Widespread 30s were felt over both Sunday /14th/and Monday /15th/mornings. In addition; pockets of sleet, graupel and snow were observed. Snow was reported at Detroit Metro Arprt on both the 14th and 15th (never seen before on these dates); while Flint reported snow on the 14th. Many areas observed some sort of frozen precipitation due to record/near record setting cold air aloft. Detroit fell to 34 degrees on the 15th; just one degree from tying the old record of 33 back in 1973.
Certainly no change in the previous thinking nor forecasts of models as a record flirting cold, in both the upper and lower layers of the atmosphere, firmly plants itself over the region into Monday. The cold is available for risk of frost and/or freezes; the big determining factor will be cloud cover and to a lesser extent, wind. There is even a possibility of some graupel /sleet-like/ precipitation in scattered cold-air producing convective showers this afternoon and evening - and again Sunday.
Overnight lows should range from around 30 in coldest, potentially clear sky areas to the 30s elsewhere over Southeast Lower Michigan both Sunday and Monday mornings.
In my last mini-blog; I strongly worded keeping cold sensitive plants in doors or at least covered in possible cold snaps projected in mid-May.
"Even a far as mid May; the GFS in la la land (last map) still cranks in another cold air mass on the 15th. Of course, its accuracy gets more questionable as we move out in time on the maps. In any event, through mid May keep the cold sensitive plants out of the ground in my advice. Seeds, which take a week or so to come up might be a better risk by mid May".
Well below normal upper heights are telegraphed for the northern US by late this week on both the GFS /Map-1/ and Euro /Map2/. The Euro's bowling-ball of cold heights nosing down around 530 /dam/ just north of the Lakes is impressive for mid May. In addition, 850MB 5kt temperatures drop sub zero across a large area /Map3/. Lows projected Sunday morning this far ahead are around 30 to the mid 30s /Map-4/...record territory.
Looking at record lows for Detroit, Flint and Saginaw at that time shows lows in the 30-34 range would be in record territory, depending on location and date. Also records for these dates are remarkably uniform across all of Southeast Lower Michigan.
DTW FNT MBS
14th 34/1984 32/1997 31/1943
15th 33/1973 30/1973 32/1953
16th 32/1984 30/1921 32/1952
The ultimate strength of the cold is still in projections of a consensus of models; therefore its reliability for exactness is questionable. In any event; a cold weekend for mid may is quite likely; just how cold remains to be realized. Updates forthcoming.