Some extraordinary warmth pushed into the region today, with some spots reaching the first 90 degree mark of the year. To help us get there, it took a dry atmosphere. Add in that southwest breeze. Put those together with the sunshine and it was an ideal day to see temperatures spike.
For Rochester, the mercury reached 90°. It wasn't record setting, but a few places did manage to break some records. The cities that did break records likely did not have records extending back to 1934 because as you can tell, that was a very warm May day.
This was a very early first 90 degree reading of the year. It was tied for our 6th earliest in the Rochester record books. The earliest in recorded history is April 21st in 1980. Average is 1980.
Compare that to last year, where the first (and only) instance was June 9th. 2014, we didn't even reach 90 degrees. So for this 'summer', we've already matched the amount of hot days we had in the previous two summers combined!
Okay. Now to the cool stuff... and why I'm writing a blog on this. Minnesota was one of the warmest states in the US today and even had some cities in the running for warmest in the entire US until the far south end of Texas stole that away... Places along the North Shore, like Two Harbors and Duluth included.
Upon looking at surface observations beginning my forecasting today, I noticed an oddball. Waaaaay up in the arrow head of Minnesota sat Grand Marais at 45 degree. 45!
It has to be an error, right? Just 80 miles away, Two Harbors was scorching! Not, one, bit. That 45 degree reading was 100% correct. So why the difference in a short distance? You can thank Lake Superior for that!
A lake breeze was very evident as winds were out of the east for most of the day in Grand Marais. Meanwhile, the rest of the state had warm, southwesterly winds. In fact, Duluth and Two Harbors were likely aided in warming by the wind direction due to an atmospheric effect called 'downsloping'. The downslope effect helps dry the surroundings and in turn helps to increase the temperatures. At least to some effect, I would say that helped some of those areas as the wind descended down the bluffs towards the shore line.
But to the northeast, the persistent lake breeze feeding off of 30-some degree Lake Superior waters didn't budge.
Here's an example of a lake breeze.
By the way... cold air always wins, since it is more dense that warm air. If the wind is carrying the cold air your way, it will move in. That's exactly what happened today.
But, upon closer inspection, I noticed another temperature observation only SIX miles away from the shoreline observation which was 35 degrees warmer. This location at the Grand Marais/Cook Co. Airport, which sits hundreds of feet higher than the shore line. The terrain, prevented the locally cold air off of Lake Superior from rising up to the level of the airport and the cold air pooled down at the lower elevations
This is one of the tightest temperature gradients I have ever seen in my 8 1/2 career as a meteorologist, if not the tightest. Often times we share potent cold fronts that will drop the temperatures 45 degrees over 80 miles like the first example above shows. But with no large scale weather feature to separate Grand Marais with the airport, it is most certainly very impressive.
It's things like this that keeps me interested in the weather world. Meteorology is so amazing and this is just one of those things that drives me.
Storm Tracker 6 Chief Meteorologist