Marine Weather and Tide Forecast for Winchester, MO

SHORT TERM
(Through Late Monday Night)
Issued at 152 PM CDT Sun Apr 12 2026

Recent GOES-East water vapor imagery reveals an amplified longwave trough near the West Coast with broad ridging across the eastern U.S. producing southwesterly flow across the region. Currently, a mid-level shortwave is lifting northeastward within the southwesterly regime from the Plains into the Midwest. This, coupled with a strong low-level jet (40-60kts), leading to increased low- level moisture convergence, is sustaining a broad area of showers that has lifted northeast out of OK/KS and is now approaching central Missouri early this afternoon. High-res guidance resolves this field of precipitation continuing northeast, with the greatest coverage of showers forecast across central/northeast MO and west- central IL. This is where the latest HRRR has the swath of greatest rainfall with the LPMM accumulated precipitation indicating a swath of 0.1-0.2" with isolated pockets up to 0.50", which is possible for locations where heavier showers move over. Some locations across southeast MO/southwest IL may remain dry as the coverage of showers across that area is forecast to be more scattered. The reason being that the greatest mid-level forcing and core of the low-level jet later this afternoon and evening is progged by guidance to move across northern MO eastward into northern IL. An isolated pop-up thunderstorm cannot be ruled out this afternoon/early evening as HRRR mean SBCAPE values reach 250 J/kg before crashing to zero after sunset. On the heels of the departing mid-level shortwave and greater forcing for ascent, model guidance unveils a subtle ridge nudging in from the west, resulting in weak height rises aloft beginning later tonight. As a result, showers are forecast to exit from west-east later this evening, with a low chance (20-30%) for scattered lingering showers across southern IL overnight.
Temperatures this afternoon are in the 70s across most the area (60s where showers are falling) and will remain warm in the 60s overnight as continued low-level WAA and cloud cover prevail.

Instability begins increasing from west-east around midnight, with mean HRRR SBCAPE values over 500 J/kg across Missouri by sunrise on Monday. This is the result of increasing surface moisture along with the passing mid-level shortwave veering winds aloft leading to steepening lapse rates, generally above 700mb. By Monday afternoon, mean HRRR SBCAPE ranges from 1,500-2,500 J/kg, with the greater values across central/northeast MO and west-central IL. Even with ample instability in place, and modest 0-6km Bulk Wind Shear near 30kts, thunderstorms are not expected due to the influence of the ridge aloft. However, it is important to note that some deterministic guidance resolves weak nebulous areas of forcing within the subtle mid-level ridge. Therefore, a scattered shower or an isolated thunderstorm Monday morning into Tuesday is still possible, but that chance is low (10-20%). With another day of strong southerly flow and at least some solar insolation in between breaks in cloud cover, Monday will be very warm with highs forecast in the 80s for the entire area.

Peine/BRC

LONG TERM
(Tuesday through Next Sunday)
Issued at 152 PM CDT Sun Apr 12 2026

At the start of the extended, the mid/upper-level longwave trough will be near the Four Corners Region with continued broad ridging across the eastern U.S. keeping the area within a southwesterly regime. With continued southerly flow leading to increased low-level moisture, instability will trend upwards into Tuesday with LREF mean SBCAPE values up to 2,500 J/kg across central/northeast MO by Tuesday afternoon. As the longwave trough slowly pushes eastward, nearing the High Plains by Tuesday afternoon/evening, chances for showers and thunderstorms return as LREF chances for QPF >0.01" steadily increase from Tuesday evening into Wednesday morning. The 12Z RRFS A resolves convection forming across northeastern OK Tuesday afternoon and pushing northeast, rapidly weakening as it approaches our area. Analysis of forecast soundings indicates a 750- 900mb warm nose associated with strong WAA in that layer that would lead to a capping inversion resulting in elevated thunderstorms. The warm nose progged by guidance appears to be weaker to the north and west, meaning that the greatest severe threat appears to be across central/northeast MO and west-central IL, as thunderstorms may weaken with eastward extent. As of now, with a setup like the one described above, the greatest hazards for Tuesday afternoon into Wednesday morning appear to be large hail and damaging winds.

An additional threat for severe weather exists Wednesday afternoon into early on Thursday, when the longwave trough is forecast to eject into the Plains and Midwest. This is when the most robust mid- level forcing for ascent and greatest 0-6km bulk wind shear (40- 50kts) will be collocated near the area. Instability looks less impressive Wednesday into Thursday, as mid-level lapse rates weaken, resulting in widespread LREF mean SBCAPE values of 500-1,000 J/kg on Wednesday. However, the previously mentioned 750-900mb capping inversion may erode Wednesday afternoon/evening, allowing for potential surface based convection. Once again, the greatest mid- level forcing/instability/shear overlap looks to be across central/northeast MO and west-central IL.

Behind the longwave trough ejection, long-range guidance has good consensus that shortwave ridging quickly moves into the area Thursday, shunting chances for showers and thunderstorms east. This gives the area a brief break from the more active pattern with dry and warm conditions forecast for Thursday afternoon into Friday morning. Just upstream, across the West Coast, another longwave trough will be advancing east nearing the region by Friday afternoon. Compared to the longwave trough midweek, this longwave looks to be more progressive and may eject into the Plains by the end of the week or early next weekend. As a result, chances for showers and strong to severe thunderstorms return to the area Friday afternoon into Saturday, along with a chance for cooler temperatures next weekend. Warmer than average temperatures will continue until Friday with LREF temperature IQR spreads around only 3-7 degrees during this period. However, on Saturday, temperature IQR spreads jump to 20 degrees with spreads down to 10 degrees or less on Sunday centered on temperatures just below average.

Peine/BRC

AVIATION
(For the 18z TAFs through 18z Monday Afternoon)
Issued at 1254 PM CDT Sun Apr 12 2026

A broad area of showers is pushing northeast into southwest/central MO and is forecast to continue moving northeast impacting area terminals this afternoon and evening. MVFR cigs/vis are possible within the heavier showers with greater potential for heavier pockets of showers across central/northeast MO than compared to the St. Louis metro. Additionally, MVFR/low MVFR ceilings are located toward the back edge of the showers with confidence in the occurrence of MVFR ceilings across central/northeast MO higher than the St. Louis metro. MVFR ceilings may linger into early tomorrow morning, especially across northeast MO. Southerly surface winds gusting to 25-30kts will continue into the late evening with gusts expected to fade overnight. A strong low-level jet core (50+ kts)
will move eastward across east-central MO this evening/late evening.
No mention of LLWS was added as surface winds are forecast to be gusting 20+ kts when this occurs. Surface winds remain southerly and begin gusting (20-25kts) again after sunrise on Monday.

Peine/Gosselin

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