Monday, July 27, 2009

No 90s in July

WRF/NMM Model for 7 am Thursday morning, showing predicted accumulated rainfall between 1 am and 7 am Thursday morning. Significant rain is possible over central and southeastern Minnesota ahead of the next reinforcing cool front, the best chance of some 1-2" amounts south and east of the Twin Cities.

A July with no 90s? According to Pete Boulay at the MN State Climate Office that hasn't happened since 1994. Come to think of it there were no 90s in July in either 1992, 1993 or 1994. So it's unusual, but not unprecedented. You have to go back 15 years to find a similar (almost comfortable) July.

Nobel Physicist Nils Bohr was reported to have said, "Prediction is very difficult, especially if it's about the future." Amen to that, brother. I would add, "Forecasting is the art of saying what will happen, and then explaining why it didn't." Nobody intentionally deceives or lies, mind you. We are paid (some of the time) to read the tea leaves and give it our best shot. The Weather Machine is a complicated beast, hot air over the tropics surging northward; far less direct sunlight leaving the poles in the cold, numbing air advancing toward the equator. The spinning of the Earth on its axis gives storms their counterclockwise spin (Northern Hemisphere), the most outrageous storms forming along the sharpest contrasts in temperature, as a rule. We're still learning how fluctuations in ocean water temperature can create a domino effect thousands of miles downwind. Now El Nino is returning, but that's no guarantee of a milder than average winter for Minnesota. Most El Nino warming trends correlate with milder, drier winters in the Midwest, but we're learning that not all El Nino's are created equal.

The weather is, by definition, variable - changeable - sometimes severe, but there's ample evidence that the day to day changes are becoming more extreme over time. For much of July we've been 3-4 degrees cooler than average, but the Yukon (far northwest Canada) has seen day after day of baking 80s, even some low 90s. I've seen 40s north of the Arctic Circle, the result of persistent high pressure over the North Pole and much of Siberia, where highs have been well above average, reaching the 70s and 80s. Just Monday an exceedingly rare tornado slammed into Tokyo. Click here to read the latest on this (apparent) Kansas-size tornado that destroyed at least 160 homes. There is actual video of the tornado (about :25 in on this clip, which is in Japanese, but you definitely get the drift). Again, one storm, one heat wave, even one month or one year doesn't prove anything. It's the frequency over time, over long periods of time, stepping back and looking at the macro trends. That's when you start to scratch your head and wonder what's really happening out there.

We cool off today, highs in the mid 70s with a dip in humidity and a fresh northwest breeze. With the exception of Friday, temperatures will average 5-10 degrees below normal through much of next week, a cool trend into the first week of August. The best chance of rain/storms? Late Wednesday into Thursday morning, more instability (late PM pop-up) showers possible over the weekend, especially over the northern third of Minnesota, where highs may not climb out of the 60s Saturday and Sunday. The "free air conditioning" rant is starting to have a hollow ring, some Minnesotans are ticked off that we didn't see any real Dog Days this summer, no extended stretch of hot, sweaty, pool-worthy days. That may be true, so as soon as I finish my update here I'm clicking over to a travel site.

Does Delta have any non-stops to the Yukon?

Weather Information Table
Precipitation and Temperature Summary for 7/20/2009 through 7/26/2009

Temperature Precipitation G D D
High Low Week Depart Week Depart From Norm Since Depart
Ave from Total Past Four Since May from
Norm Week Weeks 4/1 4 Norm
Becker          85  54  69.2  -1.4    1.13   .20 -1.93  -4.79  1258   -44
Collegeville 84 56 69.6 -3.1 1.20 .43 -.36 -3.42 1262 -165
Hutchinson 86 54 70.0 -2.4 .82 -.01 -2.61 -6.49 1313 -120
Melrose 84 48 67.5 -4.2 .58 -.21 -.77 -4.04 1122 -234
Olivia 83 49 66.6 -5.0 1.35 .60 -1.10 -5.53 1215 -188
St. Cloud 85 50 68.4 -1.9 .77 .06 -.92 -3.79 1174 -90
Staples 82 54 67.7 -.3 .84 .07 .46 -1.76 1064 -73
Willmar 84 54 69.7 -1.9 1.86 1.09 -.71 -6.26 1292 -97

Temperatures last week ran 2-5 degrees cooler than average. Willmar picked up the most rain, with 1.86", Melrose the least - only .58" fell. The Staples area is in the best shape, in terms of soil moisture and rain since April 1. St. Cloud is running a 3.79" rainfall deficit since April 1, but in Hutchinson it's up to 6.49". The column on the far right is "Growing Degree Days", the cooler weather means plant growth is generally not as far along as it should be by the end of July. There is a wealth of information at the USDA National Agricultural Statistics Service. Click here to see the latest information (week by week) for Minnesota.

Paul's Outlook

Tuesday: Plenty of sun, breezy, cooler. Winds: NW 15-25. High: 74

Tuesday night: Mostly clear and comfortably cool, bordering on chilly! Low: 49

Wednesday: Sunny start, then increasing clouds. Rain possible late, continuing into Wednesday night (heaviest amounts probably south/east of St. Cloud). High: 76

Thursday: Damp, gray start, then turning partly sunny and brisk - cooler again. High: 72

Friday: Warm sun, feels like summer. High: 82

Saturday: Cooler with morning sun, PM clouds, few showers (best chance northern lakes). High: 75

Sunday: Clouds increase, slight chance of late-day showers. High: 74

Monday: Still waiting for the Dog Days. Partly cloudy, plenty of fresh air. High: 72

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