Spring Upper Air Pattern
The latest view of the upper winds and the anomaly from mid March thru mid June continues to show the strength of the upper low and cool pocket over Canada.
Summer 2020 into September
Temperatures
Normal
Normal
Normal with notable swings at times for the summer period. Look for periods of above normal temperatures and below normal with sometimes exaggerated departures. One eye on the present upper air pattern and they other on the
analogues do in fact suggest a continuation of our spring pattern. Yes, even with heatwaves (temps
around 90 and above); still both prevailing patterns suggest there will be notable
reprieves from the hot spells with refreshing cool air masses surging out of Canada.
In the end; I look for summer temperature departures to average -1.2 below to 1.8 degrees above across Southeast Lower Michigan in keeping with upper air patterns and analogues.The more dominant upper air pattern will dictate the summer departure in the end
Precipitation
In the end; I look for summer temperature departures to average -1.2 below to 1.8 degrees above across Southeast Lower Michigan in keeping with upper air patterns and analogues.The more dominant upper air pattern will dictate the summer departure in the end
Precipitation
Above Normal to Below Normal (a wide range)
This is a tricky one as even with summer's below normal -to normal- or even above normal already in place; there is a significant trends for drier patterns in place. Thus far; June has been drier than average (up to an inch or two) over southern areas of Southeast Lower Michigan, while normal or even above in the far northern suburbs into Flint and Port Huron to the Saginaw Valley and Thumb.It seems that above normal to below normal rainfall again seems the most realistic as with many of our summers.
Analogues Data
Temperatures
When just looking at the analogues; right off the bat, it looks like cool weather relative to normal is precedent in the data. While cooler summers were slightly more dominant /8/, there still were six normal summers and even a warm summer...so basically 8 to 7 cool to normal/warm. A mixed result and with the pattern we've seen the the past few months; this clearly is understandable and almost a given when we review our upper pattern. The variable temperature forecast seems most suitable given guidance and pattern - ending within the normal range. Analogue departures on the whole, seem too cool for the summer.
Precipitation
What about rainfall? Projected summer patterns are just as important for precipitation as they are for temperatures; especially if a gardener or farmer.
Again while somewhat mixed; there is a definite lean toward a drier summer on the analogues especially southern areas while models are mixed. Still; there is enough variation that; like temperatures, precipitation trends also showed four wet summers; four normal rainfall summers against the seven drier summers.
Even more to the point is where and when the likelihood of a dry spell or two was to occur and while data suggests there was enough variability to be anytime, the precedence was during early to mid summer.
Maps
Upper Air Variations
The upper 500 MB pattern this spring continues albeit weaker with the advent of summer. Note; the 500 MB pattern trend variations in an example of recent guidance for the remainder of June fits well with what's intimated by analogues for the summer; a rather aggressive jet.
Severe Weather
Keeping in mind the contrasting patterns would also suggest bouts of severe weather - mainly depending on timing and available instability.
Model Views for summer temperatures and rainfall
/CFSv2/
Other World-Wide models combined
Look for other notable weather write-ups and trends through the summer if conditions warrant.
