Strong Upper Air Patterns This June Continue to Battle It Out For Dominance!

Anyone watching the upper air patterns these past few months have noted the strong resilience of the cold upper low periodically settling down into eastern Canada. This has partly been resultant of a remarkable oscillating Arctic Oscillation pattern since spring. While this is a somewhat normal event, the strength and tenacity of the strong reoccurring upper low pattern is something to take note of, especially now that we are into summer. Anyone reading my blogs this past several months have seen my discussions on the effect this has had, and will have on Southeast Lower Michigan's weather. My latest Outlook discussed its likely effect this summer:

"I look for the summer to continue to display the more roller-coaster type of temperature pattern (not unlike seen this spring and also dominated, the Spring of '83) with sometimes significantly above, below and everything in-between but ultimately resulting in the normal or typical summer".

Note the active oscillations of late on the Arctic Oscillation:

While every season has its roller-coaster pattern of temperatures, I stated this summer is likely to be more exaggerated at times; due to a new upper low from Canada periodically battling the upper ridge over the south-central to southwest. And thus, this creates a see-saw type pattern over North America. Over the past few months, this has materialized and now, a more contrasting upper air height pattern is expected to form next week. This will result in a battle of air masses set for early in the week.

A strong early summer season upper high pressure area over the Southwest with upper heights pushing up to around 600 dekameters has and will continue to allow temperatures to rise well over the 100 degree mark in that region. The mountainous high pressure will help surface temperatures possibly challenge some all time record highs in that region. It will also influence our temperatures this weekend and Monday with high temperature readings in mid 80s to near 90. 

Meanwhile; the balance between the strong upper high pressure over the desert Southwest and cold upper low in eastern Canada /sub-546 dekameters/ is set to become unbalanced shortly. Meaning; the Canadian upper low is projected to aggressively kick the upper ridge back west and south. The strong upper low will surge southeast once again, toward southeast Canada and bring with it cool, modified Polar air for mid June. It should be noted however; next weekend the upper ridge is once again projected to build once again into the Plains and further northeast with time (the see-saw persists). Models are consistent with this change with varying amplifications and intensities and for simplicity sake, I will stick with the American Model /GFS/.

As it stands now for early next week:

The cooler air from Canada, modified by the summer sun, will plow into the Great Lakes next Monday to Tuesday time frame. Latest indications the cold front will make it all the way into the deep south. It is also during this time frame, the potential rises for severe weather across the Lakes as the cold front dives southeast later Monday into Tuesday. If the potential increases as it is still early, I will send out a FB Weatherhistorian chat.

Note the radical change below in the upper air pattern in just a few days projected by the GFS as the upper low dives southeast and dislodges the impressive ridge west and south!

Also note the cooler, refreshing air is progged to surge well south with reinforcing waves of cooler air pivoting southeast across the Lakes early-mid week. This should push high temperatures back down into the 60s and 70s into at least mid week.

Ironically; the summer solstice this year will also be on Monday June 20th at 624 PM when the expected cold front is slated to move through the Great lakes.

In addition; here's another interesting tidbit about this years solstice: 

This June 20, the Full Moon appears on the same night as the June Solstice! A Full Moon hasn’t occurred on the same day as the Solstice since 1948.

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian



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