwest to southwest by the weekend, and that should result in the first real chance of 90 degrees since June 23! Yes, it’s really been that long.

Drought Outlook through October. Unlike the Drought Monitor which comes out every Thursday, this is a prediction of how drought conditions may change over time, for better or worse. In this case potentially encouraging news for Minnesota and Wisconsin as the rains become more frequent and widespread, moving from a showery (convective) summer pattern to a more stratiform rain pattern where everyone gets wet. Let’s hope that’s the case as we sail into September and October.

A cooler front pushes across Minnesota early today, preceded by a few stray showers, even a thunderclap or two near the Iowa border. Winds increase from the north/northwest, and in spite of a bright sun shining down we’ll be lucky to see highs in the mid 70s today. Dry weather is the rule most of this week (more shocking news) with a gradual warming trend as jet stream winds aloft start to swing around, blowing from Denver and Las Vegas (instead of Calgary and Edmonton). That should be good for mid 80s by Friday (5 degrees above average) and the first shot at 90 degrees (Saturday) since the last week of June! Not that I’m necessarily wishing for 90. Frankly I don’t mind the free air conditioning one bit, but I realize that many of my friends and acquaintances feel a bit cheated, ripped-off.

We wait most of the year for summer bliss, and when (real, superheated) summer only gets as far north as Des Moines, well, some of us scratch our heads, stare up at the sky, and wonder what we did wrong? In the end all of us are all bewildered spectators, connecting the dots, trying to make sense of what’s happening all around us.

Predicted Maximum Heat Index for Saturday. Calculating forecast air temperatures and dew points results in some impressive, and potentially dangerous conditions over southern Minnesota and Iowa, where it may FEEL like 105-110. It’s still 4 days away, but there are signs that Saturday may bring along a bout of INSTANT Dog Days, a blunt reminder that 90s are possible, even likely, right through the Great Minnesota Get Together. How far off is the State Fair now?

ECMWF Outlook for Sunday morning. These are predicted 500 mb winds (18,000 feet) for 7 am Sunday morning, showing a vigorous west-southwest to east-northeast wind flow aloft. The good news (for summer weather lovers craving a few more encounters with 90) – the cold vortex of low pressure which has been stuck, anchored over Hudson Bay, Canada, is finally showing signs of breaking down. I have a feeling August will wind up warmer than July, which doesn’t happen very often at this latitude.

Ozone Forecast for Minnesota & Wisconsin, valid last night. Note the higher concentration of ozone (sometimes called “smog”) just south/east of the Twin Cities metro area, a plume of man-made pollutants being pushed away from Minneapolis/St. Paul. The air quality in Minnesota is remarkably good most days, but during the summer, especially during weekday commutes – ozone concentrations can be high, posing some risk to people with heart and respiratory problems, the elderly, athletes who exercise (hard) outdoors, even small children who play hard out in their yards. To get your own (smog) forecast click here.

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Comments (1)

  1. Submitted by Eric O'Link on 08/04/2009 - 10:26 am.

    I was up at the family cabin on the Gunflint Trail a couple of weeks ago, dodging rain drops from the weather system you mentioned. One afternoon a thundery mass of clouds built up practically overhead. Between rumbles of thunder we heard a faint roar that sounded like a jet passing high overhead…except that the sound continued for a good 15 minutes. We guessed that this was connected with the storm. Paul, any thoughts as to what it might have been?

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