Marine Weather and Tide Forecast for Winchester, MO

SHORT TERM
(Through Late Tonight)
Issued at 343 AM CDT Mon Mar 9 2026

Persistent southwest flow along with strong early-March sunshine and deep mixing will push temperatures well above normal today. Forecast soundings show mixing up to 850mb and above this afternoon with temperatures around 14-15C. The latest deterministic NBM highs in the mid to upper 70s are a few degrees cooler than the what the 850mb mix-down temps would indicate. I think this is likely too cool due to bias correction. Therefore I am leaning toward the 75th percentile for highs today which pushes much of Missouri along and south of I-70 into the 80-82 range with the remainder of the area in the mid to upper 70s which is near to above record highs.. There is still a bit of uncertainty to throw into the equation: low level moisture will also be increasing, and a few guidance members show isolated showers developing in the afternoon due to some weak moisture convergence. However, forecast soundings show a pretty substantial inversion above 850mb, so convection looks very unlikely at this time. Warm/moist advection on southerly flow continues tonight tonight which will keep overnight lows well above normal in the mid 50s to around 60.

Carney

LONG TERM
(Tuesday through Sunday)
Issued at 343 AM CDT Mon Mar 9 2026

Tuesday looks even warmer than today due to the mild start to the morning and continuing low level warm advection. Forecast soundings mix up to between 900-850mb across most of the region, higher in northeast Missouri and west central Illinois. 850mb temps around 16C would mix down to around 84F At the surface which the latest NBM is showing across much of central and east central Missouri, with lower 80s elsewhere. Think it could get warmer, though the limiting factor will be increasing clouds as low level moisture continues to build. Regardless, highs will be near records again on Tuesday.

Attention turns to severe potential late Tuesday afternoon and evening. Most discrete guidance is showing MLCAPE values building in excess of 2500 J/Kg across parts of central and eastern Missouri into west central/southwest Illinois by late Tuesday afternoon. Some models (most notably the RAP) are showing MUCAPE values in excess of 3500 J/Kg between 21Z Tuesday 00Z Wednesday, generally across northeast Missouri into west central Illinois. Kinematics are favorable for rotating updrafts given the strong instability with 0- 6km shear between 40-50kts. However, forecast soundings show a significant capping inversion Tuesday afternoon across the area, and some doubt remains whether thunderstorms can develop during the late afternoon/early evening when instability will be highest. The most likely location for CI Tuesday afternoon will be across northeast Missouri into west central Illinois in the vicinity of a quasi- stationary front where low level forcing will be strongest and the cap will be weakest. Discrete supercells will be possible which would present all hazards including hail in excess of 2 inches, damaging winds and a few tornadoes.

The window for severe storms should close quickly as most guidance shows instability dropping to less than 1500 J/Kg by mid-late evening. Locally heavy rain then becomes a potential issue late in the evening and overnight as low pressure drifts across northern Missouri along the front. GFS/RAP show a broad 40-50kt low level jet producing at least moderately strong moisture convergence over Missouri and Illinois as it encounters the low level baroclinic zone. Forecast soundings show a relatively deep warm cloud depth (especially for this time of year) of nearly 10,000ft, and NAEFS/ENS P-wats are in the 99th climatological percentile. Therefore expect continuing thunderstorms Tuesday night to be efficient rain producers as they move across the area. Locally heavy rainfall/flooding is possible, mainly across northeast Missouri into west central Illinois if thunderstorms train over the same locations. The front should start moving before 12Z Wednesday as a short wave trough moves from the Plains into the Midwest. This forces low level cyclogenesis along the boundary, and the resulting low pushes the front through Missouri and Illinois on Wednesday.

The remainder of the forecast looks relatively quiet. The NBM is forecasting near to above normal temperatures through the period, though there is considerable uncertainty for Friday through Sunday.
Thursday will likely be the coolest day through the forecast period with near normal temperatures as high pressure moves across the Mid Mississippi Valley. The GFS and ECMWF show a clipper moving across the Upper Midwest Friday which drags a dry cold front across Missouri and Illinois. The front is forecast to stall Friday night and then lift back to the north Saturday. Another stronger trough moves into the Central U.S. Sunday which pushes the front back through the Mid Mississippi Valley with a chance for precip. The LREF is showing considerable variance in temperatures through this period as it appears its members are showing a great deal of difference in the position of the front. High temperature IQRs increase from around 10 degrees Friday to 20+ degrees by Sunday.
Confidence in the temperature forecasts is therefore low in the Friday-Sunday time frame.

Carney

AVIATION
(For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1226 PM CDT Mon Mar 9 2026

IFR to MVFR stratus has remained largely across southeastern MO/southwestern IL outside of terminals, leaving dry and VFR flight conditions persisting into tonight. With increasing moisture, some patchy low stratus is possible early Tuesday morning before lifting to stratocumulus/cumulus by late morning. Currently, KUIN is most favored to see impacts from these clouds. Development of showers and thunderstorms on Tuesday is expected to be beyond the current TAF period, during the evening into overnight most likely. Southerly winds will gust 20 to 27 at times this afternoon and again Tuesday midday/afternoon.

Pfahler

CLIMATE
Issued at 211 PM CST Sat Mar 7 2026

Daily record high temperatures may be threatened both on Monday 3/9 and Tuesday 3/10. Below are the records for each day from our official climate sites:

Monday 3/9 Tuesday 3/10 KSTL 80F (1925) 86F (1955)
KCOU 80F (1986) 82F (1955)
KUIN 75F (1986) 79F (1955)

Gosselin



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