I am sure you have all heard of the cooler than normal weather pattern shaping up, sad to say this is our main weather headline for awhile. I don’t see an early frost (yet) for southern Michigan though there will be for Gaylord to the north. The CPC is saying we will be below normal through the 22nd of September (at least).
The good news is there is no snow coming in the near term with the exception of northern Alaska where they have a nice coating on the ground. In my mind it can stay there until November. I think we will end up with August and September being below normal temperature and precipitation wise. Have we turned the corner with our long run of above normal temperatures? We shall see when I start looking at this years winter forecast…
Below are the GFS models for temperatures and rainfall through September 16th –
As we transition into September from late August, a more fall like feel to the air will be obvious. A large Canadian Polar airmass will bring in much cooler air today into Saturday. By Sunday into Monday a stronger cold front will be pushing toward the area but the southerly flow ahead of that cold front will bring afternoon temperatures to near 80 by Monday.
There could be some showers and thunderstorms Tuesday as the cold comes through then much colder air moves in for mid week. Frost is possible near Route 10 Saturday morning and during the Wednesday to Thursday time frame of next week.
HRRR and Futurecast models runs are for 12 hours beginning at 7am – a second model run begins at 3pm
Overall expect cooler than normal temperature and little if any precipitation into the coming weekend. By the middle of next week we will likely see some truly chilly temperature, cooler than we have seen since at least May of this year.
A departing upper level storm system will bring the risk of afternoon showers and possibly a thunderstorm east of Grand Rapid otherwise the fog of early this morning should burn off by 9 am or so. High pressure ridges in for tonight into Wednesday ahead of significant early fall cold front that will come through the area dry early Thursday.
Once again through we could see widely scattered showers and thunderstorms east of Grand Rapids. Wednesday should be the warmest day of the week with highs near 80. It will be much cooler Thursday into Friday behind the next cold front. Below is the GFS temperature forecast through September 14.
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Based on our regional climate database (goes back to 1895), when we put our forecast numbers in for temperatures through next week, it turns out this first week of September will likely be the coolest first week of September this area has seen since 2009. Actually 2015 had a cool start too but this first week should be colder than that.
Our current longwave pattern, continues to favors and eastern trough and western ridge. By Tuesday we will have a very impressive deep upper trough over this area and our air flow will be coming from the Arctic for the middle of next week. This is supported by nearly all of the ensembles of both the GFS and ECMWF and that has been true for many days now.
The current shortwave that is digging an eastern trough is to shallow and the polar jet never gets this far south so we only get into the shallow cold air, but by next week the polar jet will be well south of us and that will put is deeper into the cold air.
With the polar jet being to our northwest today and moving off the east Friday that leads to a large amount of sinking air at mid levels so we have the mean RH from 850 to 700 mb under 5 percent from mid morning Fri to mid morning Saturday. Air that dry will have a hard time creating any clouds. So, expect mostly clear skies into Saturday evening, once the frontal cloud band gets south of this area by late morning.
Having such deep dry air and with the surface high moving across the area I would expect chilly temperatures Friday morning and Saturday morning. I would think Saturday morning will be the coldest. Locations like Leota will likely get below freezing like what happened with our last cold push. So I have patchy frost in the forecast for our northeast CWA for Saturday morning. It would not be out of the question Friday morning either actually. .
Fair wx is anticipated Saturday night and Sunday and temperatures will continue to undergo a gradual moderating trend as south to southwest flow waa (warm air advection) develops. High temperatures Sunday will range from the middle to upper 70`s across our northern fcst area to the lower 80`s over our southern fcst area.
A strong cold front will approach from the northwest on Labor Day and bring a chance for rain and possibly some convection in the afternoon through Monday night. Strong nw flow cool air advection will occur behind the front. High temps Tuesday will only reach the upper 60`s to lower 70`s and high temperatures by Wednesday will only reach the lower to perhaps middle 60`s as the upper level trough continues to amplify over our region. Extensive diurnally driven stratocu and instability/lake enhanced showers are also anticipated by mid next week.