The Cruelest Month

Monday, 29 April 2013 | Weather

After a brief flirtation with spring, including the first 70 degree temperature on 4/28 since back on October 25, we’ll see a cool-off of several days duration starting Wednesday, 5/1. Typical for the season, a “cut-off” low — a closed, mid-level circulation of cold air, detached from the bulk of the hemisphere’s cold air further north — will develop over the eastern Midwest Thursday and Friday, wobbling around nearly in place on most forecast maps through the weekend, bringing cool and intermitantly showery weather.

But before then, we’ll have a foretaste of summer. As warmer weather starts to bring more convective activity into the area, you might find a couple of online resources quite useful.

The first is the Milwaukee-Sullivan radar image, as processed by Weather Underground. It’s especially useful since it includes tracking information (bearing, speed) that allow you to assess when a thunderstorm will arrive in your area. It also gives information on the strength of individual cells, including estimated cloud-top height and whether a mesocyclone (rotating updraft) or hail is present.

The Storm Prediction Center site is also very useful during severe weather. Of particular interest in looking forward to possible threats are the Convective Outlook pages, often refered to as SWODY 1, SWODY 2, etc. (“Severe Weather Outlook DaY 1, 2, 3″), which provide the go-to analysis for severe weather prospects on upcoming days.

As ever, the Visible/IR image of the Upper Midwest and the 12-hour Water Vapor image of the US will be of use getting a wider perspective on what’s happening.

Mondays @ ~10:00 AM
Wednesdays @ ~6:40 PM
Rob McClure
Rob McClure is the Weather Emperor, and rains his forecast into your ears during Global Revolutions and In Our Backyard.

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