Marine Weather and Tide Forecast for St. James, MI

UPDATE
Issued at 819 PM EDT Fri Apr 25 2025

Large area of very light rain/drizzle continues to work east across the area this evening. Expect this rain to gradually end from west to east overnight into early Saturday morning. Any rain amounts will remain light, largely under a tenth of an inch. Lows tonight will range through the 30s into the lower 40s.

SHORT TERM /THROUGH SATURDAY/
Issued at 225 PM EDT Fri Apr 25 2025

Pattern Synopsis/Forecast: Early this afternoon, ~1013mb low pressure continues to strengthen over southern MI into the Ohio Valley -- expected to deepen more substantially tonight as it moves toward the eastern Great Lakes. Meanwhile, an incoming mid-level trough currently over the upper MS Valley slides southeastward this evening, essentially closing off overhead late tonight/early Saturday morning. This feature slides east during the day Saturday with rising mid-upper level heights & attendant surface high pressure in its wake.

Forecast Details: Most numerous shower activity early this afternoon is situated across parts of eastern upper Michigan southwestward into northeast WI, and a secondary area to our south over parts of IN/far southern MI. Through the remainder of the day, certainly the deepest moisture and best forcing remain displaced to our south, with mid-level deformation providing the bulk of our support locally. Showers are expected to continue to expand southeast with time through the remainder of the afternoon and evening, albeit likely in some decaying fashion, especially as you head toward southeastern reaches of the forecast area near Saginaw Bay. The bulk of steadiest/most numerous showers likely to be off to our east by 04-06z tonight, although that aforementioned mid-level wave will continue to support a chance of showers across eastern upper and especially east of I-75 all the way through mid-late Saturday morning. Additional QPF through 18z Saturday expected to largely range from 0.10-0.25" (highest over the Straits/tip of the mitt) with those over the southeast likely struggling to achieve even a tenth of an inch.

Incoming high pressure and rising heights aloft for the second half of Saturday should yield increasing sunshine amidst cooler temperatures on the heels of occasionally breezy north-northwest winds. Highs Saturday in the upper 40s to low 50s.

LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/
Issued at 225 PM EDT Fri Apr 25 2025

Pattern Synopsis/Forecast:

Surface high pressure will build into the region for this weekend promoting clearing skies and warmer temperatures. Effective radiational cooling will drop Saturday night lows into the 30s, to potentially the 20s for the cooler locations, then rebound Sunday with high temperatures in the 60s to low 70s (cooler by the lakeshores). On Sunday, near-critical RHs (relative humidity) are expected to return across much of northern Michigan in the afternoon with generally light winds gusting 10-15 mph-- Something to keep an eye on for potential elevated fire danger Sunday. Temperatures will continue to warm into next week with forecasted highs into the upper 70s, to even perhaps the low 80s for southern locations, depending on where surface features set-up.

An upper-level low centered across southern California at the start of the period, will progress northeast across the Midwest into the Great Lakes as upstream troughing approaches the area Tuesday/ Tuesday night. Resultant surface low pressure looks to track through Wisconsin and the western U.P., bringing shower and thunder chances to the area Monday through Tuesday. SPC has areas west of I-75 in a 15% to 29% probability for severe weather at the beginning of next week (Monday). Looking at forecasted soundings, a good amount of moisture is being advertised for the area with PWAT values of 1.10+". A more progressive pattern should shunt this moisture eastward quickly, potentially limiting the timeframe for heavier rainfall. However, these features can track to different locations and push the best theta-e advection to our north (limiting rainfall), therefore, will continue to watch how guidance trends.
For now, it looks like the heavier precipitation looks to focus across the tip of the Mitt and the eastern U.P. Shower and thunder potential doesn't end there, as Monday night into Tuesday shows signs of strong wind fields aloft with better theta-e advection into the region. This looks like it could be a two hitter scenario where round one comes earlier in the morning and then round two later in the day as an attendant cold front to the aforementioned low tracks through... This is all very subject to change so be sure to check back with the forecast and remain weather aware as we head into next week.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
Issued at 1027 PM EDT Fri Apr 25 2025

Mixture of MVFR to IFR conditions to continue under low clouds and mist early this morning. Gradual improvement expected after sunrise, with skies trending clear from west to east during the afternoon. North to northwest winds will be gusty at times today, with winds becoming light tonight.

APX WATCHES/WARNINGS/ADVISORIES
MI...None.
MARINE...Small Craft Advisory until 5 PM EDT Saturday for LHZ348-349.
Small Craft Advisory until 5 PM EDT Saturday for LMZ345-346.