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Late-day storms may sprout

Numerous reports of large hail around the region Tuesday, possible funnel clouds near Glencoe, nearly 1″ of rain soaks the Twin Cities metro area.
By Paul Douglas

* Numerous reports of large hail around the region Tuesday, possible funnel clouds near Glencoe, nearly 1″ of rain soaks the Twin Cities metro area. More strong/severe storms may mushroom to life later today, fewer than yesterday, the greatest risk of an hour of (hard) rain around the dinner hour coming closer to Wisconsin.

24 Hour Rainfall Amounts

St. Cloud: .71″

Twin Cities: .92″

Duluth: 1.16″

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Redwood Falls: .08″

Rochester: Trace

WRF/NMM Model Prediction for 7 pm today, showing predicted rainfall amounts from 1 pm to 7 pm today. Yes, we’re still dealing with the aftermath of a “dirty front”. Unlike the classic (textbook) Canadian cold front, where cumulonimbus give way to stratocumulus, then scattered “cu” and finally clear skies out completely as high pressure builds in from the north and west, our current weather scenario is a bit more complicated, messy….thundery. The latest push of cooler air that set off moderate/heavy rain Monday night, and a spirited round of severe storms late Tuesday, just ran out of steam. The front has stalled, and that will keep a few late-day T-storms in the forecast for central and eastern Minnesota later today. There’s just enough lingering moisture (and instability) to set off a few stray storms around the dinner hour, and once again a tiny percentage of these storms (maybe 5% or so) could turn severe with large (1″+) hail and winds gusting over 60 mph.

The same thing may happen again Thursday (a rumble of thunder around the dinner hour) with a few more showers possible Friday as the next, significant puff of Canadian air hurtles south of the border. The weekend will be cooler, most of the showers to our east over the Great Lakes Saturday and Sunday. If you’re driving into Wisconsin plan on more clouds and a much higher chance of showers, especially afternoon hours.

GFS Outlook for 7 pm Saturday, displaying accumulated precipitation from 7 am to 7 pm Saturday. The heaviest showers/storms are forecast to be east of Minnesota, light showers over Wisconsin, stronger storms rumbling across the Ohio Valley into the northeast. This is the same, nagging pattern that has kept the Upper Midwest, Great Lakes and New England cooler than average much of July – unusually strong storms for mid summer, tracking unusually far south, pumping cooler air into the U.S. in their wake, each storm passage followed by another shot of cool, fresh air.
6-10 Day Temperature Outlook. Hoping for some dog days to sweat it out on the beach, or slather on the sunscreen and charo-broil by the pool? That may not happen anytime soon. The long-range guidance for last week suggests that July will end on a cool note, prevailing jet stream winds still howling from the northwest in a pattern vaguely reminiscent of late September. I swear we’ve skipped 2 months and gone right to September 21!

* For detailed storm report from last night: scroll down.

* Numerous reports of 1-2″ diameter hail Tuesday evening.

* Funnel clouds spotted near Glencoe, no reports of any touchdowns.

* Lightning claims one life near Stillwater (14 year old girl seeking shelter under a tree).

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That last headline breaks my heart, because it’s such a needless, avoidable tragedy. I know how tempting it is to avoid getting soaked by hiding under the nearest tree, cross your fingers, and wait for the storm to pass. But you’re courting disaster if there’s lightning in those thunderheads. If you can’t make it to a building (and building) or a vehicle, it’s safest to crouch down near some smaller shrubs – don’t lie down flat on the ground, this actually increases your risk.

A few signs lightning may be about to strike:

* Strange clicking noise.

* Metallic taste in your mouth.

* Hair standing on end.

If you encounter any of these danger signs, drop down into a crouching position, cover your head and lean forward until the threat has passed. During an average year the St. Cloud area sees 30-35 days with thunder and lightning – in the vast majority of cases you’ll be at home or school or the office, no worries (if you stay away from outer walls/windows).

Don’t wait until you can see lightning to head indoors – when skies begin to darken, when you hear the first growl of thunder, you should be heading for a shelter (or your car/truck). Remember that lightning can travel as far as 10 miles away from the parent thunderhead, striking with blue sky overhead! That expression “bolt from the blue” is based on bizarre circumstances with sometimes deadly results. Just because the heavy rain is over doesn’t mean the threat of lightning has passed.

It’s best to wait at least 30 minutes after you hear the last thunderclap before heading back outside to work, play or relax. That should give enough time for the storm (and accompanying lightning risk) to move a safe distance away.