Marine Weather and Tide Forecast for Monterey, IN

DISCUSSION
Issued at 230 PM EDT Sat Oct 17 2026

Clear skies and deep layer subsidence are expected to continue tonight as Great Lakes/Ohio Valley remain positioned between longwave ridging across central CONUS. An expansive low level anticyclone from MO to the western PA will allow for winds to quickly decouple this evening. The extent of temperatures drops tonight is still a bit uncertain as low level thermal trough is departing to the east this evening and will continue to moderate. This should be overcome by ideal radiational cooling condition this evening. Some weak southwest flow on back side of the sfc high is possible across western Great Lakes later tonight, but this should not have a dramatic impact on temperatures. Previous forecast still appears on track with best chance of mins at or just below freezing roughly along and east of Interstate 69, with generally mid 30s elsewhere. Frost advisories and freeze warnings remain in effect for tonight into early Sunday morning.

The primary storm track Sunday into Monday will remain across central Canada as broad longwave trough remains anchored across northern tier of CONUS. Some upstream height rises across Upper Midwest following departure of central Canadian short wave will allow for sfc anticyclone to be reinforced across southern/western Great Lakes early week. This could result in a lower end patchy frost potential Sunday night and Monday night as strong decoupling should compensate for slightly modifying low level/near sfc thermal profiles. For the middle of the week, a tendency for negative eastern Pacific upper height anomaly should develop which will allow for downstream maintenance of mean upper level ridging and little change in position of low level anticyclone. A slow day to day temperature moderation is expected in this pattern. The much drier airmass will maintain its grip across the region given stagnant longwave pattern much of this week, but given temperatures only slightly above normal and weak winds through the period, significant fire weather concerns are not expected.

Some lower forecast confidence exists for the Day 7 to 9 timeframe with deterministic/ensemble guidance showing larger spread in eventual eastward ejection of eastern Pacific negative height anomaly. Some indications another fropa could be possible late next weekend/early the following week, but this will depend on how the eastern Pacific energy phases with broader northern stream trough.
A dry forecast has been preserved through this forecast valid period.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/
Issued at 715 PM EDT Sat Oct 17 2026

VFR conditions expected at the terminals, with light and or variable winds strengthening out of the S-SW Sunday. Gusts up to around 20 knots possible at KSBN in the afternoon.

IWX WATCHES/WARNINGS/ADVISORIES
IN...Frost Advisory from 3 AM EDT /2 AM CDT/ to 9 AM EDT /8 AM CDT/ Sunday for INZ005-012>015-020-022-103-104-203-204.
Freeze Warning from 3 AM to 9 AM EDT Sunday for INZ006>009-017- 018-023>027-032>034-116-216.
OH...Freeze Warning from 3 AM to 9 AM EDT Sunday for OHZ001-002-004- 005-015-016-024-025.
MI...Frost Advisory from 3 AM to 9 AM EDT Sunday for MIZ078>081-177- 277.
MARINE...None.