Marine Weather and Tide Forecast for Jonesburg, MO

SHORT TERM
(Through Late Monday Afternoon)
Issued at 230 AM CDT Sun Apr 19 2026

A broad view of MSLP plots show a tandem of surface highs that will influence local conditions through Monday. The first of these is centered near the TX/OK border to our southwest. The second is positioned over the south-central Canadian Provinces.

The surface high near the TX/OK border is already influencing surface flow, as winds have gradually shifted from northwest to westerly. The surface high is vertically stacked below mid-level ridging with subsidence at the anticyclonic side of the upper level jet maintaining mostly clear skies early this morning.
Radiational cooling will bring temperatures into the 30s to low-40s by sunrise. Patchy frost is possible in the coolest locations, but not without a few caveats. The surface high is departed far enough to the southwest that we'll hold onto the light surface winds north of I-70 and light/variable conditions south of I-70. Mid/upper 30s are more broadly spread across northeast Missouri and west-central Illinois, where winds remain 5-7 mph. Outside of that, temperatures below 40 degrees will become more localized to typically cooler microclimates of the low-lying valleys. Surface dewpoints are also pretty low, ranging from the upper 20s to mid-30s, resulting in dewpoint depressions of 5+ degrees in the cooler locations. HRRR shows the highest mean RH values peaking at 70-75% roughly between Moberly/Columbia, MO extending east through Hannibal/Troy, MO. HRRR 90th percentile values barely reach 90% in these locations with lower RH outside of this corridor. Lastly, recent soaking rainfall has moistened the surface enough that latent heat release will combine with warm soils (60s) to help mitigate frost potential. This is not likely to be a harmful frost with primary concerns being elevated, exposed vegetation that is more susceptible to frost.

Ahead of the second surface high, westerly flow draws warmer air into the region from the central Plains. A reinforcing cold front stretches through the Great Lakes Region into the Mississippi Valley and the surface high will serve as the impetus for this front. The boundary pushes into northern sections of the CWA just after noon today, progressing southward through early this evening. While the front isn't strong, it shifts winds back out of the northwest in the later half of the day, and out of the north tonight before winds go calm to light/variable tonight. This simply maintains the west-east temperature gradient through Monday with Warmer temperatures staged west (MO) and cooler air to the east (IL).

Another chilly morning is expected Monday. The only difference is that winds lighten a bit further than Sunday morning. Patchy frost is once again on the table, but the potential is only slightly better than this morning with the lighter wind component.
Conditions remain comfortably mild and dry during the day with highs ranging from the low/mid-60s on the Illinois side of the river and mid- 60/low-70s in Missouri. Morning lows will bottom out in the mid-30s to low-40s.

Note: No headlines were issued for the frost potential given that frost remains patchy. Certainty remains limited with multiple caveats working against conditions that would otherwise lead to vegetation damage. Those with susceptible vegetation can water and/or cover plants to reduce the potential that frost would develop on elevated, exposed plants.

Maples

LONG TERM
(Monday Night through Saturday)
Issued at 230 AM CDT Sun Apr 19 2026

Monday night into Tuesday marks the start of a significant warm-up that will extend through at least Thursday. The northern surface high, mentioned in the short term section, quickly shifts eastward into the mid-Atlantic Region. The two surface ridges consolidate into a broader ridge that encompasses the eastern seaboard heading into Tuesday. Surface flow quickly shifts out of the south Monday night, which will bump Monday night's lows by 10-12 degrees. In previous forecasts, yet another reinforcing cold front looked like it might push into the region late Tuesday. Latest trends in the deterministic NAM/GFS/ECM show the front stalling before it reaches the CWA Additionally, NBM temperature data is impressively tight with the greatest spreads in the 2D output remaining north from Iowa into northern Illinois. This provides high confidence that we'll remain warm and precipitation-free. West-southesterly mid-level flow will bring 10-15C air into the area, resulting in highs well into the 70s with a few 80s in urban areas.

NBM IQRs remain tightly clustered Tuesday through Thursday with the main theme being the return to warmer-than-normal temperatures. The drivers to the warmth will be the eastward shift in the mid-level ridge with strengthening southwesterly flow setting up between it and a developing trough over the Plains. Mid-level temperatures are even more anomalous to the west (90th-99th percentile). Overhead, mid-level warmth reaches the 80-90th percentile Wednesday and Thursday with highs warming slightly each day with 80s more broadly represented Thursday.

Spread increases Friday, though deterministic guidance seems to be coming into slightly better agreement with a late week system that could bring another round of soaking rain to the area. Global guidance shows a cutoff upper low meandering into the northern Plains as an amplified upper trough crosses western Canada and consumes the lead upper low. This keeps the broad cyclonic flow further north and leaves the region within the warm sector ahead of a cold front that stretches southward of the surface low rounding the upper trough. While this builds confidence in the northern trends, it leads to some question with the front and precipitation chances late Thursday into Friday. In these scenarios, the southern end of the cold front typically take on more of a NE-SW orientation, bending more W-E with southward progress. This reduces surface convergence as the surface boundary parallels flow aloft. On top of that, timing (late Thursday/early Friday) will be key in whether we are able to tap into peak diurnal instability. At this juncture, it looks like the front moves in overnight. Thunderstorms outrun better instability to the west/northwest, much the same way it has in recent events. This shows up well in the LREF 24-hour QPF spreads, which increase and expand across the Midwest through late Friday.

All that being said, the pattern favors weakening convection that could bring widespread soaking rain Thursday night into Friday. LREF 25th-75th percentile ranges show approximately 0.25-0.75" covering much of the CWA Keep in mind that convective potential could lead to localized rainfall that is much higher, pending the exact outcome. The main message here is for another chance at soaking rainfall with details becoming more clear over the next few days.

Maples

AVIATION
(For the 06z TAFs through 06z Sunday Night)
Issued at 1051 PM CDT Sat Apr 18 2026

Dry and VFR flight conditions will continue through the end of the TAF period. Winds will remain light overnight, picking up from the southwest Sunday morning. Deep mixing will allow gusts to kick up during the late morning and persist through the afternoon area wide ahead of a surface front. The dry front will push south through the terminals during the late afternoon/early evening, causing winds to become northerly.

Delia

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