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Our First Measurable Snow?

Well, it’s happened. Our first winter storm watch of the season has been issued. Now, before you get all crazy let’s look at some of the details of the storm and why *at this point* things don’t look too bad for southeast Minnesota and northern Iowa. At the time of this post, Sunday evening, only Steele County in our area has been included in the winter storm watch which goes into effect Tuesday afternoon.

Two storm systems will impact the region over the next three days. The first arrives on Monday. We stay in the warm side of this storm with winds out of the south so temperatures will stay warm enough for rain to be the only precipitation. Scattered light rain and drizzle will move in and out of the area for most of Monday. Little to no accumulation is expected, some cities may not even see a drop of liquid.

On Tuesday, specifically Tuesday afternoon, our second storm arrives. Tropical Storm Sonia, currently in the Gulf of California entering Mexico, will continue to move towards the northeast. Moisture from the Gulf of Mexico will feed into this low pressure allowing precipitation to fall from Texas to northern Wisconsin.

The current track of the low pressure takes it to our south and east putting us on the cold side with northerly winds. It is likely that some form of precipitation will fall for all of the viewing area. The biggest deciding factor to determine where measurable snow will fall is the rain/snow line. Hand in hand with the rain/snow line are temperatures, both at the surface and in the middle levels of the atmosphere. The current location of this line for Tuesday at midnight is just to our NW, keeping the majority of MN/IA too warm to support snow.

It is to the NW of this line that snow could fall Tuesday night into Wednesday. On Wednesday, the low pressure moves off to our east and cold air surges in behind it. This push of cold air will allow that rain/snow line to move closer to SE Minnesota. Now comes our next question – by the time the rain/snow line has pushed through Minnesota, will precipitation fall? Weather models currently disagree with the answer to this question and the answer should become clearer in the coming days. Current thinking is that any precipitation that falls on Wednesday should be light enough in nature so any snow that does fall will not accumulate to more than a dusting.

Your Storm Tracker 6 Forecast currently calls for consistent rain Tuesday afternoon through Wednesday, heavy at times with rain totals above 1” possible. Snow may mix in with rain just after midnight on Wednesday. Better chance for flakes the further NW you live. Little to no snow accumulation is expected.

Any change in the track of this low pressure will greatly impact what precipitation type will fall. A shift to the south gives a better chance for snow, a shift to the north gives us a better chance for rain. Stay with your Storm Tracker 6 Weather Team for the latest on this approaching fall storm. To end, I leave you with this image of one model’s depiction of storm total snow fall. Dark pink is 1-2". Note that this is NOT our current forecast.

Justin Thompson-Gee
Storm Tracker 6 Meteorologist