Monday, July 26, 2010

Tornado Watch until 11 pm (includes Twin Cities)

Update: 3:30 pm. Tornado Watch in effect. SPC has just issued a tornado watch for all of central and portions of southern MN until 11 pm Tuesday night. Conditions are ripe for "supercell" thunderstorms and a few isolated tornadoes, especially during the evening hours. 70% chance of two or more tornadoes....30% risk of an EF-2 or stronger tornado. Stay alert.

Safest place to ride out a tornadic storm:

Home: basement, under the stairs. No basement? The smaller the room the better, near the interior of your home (closet or bathroom works best).

Office: small interior room, away from outer walls and windows, like a bathroom or concrete-reinforced stairwell.

Outside: drive away from the tornado at right angles - if you can't get away from the tornado seek shelter in ANY building - otherwise get out of your vehicle and find the nearest ditch (do NOT seek shelter under a concrete bridge overpass - this increases your risk of being hit by flying debris).

* NWS has issued a heat advisory for much of southern MN (including the Twin Cities). The combination of highs in the low 90s and dew points rising into the 70s will make it FEEL like 100-103 by early/mid afternoon. Slow down, take it easy out there later today...

* Conditions ripe for severe storms later, I expect a severe storm (or tornado) watch to be issued for the mid afternoon through the evening hours.

* Turning cooler and less humid Wednesday behind a cool front - HALF as much water in the air by Wednesday afternoon as dew points drop through the 50s and winds gust from the northwest at 15-25.

Tornado Risk. There is a 10% risk of a tornado within 25 miles of any location within the brown shaded area, which includes east central MN and the northern third of Wisconsin. This is up from a 5% risk a few hours ago - so conditions for (isolated) tornadoes seem to be increasing in an area that includes the Twin Cities.

O.K. We've had our 2-day ration of sunlight, gentle breezes and lukewarm temperatures. 48 uninterrupted hours of fair skies, smiles and meteorologists groping for something to talk about. That's about to change. Time for a little atmospheric rocking and rolling, but first a small, fleeting taste of the sauna-like heat gripping much of America. If the sun is out for at least 6 hours today (likely) we should top 90, with a gusty south wind tugging the dew point into the low or mid 70s - up into the "oh zone." Women will perspire, men will sweat like Teamsters. More than ever you'll give thanks for the most underrated of all modern inventions: air conditioning. Makes you wonder how our great great grandparents got along (just fine) without it.

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

Today: Sunny start, windy - hot and very humid. Strong/severe storms are likely by mid/late afternoon. Winds: S 15-25. High: 93

Tuesday night: T-storms likely, locally heavy rain. Low: 70

Wednesday: Breezy and less humid under partly sunny skies. Winds NW 15-25. High: 82

Thursday: Plenty of sunshine, low humidity. High: 81

Thursday night: Clouding up, growing chance of showers, possible thunder. Low: 64

Friday: Intervals of sun, sticky again - a few scattered T-storms. High: 85

Saturday: Probably the nicer day of the weekend - mix of clouds and sun, a few isolated late-day storms possible up north. High: 86

Sunday: Sunny start, growing chance of T-storms by afternoon. High: 84

Monday: Still muggy and unsettled - a few lingering storms. High: 86

Monday Memories. It was another fine day across Minnesota, although a few stray storms rumbled across far northern Minnesota during the afternoon hours. Highs ranged from 77 at Grand Marais (a little free A/C off Lake Superior) to a sticky 86 at St. Cloud and the Twin Cities

Severe Threat. SPC has a 30% risk over central Minnesota, meaning a 30% chance of severe weather within 25 miles of any location within the red risk area. Bottom line: there's a good chance of hail and straight-line winds later today. Stay alert and tune in later for live coverage at if tornadic storms approach the metro area.

Stormy Bulls-Eye. The EHI, the "energy helicity index", shows very high values just south and east of the Twin Cities by evening - enough wind shear, instability and low-level moisture for a line of severe storms later today.

Wander outdoors around 2 pm and you'll be able to almost FEEL the storm potential building. Fat cumulus clouds sprouting towards the sky, coupled with a gusty south wind (reaching 20-25 mph at times), a rapidly falling barometer on the wall and air so thick you can almost cut it with a knife will be tip-offs that the weather is souring, the sky overhead primed for "strong vertical development." Translation: the Doppler radar may be smoking by mid/late afternoon as a squall line develops over northern or central Minnesota, a wall of water towering 10 miles in the summer sky, violent updrafts lobbing ping pong to baseball size hail into a cycle of updrafts and downdrafts. I expect SPC to issue watches by 3 pm, we may have just enough wind shear, instability and low-level moisture for a few isolated tornadic "supercell" thunderstorms to pop out ahead of the main line of storms. I don't think this will evolve into a widespread tornado outbreak - nothing like June 17 - there's a greater risk of straight-line winds and large hail than tornadoes.

Watering Optional. The models print out the heaviest bands of rain just south of the Twin Cities, over an inch possible. The latest NAM/WRF prints out .82", but only. 42" at St. Cloud.

The latest NAM/WRF model prints out just over .80" of rain tonight, winds swing around to the northwest, pumping cooler, drier, less humid air of Canadian origin back into Minnesota Wednesday. By late afternoon there should be HALF as much water in the air as dew points drop off into the 50s - we'll all be breathing a lot easier within 18-24 hours. Thursday looks beautiful with bright sun, highs holding in the 70s north and low 80s south as winds subside a bit. The next chance of showers/storms? Thursday night into Friday as tonight's cool front stalls and does a U-turn, keeping us unsettled and thundery late in the week.

Sunday Boomers? The long-range GFS model is hinting at a weak cool frontal passage Sunday, a potential for a couple hours of showers and storms, but no all-day rains expected.

Don't be the farm on the extended outlook (what a shocker, gee thanks Paul) - but right now Saturday appears to be the nicer, sunnier, drier day of the weekend. Most of the T-storms should pass off south over Iowa (nothing new there - that's been the theme for much of the summer). A few isolated late-day instability storms can't be ruled out (especially far northern MN). The GFS model is hinting at a weak cool frontal passage Sunday, the best chance of storms during the PM hours. Highs both days should reach the 80s, warm enough for the lake - sticky levels of humidity returning to make that dip in the lake even more tempting.

We have to muddle through 8-12 hot, humidified, thundery hours - our reward should be a beautiful Wednesday and Thursday, and the weekend doesn't look have bad either. Stay tuned...

Tornado Fatalities in the USA. You would expect the most deaths and injuries in "Tornado Alley", from Texas to Iowa, but this year's statistics mirror a growing trend: "Dixie Alley", stretching from Louisiana and Mississippi into Tennessee and Kentucky has seen more tornado fatalities in recent years. The reasons? Fewer emergency sirens, more hills/haze makes it tougher to spot tornadoes east of the Mississippi River, perhaps people aren't as tornado-aware as they are in Oklahoma and Kansas. It's a strange statistic - Minnesota has seen as many tornado deaths so far this year (3) as Oklahoma. Strange. More details from SPC here.

How To Drain a Lake in Less than 24 hours. The roughly 900 homeowners living along Lake Delhi in eastern Iowa are staring out their windows at mud and muck - the water is largely gone, washed downstream after record flooding destroyed the dam holding back the water. Some amazing home video of the aftermath is here. More aerial footage is here.

How Do You Warn 8 Million People At Once? Friday evening the local NWS issued a tornado warning for metro New York (including Manhattan). People received not only televised warnings but e-mail texts from the NWS. One big question for a major metropolitan area, where a significant percentage of people don't have access to basements - where do you go? The answer: avoid elevators, seek shelter in a small, interior room near the center of the floor - a closet, interior bathroom, or concrete-reinforced stairwell would keep you relatively safe. Avoid outer walls and windows. The story/challenge is here. Time-lapse footage of the storm front reaching Manhattan is here.

High Pressure "Swirl". The high-res NASA "MODIS" satellite imagery from Sunday showed the clockwise wind flow around a bubble of high pressure - look carefully and you can see the center of high pressure was located right over the Whitefish Chain when this image was taken from a low-orbiting satellite, roughly 200 miles above the ground. The most recent MODIS image is here.

Triple-Digit-Heat. Residents of Raleigh, North Carolina are suffering through one of the hottest summers in recent memory. 102 Sunday with a heat index of 111 - excessive heat warnings had to be issued, the story is here.

Creative Way To Keep Your Cool. Residents of Moscow had to get creative yesterday as the mercury flirted with 100 F - so thousands of them jumped into lakes, rivers - and fountains. Most residents living in Russia don't have air conditioning - conditions in recent weeks have been unbearable across much of Asia - at least 9 countries have established all-time records for the hottest weather ever recorded. The story is here.

Extreme Heat. Temperatures in Moscow reached record levels Monday, but just to the south and east daytime highs were more than 20 F. hotter than average for late July. More on the record heatwave gripping Russia and much of the northern hemisphere is here. To make matters worse the hot, dry weather has ignited scores of fires - producing a pall of smoke and air pollution that has health authorities concerned.

Microburst. How often do you see an example of it "raining up"? Thunderstorms produce updrafts and downdrafts - on rare occasions rain and hail-cooled air can reach the ground with high velocity - spreading out and producing straight-line winds, sometimes in excess of 100 mph, capable of tornado-like damage. A good primer on the danger posed by microbursts (especially to aviation) is here.

Lightning Like You've Never Seen It Before. Click here to see amazing slow-motion footage of cloud to cloud and cloud to ground lightning strikes - remarkably complex, a spider-web of electromagnetic energy that scientists are just beginning to understand. You've never seen the formation of lightning quite like this.

Full Moon. Did you see the (amazing) spotlight moon Sunday evening? Click here to see a table of full moons for the rest of 2010.

Be Very Careful Posting Photos On-Line. On-line predators can determine where posted photos and videos were taken. I had to read this article twice before grasping the full implications. Many of the new smart phones include a GPS location "stamp" when you post to Facebook and Twitter. Hackers can use special software to "sniff" out these invisible location watermarks - a few people have been robbed, posting vacation photos - giving a thumbs-up to crooks casing out their homes. I'm not overlay paranoid, but after reading the article I've decided to stop posting photos to social networks. Good grief - what's next?

Carp Invasion Moves Closer To Home. The Star Tribune has a story about Asian carp moving up the Mississippi, threatening Lake Michigan and other waterways just south of Minnesota. Could this really become a problem for Minnesota's lakes and rivers? The story is here.

Top Secret America. Did you read the special series in the Washington Post about the shadow security industry in the U.S. An amazing read and definitely worth your time.

We're 'Gonna Be Sorry. St. Louis Park's very own Thomas Friedman recently wrote about the Senate's failure to pass a climate and energy bill - his most recent post is here.

Is Climate Change Worth Tackling? Maybe a little warming will do the world good? There will undoubtedly be a silver lining to climate change - no question. Not sure it will counteract all the unpleasant symptoms, but a post worth reading is here.

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