Thursday, July 23, 2009

Mostly-Good Weekend Weather

Thursday Almanac

High: 85

Low: 62

Rainfall: 0"

"Paul, today was a perfect summer day, what we've been waiting for. Keep 'em coming ok?" Well, uh. Yes and no. We start out the day with puddles, a slow, rainy commute, even a few growls of thunder. But the sun should be out by afternoon - your outdoor plans later today should not be in grave danger (unless you're heading into far southeastern MN, where a few strong/severe storms may flare up later).

Good News:

Much-needed rain falls on much of the region this morning, but sun should return for afternoon and evening events.

Dry and comfortably cool Saturday morning with plenty of sun. Air conditioning optional.

More sun Sunday as temperatures mellow to near 80 - better day for the lake or pool.


Bad News:

Too chilly for the lake Saturday morning? Northern MN wakes up to 40s and low 50s.

Couple hours of showers possible Saturday afternoon as Great Lakes storm circulates moisture into Minnesota. Best chance of showers/sprinkles between 3 and 6 pm.

Paul's Weekend Outlook


Today: Showers, possible thunder early, then clearing skies, drier by afternoon. Winds: NW 10-20. High: 81

Tonight: Clear, turning cooler. Low: 57

Saturday: Sunny morning, clouds increase during the afternoon with a few showers, possible thunder. Gusty winds likely. Winds: NW 15-25, gusts to 30. High: 77

Saturday night: Evening shower, then partial clearing - chilly. Low: 55

Sunday: More sunshine, warmer, probably dry. Winds: W 5-15. High: 83

Sunday night: Showers, possible thunder. Low: 62

Monday: Showers and T-storms, then PM sun. High: 82

Tuesday: Plenty of sunshine, a bit cooler. High: 78

Wednesday: Mostly sunny and lukewarm. High: 77

Thursday: Unsettled, chance of showers, T-storms. High: 77


Infrared Satellite Image showing the clipper-like system dropping south out of Canada. If you click on the image (taking it full screen) you can see individual thunderhead anvils embedded in the frontal system moving in.

SPC Prediction for Today. There is a 15% probability of severe weather within 25 miles of any location in extreme southeastern Minnesota, south/east of Rochester. The 5% risk area just barely extends into the Twin Cities.

By the time the atmosphere is unstable enough for strong/severe T-storms today's cool front should be situated over far southeastern Minnesota. I wouldn't be surprised to see some watches and warnings for southeastern counties after 3 pm. The risk of severe weather is small to nil for St. Cloud and the Brainerd Lakes area, a few strong storms may brush the Twin Cities metro, but right now I don't see a widespread outbreak close to Minneapolis & St. Paul.


Latest Drought Monitor for Minnesota. The good news: the percentage of Minnesota experiencing severe/moderate drought conditions shrank (slightly) in the last week, but severe drought conditions now include just about the entire Twin Cities metro area, moderate drought into St. Cloud, Willmar and Rochester. No, I won't be whining about this morning's rain or Saturday afternoon's pop-up instability showers.
WRF/NMM Model Prediction for 7 pm today. This graphic show expected rainfall from 1 pm to 7 pm today, the greatest risk of heavy rain/storms over far southeastern Minnesota - dry weather prevailing across most of the state. The only notable exception. Moisture approaching from the north may spark showers and a few isolated thundershowers near the Canadian border by the dinner hour.
WRF/NMM Outlook for 7 pm Saturday. Again, this is the model's prediction of rainfall between 1 pm and 7 pm. Note the (spiral) bands of mostly light showers popping up over central and eastern Minnesota - even heavier across Wisconsin. These instability showers and isolated thundershowers may drop some .05" rainfall amounts, enough to chase people inside for 20-40 minutes. The best chance of a little rain comes between 3 pm and 6 pm, skies should start to clear in time for sunset, around 9 pm Saturday night.

Sunday looks more promising, the stubborn Great Lakes storm pushing east, the atmosphere becoming more stable (ie warmer) aloft, meaning a much lower risk of showers/storms during the day Sunday. The sun should be out most of the day, luring temperatures to 80 up north at your favorite lake, 82 in St. Cloud, maybe 83 or 84 in the Twin Cities, some upper 80s south and west of the Minnesota River. Showers may arrive late Sunday night, but I think the daylight hours will be dry, and lake-friendly from the BWCA to the Iowa line.

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