Tuesday, August 4, 2009

Air Conditioning Optional

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 25! Yes, it's really been that long.

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.

A classic post-cool-frontal sky, similar to what we may witness today, mid-level "altocumulus", if anyone asks. Chance are they won't.

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.

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.

Predicted Maximum Heat Index for this upcoming 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.

Paul's Outlook for the Twin Cities

Today: Plenty of sun, cooler, less humid than yesterday. Winds: north/northwest 5-15 High: 77

Tonight: Mostly clear, comfortably cool. Low: 55

Wednesday: Lot's of sun, still comfortable. High: 79

Thursday: Partly cloudy, few complaints. High: 81

Friday: Less sun, slight chance of a T-storm. Windy and warmer. High: 87

Saturday: Instant Dog Days? Hot sun, windy - hot. High: near 95 (feels like 100-105 over much of southern MN)

Sunday: Mix of clouds and sun, slightly cooler. High: near 90

Monday: Cooler, sunshine likely. High: 87

Tuesday: Still sunny, still dry. High: 88

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