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COMMENTARY

It's a lock: A warm, sunny, dry weekend is heading our way

What is so rare this year as a weekend in spring that, by all appearances, is a "lock?” Those are always risky words when uttered by a meteorologist several days in advance. Yet my confidence level is such I could answer Dirty Harry with, “Yes, this punk feels lucky.”

High pressure will be dominating our part of the continent, supplying drier, sinking air. This trend has been showing for days with unanimity in the models and ensembles of the models. This is what Saturday looks like, following a splendid Friday (in case you’ve got that day off).

The ridge will be centered way up near James Bay, with its large circulation dominating the northeast and the Great Lakes, and a very wet area of low pressure and its front suppressed well to the south by the blocking high. Even though this is a Canadian ridge of high pressure, the atmosphere will get its chance to warm up and produce above average temperatures. Here are the Saturday high temps.

As for any remote risk of rain, National Weather Service headquarters essentially puts the kibosh on that probability.

Therein lies my confidence. As for Sunday, the ridge of high pressure will begin to send us an even warmer SE downslope flow, by which the air coming down the slopes to our southeast warms and dries by compression as it descends to the lake plain.

The downslope component to the wind will bring our high temps to at least the low and possibly mid-80s. Some high, thin clouds leaking up from the south may filter a little of the sun, but count on a high UV index both weekend days, as well as on Friday. As we approach the summer solstice, the high angle of the sun brings UV exposures up to the max. As for boaters, light east to southeast breezes should make for lower wave heights and safe conditions.

Shower and thunderstorm chances will increase by Monday into Monday night ahead of, yes, another cool front. By Tuesday, readings will be back to a little below average:

(NOAA)

As you can see, at this time of the year a “little below average” isn’t bad at all, since the average high is in the low 70s.

Now we’ll segue over to a region where warming is definitely bad news is and tied to climate change. The Arctic Ocean is suffering from record warmth and will continue to do so this month. High pressure is setting up shop right over the polar region near the North Pole, allowing the surface temperatures to reach record or near record levels.

This episodic warming in the high latitudes has occurred more and more often in recent years, and it has sped the impacts of a warmer arctic around the northern hemisphere. Among the most prominent impacts has been the increased incidence of blocking patterns, which have been tied to the inland stalling of Hurricanes Harvey and Florence, and like the long duration of concentrated tornadic supercell outbreaks in the southern and central plains during May.

This is a modeled depiction of the surface features back on Monday, with the dominant warmth in the arctic.

If you look at the orientation of the isobars (lines of equal barometric pressure), the flow favors moving ice away from shorelines and opening more areas to heat-absorbing dark ocean waters, replacing the highly heat-reflective ice. The feedback mechanism tied to such premature melting is greater exposure to the sun’s warming in those waters; record or near record ice minimums in September; and a shorter refreeze season with thinner ice resulting, making for quicker melting the following season. Dr. Jeff Masters of Weather Underground reports that the current warm spell will amplify in the next 10 days, speeding the meltdown. The University of Maine’s Climate Reanalyzer shows the warming at high latitudes, projecting temperatures at or above 32 degrees during this period, which is 2 to 5 degrees Celsius above average.

All this follows the warmest arctic May on record … and that followed a mostly anomalously mild winter, by arctic standards. Even at a time of ice maximum, take a look at this NASA research aircraft photo taken off the northwest coast of Greenland on March 30.

Because of the warmer arctic-more blocking linkage, and the potential we’re headed to the most or second-most ice-free minimum later this summer, it is possible — not conclusive — that this more frequent blocking may lead to more frequent cooler-than-average temperature periods in the Great Lakes and northeast this summer.

As for this month, the Climate Prediction Center gives higher probabilities for more below average temperature days in the second half of the month than above average days.

With that, the least I can do is remind you that “a little below average” at this time of the year might just mean fewer sultry, sticky days than usual, rather than a truly cool summer. Like I already said, that 70 on Tuesday isn’t bad, especially when compared to last Monday’s 50s. I hope you don’t take this as grasping at straws.

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