Marine Weather and Tide Forecast for Palmyra, IL

SHORT TERM
(Through Late Wednesday Afternoon)
Issued at 205 AM CDT Tue Mar 17 2026

Skies have cleared out over much of the area with the only semblance just now exiting the eastern fringes of the CWA Surface observations show gusts continuing to subside with sustained winds dropping below 10 mph over central Missouri. This eastward will continue through early morning, which may allow low temperatures to cool a bit more efficiently that previously thought. Mornings lows could be trimmed just a hair, but negligible in sensible terms. Most locations wake up to the teens with a few single digit readings in northeast Missouri.

Subtle warming is expected today after such a cold start. Calling it a warm-up may be more insulting that truthful with highs largely in the 30s to near 40 degrees. We're ahead of a weak clipper system that will bring additional clouds to the region through the afternoon. How quickly this occurs could stymie diurnal trends, mainly over central and northeast Missouri. The favored northern track, quick pace, and lack of moisture will keep winter hazards at bay. An added benefit is that precipitation chances largely lie between sunset tonight and sunrise Wednesday morning.

The clipper rides along a wing of strong warm air advection with surface temperatures at or above freezing from Kirksville to St.
Louis through Mt. Vernon (IL) through tonight. The warm nose continues to cut into northeast fringes of the CWA between 09z-11z prior to sunrise, resulting in slowly rising temperatures between 06z-12z tonight into early Wednesday morning. Even the coldest locations across the northeast fringes of the CWA only bottom out in the low-30s. HRRR spreads have been consistently showing around 0.05" of QPF from KUIN through K3LF. There's also reassurance in the LPMM data that shows an inch of accumulation in these areas.
Realistically, maybe an inches is achieved north of KUIN with less than an inch elsewhere. Moisture depth decreases southwest from there with a more notable dry layer in the surface to mid-level layer. What moisture is available is likely to be very light and in liquid form. No hazards are expected at this time.

There is high confidence in a significant warm-up starting Wednesday as a ridge axis crosses the region, shifting winds out of the southwest. H8 temperatures climb about 10C with highs largely in the 60s.

Maples

LONG TERM
(Wednesday Night through Monday)
Issued at 205 AM CDT Tue Mar 17 2026

The later half of the week features much warmer temperatures that will compare closer to the first half of May. NBM IQR provides high confidence in the warm-up with just a few degrees of separation between the 25th/75th percentiles. Global deterministic guidance shows mid-level temperatures inching upward through this stretch, starting out at 10-15C Thursday and near 20C Saturday. This will bring temperatures into the 60s/70s Thursday and well into the 70s Friday. Saturday is a touch warmer than Friday, which includes low- 80s over sections of central and southeast Missouri. Prominent flow at the surface is more westerly than southwesterly and therefore does not indicate much potential for over-performance. NBM output looks reasonable with IQR remaining tightly clustered through Saturday.

Sunday remains the biggest question with relation to a cold front that brings cooler air to the region. This morning's deterministic ECMWF/GFS are in fair agreement with the surface front arriving in the early morning over northern Missouri/west-central Illinois, mid- morning along I-70, and by 18z over the southern stretch of the CWA
NBM spreads around 30 degrees persist, which is largely playing off the warmer ECMWF solutions from prior runs. This spread also shows up in the HRRR ensembles, but I suspect this will begin to tighten over the next couple of run as we draw closer to the weekend. That being said, most areas along and north of I-70 likely reach their high temperatures in the early part of the day, then follow a non- diurnal trend through the afternoon. 70s are most favored across southeast Missouri and southwest Illinois as 20-25C H8 air is compressed along and just ahead of the boundary with some time for normal diurnal processes to have greater influence on temperatures.
Considering the surface ridge remains to our southwest ahead of the front, moisture return is lacking until the front approaches the Missouri/Arkansas border. Thus, a dry FROPA is favored.

A strong surface ridge builds eastward through the north-central U.S. early next week. NBM spreads aren't terribly large (~10 degrees) with the most notable characteristic being an initial drop in temperature Monday with modest moderation thereafter.

Maples

AVIATION
(For the 12z TAFs through 12z Wednesday Morning)
Issued at 557 AM CDT Tue Mar 17 2026

VFR conditions persist throughout the period at all terminals.
Mostly clear skies and light and variable winds will give way to increasing mid-level clouds this afternoon. Clouds will run ahead of a clipper system that brings the potential for light snow tonight. Chances are pretty slim over central Missouri and only slightly better around the metro terminals. Surface to mid- level dry air is expected to impeded much of this from making it to the surface, but may utilized PROB30 groups in later updates should it be warranted.

The best potential for light snow is around KUIN late this evening.
Guidance continues to trend northward with this activity, too, which may only last a couple of hours. Therefore, the best chances were bookended with PROB30 groups considering the uncertainty in timing and duration. Snowfall should remain light enough that impacts are largely avoided.

Maples

LSX WATCHES/WARNINGS/ADVISORIES
MO...None.
IL...None.