Thursday, July 23, 2009

Happy to see "average"

A so-so weekend weather verdict. Computer models are suggesting a stalled storm over the Great Lakes this weekend, moisture wrapping entirely around this unusually cool, ragged region of low pressure. That could mean afternoon clouds, even a few light showers/sprinkles late Saturday, the best chance over the eastern half of Minnesota and Wisconsin - the sky may look something like this around sunset Saturday evening up in the Brainerd and Alexandria Lakes area (most of the thick clouds/showers should remain just to the east of the Whitefish Chain, Gull Lake and North Long Lake).



Wednesday Almanac

High Low Rainfall

St. Cloud 81 52 Trace

Twin Cities 80 58 .20" (.36" rain in St. Paul)

Towering Wall of Water! Here was the view from WeatherNation's offices yesterday at about 4:30, showing strong/severe thunderstorms mushrooming directly above the metro Minneapolis/St. Paul area, producing 1/2 to 3/4" (nickel size) hail in Bloomington, torrential rains, even a few "cold air funnels" spotted near Montrose, Winsted and Silver Lake, in Wright County. No reports of any touchdowns or damage.

Amazing but true: you may be able to work up a minor sweat today with highs reaching the mid 80s across much of the region, possibly a degree or two ABOVE average for July 23!

Thunder-wear should remain optional today - the atmosphere is a bit more stable than it was yesterday, when swarms of storms sprouted, especially east of St. Cloud. About 5% of the storms turned severe with 1"+ hail, gusty winds topping 50 mph, even a few "cold air funnels". These rarely touch down and when they do damage is usually minimal, but they certainly shake people up a bit.

No weather-drama today, just warm sun, temperatures where they should be - no hail or high water. Just blue sky, reasonable humidity, light winds, seasonably warm weather - for a brief fleeting (day) everything will be right with the world of Minnesota weather.

Tomorrow will be unsettled, with a growing chance of bumping into a shower as the day goes on, computer models hinting at a healthy half inch for many communities as a cooler front approaches. Friday looks grayer, cooler with 3-6 hours of rain in many towns and neighborhoods.

The weekend weather is an enigma, wrapped in a riddle. Normally (USUALLY!) the weather is progressive, it moves along from west to east at 20-25 mph. This summer, since July 1, give or take, the weather over North America has been stuck in a rut, one favoring unusually warm weather from Alaska into the far west, and a cold, stormy swirl of low pressure over Hudson Bay, Canada. Storms that should be tracking across southern and central Canada have been forced south, detouring across Minnesota into the Great Lakes and New England.

There is a strong tendency, a predisposition, for storms to form - and linger - over the Great Lakes. That's what sparked our lousy weather last week at this time (clouds, wind chill, highs stuck in the 60s). A similar storm is forecast to stall over the Great Lakes tomorrow and Saturday, the chance of rain increasing as you drive east across Wisconsin towards Michigan. Saturday should start out sunny, but clouds will increase by afternoon, showers blossoming over central and eastern counties by late afternoon, most likely east of Bemidji, Brainerd and Little Falls.

WRF/NMM Outlook for 1 pm Saturday. A dry start Saturday morning gives way to building PM clouds and a few (spiral) bands of showers rotating in a counterclockwise fashion around the cold, stubborn, low pressure system anchored over the Great Lakes.

GFS Outlook for 1 pm Sunday. The Great Lakes storm finally weakens and drifts eastward. Meanwhile a band of showers is forecast to approach from the Dakotas, possibly entering western counties of Minnesota by Sunday evening.

Sunday should be the finer day of the weekend as that Great Lakes storm gets a gentle nudge to the east, a more westerly breeze treating Minnesota to more sunshine and warmer afternoon temperatures, topping 80 - probably the better day to stake out the lake or pool.

With this wacky, almost autumnlike trend to the evolving weather patterns over North America I shouldn't even bother to look at the GFS, which goes out 15 days. Lately the Day 10-15 Outlook has been even worse than usual, and I'm wondering if our abnormal weather rut (possibly linked with a strengthening El Nino) is one reason why the long-range forecast is even more problematic than usual. I have noticed a tendency for Minnesota weather to fall into a rut when things are brewing in the Pacific, water warmer or cooler than average - that seems to increase the potential for the jet stream to become locked in a pattern that favors one kind of weather - consistently - week after week.

Sea Surface Temperature Anomalies. Regions of red-shading represent ocean water temperatures warmer than average, blue regions display cooler than average water.

OK. So the 15-Day GFS is hinting at 90 by August 6 or 7, but I'm not holding my breath any more. I'm resigned to the fact that summer is going to be cooler, potentially 2-4 degrees cooler than a typical Minnesota summer. It's also shaping up to be drier - my concern is drought conditions will expand and worsen in the coming weeks. That could set up an especially fierce potential for wildfires late summer into September and October. The winter to come? Although most El Nino winters tend to be milder than average, it's not a guarantee by any stretch of the imagination. We're discovering that every El Nino is different, unique. It's not one-size-fits-all. On the surface odds might seem to favor a more moderate winter, but I'm not going to go out on a limb and predict that, at least not yet. One thing is certain: there's a 100% probability it's going to be a wild ride in the months to come.

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