Minnesota is on a weekend weather winning streak.
A mild high pressure cell drifts lazily overhead this weekend. The exquisite timing means another mostly sunny and mild weekend. Fall colors are beginning to pop up north. Lakes are still warm enough for a late season swim for the brave of heart.
We count and savor the sunny warm days at 45 degrees north latitude this time of year. Our internal Minnesota genetic weather ticker knows there are only so many top 10 weather days left before the seasonal curtain drifts closed. I still think this fall will be a long pleasant affair.
The latest maps suggest another warmer than average week next week, and 70s and even a few 80s as we turn the corner into October.
Does it get any better than this?
Get. Out. There.
High pressure: Timing is everything
Yes, timing is everything in life and in weather. If they made me Weather Czar for Minnesota (a scary thought) I would probably schedule big sprawling fair weather high pressure cells every weekend. Actually, a cool rainy Sunday occasionally can also be a blessing. Not this weekend. Enjoy the sun fresh September air mass.
Seven day forecast: Summer returns?
Let’s cut to the forecast chase. You can’t draw it up any better for the last weeks of September.
The most advanced weather model on the planet in terms of sheer computing power and resolution is the European Centre for Medium-Range Weather Forecasts model.
Here’s the Euro output through next weekend for the Twin Cities. First, a perfectly pleasant fall weekend with dew points in the comfy 40s and temps in the low 70s. Next, a return to southerly wind flow and summer like weather next week. Four more days at or near 80 degrees with another glorious weekend next weekend?
Somebody pinch me.
We string together at least three or four mainly dry days in a row through the middle of next week. A good opportunity to dry out after another timely but heavy rainfall.
Here’s another look at the record deluge that fell from the Twin Cities east into Wisconsin Thursday.
NOAA’s Global Forecast System model hints at another potentially significant soaker next Wednesday night into Thursday.
As always don’t become attached to the magnitude of longer range forecast output, but pay attention to the trends. There’s more skill there.
Fall forecast: Mild bias lingers into October?
Overall trends seem to favor a mild bias into early October for the Upper Midwest, and most of the lower 48.
Right now, I don’t see an early frost in the cards for the Twin Cities and southern Minnesota. The average date for the first 32 degree temp in fall at Minneapolis-St. Paul International Airport? Oct. 6.
NOAA’s experimental three week outlook paints a mild bias across most of the U.S. into mid-October.
Our endless Summer of 2015 lingers on, for now.
El Nino Update: Game on
Pacific sea surface temperatures continue to show a bold ribbon of much warmer than average water. Sea surface temperatures exceed +2 degrees Celsius over a big chunk of the tropical Pacific now.
Here’s more from NOAA’s latest El Nino update.
ENSO Alert System Status: El Niño Advisory
There is an approximately 95% chance that El Niño will continue through Northern Hemisphere winter 2015-16, gradually weakening through spring 2016.
During August, sea surface temperature (SST) anomalies were near or greater than +2.0°C across the eastern half of the tropical Pacific (Fig. 1). SST anomalies increased in the Niño-3.4 and Niño 3- regions, were approximately unchanged in the Niño-4 region, and decreased in the Niño-1+2 region (Fig. 2).
Large positive subsurface temperature anomalies persisted in the central and east-central equatorial Pacific during the month (Fig. 3), with the largest departures exceeding 6°C (Fig. 4). The atmosphere remained coupled to the anomalous oceanic warmth, with significant low-level westerly wind anomalies and upper-level easterly wind anomalies persisting from the western to east-central tropical Pacific.
Also, the traditional and equatorial Southern Oscillation Index (SOI) were again negative, consistent with enhanced convection over the central and eastern equatorial Pacific and suppressed convection over Indonesia (Fig. 5).
Collectively, these atmospheric and oceanic anomalies reflect a strong El Niño. All models surveyed predict El Niño to continue into the Northern Hemisphere spring 2016, and all multi-model averages predict a peak in late fall/early winter (3-month values of the Niño-3.4 index of +1.5°C or greater; Fig. 6).
The forecaster consensus unanimously favors a strong El Niño, with peak 3- month SST departures in the Nino 3.4 region near or exceeding +2.0°C. Overall, there is an approximately 95% chance that El Niño will continue through Northern Hemisphere winter 2015-16, gradually weakening through spring.
What about Minnesota this winter?
NOAA’s latest El Nino update confirms my earlier thinking that the smart money is on a (much?) milder than average winter for Minnesota.
It’s not a slam dunk, but the odds of a milder than average winter during strong El Nino years is over 70 percent for Minnesota and the Upper Midwest. The biggest El Nino events of 1982-83 and 1997-98 produced winter between 8 and 11 degrees warmer than average in the Twin Cities.
How about snowfall?
Winter snowfall in El Nino years? A bigger role of the dice. It could go either way. Even when you’re 10 degrees warmer than average in January in Minnesota, it’s still usually cold enough for snow.
El Nino winter can still be big snow producers. My hunch is for below average snowfall in southern Minnesota with more snow up north. Keep in mind there is much less skill at predicting snowfall in El Nino winters in Minnesota than with temperature.
Here’s a good primer on the typical winter effects from El Nino on the U.S.
When an El Niño develops, it can start a chain reaction in the atmosphere influencing the weather in places much farther away from the tropical equatorial Pacific Ocean, including the United States. This means certain changes to the typical climate, or long-term average for temperature or precipitation, for folks in some parts of the U.S. Climate is like the tides. Just like the tides roll in and out, our climate warms during the summer and cools during the winter. El Niño’s would be like changing the level of those tides in some places. Perhaps they come in a little higher or earlier now, getting you wet before you have a chance to move your blanket back.
The map above highlights areas of the U.S. that experience temperature or precipitation conditions that may be different from normal when an El Niño is present. Impacts from El Niño are most noticeable during the late fall through early spring months. During late spring and summer, climate patterns may not be affected at all.
Not every El Niño event leads to the same climate conditions, however, and the strength of the El Niño event can have an impact on just how warm, cool, dry, or wet the affected areas become. As of summer 2015, the current El Niño has strengthened over the past few months, with a strong event currently favored during the late fall and early winter, according to the latest report from the Climate Prediction Center.
In instances when a strong El Niño occurs, there can be large impacts to communities and the U.S. economy. Strong El Niños are often associated with heavy winter rains across California, which could bring much needed moisture to a region devastated by drought. Even if above normal precipitation falls across California, one season of above-normal rain and snow is very unlikely to erase four years of drought.
Meanwhile, heavy rains in the southern half of the U.S. could lead to flooding causing widespread damage to towns and communities, lives and livelihoods. In addition, El Niño could elevate the risk for severe weather across the Southeast during winter. On the other hand, above-average late fall to winter temperatures across the northern tier of the U.S. might mean a milder winter and lower energy costs. It’s important to understand that a strong El Niño only favors these impacts, but doesn’t guarantee they will happen.
Climate Generation event in Mankato Monday evening
Please join me as we talk about climate change in Mankato Monday evening at Will Steger’s Climate Generation event at South Central College.
In light of this week’s incredible climate change news linking drought and devastating western fires and record summer heat globally this should be a great opportunity to talk about how climate change is affecting us here in Minnesota and worldwide.
Hope to see you there.