Marine Weather and Tide Forecast for Monterey, IN

DISCUSSION
Issued at 126 PM EST Sat Nov 29 2025

The inherited forecast remains very much on track w/ minimal changes necessary to ongoing messaging. Snow has already overspread much of the area this afternoon and will likely continue to increase in intensity over the next several hours. Heaviest snowfall still seems likely to occur in the 21z to 06z time frame as a strong vort energy and mid-level speed max interact with broad, intense isentropic lift across a large portion of the CWA Greatest accumulations should be found north of US-24 with a rather sharp gradient expected to the south courtesy of the impressive low-level warm air advection regime potentially allowing rain to mix in with the snow for a time, which would significantly impact total accumulations. Naturally, this will also influence the character of the snow which is expected to be very heavy and wet, especially later in the event with the main WAA push. SLRS will transition from near 12:1 early to around 8:1 late this evening. A short burst of convectively enhanced heavy snowfall rates (thundersnow cannot be entirely ruled out) may occur during the mid/late evening hours w/ the main push of warm advection aloft. Overall, still looking at decent probabilities of 6-10 inches of total (system) snowfall accumulation mainly focused along/north of US-24. Localized lake effect bands on Sunday may push total accumulations into the 12-14 inch range closer to Lake Michigan.

Please refer to the previous forecast discussion for a more detailed meteorological overview. /Hammer

Previous Discussion (Issued 414 AM EST Sat Nov 29 2025):

Just some minor forecast changes made this morning, but overall messaging remains intact with period of heaviest snowfall and greatest impacts late this afternoon into this evening. The Winter Storm Warning and Winter Weather Advisories areas remain intact with some minor adjustments to ending times of the headlines on Sunday.
Winter Storm Warning headlines continue into Sunday afternoon mainly for lake effect snow favored areas in phase 2 of this system.

A quick ramp-up of isentropic ascent is expected through the remainder of the morning hours. An expansive precip shield has already developed across the Lower/Mid MS River Valley this morning.
Near term progs of 290K surface depict strongest isentropic lift across northern Missouri/west central Illinois as of 08Z. Short term progs take zone of strongest ascent on this surface into northwest Indiana/southwest Lower Michigan by 18Z. Track of this advective/isentropic forcing may be a little more muted across far southeast portions of the forecast area this afternoon. Initial low level thermal/moisture profiles and 285K condensation pressure deficit analysis suggests that this saturation process could take a bit longer than previously expected, particularly across eastern half/southeast portions of the forecast area where isentropic forcing is slightly weaker. Have made some minor adjustments to start time of headlines (pushed back 3 hours across the east), although snow accumulations across northwest Ohio may not occur until the mid afternoon hours today. Some localized low level fgen at nose of stronger low level flow could enhance late morning through mid afternoon snow accumulations for some areas west of I-69.

Guidance has been fairly consistent with handling of this system although some slight dprog/Dt trends could have an impact. Some guidance appears a bit more disjointed in handling of mid/upper level system, with a likely diabatically generated mid level PV anomaly pushing through this afternoon deriving from ongoing MO/IL precip. A tendency to perhaps slightly less phasing of primary synoptic trough and this diabatically generated interior anomaly appears to be trending solution to slightly weaker (albeit still quite strong) kinematic fields and consequently just slightly weaker northward moisture transport. Latest suite of guidance also may not be quite as supportive for CSI type banding given some weaker unidirectional mid level wind shear resulting from the above guidance trends. Nonetheless, very strong advective fields and increasing synoptic scale support via primary upper trough and left exit region of central CONUS upper jet streak should support greatest snowfall rates in the 21z-02Z time period this evening. 00Z HRRR suite also points to this time period as greatest probs of experiencing 1-2 inch/hour snowfall rates for a time. The strong warm/moist advection will result in a highly elevated DGZ, although with some respectable depth of 3-5K feet in the mid levels across far NW IN/SW Lower Michigan. However, overall snow efficiency still appears to be limited with this system across most of the area given strongest lift in lower reaches of DGZ and more limited time window of better DGZ moisture quality. Event average 9-12 snow to liquid ratio was maintained in this forecast with warning level snow amounts dependent on the high QPF nature of this system. Some concern that relatively narrow window of strongest forcing mechanisms late afternoon/evening and inefficient snow production could lead to lower than forecasted snow amounts, particularly east of I-69. At this time have made only minor adjustments to forecasted snow amounts through tonight, with just a slightly lower trend in most places. Highest accumulations of 6 to 10 inches through 12Z Sunday are still forecasted for northwest third of the area where some cross-hair signature of mid level lift/DGZ is noted in forecast time/height sections. Some consideration given to transitioning the warning to an advisory south of US Route 24 across far northeast Indiana/northwest Ohio but will allow dayshift to assess trends this morning.

A mid level dry slot still looks to overspread the area overnight into early Sunday morning, with a quick tapering of snow across most of the area and a likely transition to light snow/areas of drizzle with drying DGZ and near sfc wet bulbs warming to near freezing across south/southeast areas. A quick transition to stronger low level CAA ensues for Sunday morning and afternoon as stronger upper vort lobe drops across the southern Great Lakes. This should allow for at least a 6 to 9 hour period of favorable lake effect snow showers for additional accumulations/impacts with gusty CAA-induced winds also expected. Some higher res guidance also suggests potential of mesovort-type feature to accompany a sharper low level trough passage across southern Lake Michigan Sunday morning/midday.
Have maintained the Winter Storm Warning headline into Sunday afternoon for areas possibly impacted by lake effect snow, and have expired the warning by 15Z Sunday for remainder of the area. This timing may need to be moved up further as most of the synoptic accumulating snow could depart after 09Z Sunday morning. Lake effect snow showers should wane Sunday evening.

Monday will feature quiet conditions as a progressive low level anticyclone sweeps across the area, but attention quickly turns to a lower amplitude fast moving system for Monday night/early Tuesday.
Primary low level baroclinic zone and better moisture will be initially suppressed well south, but a period of northward moisture transport is expected across the Ohio Valley ahead of this system.
Guidance differs with details in the amplitude of this wave and northward extent of sfc reflection/moisture return. Even if a more suppressed sfc reflection verifies, would expect a strong mid level baroclinic zone to be in place locally, with fgen band likely to affect area with some additional snow accumulations Monday night/early Tuesday that could bring an additional 1-3" of snow across the area. Thus, have accepted the sharp ramp-up in PoPs for this period suggested by the model blended guidance.

No major changes to the extended forecast at this time with fuller latitude longwave trough bringing stronger cold frontal push for the Wed-Thu timeframe. Some single digit lows are possible Thursday night under the influence of sfc high pressure, also aided by potential of some light additional fresh snowcover with the frontal forcing. Some moderation in temperatures is possible by next weekend, but still below normal for early December. /Marsili

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
Issued at 1208 PM EST Sat Nov 29 2025

A significant winter storm will impact the area today through Sunday. Snow is overspreading the area and will continue throughout the afternoon with the heaviest snow expected between 21Z today to 03Z Sunday at both KFWA and KSBN. Heavy snow will result in IFR to potentially LIFR ceilings and visibilities.
Moderate snow and IFR visibilities continue into the early morning hours on Sunday. Some rain may mix in at times after 09Z Sunday at KFWA. In addition to the snowfall, south winds will be breezy throughout the period. Winds will be out of the southeast today, shifting to become southwest overnight into early Sunday. Winds will be sustained around 15 kts with gusts up to 25 to 30 kts.

IWX WATCHES/WARNINGS/ADVISORIES
IN...Winter Storm Warning until 7 PM EST /6 PM CST/ Sunday for INZ005>008-012-014-103-104-116-203-204.
Winter Storm Warning until 10 AM EST Sunday for INZ009-013-015- 017-018-020-022>027-032>034-216.
OH...Winter Storm Warning until 10 AM EST Sunday for OHZ001-002-004- 005-015-016-024.
Winter Weather Advisory until 10 AM EST Sunday for OHZ025.
MI...Winter Storm Warning until 7 PM EST Sunday for MIZ078>080-177- 277.
Winter Storm Warning until 10 AM EST Sunday for MIZ081.
MARINE...Small Craft Advisory until 7 AM EST Sunday for LMZ043-046.
Gale Watch from Sunday morning through Sunday evening for LMZ043-046.