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Flood potential

Flood threat grows across metro area.

Flood threat grows across metro area. Doppler radar shows a very impressive, tightly-wound “meso-low” winding up over southeastern Minnesota, the latest WRF computer model prints out over 3″ of rain [not a typo: three inches of rain] by late afternoon today. I’m starting to get more and more concerned about the potential for flash flooding today. This is a pretty amazing turn of events, from drought to flood in less than 10 hours. Even that may be a new record. Plan on extremely slow commutes with standing water on many highways, wet basements and a few overflowing streams later today as this zone of strong to severe thunderstorms lingers. Some storms will produce frequent lightning and 1/2″ hail, winds gusting past 50 mph.

If you can, do yourself a favor and leave early for work today, because the weather promises to be extremely soggy and messy, with standing water on area highways, even a potential for some minor flash flooding. The very latest computer models are printing out anywhere from 2 to 3″ of rain by Monday evening. A few farms over southern Minnesota could get swamped under 2-3″ of rain by lunchtime today. The heaviest rains will probably come during the morning and midday hours today, possibly accompanied by a little lightning and thunder, although the potential for severe weather is quite small (except for far southeastern MN and counties along the MN/Iowa border, where we can’t rule out large hail and damaging winds in a few of the storms).

Most of us will just see window-rattling, gulley-gushing, torrential rains. If the models are on the right track (and right now there does seem to be continuity/agreement between the models. Much of this rainwater won’t have a chance to soak into the ground, where it’s needed, but rather run-off into streets, streams and storm sewers. If you routinely struggle with a wet basement, or live next to an intersection that floods, or a small stream that often jumps out of its bank, be alert tomorrow – if this forecast verifies I have a hunch there may be some flash flood warnings issued.

Simulated night image (NexSat) with city lights and IR satellite imagery, which measures the temperatures of clouds, and can be used/displayed 24 hours/day. The colder, thicker clouds (that are most likely to produce precipitation) show up as bright white. Low clouds, fog, etc are shallow and relatively warm, they show up as dark gray. Thanks to the Naval Research Lab you can click here to get the very latest image; lot’s of great options to choose from.

The heaviest rains should be winding down by 2-3 pm, shifting north toward Duluth, so you may be able to salvage late afternoon and evening plans, in spite of lingering mud and muck. The rest of the week looks fairly dry, culminating in a MUCH nicer spell of weather next weekend, when temperatures will be well into the 70s with some badly-needed sun both days. But today your drip-dries will be drooping. Look at the bright side: I seriously doubt you’ll have to water the lawn or garden anytime soon. Certainly not for the rest of this week.

Infrared satellite image showing the tops of massive thunderstorms just south/east of Minnesota (appear as orange and red). An area of low pressure tracking from western Iowa toward La Crosse and Green Bay will soak the region with moderate/heavy rain this morning, but as it passes to our east winds will swing around to the northwest, drying us out later this afternoon and evening. This image is from Penn State; to get the most up-to-date imagery click here.

Check out these cloud photos, especially the first one. Looks like something you might see on Venus! There is growing evidence that scientists may have stumbled upon a new class of clouds called “asperatus”. According to National Geographic it may be the first time in over 50 years the WMO, the World Meteorological Organization, may have to update their official Cloud Atlas!
For more information check out my ClimateSpot blog, which also has an exhaustive update on the meteorological conditions encountered by the doomed Air France Flight 447.

Weather Headlines

* 53 degree Sunday high at St. Cloud, 57 in the Twin Cities (20 degrees cooler than average).

* Today: just as cool, and super-soggy. Potential for 1-3″ of rain. Heaviest rain falls between 4 am and 10 am this morning.

* Potential for standing water on area highways, some flooding of poor drainage areas and intersections.

* Wind shift to the northwest dries us out this afternoon, dry after 2-3 pm, no problems for late afternoon/evening activities (just plan on lot’s of mud).

* Another half inch of rain possible Wednesday night.

* Slow warming trend as the week goes on, prospect of a nicer weekend with ample sun, temperatures much closer to average (75-80 degrees). Sunday appears to be the warmer day right now.