FXUS63 KLOT 250819 AFDLOT Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 319 AM CDT Sat Oct 25 2025 .KEY MESSAGES... - Seasonable temperatures through the end of the month. - A few sprinkles across northern Illinois today, then increasing rain chances for portions of the area Tuesday into Wednesday. && .DISCUSSION... Issued at 319 AM CDT Sat Oct 25 2025 Blocking from a prominent ridge over central Canada and upper- level low centered over Oklahoma today will persist into early next week, resulting in a slow evolution of the broader flow across central North America. Precip chances during this period look to be quite low amid generally seasonable temperatures for late October. Mostly clear skies early this morning will gradually fill in with mid and upper-level clouds from both the northwest and south through the remainder of the morning. An area of modest mid-level moisture evident in satellite and obs over Iowa early this morning will gradually advect eastward today as a compact wave just east of the Twin Cities tracks southeastward. Scattered mid-level showers have been common across southeast Minnesota and northern Iowa this morning. With the added mid- level moisture interacting with the approaching wave, expectations are for at least isolated light showers or sprinkles over northern Illinois later this morning into the afternoon hours. Farther south, the northern periphery of the upper-level low may bring a few sprinkles across central Illinois later this afternoon and this evening, but expectations are for precip to remain south of the forecast area. Mostly clear skies are then in store Sunday through Monday as some additional cirrus from the low to the south filters northward across the area. As the upper low (ridge) drifts eastward to the southeastern states (western Quebec) by Tuesday, a mid-level low dislodging from a broader trough over the northwest U.S. will unravel while attempting to phase with the eastern low. Consensus guidance continues to come into better agreement that the low will pass southwest of the forecast area Tuesday afternoon through Wednesday. However, a residual reservoir of mid-level moisture from the eastern low will be drawn into the approaching wave as the entrance region of a northwestward directed upper-level jet streak settles just west of the forecast area. This should support a NW to SE oriented band of rain over at least some of the forecast area (especially the southwest half) during this time. Interactions with the two lows later in the week, as well the any potential interactions from (currently) Tropical Storm Melissa, seem to point toward an overall transition to a longwave trough developing across the eastern Great Lakes, Northeast, and eastern Canada by early next weekend. Any weak wave rotating on the western flank of the low will likely yield isolated to scattered showers and perhaps some a few lake effect rain showers during this time. With no artic air masses behind the broad trough, temps should remain seasonable as we close out October. Kluber && .AVIATION /06Z TAFS THROUGH 12Z SUNDAY/... Issued at 1240 AM CDT Sat Oct 25 2025 VFR conditions are forecast through the period. Light and variable winds overnight will return to a prevailing east southeast direction after daybreak around 5-10 kt then ease again with sunset. Increasing cloud coverage is expected by daybreak as a mid- level impulse moves through the region. The low-levels remain rather dry and suspect the majority of this will remain virga. However, a few sprinkles/spotty showers can't be fully ruled out early to mid afternoon (<30% chance). For now have kept the TAF's dry. Petr && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at weather.gov/chicago