We made it through Halloween without any spooky weather incidents, but November can be a scary weather month in Minnesota.
First the good news. The upcoming weekend looks pretty decent. Now the slightly scary news? The weather maps are starting to look much more chaotic by mid-November.
People sometimes ask me if on time of the year is more difficult to forecast. My answer is “November.”
Late fall brings large changes in the speed and configuration of the jet stream. Large hemispheric “long waves” jockey for position this time of year. Dramatic shifts in the so called ‘wave train’ can cause sudden changes on the position of cold and warm air. The weather maps have a difficult time keeping up as small errors in the position and intensity of pressure systems can quickly magnify in just a few days.
It’s buyer beware for forecasts beyond about five days in November. You should have to sign a weather waiver before reading projections any farther out, including this space.
That said, November chaos seems to be ready to take over the weather maps in the next two weeks. Stay tuned.
Nicer weekend ahead!
For once, the timing seem good. Our dreary wet week wraps with a few stray showers Friday, then skies look to brighten just in time for the weekend. I’m still waiting for a lot of leaves to drop from the trees at the Weather Lab in the west metro.
Here’s the latest ‘weather briefing’ from the National Weather Service office in the Twin Cities.
Skies may open enough to see a little sun this weekend around Minnesota. Saturday looks less windy, a good day to pull the boat or get some leaves up. Sunday looks breezy from the south, but milder with highs in the 50s.
Here’s the Euro take on the weekend laid out in a nice graphic from Weatherspark.
On the edge of snow next Tuesday?
I’m eying a potential weather system in the Central Plains next Monday and Tuesday. It looks warm enough for all rain showers Monday with temps in the 50s.
Tuesday could be a different story. One of the little weather tricks meteorologists use is to track the so-called 540 decameter line as the rain/snow boundary. It’s not perfect, and there are other methods like the 850 millibar (around 5,000 feet above ground) freezing level that approximate rain snow boundaries.
The 540 line is setting up close to Minneapolis-St. Paul late Tuesday, and that could be near the back edge of low pressure tracking into eastern Iowa late Tuesday night.
It’s way early to be precise, but we’ll have to watch how this system evolves on the weather maps over the next few days.
The Global Forecast System model is hinting at some minor accumulation potential for the metro. I’m not holding my breath, but I’ll keep one eye on this.
After that the weather maps start to look a little more chaotic by mid-November. Stay tuned for some potentially rapid weather changes in the month ahead!