FXUS63 KILX 150459 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 1159 PM CDT Tue Apr 14 2026 .KEY MESSAGES... - Periods of thunderstorms will continue through early Saturday. A 15-30% risk for severe weather exists this afternoon, tomorrow night, and late Friday into Saturday. The primary risks this afternoon will be large hail and damaging winds. - With any training storms, heavy rainfall may result in localized flooding. There is a level 2 of 5 (slight) risk for excessive rainfall this evening northeast of a roughly Galesburg to Mattoon line. - After a warm work week, conditions will turn sharply cooler on Saturday. There will be a low (20-30%) chance for frost Saturday night north of I-70, and a higher chance area-wide Sunday night. && .UPDATE... Issued at 728 PM CDT Tue Apr 14 2026 We continue to closely monitor storm potential across central Illinois this evening, however, the threat remains best across northern Illinois in the near term. Locally, very unstable conditions (MLCAPE in excess of 2000 J/kg) are in place as sampled by both 18Z and 00Z soundings, albeit strongly capped at 18Z around 800mb. While the cap has largely eroded, the early afternoon shortwave trough has left subsidence in its wake across central Illinois this evening, which when coupled with loss of peak daytime heating, has resulted in dramatic thinning of the cumulus field across the central part of the state. Given the lack of forcing, lowered PoPs considerably to around 20% across central Illinois through the remainder of the evening. If on the off chance a storm is able to develop (perhaps associated with outflow from northern storms or strengthening low level jet), shear and instability remain favorable for any storms to be severe. && .DISCUSSION... Issued at 133 PM CDT Tue Apr 14 2026 ***** BOOM OR BUST CONVECTIVE SCENARIO THIS AFTERNOON ***** At 1pm, a warm airmass was in place across central and southeast Illinois with temperatures in the upper 70s to low 80s. Gulf moisture continues to surge into the region on 15-20 (gusting to 30) mph southwest breezes, with dewpoints currently in the mid 60s. Consequently, the airmass is becoming increasingly unstable with RAP mesoanalysis indicating 1500-3000 J/kg SBCAPE. A capping inversion should prevent convective initiation unless and until a trigger lifts parcels to the LFC, which at this point remains unclear. Recent iterations of the HRRR and several members of the 12z REFS suggest that cap will break, resulting in explosive convective development and scattered severe weather across the CWA by mid afternoon. However, about 60-70% of CAMs keep the cap in place throughout the evening - maintaining warm and breezy conditions. The 18z raob confirms this notion, depicting a 3 degC capping inversion around 800mb which would take a lot of forcing to overcome. Given the parameter space for severe weather is forecast to become volatile over the next few hours, with SBCAPEs climbing to 2500-4000 J/kg, 700-500 lapse rates reaching 8-8.5C/km, and 45-55 kt effective bulk wind shear, any storms that form would pose a risk for severe weather, especially large hail where storm relative inflow (from the SSW/SW) is unimpeded in right- moving supercells (favored by clockwise curved hodographs). In addition, a few of the more bullish models show localized pockets of 3+ inches of rain falling in a few hours with training storms, which could result in some hydrological issues; accordingly, WPC has expanded the level 2 of 5 (slight) risk for excessive rainfall southward into much of our CWA. We'll be keeping a close eye on mesoscale trends this afternoon to assess the potential and issue any necessary warnings. ***** MORE NUMEROUS SHOWERS AND STORMS TOMORROW ***** We'll likely (50-70% chance) have a few more storms overnight tonight as a weakening MCS lifts up into our area from northeast Missouri. We may end up needing some short-fused wind headline if the HRRR and RRFS are correct in their depiction of a meso-high feature impacting our west/southwest counties between 11pm and 4am, though confidence in this scenario is also low. The upper level low will slowly approach our area tomorrow, with continued warm advection ahead of it bringing waves of thunderstorms through the Prairie State. It appears instability will be a bit weaker tomorrow due to widespread clouds and scattered storms limiting surface heating, though the risk for severe weather will increase during the late evening or early overnight period (8pm-2am) west of I-55 where a few CAMs bring a weakening line of storms capable of locally severe winds. ***** DRY THURSDAY(?), STORMS RETURN FRIDAY NIGHT ***** A weak cold front will settle across the district on Thursday, bringing a moment's repose from the active pattern. However, the front will lift back north Thursday night into Friday, when instability will build ahead of a more potent kinematic system. As with today, we'll be in the warm sector on Friday, so a volatile thermodynamic environment would support severe weather if a trigger ruptures the capping inversion. Otherwise, more numerous showers and storms will pass through the area along the cold front sometime late Friday night or Saturday morning. While this is not a diurnally favorable period for severe weather, the strong forcing with the cold front and 45-55 kt deep layer shear could result in at least scattered severe winds if a mature line of storms enters our area from the west Friday night...or develops along the cold front in eastern Illinois on Saturday. ***** COOLER WEATHER RETURNS SATURDAY ***** A cold front will cross the area sometime on Saturday, with stiff west winds ushering in a more seasonably cool airmass for the second half of the weekend. NBM indicates a 30-50% chance low temperatures by Saturday night fall to 36 deg or cooler north of I-70, though winds should remain elevated to prevent frost formation. The better opportunity will be Sunday night, when NBM chances are 30-60% area- wide for sub 37 degF lows and winds should be calm with surface high pressure parked across the CWA. Protective action may be needed to prevent frost from damaging tender vegetation. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 1159 PM CDT Tue Apr 14 2026 A few rounds of TSRA are likely across the central IL terminals over the next 24 hours, starting around or just prior to daybreak. Timing when these may impact a particular terminal is very low confidence at this point, resulting in an extended period of PROB30 for TSRA into Thursday evening. Away from storms, VFR conditions are expected. Southwest winds will continue through the period, gusting to 25 kt at times. && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$ KEY MESSAGES...Bumgardner UPDATE...Deubelbeiss DISCUSSION...Bumgardner AVIATION...25