textproduct: St. Louis

KEY MESSAGES

- Cloudy and occasionally wet weather continues through at least Saturday night with mild temperatures for late December.

- A pattern shift is expected by the middle of next week with much colder temperatures returning to the region.

SHORT TERM

(Through Late Friday Afternoon) Issued at 259 AM CST Thu Dec 26 2024

Warm front along I-70 corridor will gradually weaken as it lifts north today. In the meantime, areas of dense fog have developed and spread a bit further east into west central Illinois, so added Brown and Pike counties in Illinois and Pike County Missouri to the Dense Fog advisory. The fog will gradually lift and dissipate this morning, but exact timing hard to pin down, so will leave advisory in effect until 15z. Otherwise, drizzle will persist through the morning hours, then transition to mainly rain as the next shortwave associated with the trough over the southern Plains lifts northeastward towards the region. This combined with plenty of moisture and upper level divergence will generate another round of more intense rain late tonight through Friday morning. There are strong dynamics with this system, but the best instability will be just south of the forecast area. Thus the probability for any thunderstorms is very low, though a few claps of thunder are possible.

With so much cloud cover and precipitation through Friday, temperatures will be tempered somewhat, but remain well above normal in the upper 40s to mid 50s for highs and lows tonight will be around 20 degrees above normal in the low to mid 40s.

Byrd

LONG TERM

(Friday Night through Wednesday) Issued at 259 AM CST Thu Dec 26 2024

As the system lifts northeast into the Great Lakes region Friday night, the rain will taper off with a bit of a break during the day on Saturday. Then the latest deterministic as well as ensemble models indicate that another shortwave will lift northeast out of the Southern Plains towards the region with another round of rain Saturday night.

For the remainder of the forecast period, pattern begins to change with dry weather late Sunday through Monday. The latest deterministic as well as ensemble models indicate another round of rain moving through the region Monday night into Tuesday. However, the latest LREF cluster analysis still has location, strength and timing issues with this system, so stuck with the latest NBM solution.

As for temperatures, warming trend still expected with highs in the 50s Saturday through next Monday, before colder air returns to the region for the beginning of the new year.

Byrd

AVIATION

(For the 06z TAFs through 06z Thursday Night) Issued at 1054 PM CST Wed Dec 25 2024

A broad area of IFR ceilings will continue to persist across much of the area along and west of the Mississippi River for the rest of the night and into Thursday morning. Patchy drizzle and fog will occasionally reduce the visibility to to 1 mile or less as well. The fog will be more persistent and dense across parts of central and northeast Missouri through at least 10-12Z with occasional visibilites less than 1/2 mile. Ceilings and visibilities will improve slowly during the mid to late morning.

Carney

LSX WATCHES/WARNINGS/ADVISORIES

MO...Dense Fog Advisory until 9 AM CST this morning for Audrain MO- Boone MO-Callaway MO-Cole MO-Knox MO-Lewis MO-Marion MO- Moniteau MO-Monroe MO-Osage MO-Pike MO-Ralls MO-Shelby MO.

IL...Dense Fog Advisory until 9 AM CST this morning for Adams IL- Brown IL-Pike IL.