Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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273 FXUS63 KILX 171015 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 515 AM CDT Tue Sep 17 2024 .KEY MESSAGES... - Summer-like warmth continues through the end of the week with daytime highs in the middle 80s to near 90. - Precipitation looks more promising later in the forecast period as a few frontal systems bring rain chances back late this week and again this weekend into early next week. && .DISCUSSION... Issued at 153 AM CDT Tue Sep 17 2024 Nighttime Microphysics satellite imagery shows clear skies over the state of Illinois early this morning. Dewpoints as of 2 am are sitting in the 50s, with the lowest readings in east-central Illinois. Temperatures will continue to fall, bottoming out in the middle to upper 50s over the next few hours. A Rex block remains stoutly in place over the eastern CONUS with strong high pressure ridging over the northeast US and an upper low over the southeast. The remnants of Tropical Depression Eight will continue to slowly move inland today before becoming stationary as it encounters ridging. Moisture associated with this feature will remain east of here, with the weather pattern staying dry until later in the week. Daytime highs will continue to sit between 5-10 degrees warmer than normal for mid September. However, a lower dewpoint airmass will favor more seasonable lows the next few nights. Precipitation chances begin to increase later this week as an upper trough currently situated over the southwest CONUS emits shortwaves northward, acting to break down the strong upper ridge. The first frontal system will bring a cold front toward the area late Thursday night into Friday, introducing low end precipitation chances to locales west of I-55. The front looks to stall or wash out as it encounters upper ridging, so rain amounts don`t look overly impressive. However, some guidance suggests daytime heating on Friday may reinvigorate the boundary and perhaps support a few storms. The NBM came in dry during that period for now, but this may need to be increased in future forecast cycles. A stronger wave will lift north through the Plains states this weekend. Subtle shortwaves ahead of this feature will increase rain chances Saturday night into Sunday as a warm front lifts through the area. The system`s cold front will approach Sunday night into Monday, bringing a better push of moisture advection especially west of I-55. A strong LLJ should support some storms with FROPA, but unfavorable timing should keep any severe threat west of here. Ensemble probabilities for receiving at least 0.50" of rain through early next week are highest west of I-55 (30-40%), with lower chances east of there. However, storm activity could increase total amounts. Temperatures look to briefly return back to our seasonable norms (upper 70s to low 80s) late this weekend into early next week. Longer range guidance is split on whether the seasonable temperatures will persist through next week with the GFS favoring longwave troughing lingering over the central CONUS (cooler) and the ECMWF indicating ridging building back in (warmer). For now, the Climate Prediction center still favors warmer than normal temperatures from the middle of next week through the end of the month. NMA && .AVIATION... (For the 12z TAFs through 12z Wednesday Morning) Issued at 515 AM CDT Tue Sep 17 2024 VFR conditions with mostly clear skies and light easterly winds are expected through the TAF duration. NMA && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$