Marine Weather and Tide Forecast for Hettick, IL

SHORT TERM
(Through Late Thursday Afternoon)
Issued at 320 AM CDT Wed Jun 17 2026

Monday's cold front has stalled near the I-70 corridor, but will begin to lift northeastward as a warm front through sunrise in response to surface cyclogenesis across the Northern Plains with an approaching upper-level shortwave trough. A strong, 50+ kt southwesterly LLJ will veer toward the Upper and Mid-Mississippi River Valley with increasing showers and thunderstorms expected across IA near its nose through sunrise among strong WAA and moisture transport. Most CAMs bring the southwestern edge of these showers and thunderstorms southeastward into portions of northeastern MO, west-central and south-central IL through the morning, which could pose a marginal hail threat with the potential for a couple of embedded supercells within a larger cluster of thunderstorms.

Through midday or early afternoon, these showers and thunderstorms should migrate to the east of the CWA, with quick moderation and northeastward lifting of any remnant outflow or cold pool out of the CWA given synoptic-scale maintenance of the strong southwesterly LLJ. Increasing insolation, favorable southwesterly flow, and some downslope warming off the Ozark Plateau will support high temperatures in the upper 80s to low-90s F for most of the CWA
Given BL mixing facilitating downward momentum transfer from the LLJ to the surface, occasional wind gusts of 40 to 50 mph are forecast from late morning through late afternoon, warranting expansion of the Wind Advisory for all of the CWA aside from a portion of southeastern MO.

With a capping inversion across the portion of the warm sector across the CWA, initiation of thunderstorms is not expected until a cold front enters northeastern MO and west-central IL sometime in the 2 to 4 pm timeframe this afternoon. Anomalously strong flow at lower and mid-levels will lead to 45 to 55 kt deep-layer wind shear which, combined with 1500 to 3000 J/kg MLCAPE, will be favorable for organized severe thunderstorms including supercells. With 45 to 60 deg orientation of deep-layer wind shear with the front, there is a slight favoring of supercells remaining the dominant storm mode, which is support by nearly all CAMs, leading to thunderstorms capable of all severe hazards. With 1000+ J/kg of DCAPE, inverted V signatures in forecast soundings, and 50+ kt winds not far above the surface it will not be difficult for thunderstorms to produce damaging winds, leading to that being the most common hazard. The greatest tornado risk, including the potential for a strong tornado (EF2+), will be across west-central and south-central IL (moreso in central IL) where the largest low-level hodograph curvature exists and LCLs will be lower. Further south along the cold front, high LCLs from deeper BL mixing throughout the day will potentially be less favorable for tornadogenesis along with some concern for deconstructive storm interactions. There could be a brief window that is more favorable just around/after sunset when LCLs lower and the LLJ nocturnally strengthens, further elongating hodographs, but frontal convergence and forcing altogether will be decreasing/departing around that time.

The threat of severe weather will decrease late in the evening, but there is a low threat of locally heavy rainfall with some training of thunderstorms possible as the front slows south of I-70 overnight. However, fast storm motions will otherwise limit the residence time/duration of any efficient rainfall (90th+ climo percentile PW and deep warm cloud depths).

The cold front is progged to finally advance south of the CWA on Thursday morning, but another wave of scattered showers and thunderstorms are anticipated on the cool side of the front along/south I-70 on Thursday as weak mid-level isentropic ascent overruns the front and FGEN ebbs and flows. However, elevated instability, and thus thunderstorms, will be mainly confined to southeastern MO/southwestern IL. The post-frontal airmass and waves of more abundant cloud cover will result in much cooler high temperatures on Thursday, largely in the mid-70s to low-80s F.

Pfahler

LONG TERM
(Thursday Night through Tuesday)
Issued at 320 AM CDT Wed Jun 17 2026

With gradual mid-level height rises and a weak surface high pressure center in the Mid-Mississippi River Valley, seasonably cool temperatures will persist through Friday along with dry conditions.
However, model guidance signals upper-level northwesterly flow transitioning to quasi-zonal over the weekend, with at least one more prominent shortwave trough passing between sometime late Saturday and early Monday accompanied by another opportunity for showers and thunderstorms. There are some indications for at least a low threat of heavy rainfall Saturday night through Sunday night with PW projected to be near the 95th climatological percentile and a slow moving front in the region. The threat of strong/severe thunderstorms will also need to be monitored on Sunday as well, but potential morning showers and thunderstorms and the overall variability and inconsistency precludes of model guidance precludes the resolution of any details and leads to low confidence in either threat at this point.

Early next week, there is a general consensus that upper-level flow will become more northwesterly and greatest support in ensemble membership for a wavering front to shift south of the CWA These ingredients support another period of seasonably cool and largely dry conditions.

Pfahler

AVIATION
(For the 12z TAFs through 12z Thursday Morning)
Issued at 625 AM CDT Wed Jun 17 2026

Two rounds of showers and thunderstorms are expected today with the first associated with a cluster of thunderstorms headed southeast out of IA this morning that could track into northeastern MO/west- central IL. Confidence is increasing that these thunderstorms will impact KUIN. The next round will develop with a passing cold front this afternoon and progress eastward, potentially impacting all terminals. Confidence is greatest in impacts at KUIN, KCOU, and KJEF; and slightly lower at St. Louis metro terminals as coverage may decrease some later in the evening. Thunderstorms will be capable of MVFR to IFR flight conditions, gusty winds, and hail.
Outside of thunderstorms, VFR flight conditions will prevail.

The other concern this TAF period is strong southwesterly winds outside of thunderstorms late this morning into early evening with occasional gusts of 30 to 40 kt. Winds will veer to westerly/west- northwesterly as the cold front passes, with winds also slackening later this evening.

Pfahler

LSX WATCHES/WARNINGS/ADVISORIES
MO...Wind Advisory from 1 PM this afternoon to 8 PM CDT this evening for Franklin MO-Gasconade MO-Jefferson MO-Lincoln MO- Madison MO-Saint Charles MO-Saint Francois MO-Saint Louis City MO-Saint Louis MO-Sainte Genevieve MO-Warren MO.

Wind Advisory from 10 AM this morning to 6 PM CDT this evening for Audrain MO-Boone MO-Callaway MO-Cole MO-Knox MO-Lewis MO-Marion MO-Moniteau MO-Monroe MO-Montgomery MO-Osage MO- Pike MO-Ralls MO-Shelby MO.

IL...Wind Advisory from 1 PM this afternoon to 8 PM CDT this evening for Bond IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL- Jersey IL-Macoupin IL-Madison IL-Marion IL-Monroe IL- Montgomery IL-Randolph IL-Saint Clair IL-Washington IL.

Wind Advisory from 10 AM this morning to 6 PM CDT this evening for Adams IL-Brown IL-Pike IL.