Summer 2012 Outlook For Southeast Lower Michigan - UPDATE

                  Summer 2012 Outlook For Southeast Lower Michigan - UPDATE

                  By: Bill Deedler; Southeast Lower Michigan Weather Historian

                                                   July 8th, 2012

Temperatures:

Summer temperatures will continue to average above normal due to earlier discussed dominant ridge of high pressure in the picture. While originally it was thought this would be the case, the ridge has proven exceptionally resilient and containing above normal temperatures as in previous hot summers. This, along with the predominant drier pattern over the region and points west and south (though intermittent convective rains have appeared); will only add to the heat. Originally; I went for temperatures up to two degrees above normal on the warm side and I'm adjusting that upward to; two to around four degrees above normal! If we attain the higher end of the range (around four degrees); that would place the region in the top five hottest summers.

The only saving grace for cooler temperatures over our region has been the periodic plunge of the cooler air from Canada brought on by the large semi-permanent upper low over eastern Canada. Note the pattern expected (below) has appeared with some regularity with the ridge certainly dominant.

Ridging over the High Plains eastward into the Mississippi Valley; will periodically expand east across the Great Lakes and East bringing heat into the region. In spite of the strong upper ridge however; will be the occasional influence of the upper level low and trough that made itself known this spring over eastern Canada when it still was able to penetrate; albeit infrequently, well south into the Great Lakes and Ohio Valley eastward to the East Coast.

Overall; the strong ridge is expected to continue to be a dominant player and will oscillate from the center part of the country to the east; bringing the periods of heat. Normal to below trends will be brought about by the dubious North Atlantic Oscillation /NAO/ cycling lower into neutral to possible negative phases (more below) which would aid in emphasizing the upper low and troughing over central and eastern Canada.

Rainfall:

In my original Outlook, I basically looked for normal to below normal rainfall over much of the region, particularly the southern two thirds. The only change here is expanding the normal to below rainfall over the entire region. While some areas will see normal rainfall; I suspect more areas will see below normal and thus; have a dry summer overall because of the pattern established. My original rainfall Outlook is written below:

 As I look into the summer; I feel this basic pattern will continue with normal to above rainfall from the I-69 corridor north; but normal to below south over the southern two-thirds. 

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