Marine Weather and Tide Forecast for Huey, IL

SHORT TERM
(Through Late Sunday Night)
Issued at 232 PM CST Sat Dec 7 2024

The Mid-Mississippi River Valley will remain positioned within upper- level northwesterly flow atop low-level west-southwesterly flow into Sunday, promoting deep WAA and a continued warming trend. With passing upper-level clouds and the SLP gradient remaining relatively tight, temperatures tonight will be mild and in the mid-30s to mid- 40s F--above average and warmer than most high temperatures we saw earlier this week.

Ahead on an upper-level closed low beginning to eject northeastward from the Desert Southwest, low-level flow on Sunday will back slightly and become more southwesterly, setting the stage for widespread well-above average high temperatures in the mid-50s to low-60s F. The only loose end will be increasing low-level moisture from the southwest that potentially results in the development/ increasing coverage of stratus/stratocumulus through the day, but the moisture-blocking effect of the Ozark Plateau and frequent fast- bias of stratus development among models during the cool season still leads to high temperatures leaning toward the warmer end of guidance in the current forecast, especially given a notable cool bias in the NBM today and Friday.

Sunday evening, the closed low, evolving into a compact shortwave trough, will propagate over the Mid-Mississippi River Valley, but the growing consensus among model guidance is that the strongest associated synoptic-scale ascent will remain to the southeast of the CWA along with the most persistent and widespread rain. That being said, the latest HRRR maintains confidence that some of the showers/rain will reach southeastern MO and southwestern IL Sunday evening, with 60 to 90 percent probabilities of measurable rainfall (per 6 hours). Across the remainder of the CWA to the northwest, these probabilities decrease to around 30 percent or less. An isolated thunderstorm is possible across southwestern IL with modest elevated instability advertised, but a lack of stronger ascent will limit the overall intensity of the rain (HRRR probabilities of 0.25" of rainfall 30 percent or less). Although most of the showers/rain will depart with the shortwave trough overnight Sunday, forecast soundings indicate plentiful low-level moisture lingering across much of the area but differ on the amount of low-level ascent and depth of moisture. These factors limit confidence in drizzle occurring, but there should at least be widespread stratus.

Pfahler

LONG TERM
(Monday through Next Saturday)
Issued at 232 PM CST Sat Dec 7 2024

On Monday, a cold front trailing the aforementioned mid-level shortwave trough is expected to pass through the CWA This front will mainly act to veer surface and low-level flow to westerly with stronger low-level CAA lagging upstream, providing another mild but slightly cooler day with high temperatures reaching the 50s F beneath widespread (upper-level and low-level) clouds. Global model guidance is in agreement that a much longer wavelength upper-level trough will traverse the central CONUS late Monday through early Wednesday, strengthening the front and increasing low to mid-level flow overrunning the cool (northwest) side of the front. This process is not likely to result in any precip until the front is well east of the CWA, with only 20 percent or less of ensemble membership depicting any measurable precip in southeastern MO and southwestern IL. Instead, the main impact of the trough will be to facilitate an extended duration of low-level CAA that will gradually cool temperatures from above average on Monday to below average by Wednesday. The vast majority of ensemble membership remains dry through the week, but 10 to 20 percent have very light QPF around Wednesday or Thursday associated with a shortwave trough potentially plunging the backside of the main trough when temperatures across much of the northern-half of the CWA would be supportive of frozen precip. This period will need to watched, but, again, dry conditions are most likely.

Aside from any passing shortwave troughs, mid-level height rises are expected to occur across the central CONUS through much of Wednesday and Thursday with low-level flow becoming increasing southerly or southwesterly. Exactly how quickly WAA becomes established and temperatures warm through the end of the week is uncertain with NBM interquartile temperature ranges between 10 and 15 F Thursday and Friday, but the 25th percentile rises to at least average by Friday.
Differences between global model guidance in the large-scale upper- level wave pattern across the CONUS grow quickly through the end of the week, namely the timing and amplitude of one or more troughs traversing the central CONUS, determining any additional opportunities for precip.

Pfahler

AVIATION
(For the 00z TAFs through 00z Sunday Evening)
Issued at 533 PM CST Sat Dec 7 2024

Mainly dry and VFR conditions are expected through 18Z on Sunday.
Then there will be an increasing chance for MVFR ceilings (1500-2500 feet AGL) at COU/JEF on Sunday afternoon and at STL after 00Z on Sunday evening. There will also be an increasing chance for rain after 00Z on Sunday evening so I have included a PROB30 group with MVFR visibilities. The best chance of rain will stay to the south of the terminal. Otherwise, LLWS remains likely late tonight into early Sunday at all of the terminals as a 40-50 knot low level jet sets up between 1500-2000 feet. Southwest winds this evening will shift out of the south tomorrow with gusts up to 20 knots.

Britt

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