Thursday, August 12, 2010

Lingering Severe Threat

Update: 11:15 am. Severe Storm Watch remains in effect for southeastern third of Minnesota (including Twin Cities and St. Cloud) until 1 pm. Conditions are still ripe for more strong/severe storms into the afternoon and evening hours - a tropical airmass overhead, dew points in the 70s, sufficient wind shear for a few isolated "supercell"thunderstorms capable of large hail, even an isolated tornado or two.

* 1.47" rain falls at MSP International Airport Thursday night/Friday morning, minor flash flooding reported (along with nearly continuous lightning).

* 2.65" falls at Eden Prairie (nearly 3 weeks worth of rain) from overnight T-storms.

* Tornadoes reported near Louisburg and Dawson in Lac Qui Parle county Thursday evening.

* Funnel clouds spotted near Foley and Sartell, in the St. Cloud area, as well as Walnut Grove, in Redwood county.

* Straight-line wind gusts over 60 mph toppled trees and powerlines across central Minnesota.

* Slight severe storm risk again today - but threat eases over the weekend as Canadian air returns (by Sunday).

Update: 3:30 am. Wave after Wave. Flash Flood Warning in effect for much of Hennepin and Ramsey county - repeated (training) thunderstorms capable of 3-6" rainfall amounts continue to track across central and east central MN - accompanied by nearly continuous lightning and torrential rains. Expect to see standing water on area highways - very slow commutes Friday morning - areas that normally flood may experience problems Friday. Stay alert, be ready to move to higher ground, if necessary - serious flooding is possible in portions of the 7-county metro area.

Bow Echo. This is what NWS Doppler looked like shortly after 8 pm Thursday night - the line of storms "bowing out", resembling a colorful boomerang - strong evidence of strong, straight-line winds in excess of 60 mph. When you see a fast-moving bulge in a line of storms - time to batten down the hatches - odds are high strong, potentially damaging, winds are imminent.

Rotation. The GR2 Analyst software detected strong rotation in the Foley area at about the same time funnel clouds were spotted. Using this new technology we can take a 3-D slice of a severe thunderstorm and literally peer inside, looking for evidence of large hail or the swirling winds capable of spinning up a tornado.

Sweaty Thursday. Highs reached 93 at Twin Cities International Airport and Eden Prairie, 92 at Redwood Falls and 91 in St. Cloud. Sick of the 90s yet? Me too. That's 15 days above 90 so far this year.

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

Today: Patchy clouds, sticky & unsettled with scattered T-storms (a tiny percentage may turn severe). Winds: S 10-20. High: 87

Friday night: More T-storms, locally heavy rain. Low: 73

Saturday: Partly sunny, still warm and humid - but dry most of the day. A late afternoon shower/T-shower is possible. Winds: W 10-20. High: 86

Sunday: A mix of clouds and sun (best chance of PM clouds up north). Noticeably cooler and less humid. Winds: NW 10-20+ High: 78

Monday: Plenty of sun, less wind - still comfortable. High: 75

Tuesday: Sunny start, then high clouds increase later. High: 79

Wednesday: Another round of showers, possible thunder. High: 82

Thursday: Clearing, seasonably mild. High: 82

The hot vinyl car-seat warning and small cooler advisory has been lifted - the worst of the heat is now in our rear-view mirror - I pray.

This is what it must be like doing the weather in San Juan, Abu Dhabi, or parts of the central Congo. Blazing sun - tropical deluges - flash flooding - repeat. Thursday was the 5th day above 90 in a row, the 7th day above 90 so far this month. If you're keeping score (and who among us isn't) that adds up to an impressive 15 days above 90 so far in 2010. For the month of August temperatures in the Twin Cities are running nearly 8 F. warmer than average. Yep, we're getting a taste alright. Suffocating heat engulfing much of the northern hemisphere has been surging north for the better part of a month, wild T-storms forming and re-forming along the northern fringe of this blast-furnace, sauna-like heat. The result: historic flooding across parts of Iowa and Illinois, some of the worst inundations on record going back 150 years or more. We've seen our fair share of downpours, but not nearly as much rain as Iowa, where some farms have picked up 40-50" of rain so far this year.

What Else? Another Severe Risk. This summer, when in doubt (which is much of the time, come to think of it) just predict scattered severe storms - chances are you'll be close to the mark. Instability, wind shear and low-level moisture is marginal, but we may have enough conditions converging for a few isolated reports of large hail and damaging straight-line winds later today, the best chance between 4 pm and 8 pm this evening.

A slight risk of severe storms lingers today, the best chance of thunder early morning, again late afternoon/evening (when the best odds of a few isolated severe storms should come). More cloud cover and showers in the area should keep us a few degrees cooler, reading holding mostly in the 80s (to low 90s far southeastern MN). It now looks like the main cool frontal passage will hold off another 24 hours, arriving late Saturday with one more outbreak of showers/storms. Most of Saturday looks dry (still plenty warm with highs well up in the 80s). By Sunday we will FINALLY start to feel some real relief as winds swing around to the northwest (10-20 mph) and dew points drop into the 40s and 50s - a taste of mid September with highs holding in the 70s statewide. By Monday morning folks up north may be reaching for sweatshirts and light jackets, with wake-up temperatures in the 40s and low 50s. Next week will be "average" with highs in the upper 70s and low 80s, much closer to where we should be the third week of August. No more sizzling 90s. We're due for a break, for a little breathing room - I know it's been miserable out there. Give it 36-48 hours and we'll all start to feel the effects of that badly-needed cool front. Sunday should make it all worthwhile.

Cleanup. Hundreds of residents of Ames, Iowa have been forced from their homes by record floods - the Hilton Coliseum looks more like a swimming pool than a basketball arena. More details in a story here.

Historic Flooding. Check out the ultra-high res NASA "Terra" MODIS imagery centered on central Iowa. Look carefully and you can see rivers out of their banks near Ames and Des Moines, the result of 4 nights of heavy T-storms and flash floods in the span of less than 1 week. The latest MODIS image is here.

Lucky Shooting Star. We are smack dab in the middle of the Perseid Meteor Shower, the result of planet Earth plowing through dust and debris left over from Comet Swift Tuttle. As many as 20 meteors/hour may burn up in the Earth's atmosphere, producing a rash of "shooting stars" i the days to come. More on the Perseids here and at - photo courtesy of Brian Klimowski.

Don't Even Think About It. There is never an excuse to leave a child (or pet) in a car, not even for a few seconds. During the summer months temperatures can quickly rise to 125-150, lethal levels of heat within 10 minutes or less. According to reporter Matt McKinney, 4 Minnesota children have perished in just this (tragic) manner since 2001. The Star Tribune had a good story on the perils of leaving kids in cars here.

Excessive Heat Warning. Chicago is expecting a heat index in the 98-107 F. range in the coming days, not nearly as threatening as July, 1995, when a high of 106 at Midway combined with a dew point of 82 (!) to produce a truly life-threatening heat index of 125 F. I was working in Chicago at the time - the local media dubbed it a "heat storm", not a heatwave, because it came on so suddenly. Over 700 people died, many of them elderly and shut-ins, some of them afraid to open their windows for fear of crime. It was Chicago's worst natural disaster, and climate researchers are predicting the odds of similar "heat storms" will increase in the coming decades as background temperatures (and humidity levels) continue to rise. The story from Tom Skilling is here.

This Summer and Climate in Minnesota. Conservation Minnesota recently submitted a list of questions about climate change. No, this summer doesn't PROVE climate change, but it IS consistent with the theory of climate change. Many climate scientists would argue that we've gone from theory to reality. As I've said in previous posts - we're talking about an incredibly complex "climate puzzle." Pieces of the puzzle keep falling into place (see below).

Summer Heat Brings Dangers For Seniors. The elderly have a much tougher time adjusting to summer heat & humidity - their bodies can quickly overheat, resulting in heat exhaustion and heat stroke, which can be fatal if not treated quickly. Click here for a good summary of the risks in

Climate Change: How Extreme Heat May Affect Your Food. Every year the world's farmers have to feed an extra 80 million people. Yet some researchers predict for every 1 C (roughly 2 F.) rise in temperature grain yields may fall by 10% Russia's scorching heat/drought has already resulted in a ban on exports - possibly a sign of things to come. The story in Time is here.

Long Hot Summer of Fires & Floods Fits Predictions. From the Arctic to Russia, China and Pakistan it's been a record summer. It's estimated that 1/5th of Pakistan is currently under water. The floods have impacted 14 million residents of Pakistan, roughly 8% of the population. Can you imagine if a flood in the USA impacted 8% of our population? Russia has lost an estimated 1/5th of its wheat harvest to drought and fire. How much of this is natural variability vs. symptoms of something bigger? Click here to try and get a little more perspective on today's weather headlines.

* "Global Weirding": Extreme Climate Events Dominate the Summer. Climate records are being set at a record pace, worldwide. The pattern is unprecedented - described by some as "global weirding" - one of the best summaries I've read in recent weeks is here.

Russia Fires - Pakistan Floods Linked? Proving cause and effect with the atmosphere is always tenuous - but a slow, subtle rise in background temperature not only increases the potential for more extreme heat events, but it sparks more evaporation, putting more moisture in the atmosphere, increasing the odds of flooding as well. The story at is here.

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