Freeze warnings out for much of northern & central Minnesota tonight
20s in International Falls, Ely, Brainerd Duluth & Hibbing
Frost likely even in metro suburbs Tuesday morning
39 at MSP Airport Tuesday morning?
Kinder & gentler: Much milder next week
Scattered snow showers possible in northern & central Minnesota tonight & Tuesday
Growing fall snow indicators for Minnesota this year?
The real deal:
Enough for beach & summer babble this week.
The season's strongest cold front delivers the first frost & freeze for many Minnesota & Wisconsin locations tonight.
With Monday morning temps already in the 30s in northern Minnesota, this air mass is plenty cold enough to deliver sub-freezing temps for several hours up north tonight.
Frost in the metro suburbs?
I'd bank on it in the north & east metro suburbs tonight...and even south & west of the metro by Tuesday morning. The inner core of the metro (inside the I-494/694 ring) will likely escape frost tonight...but even MSP Airport could dip to near 39 by around 7 am Tuesday.
Kinder & gentler by midweek:
The weather will mellow over Minnesota by Wednesday as highs return to the 60s statewide, with a stray 70 not out of the question.
The milder spell will be short...as a second punch of colder air sags south Friday into the weekend.
There will likely be another frost/freeze and high may not climb out of the 50s Friday & Saturday.
At this point, it looks like we may get an extended spell of mild sunny weather next week. The 70s could return.
Growing indicators of possible early season snowfall in Minnesota this year?
Yes, we're transitioning into an "El Nino" phase this winter...and the odds overall favor another milder than average winter in Minnesota.
That said there are some growing indications that early snowfall is a possibility for parts of Minnesota this fall.
1) "High Amplitude" Jet Stream pattern:
After taking a long summer vacation in northern Canada, the jet stream has returns to Minnesota. Today's cold front is the result of a large dip or "trough" in the "polar front" jet stream.
Large north to south undulations in the jet stream have evolved lately over the northern hemisphere. This "high amplitude" pattern looks to become "progressive" ...meaning it will deliver shots of cold air south into Minnesota like this week...followed by much warmer spells like the one I'm seeing for next week.
If the cold (sub-freezing) air dips in the jet "phase" with moisture at times this fall...we could see an early shot of accumulating snow in parts of Minnesota.
2) Hudson Bay Vortex: Setting the table?
This week's upper air pattern...and family of cool fronts is brought to you by the "Hudson Bay Vortex."
This swirling pool of unseasonably cold air is dealing cold shots south into Minnesota this week.
If the Hudson Bay Low becomes a frequent feature this fall...it may keep enough cold air coming south to change potential rain systems to snowy "Clippers" in parts of Minnesota.
3) Above average early Siberian snow cover:
One emerging and "sexy" predictor in forecasting winter weather in the USA is tracking early snow cover in Siberia.
Above average fall snow cover in Siberia can be an indicator of colder than average weather in the USA.
Last fall snow cover ran below climatology in Siberia. Today, snow cover is running above climatology in Siberia and northwest Canada's Yukon Territory.
This has the potential to chill air masses, and shift the jet stream to deliver colder air into the USA at times this fall.
4) El Nino transition:
The backdrop of the developing El Nino this winter suggest milder weather overall. But as we transition into El Nino this year...it's worth remembering that 1991 was also a developing El Nino year.
I'm not saying we're going to see another early season blizzard like the infamous "Halloween Mega-Storm"...but it's worth noting that big snows have happened in a developing El Nino year.
As we say in the weather biz....stay tuned!
Freeze warnings out for northern Minnesota
20s in most of northern Minnesota Tuesday AM
Frost advisories out just north & west of the metro
30s in (especially northern) metro suburbs
Fall color change accelerating in Minnesota
Frosty start Tuesday:
Well it is mid-September after all.
The season's coldest air mass is here, and the freeze is on "up north."
Even some metro suburbs will see a touch of frost early Tuesday.
When it comes to plants there is a big difference between a light frost and a "hard freeze." Many plants may survive a light frost, but several hours of temps below 28 degrees can freeze out sensitive annual plants.
It's hard to say we're too far ahead of schedule with Tuesday's frost/freeze. The average date for the 1st 32 degree temps at MSP in fall is October 7th. In the northern metro suburbs that's closer to September 24th. But "average" is made up of extremes...so September 18th is definitely "in bounds" for frost in the north metro.
Colors change accelerating:
Last Thursday I made the drive up to beautiful Grand Marais. I was a little surprised to see relatively few pockets of color along the way.
Different ball game on the way home Sunday.
I was pleasantly shocked at how fast the colors exploded along the ridges above Highway 61 and along I-35 north of Hinckley.
There are now splashes of yellow & red color all over the place, and the sumac are putting on a vibrant red show of red along I-35.
"Peak Color" ahead?
It seems many Minnesotans are enamored with the concept of finding the elusive "peak color" each year.
Defining...and finding "peak color" is a subjective art. Individual leaf peepers enjoy different intensity and types of color. Color changes can be highly localized and determined by drought stress, local temperature patterns and mix of trees & other vegetation.
When people ask me about finding peak color...my answer is usually the same. Just plane for the last two weeks of September or early October and enjoy the journey.
Often times leaf peeping is what you make of it...and I find that the colors seem to be spectacular just about every year in Minnesota.
I frequently post updated DNR fall color maps this time of year on Updraft.
Source: MN DNR
Here's another excellent resource for tracking fall color changes in the Superior National Forest.
Thanks to Steve Robertson form the U.S. Forest Service for the info.
I heard you mention the DNR fall color site the other day on my drive home, and I wanted share with you that there is also a fall color website for the Superior National Forest. It has current conditions, fall essays, and photos.
So far, phenology wise, this has been a weird color season. ...It is pretty hard to write concise reports this year though, it is all over the board for levels of color. Even the tamaracks in some places are done, and they don't even usually start until mid October.
Attached is the other very useful tool we use as a predictor.
Hope you had fun in Grand Marais.
Thanks for saying more in one picture than I could in an entire post Steve. Do I get paid by the word?