Marine Weather and Tide Forecast for La Porte, IN

DISCUSSION
Issued at 228 PM EST Fri Dec 12 2025

Primary topics of interest this afternoon are 1) incoming clipper system Saturday afternoon and night (snow duration ~6 hours), followed by lake effect snow, and 2) below-zero wind chills Saturday night and Sunday night.

A compact but strengthening upper-level disturbance races across the northern Rockies this afternoon, arriving on our doorstep Saturday afternoon just as an upper-level low drops due south from Ontario.
This results in a strengthening area of frontogenesis across central Indiana. Forecast soundings depict a shallow dry layer saturating quickly amid this highly-forced environment and a deepening Dendritic Growth Zone through time (approaching 500mb after 21z/4PM EST). Given the continental polar source region of this air mass, snow ratios will be high (+/-15:1) resulting in efficient accumulation despite the brief residence time. Snow amounts of 2" to 3" are expected south of US 24 while most of the forecast area will see 1-2" from this clipper. The exception will be south-central Michigan which will generally miss both the clipper and subsequent lake effect. Wind from the northwest near 10 mph Saturday will result in some blowing and drifting. Wind gusts near 20mph will be confined to those downwind of lake Michigan. Synoptic ("system")
snow ends before midnight. An advisory was considered for my far southern Indiana Counties, but seeing such low-end advisory amounts amid an above-average snow season so far made me less enthused for headlines. The incoming shift may update as needed, especially if the storm track shifts north.

In the wake of this clipper, lake effect snow develops Saturday evening and persists through Sunday. This is preceded by a brief period of lake effect snow tonight, primarily for Berrien County and those along the toll road. Equilibrium levels are shallow (< 5k FT)
with an elevated and poorly saturated DGZ. Thus, amounts by daybreak Saturday will be less than 1". Given this < 1" accumulation for tonight, opted to delay any headline issuance for the time being.
For lake effect snow Saturday afternoon through Sunday, accumulation will favor Berrien, Cass (MI) La Porte, and St. Joseph (IN)
Counties. Lake effect parameters will be most favorable Saturday night / early Sunday morning.

Outside of the lake effect snow, temperatures will plummet Saturday night as skies clear and Canadian high pressure becomes established over the Ohio Valley. Those near White and Cass (IN) Counties will see lows below zero while the remainder of the forecast area will see single-digit lows. Being at the mercy of decreasing clouds, this decreases forecast confidence for the issuance of any Cold Weather Advisories at this time. Sunday night, with lake effect clouds decreasing, all areas are expected to be on either side of 0. Wind chills of -15 to -20 may warrant a Cold Weather Advisory.

Thawing out Tuesday through Thursday as upper-level ridging moves in. Highs will creep into the 40s Wednesday and Thursday. Low pressure moves through the Upper Midwest late in the week bringing renewed chances for rain and snow.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
Issued at 1230 AM EST Sat Dec 13 2025

Initial cold front is currently approaching the area and may bring some brief light snow to KSBN during the next 3 hours.
Otherwise fuel-alternate ceilings will continue through the early morning with some improvement to high-end MVFR possible for the late morning. Next shortwave then arrives this afternoon with widespread light-moderate snow. The heaviest snow (1-2")
will be at KFWA where visibilities may briefly drop to 1/2SM around 20-21Z. Lighter snow is expected at KSBN with visibilities likely remaining at or above 1SM. System snow exits around 00Z but lake effect snow will impact KSBN late Sat night into Sunday.

IWX WATCHES/WARNINGS/ADVISORIES
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 10 PM EST Sunday for LMZ043-046.