Marine Weather and Tide Forecast for Harbor Springs, MI

UPDATE
Issued at 1125 AM EDT Wed Apr 23 2025

Inherited forecast remains on track today. Increasing mid-high cloud underway across the majority of the forecast area in advance of slowly decaying convection over WI/northern IL.
Scattered shower/storm chances still progged to increase from west to east later this afternoon.

SHORT TERM /THROUGH TONIGHT/
Issued at 240 AM EDT Wed Apr 23 2025

Increasing chances of showers and thunderstorms this afternoon and tonight...

Low pressure continues to develop along the Minnesota/Canadian border early this morning...with the associated occluded front stretching SE thru Wisconsin and a warm front lifting into far Southern Lake Michigan. Western Great Lakes regional radars are rather quiet attm...with just some sporatic shower activity dotting the area. Temps are currently in the mid 30s to lower 40s.

Wx becomes increasingly active today and tonight as the surface low drives east thru the Arrowhead of Minnesota and Lake Superior...
reaching SE Ontario by late tonight. Deep moisture will lift up and over the warm front as it too lifts into Lower Michigan. After a rather quiet/uneventful morning...chances of showers will gradually increase this afternoon thru tonight as that deep moisture gradually spreads northeastward into Michigan.

The big question is the potential for thunder. Models have had a difficult time resolving potential instability for today into tonight. Ongoing WAA will likely boost temps into the upper 60s to around 70 degrees across much of Northern Lower Michigan this afternoon...with surface dwpts rising into the 50s. Steepening lapse rates during late afternoon/evening combined with the development of deep-layer shear along with steadily increasing low level moisture suggests a good chance for the development of thunder...especially across Northern Lower Michigan. Latest NAM shows only modest instability (MUCAPES of 500-750 J/kg) developing across mainly our southern CWA late this afternoon/evening...which may be a limiting factor regarding the potential for stronger storm development. While severe storms are not expected (SPC Day 1 General Thunder)...a few stronger storms producing some small hail and gusty winds are not out of the question during late afternoon/evening.

Temps will be noticeably more mild today...with afternoon highs in the mid to upper 50s across Eastern Upper Michigan and in the mid 60s to around 70 degrees across most of Northern Lower Michigan.
Temps will be cooler along our Lake Huron shoreline thanks to easterly low level winds. Low temps tonight will cool into the mid to upper 30s across Eastern Upper Michigan and into the 40s across all of Northern Lower Michigan.

LONG TERM /THURSDAY THROUGH TUESDAY/
Issued at 240 AM EDT Wed Apr 23 2025

Forecast Details:

Stationary boundary will stall out over far northern lower on Thursday, resulting in a bit of a wicked temperature contrast across the region, as areas along and north of the front hold cloudier and cooler while the far southern reaches of the CWA get to 70 to 75+.
Anticipating some residual showers / drizzle through the day Thursday, especially in the northern half of the CWA Surface low pressure surges in from the southwest Thursday night into Friday, forcing the front through the region (as a cold front), bringing a round of more widespread showers and thunderstorms amid breezy to perhaps windy conditions (esp. Friday). Will have to see how atmospheric dynamics and instability align for severe potential Thursday night into Friday, but the details are murky at this juncture.

Latest guidance is bullish on high pressure influences really flexing Friday night into Saturday with some aggressive clearing, yielding a dry weekend. Saturday temps will be cooler with highs 55- 65 Saturday and 60-70 Sunday (cooler lakeshores). The warmup trend continues into next week... latest guidance wants to bring another disturbance to our west to start next week, which should send temperatures well into the 70s...perhaps even touching / exceeding 80, especially south... if (and it's a big IF) we can snag partly to mostly sunny skies and favorable frontal boundary positions. This system seems favorable to force some additional shower and thunder activity as well, which is certainly welcome news for keeping pre- greenup fire danger in check.

Normal highs: 53-63, normal lows: 31-40

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
Issued at 645 AM EDT Wed Apr 23 2025

Low pressure will track thru the Arrowhead of Minnesota and Lake Superior...reaching SE Ontario late tonight. Chances of showers and thunderstorms will increase this afternoon and tonight as this system passes north of Michigan. Prevailing conditions will remain VFR thru this evening...but will drop to MVFR overnight.
Surface winds will remain from the E/SE AOB 10 kts.

APX WATCHES/WARNINGS/ADVISORIES
MI...None.
MARINE...None.