Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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252 FXUS63 KILX 292002 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 302 PM CDT Mon Apr 29 2024 .KEY MESSAGES... - Patchy fog will develop across much of central and southeast Illinois tonight...with a 30-50% chance of visibilities dropping below 1/4 mile in spots along/south of a Danville to Taylorville line. - Above normal temperatures will prevail for the remainder of the week. - The next significant chance for rain will arrive Thursday into Friday, followed by slightly cooler conditions by next weekend. && .SHORT TERM...(Tonight through Tuesday) Issued at 302 PM CDT Mon Apr 29 2024 19z/2pm surface analysis shows a weak cold front pushing slowly eastward through the Illinois River Valley. Low clouds persist east of the front, with persistent showers impacting locations along/southeast of a Paris to Effingham line. Showers will continue across the far E/SE KILX CWA through early evening before gradually pushing further eastward into Indiana. The cold front will eventually exit the CWA as well, but this will not occur until late evening. While the upstream airmass behind the boundary is considerably drier with current dewpoints only in the 40s across Iowa/far western Illinois, this airmass will only gradually trickle eastward after FROPA. As a result, there will be quite a bit of lingering boundary layer moisture. Given clearing skies and light winds, patchy fog looks to be a good bet...especially across the E/SE where the drier air will be slowest to arrive. HRRR/RAP/GFSLAMP all suggest the potential for locally dense fog in a few spots across this area. In addition, the 12z Apr 29 HREF indicates a 30-50% chance of visibilities dropping below 1/4 mile along/south of a Danville to Taylorville line. Am not confident enough to issue a Dense Fog Advisory at this time, but have included areas of fog across the E/SE accordingly. After any early morning fog dissipates, Tuesday looks to be a mostly sunny and pleasant spring day with high temperatures topping out in the middle to upper 70s. Barnes .LONG TERM...(Wednesday through Next Monday) Issued at 302 PM CDT Mon Apr 29 2024 A short-wave trough is progged to eject northeastward out of the Rockies on Tuesday, then track into the Upper Midwest by Wednesday. While the strongest lift associated with this feature will remain well northwest of Illinois, it will drag a weak cold front into north-central Illinois by early Wednesday. Scattered showers and perhaps a thunderstorm will precede the front Tuesday night with any showers dissipating before daybreak Wednesday. Despite the lingering weak boundary in the area, short-wave ridging aloft in the wake of the system will ensure a warm/dry day on Wednesday with high temperatures topping out in the upper 70s/lower 80s. A more significant short-wave will cross the Rockies into the Plains by Thursday...and this system will bring the next significant chance of rain to central Illinois by the end of the week. 12z models continue to be too fast with the eastward progression of this amplifying system, so rain chances Wednesday night/Thursday morning will likely be removed as models come into better focus. The main window for the strongest forcing/deepest moisture continues to look like Thursday afternoon through Friday morning when GFS precipitable water values increase to 1.50-1.75. Have therefore carried likely to categorical PoPs during that timeframe. Once the late week system passes, slightly cooler/drier weather can be expected Friday night into Saturday before another short- wave trough approaches by Sunday. Barnes && .AVIATION... (For the 18z TAFs through 18z Tuesday Afternoon) Issued at 1235 PM CDT Mon Apr 29 2024 IFR/MVFR ceilings persist at the central Illinois terminals at midday: however, latest satellite imagery shows the lower clouds beginning to steadily clear across the Illinois River Valley. Based on satellite trends, have scattered ceilings at KPIA by 21z...then further east to KCMI by 23z. Aside from high/thin clouds streaming northeastward along the I-57 corridor this evening, the remainder of central Illinois will be clear through Tuesday morning. Winds will initially be S/SW at 10-15kt, then will veer to W/SW after FROPA late this afternoon into the evening. SW winds at 5-10kt will resume Tuesday morning under mostly clear skies. Barnes && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$