SHORT TERM
(Through Late Monday Night)
Issued at 335 PM CDT Sun Sep 15 2024

Easterly flow from high pressure centered off the coast of New England continues to push low level dry air into the Mid-Mississippi Valley. Meanwhile aloft, the remnant low from TC Francine continues to weaken and lose identity as a closed circulation. With that said, it's still producing clouds and showers over the area.
All deterministic model guidance shows nearly continuous weak to moderate 850mb moisture convergence over southern Missouri and Illinois where the drier easterly flow on the periphery of the ridge meets the more moist southeast flow around the remnant low, with corresponding light QPF.
CAMs also produce intermittent showers in these areas, and persistence would also support the idea of continuing isolated to widely scattered convection until the low finally opens up and is absorbed into the mean flow late Monday. Temperatures through the period will be very dependent on clouds and precip, particularly highs Monday afternoon, though persistence should be an excellent forecast, but with temperatures a bit warmer across the eastern Ozarks Monday afternoon due to fewer clouds and showers than today.

Carney

LONG TERM
(Tuesday through Next Sunday)
Issued at 335 PM CDT Sun Sep 15 2024

The remainder of the week at least through Friday looks dry as a very blocky pattern sets up with closed low pressure systems over the eastern and western CONUS and a weak ridge in the middle over the Plains and Midwest. The surface ridge that was centered off the New England coast gets stretched back to the west and ends up back over the Great Lakes and Ohio Valley by mid-late week. The combination of low and upper level ridging should effectively suppress convection. Medium range deterministic guidance shows 850mb temps stay in the 16-18C range which mixes down to 84-88F for highs. This agrees well with NBM highs through the end of the week.
The pattern shifts slowly eastward Saturday into Sunday which brings the western long wave trough into the Plains, but the upper ridge hangs tough over the Midwest until the end of the period.
Even the 75th percentile of the LREF is dry in our area through Saturday and only show a small amount of precip on Sunday. Will keep the slight chance/low chance PoPs the NBM gave us for late Saturday into Sunday for now, but they may need to be removed in subsequent forecasts if the rest of the guidance remains dry.

Carney

AVIATION
(For the 00z TAFs through 00z Monday Evening)
Issued at 554 PM CDT Sun Sep 15 2024

The showers and isolated thunderstorms are expected to dissipate early in the period. Additional isolated showers and thunderstorms will develop on Monday over central Missouri which could affect COU/JEF, but coverage will not be enough to include in the TAF at this time. Otherwise, dry and VFR conditions are expected with light winds.

Britt

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