Fab but smoky Friday, stormy Saturday

The season formerly known as summer is back.

We enjoy sunny (but potentially smoky) skies and soaring temperatures Friday across Minnesota. Warm southerly breezes will feel nice as temperatures push the 80-degree mark Friday afternoon.

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NOAA

Smoky skies?

We gaze up through a potentially white-tinted sky as smoke from western fires makes a move on Minnesota. Dozens of active fires continue to burn in the western U.S.

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NOAA

You can clearly see the dense smoke plumes being carried east toward Minnesota by the upper winds on NASA's high resolution MODIS satellite shot.

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NASA

Westerly breezes aloft will continue to blow the diffuse smoke layers over the Upper Midwest Friday.

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NOAA

Stormy Saturday?

Our next front brings another wave of scattered storms into Minnesota Saturday.

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NOAA

Dew points in the 60s ahead of the advancing front will feel sticky, and destabilize the atmosphere enough to produce a few severe storms Saturday. NOAA's Storm Prediction Center paints a slight risk for most of Minnesota Saturday.

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NOAA

Hurricane Danny is first of the Atlantic season

Hurricane Danny flared and has become the first hurricane of the 2015 Atlantic Hurricane season.

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NOAA

The storms continues on a westward track.

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NOAA

Danny is expected to encounter drier and more hostile wind shear conditions in the next few days. Here's more from Bob Henson at Weather Underground.

Danny’s other nemesis is vertical wind shear, a perennial feature in the North Atlantic tropics during El Niño years. The widespread rising of warm air over the eastern tropical Pacific during El Niño helps foster unusually strong west winds at upper levels, pushing away from the Niño region into the Caribbean and western Atlantic. Such shear can easily disrupt the chimney-like vertical structure that helps to maintain a tropical cyclone’s strength. Currently, wind shear over the Caribbean is below the record values observed earlier this summer, but values of 30 - 60 mph remain widespread. (Anything above 20 knots, or about 23 mph, is problematic for tropical cyclone development.) For now, shear over Danny remains low, in part because its potent convection has produced a small zone of high pressure overhead. This weekend, Danny will be hard-pressed to avoid encountering a belt of higher shear, which would not only jeopardize its structure but also help push dry, dusty air into its circulation. If Danny survives that passage as a well-structured tropical cyclone, then it may encounter somewhat lower shear values ahead of its path early next week (see Figure 5), as a weak but persistent upper-level low is predicted to move northward from the Bahamas and a ridge builds in to replace it.

atsani-vs-danny-8.20.15
. A side-by-side comparison of visible satellite imagery from Thursday, August 20, for Super Typhoon Atsani in the Pacific (left) and Hurricane Danny in the Atlantic (right), both at the same scale, shows how much tropical cyclones can vary in size. Even smaller systems like Danny can be devastating if they grow intense enough and strike a highly populated area. Composite image credit: Mark Lander, University of Guam.