GAME CHANGERS VS SEASON CHANGERS...
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In the world of weather we have storms that we consider game changers. These usually are strong systems powerful enough to break and often change a pattern, sometimes for weeks at a time. Wet to dry, hot to cool, that sort of thing.
Then there are what I like to call season changers. Every spring and fall, we get a significant storm that brings in the first big blast of hot or cold air that signals this is the type of weather that's going to be the norm going forward. It's what I call the hand off of seasons. It's abrupt, unmistakable, and a wake up call that summer has left the building
Within the next 24 hours were going to get the inevitable call, winter is waking up and gaining a foothold.
Here's what such a storm looks like at the jet stream level (500mb) The closed upper air low over NC Minnesota.
Here's what temperature departures look like at the surface Friday morning. Warm VS cold!
Moisture (water vapor) departures Friday morning. Wet in the warm sector, much drier in the cold sector.
The pressure and precipitation depiction early Friday. Deformations snows west of the low. Warm sector rain ahead of the powerful cold front.
Total snow GEFS
Max wind gusts. Most areas 35-40 mph.
Wednesday evenings GOES satellite showing the storm coming together.
The previous 8 images are all reflections of what a season changing storm looks like to a meteorologist like me. Clearly the area that really gets hammered is the northern Plains. Some parts of North Dakota have a 50% chance of seeing at least 24 inches of snow. Bang the gong, those would be historic totals. There are likely to be major travel disruptions, downed trees and power lines with power outages, along with significant impacts to agricultural and livestock.
Winter storm warnings and watches cover much of the Dakotas.and NW Minnesota. Some areas will likely be upgraded to blizzard warnings which is astounding for early October!
In my area the 3 key impacts will be rain, wind, and dramatically colder temperatures. Prospects for a freeze are quite high. All of the areas in red have a 90-100% chance of see a temperature of 32 or below by Saturday morning. Frost and freeze warnings will likely be issued in the next 24-48 hours as conditions become more apparent. The one savior that could keep parts of my area from a hard freeze (28 or below) are the winds. They should stay quite brisk with enough mixing to hold readings in that 30-32 range. We'll worry about that later.
To give you an idea of the magnitude of the cold shot, all these areas in red have 90-100% odds of temperatures being at least 20 degrees below what is typical.
As for the rain, that will be around on an occasional bases through Thursday night, especially before midnight. It ends abruptly when the cold front hits with its dry slot, wind, and falling temperatures. WPC has this as their official rain forecast. I could see some locally higher amounts well over an inch but the banded nature of it makes it hard to say where at this point. I would think most spots can expect at least 1/2 inch in my area with the potential for more.
Last but not least the cold air that wraps into the region Saturday will create steep lapse rates. That should bring low clouds that will keep things very brisk all day. The wind chills Saturday morning should be down around 19-20 degrees. That will get your attention!
There is still a chance a few flurries or snow showers could pop up Saturday but the area along and north of HWY 20 stands the best chance of seeing any flaky objects. By the way the Iowa Penn State game will be plenty fresh with readings into the upper 30s and wind chills close to 32. I would suggest the heavy coat and a reliable anti-freeze. Roll weather...TS