Typical Peak Color
According to the MN DNR, here is the typical peak of fall color across state. Note that fall colors typically peak across the international border mid to late September, which is only a few weeks away. Meanwhile, peak color in the Twin Cities metro generally isn't until around MEA Weekend.
What Causes Fall Color?
The following information is from the MN DNR via Joe Zeleznik, Extension Forester, North Dakota State University. 2007. Fall Colors of North Dakota. Pages 15-16 in North Dakota Climate Bulletin.
"What Causes Fall Color? The Chemicals! Four main groups of biochemicals are responsible for the various yellows, oranges, reds and browns that we see in the fall:"
"Each has its own color and chemistry. As the amount of these chemicals vary, they will cause subtle variations in color from one leaf to the next, or even from tree to tree. "
"The green color that we see on most plant leaves throughout the spring and summer is caused by a pigment called chlorophyll. Chlorophyll is one of several pigments that gather energy from sunlight in the process of photosynthesis. Chlorophyll absorbs both the blue and the red wavelengths from sunlight, and reflects the green wavelengths. Nitrogen is one of the main components of chlorophyll. As our days shorten and temperatures get cooler, chlorophyll is broken down faster than it's produced. The majority of the nitrogen migrates back to the twigs, where it is stored for next year's new growth. As chlorophyll breaks down, the carotenoids are revealed."
"Many of the yellows and oranges we see in nature are the result of carotenoid compounds. They are what make carrots orange! Carotenoids play a minor role in photosynthesis—they are present throughout the growing season, but are only revealed when chlorophyll breaks down. You are more likely to see brilliant colors when the fall weather has warm, sunny days with cool nights between 32° and 45 °F. Look at a leaf that has been grown in the shade, and you may notice it is a duller color than leaves that grew in the full sun, even on the same plant."
"The reds and purples you see in the fall are caused by anthocyanins, which are what you get when sugars combine with compounds called anthocyanidins. Many things affect the exact color produced by anthocyanins, including the pH (acidity or alkalinity) of the cell sap in the leaves. With an acid pH, anthocyanins are often red; with a more alkaline pH they turn purple-to-blue. Because anthocyanins need sugar for their creation, weather that favors photosynthesis (sugar production) is essential. Bright, sunny fall days produce the best colors. Very little photosynthesis occurs on cloudy days, and rain can actually leach the anthocyanins and carotenoids out from the leaves. Different combinations of anthocyanins and carotenoids can result in there being yellow, orange and red leaves all on the same tree at the same time. The exact color a tree produces will vary from year to year. Some people believe they can force a more brilliant red color by adding acid-forming fertilizers to the tree, especially aluminum sulfate. This method may sound like it should work, but there is no scientific evidence to support it."
"In many forests, oak trees don't add much to the collage of fall colors. They often just turn brown, thanks to a group of compounds called tannins. Tannins are revealed when both chlorophyll and carotenoids break down in the leaves. Some oaks do produce a light red or pink color in the fall, but our native bur oak does not."
(Image below courtesy MNDNR via Park Staff at Mille Lacs Kathio State Park)
How Does Weather Affect Fall Color?
The following information is from the MN DNR via Val Cervenka, DNR Forest Health Specialist.
"Here's why fall colors vary from year to year and place to place:
Weather is most critical in determining the colors displayed each fall.
Colors are best when high quality foliage - a product of a warm, moist summer is exposed to sunny, cool fall days.
Light frosts may also help, but hard freezes can ruin the display.
Physiological stresses placed on trees can impact fall colors.
Cool, we summers can cause premature displays of color.
A mild summer drought may actually increase the display, but severe drought usually dulls colors noticeably. In some cases, foliage may die early and turn straw-colored due to a lack of water.
The slightest changes in weather in September - too warm, too cold, too wet, too dry - can slow color change or cause trees to drop leaves before they change color.
Becuase it is too dry to produce the vibrant reds, yellows, and orages, a severe summer drought will create a landscape filled with the subtler colors of tans, bronzes and auburns."
(Image courtesy MN DNR via Park Naturalist at Fort Snelling State Park)
Minnesota Crop Update
The information below comes from the MN USDA...
Precipitation Potential Through PM Monday
Here's NOAA's NDFD precipitation potential, which shows that most of the accumulations will be found in the northern tier of the state with some 0.50" tallies possible.
Northern Snow Potential
As this system moves in, there could be some minor snow accumulations. Keep in mind that the ground is still fairly warm, so much of this will melt on contact, but there certainly could be some stuff that sticks!
Weekend Weather Outlook
Weather conditions on Saturday will be wetter as the storm system scoots through. Most of the precipitation, including snow, will be found across the northern half of the state. Cooler air will settle in on Sunday with high temps possibly not even making it out of the 30s.
Saturday Weather Outlook for Minneapolis
Sunday Meteograms for Minneapolis
Saturday will be chilly and somewhat soggy with rain chances moving through during the first part of the day. It'll be a bit breezy with winds exceeding 20mph much of the day.
Sunday Weather Outlook
Saturday will be a chilly day across much of the region with high temps staying below average for this time of the year. Note that most locations in the northern half of the state will stay below average by nearly -10F to -15F.
Extended Temperature Outlook For Minneapolis
The extended outlook looks quite chilly with highs staying well below average and getting ever cooler by the end of the week. Wait, is that snow in the forecast for Tuesday?
Extended Temperature Outlook For Minneapolis
The extended outlook through the end of October shows some pretty chilly temps. It definitely looks like late Fall weather with highs only warming into the 30s and 40s. We might even see temps only warming into the 20s later this month.
Average First Frost Minneapolis
The average first frost in the Twin Cities is typically around mid October. Note that we had our first official frost in the Metro on the morning of October 4th. The temperature at the KMSP Airport dropped to 32F on Sunday the 4th, which is about a week and a half earlier than normal (October 13th).
Average First 1" Snowfall at MSP
The first 1" of snow typically happens around the 3rd or 4th week is November. The lastest first 1" of snow didn't fall in the metro until January 1st, back in 2005!
Warmer With Some Sun Saturday
By DJ Kayser, filling in for Douglas
Who is ready for winter? I'm guessing a lot of you might have groaned looking out your window Friday morning as a batch of snow moved across the metro, heavy enough at times to coat the ground before innocently melting away. The average first measurable snow (0.1"+) in the Twin Cities over the past 30 years is November 6th. Last year it occurred on November 1st. Just a harsh reminder that winter will be here soon.
A few showers will be possible early this morning across the Twin Cities, but skies are expected to clear into the afternoon hours with highs climbing into the 50s. Meanwhile, the first significant snow of the year will continue to fall across portions of northern Minnesota where some could pick up 2-5" through the evening hours.
For those that would like to keep today's warmer temperatures around, I have some bad news. Highs plummet back into the low 40s on Sunday and look to remain mainly in the 40s next week with occasional chances of some rain and, yes, even some snow showers.
SATURDAY: AM showers, PM sun. Winds: W 10-15. High: 54.
SATURDAY NIGHT: Mostly cloudy. Winds: WNW 10-15. Low: 31.
SUNDAY: Mix of sun and clouds. Cooler. Winds: NW 5-10. High: 42.
MONDAY: Mainly cloudy. PM rain/snow shower? Winds: W 5-10. Wake-up: 28. High: 43.
TUESDAY: Early rain/snow mix, becoming all rain. Winds: SE 5-10. Wake-up: 32. High: 45.
WEDNESDAY: Sunny start, but clouds increase. Winds: SW 5-10. Wake-up: 34. High: 48.
THURSDAY: Rain moves in. Snow to the north. Winds: SE 5-10. Wake-up: 37. High: 48.
FRIDAY: More clouds than sun. Winds: W 5-10. Wake-up: 32. High: 43.
This Day in Weather History
1971: Heavy rain falls in NW Minnesota. 4.02 inches is recorded at Georgetown (20 miles N of Moorhead).
1952: Record lows between 10 to 15 degrees are reported across central Minnesota, including a low of 10 at St. Cloud, 12 at Glenwood, and 14 at Alexandria, Litchfield, and Mora.
Average High/Low for Minneapolis
Average High: 61F (Record: 85F set in 2015)
Average Low: 41F (Record: 22F set in 1876)
Record Rainfall: 1.36" set in 1881
Record Snowfall: 0.5" set in 1977
Sunrise/Sunset Times for Minneapolis
Hours of Daylight: ~10 hours & 52 minutes
Daylight LOST since yesterday: ~ 3 minutes & 00 seconds
Daylight LOST since Summer Solstice (June 20th): ~ 4 hour & 45 minutes
Moon Phase for October 17th at Midnight
1.5 Days Since New Moon
What's in the Night Sky?
"The closest new moon of the year was October 16, 2020, at which time the moon was transitioning out of the morning sky and into the evening sky. On October 17, some people might spot the young moon’s rebirth at day’s end. If you do see it, the moon will be low in the west, in the glow of sunset. Be forewarned … this young, pale, fragile crescent after sunset October 17 will be a challenge to spot, even with binoculars, especially from Northern Hemisphere locations. It’s hard to spot a young moon that’s less than a day old (less than 24 hours after new moon), especially in the autumn. If you want to try your luck on October 17, be sure to find an unobstructed horizon in the direction of sunset. Find a hilltop if you can. Bring along your binoculars! Southern Hemisphere viewers will have an easier time spotting the young moon on October 17 than those of us north of Earth’s equator. That’s because it’s spring now in the Southern Hemisphere, and springtime young moons are the easiest to see. From everywhere worldwide, the young moon will appear as a fatter crescent, farther from the sunset and easier to spot, on the evenings of October 18, 19 and 20. Day by day, a wider lunar crescent will appear higher up at sunset and will stay out longer after sundown."
(Image Credit: EarthSky.org)
National Forecast Map For Saturday
The National Forecast on Saturday looks quite a bit more active across the northern half of the nation with areas of rain/snow possible.
National Weather Outlook
Here's the national weather outlook through the weekend, which shows areas of rain and snow across the northern tier of the nation. Note that the potent cold front will settle south across the Southern Plains in a few days.
Delta Rains Move Northeast; Heavy Precipitation in the Northwest.
Here's the 7-day preciptation outlook across the nation, which shows some fairly heavy amounts across the Central US and into the Great Lakes. A few areas in the Northwest will see heavy precipitation, but much of the Southwest will remain dry.
National Snowfall Potential
The national snow over the next several days suggests areas of decent snowfall potential as we enter the back half of October.
Ongoing Wildfires in the Western US
Take a look at how many ongoing wildfires there are across the Western US. Of course it has been extremely hot and dry as of late, but recent thunderstorms have resulted in hundreds of new fires since last week. Cal Fire reports that:
Today Nearly 9,000 firefighters remain on the frontlines of 21 wildfires across the state, 12 of which remain major incidents. Yesterday, firefighters across the State responded to 29 new wildfires, and despite Red Flag Warning conditions in many areas, all were quickly contained. A Red Flag Warning remains in effect through today in much of Northern California, as well as the mountain regions of Southern California. Critical fire weather, including gusty winds, low humidity and unseasonably warm temperatures continue throughout the day in these areas. Weekend temperatures are expected to cool slightly, but conditions remain dry with no precipitation forecasted for the next week. Since the beginning of the year, there have been over 8,500 wildfires that have burned well over 4.1 million acres in California. To date, the total number of fatalities statewide is 31 and more than 9,200 structures have been destroyed.
The tropics aren't dead yet. There are still a couple of areas that the NHC is monitoring. Will this be the most active Tropical Season on record? Stay tuned!!
Secondary Spike in Mid October?
While the peak of the Atlantic Hurricane Season is behind us (September 10th), there is usually a secondary spikes that happens around mid October. Things are rather quiet in the Atlantic now, but don't let your guard down, things could still get interesting. Stay tuned...
No More Regular Alphabet Names
It has been an active season so far as we've used up all 21 names that NOAA's NHC set for the year. Interestingly, Tropical Storm Arthur developed back in mid May, more than 4 months ago! Since then, we've had a total of 9 huricanes!
We're Into the Greek Alphabet - First Time Since 2005
Not only did we use up all 21 names in the list above, but we've entered the Greek Alphabet, which is only the 2nd time in recorded history that we've done that and the first time since 2005. Delta became the 25th named storm and the 9th hurricane of the 2020 Atlantic Hurricane Season.