Archive for the ‘summer cool weather’ Tag

Polar Vortex To Take a Summer Vacation Next Week; South to the Great Lakes

Ironically, just over six months to the date of the first notable visit of the winter polar vortex (this is nothing new of course; happens every year but with varying intensities); she is expected to make a return visit mid summer. What IS impressive on this visit (not unlike her past winter visits) is the depth and position south. At early inspection, the upper low “polar vortex” is expected to average around 3 deviations BELOW average for a summer type upper low over the upper Great Lakes. Along with the fanfare of her arrival will be strong upper winds /jet stream/ and possibly some tough weather in the form of wind storms with such impressive energy at and above ground level. When such cold air (for summer standards) rudely plows into even temperate summer like temperatures (in this case 70s to lower 80s), something’s got to give.

The two questions are when and where the best clash of the notably different atmospheres will be; which will be involving very impressive dynamics and instability levels at the time. It’s much too early to give an exact timing but an estimate seems to be in the late Sunday into Monday time frame for it’s arrival – and early – mid week when she spins up over southern Canada and northern Great Lakes. Even at this time, if available moisture is in place, it wouldn’t take much to pop a gusty storm or shower with such cold conditions aloft along with the impressive strong winds.

Projections for upper heights and widespread low level cool temperatures are some of the best (lowest) I’ve seen for mid July. Upper low height projections are sub 550 MB /546 MB/ on the GFS along with 850 MB temperature projections in the single digits. At the coolest (preliminary timing; Tuesday night-Wednesday morning) widespread overnight lows in the 40s to lower 50s are likely across Southeast Lower Michigan with highs around 60 to the mid 60s. If these temperatures are realized, both record low maxs and record low mins may be in jeopardy. Record low max’s for mid July are in around 60 to mid 60s across the region, while record lows are in the 40s to near 50. One glaring exception is a record low max of just 74 degrees in Flint on the 16th, much higher than other record low maxs from the 14th thru the 16th.

Its too early to predict the exact coolness of the air mass due over the area early-mid week during next week but model projections have been pretty well unanimous on this summer cool outbreak – it is coming with the particulars yet to unfold. If you are heading up north this weekend and plan to stay awhile pack for fall-like weather for a few days – LOL- really not a bad idea in Southeast Michigan too.

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