Thursday Forecast – 5/29

Note: Saturday, Slim will provide our last post on this site. We will be transferring to Substack—the links are in the sidebar.

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Weather History

1895: The second heat wave of the month gets underway with record highs of 94 degrees at Grand Rapids and Lansing.

1947: Muskegon records its latest snow on record as some wet snowflakes mix in with a cold rain. The high temperature for the day is only 47 degrees after a low of 35.

On May 29, 2011, a thunderstorm complex rolled through southeast Michigan during the peak heating of the day, resulting in scattered wind damage reports across the area, mainly south of Interstate 69. Embedded circulations within the line of thunderstorms lead to localized wind gusts of 80 mph with one EF1 tornado over southern Shiawassee County.

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Forecast Discussion

Today: Mostly cloudy, with a high near 67. West wind 5 to 10 mph, with gusts as high as 20 mph.

Tonight: Partly cloudy, with a low around 47. West northwest wind 5 to 7 mph becoming calm in the evening.

Friday: Isolated showers between 2pm and 5pm, then isolated showers and thunderstorms after 5pm. Partly sunny, with a high near 73. West wind 5 to 13 mph, with gusts as high as 23 mph. Chance of precipitation is 20%.

Friday Night: Isolated showers and thunderstorms before 8pm, then a slight chance of showers between 8pm and 2am. Partly cloudy, with a low around 46. Northwest wind 6 to 10 mph, with gusts as high as 20 mph. Chance of precipitation is 20%.

Saturday: Sunny, with a high near 70. North northwest wind 6 to 11 mph, with gusts as high as 22 mph.

Saturday Night: Partly cloudy, with a low around 44.

Sunday: Sunny, with a high near 72.

Sunday Night: Mostly clear, with a low around 47.

Monday: Sunny, with a high near 80.

Monday Night: Mostly clear, with a low around 58.

Tuesday: Sunny, with a high near 85.

Tuesday Night: Mostly clear, with a low around 63.

Wednesday: A chance of showers. Mostly sunny, with a high near 85.

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The end of the broad blocking flow regime encompassing nearly all of
North America is now in view. The ongoing intense Gulf of Alaska
cyclone has induced sharp downstream ridge development west of the
Rockies. In turn the westerlies, that have been bottled up near the
Arctic circle, are getting a geopotential gradient boost -
initiating jet amplification and shortwave perturbation production.
The lead trough will amplify over the Hudson Bay region today and
surge south into the weak geopotential field across the Great Lakes
region on Friday. As this is occuring the tail end of the old
resident closed low will re-invigorate some through contributions
from convective upscale growth. The plunging wave will interact with
the last remnant of the current system and carve out a full latitude
trough east of the Mississippi River by Saturday. Meanwhile, the
longwave ridge will continue to build and begin a march east as the
overall wavelength contracts. This deep ridge will strongly
influence the weather the first half of next week - bringing a
legitimate taste of summer. As for tendencies to this new flow
pattern, the overall trend within the guidance suite is to shorten
the planetary wave wavelength - making the pattern slightly more
progressive.

As for the tangible weather, expansive low clouds with light fog and
patchy drizzle occupy much of the southern Lower Peninsula early
this Thursday. The broad area of low pressure responsible for the
unsettled conditions will linger through the day - maintaining
mainly cloudy conditions with light winds. The pocket of cooler air
aloft will remain overhead today (850-mb temps around +7*C), in
combination with the existing weak moisture convergence along the
trough axis draped across Central Michigan, coupled with a modicum
of diurnal recovery to the boundary layer will support some
instability production (up to 200-J/kg of MLCAPE) this afternoon.
Any instability within the moist profiles will be more than adequate
to support isolated to scattered light shower development - mainly
along and north of I-96.

The previously mentioned shortwave driving south into the region on
Friday will interact with a convectively charged wave traversing the
Ohio Valley. This merger process will help send a cold front
aggressively from north to south through the region late in the day.
In advance of the boundary, modest instability will build - possibly
exceeding 1-kJ/kg - with very little inhibition immediately
preceding the front. The combination of wave merger dynamics,
supportive thermodynamics, and a coherent boundary driver via the
cold front will result in a few clusters of showers and storms.
Prospects for severe weather will be low, as there is a lack of deep-
layer shear to support greater storm-scale organization.

Cool northeast flow associated with the incoming high pressure
system on Saturday - with some help from a cold Lake Huron - will
control the weather setup this weekend. The net result will be
pleasant conditions with a cool starts in the 40s and daytime highs
around 70.

On the heals of the surface high, deep southwest flow will usher in
a much warmer airmass starting Monday. The heat will continue to
build as the upper ridge advances overhead Tuesday and Wednesday.
Highs will easily climb into the mid-80s. A small cluster of the
extended guidance suite (< 20%) flattens the long-wave ridge with a
leading shortwave trough and is suggesting Wednesday may be the
earliest opportunity for showers and storms. However, Thursday is
still the favored timing amongst the rest of ensemble membership for
the arrival of the next system.