Marine Weather and Tide Forecast for Grand Beach, MI

DISCUSSION
Issued at 322 AM EDT Tue Apr 14 2026

A complicated forecast over the next 72 hours with several rounds of convection possible. Severe weather is possible each day through Thursday, with greatest confidence in scattered severe storms tonight.

A convective complex is ongoing this morning across Wisconsin to the Lake Michigan vicinity with an associated outflow boundary extending from northeast Iowa to far southeast Wisconsin. This convective system has shown signs of both downwind propagation (eastward across east central Wisconsin) and upwind propagation (southeastward across south central Wisconsin). A strong low level jet feeding into this boundary should help sustain additional convection and southeast push of the outflow to southern Lake Michigan this morning. The tendency over next few hours may be for increasing trend in stronger cores to be displaced further behind outflow boundary due to some stronger downstream MLCIN across the southern Great Lakes. May need to watch for potential of isolated severe gust across primarily southern Lower Michigan this morning where more of a forward propagation may be favored, but a higher confidence potential does exist across NW IN/southern Lower MI for some 40+ mph wind gusts this morning. There have been some instances of small scale circulations developing at leading edge of the line across SE Wisconsin in QLCS type setup. If forward propagating system can reach southern Lower Michigan this morning cannot completely rule out similar evolution where westerly 30-35 knot 0-3 km shear vector has a more favorable orientation, but more limited instability with southward extent and more likely more parallel orientation of shear vectors to line through time may limit this potential.

Another thing to monitor for today could be possibility of some small scale convectively enhanced short wave kicking northeast out of eastern Missouri this morning which could interact with the southward dropping outflow boundary across northeast or east central Illinois. Timing of this interaction would probably be late morning/midday period in unfavorable timing in terms of peak diurnal instability, but may need to watch for some uptick in convection across far west/southwest late morning given steep mid level lapse rates in place.

Overall forecast thinking has not changed greatly for the primary severe weather threat period tonight. The outflow boundary will likely stall from NE Illinois into portions of IWX forecast area this morning, with instability recovery likely by late afternoon as this instability gradient is advected back northward via stronger low/mid level flow associated with convectively enhanced short waves to the southwest. Some isolated stronger storms are possible in vicinity of this instability gradient as it lifts north, but the possibility exists for weak CIN to hold.

By this evening low level flow will back some to the southwest in response to a progressive wave across working across the Upper Midwest. This should yield a pocket of strong 925-850 mb moisture convergence from eastern IA into southern WI this evening which looks prime for convection initiation. Some lower confidence still persists in how convection will evolve tonight, whether a coherent cold pool and southeast propagating convective system occurs, or if storms remain just slightly elevated north of the composite boundary. Supercell wind profiles will likely be in place again by this evening as a stronger mid level jet lifts across northeast IL late afternoon with a wind/hail threat. Best combination of shear/instability still looks possible across NW IN/SW Lower MI where all severe hazards would appear more likely, although helicity profiles more favorable for tornadoes may be displaced west across northern IL where shear may be augmented by the low/mid level jet. As mentioned, still uncertainty with details in convective mode tonight, but overall key themes from previous forecast remain intact. Some heavy rain potential may materialize later tonight as potential outflow with southern Great Lakes storms could become more favorably oriented parallel to veering low level westerly flow.

It is difficult to get into too much detail regarding severe potential for Wed/Thu as this be highly dependent on previous day's convective evolution and hard to resolve smaller individual smaller scale waves in this pattern. This situation is a complex one as stubbornness of longwave ridging to break down across eastern CONUS results in multiple upstream short waves shearing out as they encounter this ridge, and also an added increased susceptibility to convectively enhanced short waves from southern Plains/lower MS Valley. Instability profiles will likely be more limited for Wednesday and Thursday, although at least Wednesday should still feature respectable wind shear profiles that could allow for at least an isolated severe threat. Some small increase in instability is possible Thursday as upper ridge finally appears to be broken down by stronger mid level wave, but shear profiles may become a bit more marginal by this time.

The extended period of above normal temperatures will continue through the first part of the weekend. Medium range guidance is starting to come into a little better agreement in timing frontal passage with next more substantial longwave trough for first part of the weekend. Much too early for details, but some strong/severe threat could accompany frontal convection Saturday depending on timing. May also need to watch for periods of strong synoptic winds this weekend in both pre-frontal and post-frontal environments.
Cooler, below normal temperatures should build in for second half of weekend into next Monday, but residence time of this cooler air looks to be limited.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
Issued at 628 AM EDT Tue Apr 14 2026

An outflow boundary from the organized convective complex across Wisconsin has lost much of its momentum this morning across north central Indiana. An additional convectively enhanced short wave lifting out of northern Missouri will likely interact with this lingering outflow for additional storms in vicinity of the boundary and in a more elevated sense behind it. This greater precip threat should diminish late morning/midday.
There is a potential for an isolated storm along the old outflow boundary this afternoon, although some capping and weaker large scale forcing should limit this overall threat. It still appears as though favored convective initiation should occur across nrn IL/srn WI later tonight and likely propagating into northern Indiana late evening. Still some uncertainty persists regarding convective mode and whether storms may develop a cold pool and sink south, or remain mainly confined across far northern Indiana for much of the night. Given this uncertainty will keep PROB30 TSRA mention going at this forecast distance.

IWX WATCHES/WARNINGS/ADVISORIES
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 8 AM EDT this morning for LMZ043- 046.