77 to 45 - 32 degree temp swing at MSP from Monday PM to this morning
Delightfully average - temps next few days in Minnesota
Milder weekend - 70s return but not Indian Summer yet
(see definition below)
Metro color burst? - Why Twin Cities may see best fall colors this year
MSP quick look forecast:
Who knew "average" could be so awesome?
Temperatures the next few days look very close to seasonal averages in Minnesota. Daytime highs in the mid to upper 60s south...and near 60 north are just about average for late September.
This is the time of year where "average" is just fine with many of us. Throw in a little fall colors and you get "awesome."
Not Indian Summer - yet:
As temperatures warm up this weekend you might be tempted to call it "Indian Summer." According to the AMS and every sensible definition I can find, you'd be premature.
It's still way too early for Indian Summer when it was still "actual summer" just a little over 72 hours ago.
Heres' the definiton of Inidan Summer from the AMS, the professional organization for meteorologists.
Indian summer--A period, in mid- or late autumn, of abnormally warm weather, generally clear skies, sunny but hazy days, and cool nights.
In New England, at least one killing frost and preferably a substantial period of normally cool weather must precede this warm spell in order for it to be considered a true "Indian summer." It does not occur every year, and in some years there may be two or three Indian summers. The term is most often heard in the northeastern United States, but its usage extends throughout English- speaking countries. It dates back at least to 1778, but its origin is not certain; the most probable suggestions relate it to the way that the American Indians availed themselves of this extra opportunity to increase their winter stores. The comparable period in Europe is termed the Old Wives' summer, and, poetically, may be referred to as halcyon days. In England, dependent upon dates of occurrence, such a period may be called St. Martin's summer, St. Luke's summer, and formerly All-hallown summer.
According to AMS we can't call "Indian Summer" in the metro anytime soon for 3 reasons:
1) We haven't had a frost in most of the metro yet. While we have seen frost and a hard freeze in much of Minnesota, the inner core of the metro is still frost free...and the growing season continues.
2) It's not "mid to late autumn." Fall began Saturday at 9:49am. It was actually still summer on Saturday morning...just 3 days ago. The AMS definition of "mid-to late autumn" implies at least the second half of October, or early November for true "Indian Summer."
3) It's not "abnormally mild." With the average high still at 67 this week, it's not at all unusual to see temps in the 70s in late September. So right now the forecast doesn't look "abnormally mild" either.
We may still get a glorious Indian Summer this year...but we'll have to wait for frost in the metro and then warm weather in mid-late October or early November. Declaring it sooner is pushing the season.
Metro Colors: Best in show for 2012?
We're getting reports from the MN DNR and photos that suggest some of the most vivid fall color this year in Minnesota seem to be centered on parts of the Twin Cities metro.
What could be causing the metro show?
2012 may be the "perfect color storm" in the Twin Cities.
We saw heavy rainfall at the beginning of the growing season as the trees leafed out in late April and May this year. That meant plenty of moisture for trees to produce excellent and healthy foliage.
As drought set in during late summer, that may have provided additional "stress" to metro trees at just the right time to induce a blaze of color.
Trees in southern & western Minnesota battled drought all year, and may be too stressed to put on the best color show.
Leaf peepers in the metro may be treated to some of the best fall color shows in Minnesota over the next 2-3 weeks.
68F high temp at MSP at 2:59pm Tuesday
68F average high temp at MSP for September 25th
60s again Wednesday
70s return later this week into the weekend
80F possible in southern Minnesota (and the metro) by next week
0" rainfall forecast for most of Minnesota through at least October 3rd
El Nino defies forecasts so far this fall - details below
ClimateCast: Heat wave & drought of 2012 affecting power plants generating capacity -story below
MSP quick look forecast:
Dead on average:
So this is "average" weather!
Tuesday's high of 68 was dead bang on average for September 25th. If you're wondering what September 25th is supposed to feel like, now you know.
There was actually a pretty strong north to south temp gradient across Minnesota Tuesday. I saw 48 in Grand Marais, and 73 in Fairmont...a difference of 25 degrees.
Warming trend resumes Thursday:
We'll (enjoy?) one more "coolish" day Wednesday with highs again in the 50s north & 60s south.
The next warming trend kicks in Thursday and builds into the weekend. Temps should crack 70 by Thursday & Friday, and mid-to upper 70s will return this weekend. This looks like one of the best weekends of fall shaping up...so plan to enjoy accordingly.
Warm southwest breezes and late early October (did I just type "October?") sunshine will boost temps toward 80 degrees again as October kicks off on a warm note early next week.
The milder return to summer like weather for the first full weekend of fall is nice, but comes against a backdrop of deepening drought in Minnesota.
Looking at the medium range models reveals little hope for a good soaking rain anytime soon. The GFS is cranking out a big goose egg for model output rainfall through at least October 3rd.
There are some signs a low pressure system could sweep into Minnesota with decent rains next Thursday or Friday.
Stay tuned on that one.
Reluctant El Nino?
I've talked about the potential (and CPC forecast) for a developing El Nino this winter. Indeed an "El Nino Watch" continues.
But so far tropical Pacific Sea Surface Temperatures (SST's) have been slow to warm.
In fact, some areas have actually cooled slightly in the past 30 days.
Most CPC "dynamic & statistical" models had forecast warming in September. That forecast warming is behind schedule at this point.
El Nino winters show about a 70% statistical bias toward milder than average winter temps in the Upper Midwest. It's not a slam dunk in an El Nino year...and this El Nino has yet to fully develop.
The safe and easy play so far is to suggest that this winter will be milder than average in Minnesota, but probably not as mild as last year. There are still several "plates" spinning that drive seasonal climate... to so speak. We need a little more data on AO, PDO, ENSO evolution etc etc. before we can make a reasonable (but far from certain) outlook that may have some actual value.
Look for the Weather Lab "Winter Outlook" in mid-late October.
ClimateCast: Climate Change affecting power plants access to "cooling water?"
Climate changes seem to be exposing many previously "unthinkable" scenarios.
The record heat wave and drought of 2012 appears to have exposed a significant flaw in the amount of "cooling water" is delivered to many power plants in the USA & Europe. Lower water levels, and warmer water temps make it more difficult to rely on adequate cooling after for both nuclear and coal fired plants.
Low water levels and "overheated water" actually limited generating capacity or completely shut down power plants at times this summer.
The story from Andrew Freedman at Climate Central.
During the scorchingly hot and dry summer of 2012, low water levels and hot temperatures forced several power plants in the Midwest and the East to curtail their output or cease operating altogether for a time. The drought that reached its peak during late summer has been the worst to strike the U.S. since the 1950s, and comparable in some ways to the Dust Bowl-era droughts of the 1930s. Climate projections show that drought conditions as well as heat waves are expected to become more intense and frequent in coming decades as the climate continues to warm.
This past summer there were several instances when power plants had to shut down after running into water temperature thresholds. For example, the Millstone nuclear plant in Waterford, Conn. had to partially shut down in mid-August because the waters of Long Island Sound had become too warm to cool the plant, a development that plant operators had never encountered before.
In July, the New York Times reported that the Braidwood Generating Station, a nuclear plant about 60 miles southwest of Chicago, had to be granted a special waiver to continue operating after the water it was taking in for cooling purposes hit 102°F, two degrees above the legal operating limit for the plant.
And according to an article in the Washington Post, the Illinois Environmental Protection Agency also granted special exceptions to four coal-fired power plants, along with three other nuclear plants this summer, in order to allow them to discharge water that exceeded water temperature limits.
When power utilities have to shut down plants or reduce generating capacity unexpectedly for any reason, it can create power disruptions during peak need and raise electricity costs as provider may have to unexoctedly buy more expensive power on the spot market.
I used to work in Chicago for a weather firm issuing specialized weather forecasts for Braidwood and other ComEd power facilities. Back in those days, low water levels or water that was "too warm" never presented a problem.
Climate changes are increasingly testing many of the "climate assumptions" that were the foundation for engineering much of our society.