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KEY MESSAGES

- Much warmer weather is expected across northeast Lower Michigan - with slightly warmer conditions elsewhere.

- Cooler with periods of showers and storms Thursday through the weekend.

SHORT TERM /THROUGH TONIGHT/

Issued at 354 AM EDT Wed Jun 11 2025

A couple of batches of persistent stratus continue to loiter over most of the northern Lower Peninsula and sections of the eastern Upper Peninsula early this Wednesday. The surface troughing responsible for the the weak low-level convergence is slowly filling as the parent low - well to the northeast - loses influence. This will allow for continued dissipation of the lingering clouds.

Deep southwest flow in advance of the next frontal zone will briefly usher in a warmer airmass today - especially south of the bridge. While rather moisture starved, a pocket of really good isentropic ascent on the 306-K surface (around 700-mb as it glides overhead) will swing across the region. Furthermore, the latest guidance is showing some weak instability (elevated CAPE 75-J/kg) nuzzled in the inflow pocket. Currently, there are a few showers and an isolated thunderstorm with this developing feature upstream over southern Minnesota. So, carrying the slight chance continues to seem appropriate.

At the surface a small-scale wave will dart east in response to good mid/upper level entrance region dynamic forcing. The warm advection sector of this wave will have the greatest influence south and east of a Muskegon to Alpena line - where strong southwesterly flow (gusting to 30 mph) coupled with 850-mb temps around 18-C will support highs in the lower 80s. Closer to the surface low, highs in the lower 70s will be most common. As the wave cruises east, the surface cold front will quickly settle south into southern Lower Michigan by tonight.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 354 AM EDT Wed Jun 11 2025

The best steering flow aloft will be well displaced to the north. As a consequence, much of the tangible weather will depend on how the weakness in the central CONUS geopotential ridge over Texas evolves. The inception and maintenance appear to be tied to reoccurring convection. Furthermore, the weaker steering flow over the Great Lakes region will ensure the incoming frontal zone will stall out across southern portions of the state for the next several days.

Ultimately, the soft zone in the ridge will try reconnecting with the main upper trough - still residing over Quebec. This action will introduce moisture and instability into the region starting Thursday. Early indications (as offered by solutions like the 11.21z RAP) suggest the instability buildup over the central Plains will plume out to the east along the lower tropospheric boundary somewhere in the vicinity of central Lower Michigan. If enough moisture can accompany this elevated showers and possibly thunder may develop. Otherwise, farther north the unsettled conditions will likely wait on the approach of the weak upper low on Friday into Saturday. The wave will generate showers and thunderstorms - additionally, upstream storm production over the Northern Plains may wander into the region. There is a lot of spread in the global ensemble suite regarding the key features during this time frame. Much of the uncertainty is associated with the timing of convection in the approaching upper low from the southwest and convection associated with a weak jet impulse sweeping in from the west/northwest.

A dramatic amplification of the upper level ridge will occur early next week. As the initial surge north occurs over the Northern Plains, one last height fall event occurs Saturday and Sunday - setting the northern Lakes region up for another coolish weekend. As the ridging expands east early next week, the entire column will warm appreciably - allowing temps to get back to typical early summer readings.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1141 PM EDT Tue Jun 10 2025

Recent satellite trends are showing a slow but somewhat steady erosion of the low end VFR clouds which are lingering over portions of northern Michigan, a trend that will continue during the early portion of the TAF period. Once these clouds erode, overall tranquil aviation conditions will prevail through the overnight. Weak low pressure is then forecast to develop in vicinity of far northern Lower Mi Wed morning within a region of warming aloft and along a cold front. Probabilistic guidance justifies a prob30 for some showers at KCIU with low level moisture convergence also supporting a prevailing MVFR based cloud deck across the eastern UP through the morning. The low levels are forecast to be a little drier across the northern Lower terminals, supporting prevailing VFR conditions. The low and cold front will move across nrn Lower Mi in the 15Z to 19Z time frame, marked by a wind shift from SW to WNW.

APX WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...Small Craft Advisory from 10 AM this morning to 8 PM EDT this evening for LHZ349. Small Craft Advisory from 8 AM this morning to 2 PM EDT this afternoon for LMZ346.