Saturday, July 24, 2010

Global Heatwave, El Nino or Global Warming?

"Bow Echo" Here is a 3-D slice of the severe thunderstorms that raced across southern Minnesota Friday night at forward speeds as high as 50 mph, producing marble to golf-ball size hail and wind gusts as high as 70 mph. The red blow rising up near Red Wing is a "hail core", showing where the most intense hail is located in the squall line. The bulge in the line, the horseshoe-shape, is evidence of powerful straight-line winds pushing the storms east into Wisconsin.

Saturday Details. It was, in fact, a "partly sunny" Saturday. Keep in mind the strange vernacular meteorologists employ. Partly sunny means the same thing as mostly cloudy (a day in which roughly 75% of the time is cloud-covered, only 25% sunshine). Why do we even use the term, when mostly cloudy would suffice? To emphasize the fact that there should be SOME SUN, as opposed to a prediction of "overcast", which implies that more than 95% of the day will be cloudy. Confused? Me too. To make the confusion complete: partly cloudy implies more sunshine on a given day than partly sunny. A partly cloudy day would be sunny 75% of the time, clouds expected less than 25% of the day. Moving on - highs reached the 80s across most of the state, in spite of instability PM clouds/showers. The Golden Rain Gauge Award goes to Redwood Falls, where 1.73" of rain fell. St. Cloud picked up .29", with .51" falling on the Twin Cities.

Paul's Conservation MN Outlook for the Twin Cities and all of Minnesota

Today: Bright sun, light winds, low humidity - almost perfect. Winds: E/SE 5-10. High: 83

Sunday night: Clear and comfortable. Low: 62

Monday: Plenty of sun, still very nice. High: 85

Tuesday: Sunny start, PM clouds, thunder possible later (better chance north). High: 88

Wednesday: Damp start, then sunshine, a bit cooler. High: 84

Thursday: Clouds increase, heavy T-storms possible later. High: 86

Friday: Intervals of sun, a few scattered T-storms around town. High: 88

Saturday: Wet start, then partly sunny and pleasant much of the day. High: 85

Sunday: Mix of clouds and sun, plenty warm. A few T-storms far north PM hours. High: 86

I'm up at my cabin on Pelican Lake, writing this weather-blog by candlelight, connected by blazing-fast 300 baud dial-up connection, swatting away angry swarms of mosquitoes, giving thanks for many things. Residents of eastern Iowa are experiencing historic flooding, a major dam is in danger of being swept away, thousands of local residents may have to flee their homes. Expressways in Chicago have been shut down because of flash flooding, meanwhile from the Midwest to the east coast weather-weary residents are sweating through record heat and humidity. From Nashville to Atlanta to D.C. it's felt as hot as 110 F. in recent days, nasty-hot.

Tropical Deluge. This graphic shows the last week's worth of rain, nationwide. Much of Minnesota picked up 2-4" of rain, but some counties form Iowa & Illinois saw as much as a FOOT of rain in less than 7 days, producing historic flooding from eastern Iowa into the Chicagoland area. The storms formed along the northern boundary of record heat gripping the nation's midsection, a stationary, west to east frontal boundary allowing storms to "train", multiple storms passing over the same counties, time and time again, day after day. Graphic courtesy of Intellicast.

"Catastrophic Failure". The Lake Delhi Dam, about 45 miles north of Cedar Rapids, Iowa, has suffered a "catastrophic" failure, water not only pouring over the top of the dam from recent record rains, but also flowing beneath the dam, leading experts to worry about the dam's structural integrity. Some counties upstream of the dam reported 10" of rain in less than 12 hours. Another 1-in-500-year flood? CNN has the latest here.

Record Rains. Here are records for just the last 2 days, according to the NWS. Parts of eastern Iowa picked up 3-4" of rain, a month's worth, falling in just a few hours. The green dots are 24 hour rainfall records, the yellow dots record warm nighttime low temperatures. Click on the interactive graphic from Ham Weather here.

Saturday's pop-up instability showers and long-gone, a weak bubble of high pressure sailing south from Winnipeg will donate bright sun today with less wind and very comfortable humidity levels for late July (dew points in the 40s and 50s, more typical of mid September). The "lapse rate", the rate at which temperatures are cooling as you rise up through the atmosphere, will not be as steep as it was yesterday. Translation: it's not as cold 4-6 miles above the ground as it was yesterday - this warming aloft will mean a more stable atmosphere - little or no risk of popcorn showers and T-showers sprouting up by mid afternoon. Throw in a light east/southeast breeze at 5-10 and you have all the ingredients for one of the best days of the entire summer.

Step away from your PC or Mac. Turn off the TV. Please proceed to the nearest open door (and don't look back). You will want to spend some quality time outside today. This is the way July is supposed to be in Minnesota, like something ordered up by the Chamber of Commerce, the stuff of picture postcards. You get the picture.

High pressure hangs on Monday, but a weak clipper-like system may brush us with thundery weather late Tuesday - another round of heavy storms possible Thursday, again late Friday into Saturday morning. The GFS is printing out over 2" of rain late in the week, but the GFS has been way off in recent weeks, so I don't even know why I brought that up. Much will probably change between now and next weekend. No obscene levels of heat & humidity, no severe weather in sight (at least not yet). Compared to much of America Minnesota and western Wisconsin will be in pretty good shape, weatherwise.

I'm heading outside to get an all-over tan, maybe scare the neighbors a little. With any luck the fish will be biting and my 20 year old pontoon will start up on the first try.
Star Tribune Print Weather Column for Sunday

Summer overload

I have every intention of sitting down by the lake. After I... mow the lawn/run a few errands/hit the hardware store/drop the kids off/water the garden/inflate my bicycle tires/clean the kitchen/do a load of laundry/read the paper/work out - then collapse into a nervous, over-scheduled puddle. Summers are way too short in Minnesota. We spend much of winter and spring planning/scheming what we're going to do during 12 precious weekends of summer and then try to cram EVERYTHING into 48 whirlwind hours. I'm trying to slow down (the controversial "less is more") theory. "Hey, STEP AWAY THE DOPPLER, PAUL." It's a process.

Step 1: atmospheric therapy; sitting under a expansive blue sky. A weak bubble of Canadian high pressure should see to that today, highs topping 80, a very light breeze promising fewer whitecaps on Mille Lacs than yesterday, when winds gusted to 25 mph behind a weak cool frontal passage, and cauliflower-cumulus congestus leaked showers up north. Today may just be the nicest Sunday of July. Blue sky lingers Monday, a few storms return late Tuesday. No blazing heat, just 80s all week. Snub your day planner. Ignore FB. No more tweets. I dare you to disconnect.

The New Normal? Average Global Temperatures Continue to rise. A story from Scientific American here.

Temperatures Hit Record Highs Globally. El Nino or Global Warming? Russia is baking through the hottest summer ever recorded, mirroring trends across much of the northern hemisphere. A fluke or a trend? The story is here.

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