DIRTY RAIN, SAY WHAT?

TAKING THE EDGE OFF...

That powerhouse late winter storm Wednesday produced a remarkable day of weather that included rain, sleet, snow, hail, and winds that reached 60 mph (all within a 12-hour window). One of the things I didn't touch on until now is the unique element known as "dirty rain". It's evident on Wednesday's high resolution GOES satellite imagery by the milky brown colors (circled for identification).

You can even see it in this larger perspective, extending from Illinois and Wisconsin into Louisiana.

A number of people asked me why their car was dirty or dusty after Wednesday's rain? You can blame it all on dust particles that originated from as far away as Texas and Oklahoma, even the desert regions of the SW. It was transported into the Midwest by the powerful winds aloft and at the surface associated with the intense weather system that clipped the region. You can clearly see the explosive circulation that tapped into the dust and thrust it our way.

Dust in the air often serves as condensation nuclei for tiny droplets to form that may eventually become raindrops. They may even begin as snowflakes if they are found far enough aloft. That's likely what happened with the dust and dirt steered into the Midwest March 19th. Some of the "dirty rain" was also the result of falling rain drops colliding with the dust particles on their way to the surface. The bottom line is a lot of cars around the central U.S. instead of being washed by the rain, ended up being dirtied by it.

These are some of the wind gusts reported by the NWS Wednesday. The strongest, 45-60 mph were located to the NW of the surface low.

Another unique aspect of the storm was the fact that it split Iowa with 2 snow bands. One Wednesday over the NW half of the state into Minnesota and Wisconsin, that largely missed my area. The second band, Wednesday night, formed over SE Iowa and traveled just south of the Quad Cities towards Chicago. 2–4 inches fell from Burlington to Galesburg on to Galva, where temperatures earlier in the day were in the upper 60s to low 70s!

The resulting snow bands were apparent on the visible satellite image early Thursday after skies had cleared.

One last aspect of this full-bodied storm was the amount of hail it produced. There was a fair amount of it in my area and as the NWS points out in their graphic below, the most impactful severe weather was found just to the SE, and the heaviest snow with near blizzard conditions was just NW, with my area getting a little taste of both. Low freezing levels compared to what you would see in the summer made this a prolific hail producer. Overall, this was just a manic storm. I had to work really hard to get this one laid out. It was a good challenge for me...

THE FIRST FULL DAY OF SPRING

It didn't feel much like spring when it clicked in at 4:01am Thursday, but nonetheless, the vernal equinox arrived as scheduled. Longer days and more direct sunshine are in our future for 3 months and that no doubt means we've put the worst of another winter behind us (it really wasn't that bad in my opinion).

Friday, the first full day of spring, will have what it takes to produce springlike conditions. South winds will be on the increase, allowing temperatures after a frisky start to climb into the upper 50s north to the low 60s south. Ahead of a fast moving front, clouds will be on the increase, especially in the afternoon. Towards evening, enough return moisture may be in place for a brief shower or isolated thunderstorm to form in my western counties that may accompany the front as it travels east during the evening. The 3K NAM shows some broken development. Amounts are far from exciting, generally a .03" or less. Some areas will see nothing at all. In other words, only a small interruption is expected that will be brief. Dry air should really make it a struggle to get much rain to the ground.

Behind it, Saturday looks to be a crisp but quiet, dry day. Highs will range from the mid 40s north to the low 50s south under mostly sunny skies.

The next system is upon us quickly Sunday and with better dynamics and slightly more moisture, is likely to produce some light rain, especially in the morning. Highs should peak in the mid 50s NW to the low 60s SE. Sharply colder air arrives Sunday night that holds highs Monday largely in the 40s. Here's what models are indicating for rain potential Sunday. Amounts are generally 1/4 inch or less.

The GFS

The EURO

Overall, the next week is dominated by NW flow, keeping the threat of major storms low, but temperatures for the most part below normal levels.

So there you have it, on a Friday. Have a solid weekend and roll weather...TS

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