Sunday, August 29, 2010

Tornado Watch Northwest MN until 10 pm

Tornado Watch until 10 pm. We've seen somewhere between 14-18 days with tornado watches since June 17 (somewhere in the state). A new tornado watch has been posted for northwestern and parts of west central MN until 10 pm tonight - meaning conditions are ripe for a few isolated "supercell" thunderstorms capable of large hail and even a stray tornado or two. Tuesday the severe threat shifts south and east, into parts of central and southern MN. Expect another rash of watches & warnings by late afternoon and evening Tuesday.

Staggering Numbers. I checked the SPC site and nearly fell off my little stool! Somehow - we're now up to 145 tornado reports, 211 reports of large hail, 365 reports of straight-line wind damage, for a total of 721 severe storm reports in 2010. Where are we living again? That compares with 60 tornadoes in Wisconsin, 52 in Iowa, 87 in Texas ad 70 tornadoes in Oklahoma. Wait - TWICE as many tornadoes in Minnesota than Oklahoma? Stop this ride - I think I want to get off. Don't believe me? Click here to see the SPC numbers for yourself (plug in different state abbreviations in your browser's URL address above to compare with other states).

* This is an almost incomprehensible number, nearly twice as many as Kansas, Texas and Oklahoma - 6 to 7 times more tornadoes than "normal" for a summer season here in Minnesota.

A Very Close Call. Hurricane Earl is forecast to take a track around the periphery of a bloated Bermuda high, coming precariously close to the east coast of the USA later this week. Although the core of the storm is forecast to stay a few hundred miles out to sea, coastal flooding and beach erosion is possible from the Carolinas northward to Long Island and Cape Cod. Track Earl on the NHC site here.

First Strike? Disclaimer: don't trust any forecast beyond 5 days (ok, 5 minutes). This is the ECMWF (European) outlook for next Tuesday, September 7 - showing Hurricane Fiona surging into the southeastern USA. Too soon to panic (or even worry) - but residents of the southeast will be keeping a very close eye on the extended model guidance in the coming days.

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

Today: Hot sun, windy and sticky (dew points in the low to mid 70s). High: 94 (Heat Index: 95-100 this afternoon).

Monday night: Partly cloudy and muggy - unusually warm. Low: 74

Tuesday: Humid with T-storms, some strong to potentially severe. High: 85

Wednesday: Some sun early, another round of showers possible late. High: 82

Thursday: Windy and cooler with clearing skies (clouds/sprinkles north). High: 78

Friday: Gusty and cool with plenty of sunshine. High: 73

Saturday: Probably the nicest day of the holiday weekend. Sun giving way to increasing clouds late. High: 74

Sunday: Mostly cloudy with showers (best chance central and southern MN). High: 75

Labor Day Outlook: Mostly cloudy, chance of showers (and drizzle) - a cool breeze. High: 75

On your mark - get set - sweat. What a way to start a new week, another free sauna, in the comfort and privacy of your own yard. The 7th day above 90 this month. Another day of dew point drama. Good grief. Another 2-shower day is shaping up, probably even hotter than Sunday, when the mercury peaked at 94 in the Twin Cities, 2 degrees away from a record, 17 degrees above average, and 28 degrees warmer than last year.

Bob Dylan once famously remarked, "you don't need a weatherman to tell you which way the wind is blowing." He got that right. Yes, it's been a sticky, steamy, SOUTHERLY wind for much of the summer, which isn't all that unusual. But continuing a trend we've noticed in recent decades the number of super-humid days in Minnesota is most definitely on the rise. According to the MN State Climatology Office we've muddled through 26 days with a dew point greater than 70; that's 252 hours above 70 (80 more than average). Since June 1 the average dew point at MSP has been 61.1 F, that 5 degrees higher than usual. Doesn't sound like much, but let me try and put those 5 degrees of added dew point into perspective. For every 20 degree increase in dew point the amount of water in the air DOUBLES. So it would be safe to say that the Summer of '10 has been 25% more humid than "average." And summer isn't quite through with us just yet. Today the combination of mid 90s + dew points in the low to mid 70s will make it feel like 95-100 F. by mid afternoon. Pray the air conditioning keeps working.

The Sweaty Details. The MN State Climatology Office has been keeping track of our unusual number of sticky days so far this summer: 26 days with a dew point > 70 F. More details here.

Speaking of air conditioning the National Weather Service calculates something called "cooling degree days", which you get by adding up the high and low for a given day, and subtracting 65. It's the combined number of degrees above 65 F for any given day. If the high is 90 and the low is 70, the average is 80: that's 15 "cooling degree days." Well, based on this arcane calculation we've racked up 876 cooling degree days. We should have seen closer to 599 cdd's. That means we've spent about 46% more cold cash on keeping our homes & businesses cool than during a typical summer. No kidding.

Good Water Cooler Ammunition. Sick and tired of gossiping about who the receptionist is dating, or how many pounds the boss has put on lately? Launch into a tirade about cooling degree days, and I can almost guarantee you that you'll get a few heads nodding (before emptying the lunch room, faster than you thought possible). Why has the metro area had so many more cooling degree days than St. Cloud, even Rochester? Good question: my hunch, a little of the urban heat island (more concrete/asphalt retains heat, prevents temperatures from cooling as much at night, adds a few degrees to the daytime highs). Whatever the reason, we've spent almost 46% more money cooling our homes so far this summer than "normal."

Is there a link between more higher dew points, more humidity - and our (outrageous) spike in severe weather this summer: we're up to 721 severe storms and 145 (!) tornadoes so far in 2010? The greater the amount of water in the air, the more juice available for severe storms, the greater the potential for extreme rainfall amounts (ie flooding across Iowa) and the greater the risk of spinning up tornadic storms and large hail. It sure appears like there's a link: more water vapor floating overhead = enhanced severe storm risk. Tornadoes don't form in a drought - you need a steady supply of moisture from the Gulf of Mexico. I still maintain there's something else going on here - many days the dew points across southern Minnesota and Iowa are HIGHER than those found along the Gulf coast, higher than Louisiana and Texas. Something doesn't add up here. SOMETHING is putting more water in the air, making our dew points even more ridiculous, loading the dice in favor of more severe local storms. The most likely candidate? Corn. I want to go on record as saying that I am very "pro-corn" (had some for dinner Sunday evening, come to think of it) but the truth of the matter: by planting corn rows closer together and getting more yield out of every acre of farmland, we are pumping more water into the air. It's probably not so much the irrigation for these fields, but something known as "evapo-transpiration." Put simply, corn sweats. At night corn releases water into the air. And the more corn in a given field, the more water that's going to "sweat" into the nighttime air.

Could planting more corn have the unpleasant side-effect of sparking more severe storms downwind? The theory isn't as ridiculous as it looks on the surface. Seems like there's a research paper here. If only I had the time...

We'll all have plenty of time to sweat out the details today, one of the 3 hottest days of the entire summer, but it's the LAST day of gag-worthy heat and humidity. An eastbound cool front sparks showers and T-storms Tuesday (a few storms could be severe tomorrow - what a surprise). Another wave of showers may brush southern and central Minnesota late Wednesday, the latest models hinting at over three quarters of an inch of rain around by Wednesday.

The good news: a much cooler front sweeps out of Canada late in the week, skies begin to clear on Thursday - by Friday dew points sink into the 40s and 50s, meaning less than HALF as much water in the air by the end of the week. Something to live for.

Sunday Showers. Saturday looks ok (at least right now) with morning sun giving way to increasing clouds later in the day - but an atmospheric tug-of-war may spark a period of showers, even some steady rain, next Sunday, showers possibly spilling over into a part of Labor Day. Maybe the forecast will improve, like a fine (box) wine, as the week goes on. Don't count on it.

Right now Friday and Saturday look like the two best days, in terms of sunshine and lack of rain. As warmer air tries to return northward over the weekend clouds will start to increase late Saturday, a good chance of showers Sunday and Labor Day, especially over the southern half of Minnesota. The farther north you go (especially toward Leech and the BWCA) the better your odds of salvaging some cool sun over the weekend, but I'm not too optimistic about the rest of the state. It probably won't be a steady, all-day rain, but I'd start pondering a Plan B for part of the day Sunday and Monday - be rapturously happy if the heavens conspire to cut us a break. It could happen, but we've had an awful lot of amazingly sunny (quiet) weekends as of late. We're due for a change in the weather. Sorry about the (potentially lousy) timing.

Wisconsin: doesn't even close close, a mere 60 tornadoes. Less than HALF as many tornadoes as Minnesota in 2010. Iowa: 52 tornadoes so far in 2010. Minnesota has seen nearly 3 times as many tornadoes as Iowa. Southern Iowa is (technically) in "Tornado Alley." It would appear that the alley has taken a northward detour this year.
Oklahoma: 70 tornadoes. Send a postcard to a buddy in Tulsa. Minnesota has seen TWICE as many tornadoes as Oklahoma...? In what parallel world is that even possible?

Texas: 87 tornadoes and counting. Let me get this straight: Texas is 3 times larger than Minnesota, the largest state in the lower 48 at last count (with 268,601 square miles, compared with 84,0068 square miles in Minnesota - the 12th largest state in the USA). In spite of that fact, Minnesota has seen 58 more tornado reports than Texas - another mind-boggling statistic.

A Hurricane Named Earl. The University of Wisconsin has a web page devoted to Hurricane Earl - satellite imagery from GOES-13 available here.

Bolt From The Blue. Every year a handful of Americans are struck (and either injured or killed) by cloud to ground lightning - with BLUE SKY directly overhead! Lightning can travel as far as 10 miles horizontally from the cloud base. That's why the National Weather Service has the "30-30 Rule". If you can count 30 seconds from the flash of lightning to the bang of thunder, it's time to make a mad dash indoors. And wait 30 minutes after the last thunderclap before heading back outside. Just because the rain has subsided does NOT mean the lightning threat has ended. The most dangerous time during an electrical storm: the very beginning and tail-end of a storm. This quick YouTube clip was taken in the Haruaki Plains on the northern island of New Zealand - yes, a little too close for comfort!

Waterspout! Unusual footage from Jurmala, in Estonia. Click out the YouTube video here.

UN Climate Change Panel Warned Over Reports. Some changes are coming to the IPCC, in the wake of the hacked e-mails of last December and the subsequent "ClimateGate" backlash. Apparently the IPCC will be warned over how it uses scientific facts in its final reports, the way it gathers and vets information, and how quickly it corrects obvious inaccuracies. More on the story here.

* Thousands Affected By Flooding in Southern Mexico. Another day, another severe flood somewhere on the planet - the latest from here.

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