Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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035 FXUS63 KILX 281909 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 209 PM CDT Tue May 28 2024 .KEY MESSAGES... - Isolated to widely scattered (20-30% coverage) storms are expected this afternoon and evening (2pm-10pm) across central Illinois. Storms are not expected to be severe but gusts up to around 50 mph or penny size hail will be possible with the strongest storms. - Fair weather and overall quiet conditions are expected during the latter half of the week. A more unsettled pattern returns this weekend into next week. && .DISCUSSION... Issued at 204 PM CDT Tue May 28 2024 This afternoon, long wave trough is in place over the Great Lakes with northwest flow over central Illinois. This is driving steep low to mid level lapse rates while a shortwave trough digging across southern WI/northern IL is allowing a few storms to develop. Some of this activity will build south into portions of central Illinois this afternoon, but coverage should remain isolated to widely scattered (20 to 30 percent), and chances will fade with loss of daytime heating this evening. Severe storms are not anticipated in part due to weak instability (dew points in the lower 50s contributing to MLCAPE values of around 300-400 J/kg. That said, isolated stronger wind gusts may still be possible given the steep lapse rates down low. High pressure over the northern Great Plains and Canadian Prairies today will overspread the Midwest through the latter half of the week with the surface ridge axis passing over central Illinois Thursday. Temperatures will undergo a very gradual warming trend during this time frame with low 70s in the forecast for Wednesday and upper 70s by Friday. The air mass will be quite dry with dew points mixing down into the 40s for portions of the area, possibly dipping into the 30s in spots Thursday. The dry air will help keep skies clear and allow large diurnal swings with overnight lows generally in the upper 40s to lower 50s. Upper pattern will transition to more zonal by this weekend and continue into the first part of next week with several low amplitude waves bringing periodic chances for showers and a few storms. Surface ridge will shift to the mid Atlantic coast Saturday allowing return flow into the Midwest. The warming trend will continue into the weekend with widespread 80s back in the forecast for Sunday and mid to upper 80s early next week. Gulf moisture also returns to the region with dew points back into the 60s and pushing 70 by early next week. With the jet stream migrating well to our north, and at least initially modest dew points, a severe weather threat does not seem apparent, but as humidity builds early next week, some stronger storms could be possible, especially during the afternoon and evening hours with any waves that coincide with peak heating. Given the fast moving, low amplitude shortwaves, timing details for precip chances remains uncertain and the extended portion of the forecast is broad-brushed with slight chance to chance PoPs due to model timing differences. && .AVIATION... (For the 18z TAFs through 18z Wednesday Afternoon) Issued at 1232 PM CDT Tue May 28 2024 Northwest flow will prevail across central Illinois through the period. Gusts will develop in the 20-25 kt range this afternoon and evening, then taper off again right around sunset. A few isolated to widely scattered afternoon and evening thunderstorms are expected today, but low coverage precludes more than a VCTS mention at this time. Outside of one of these stray storms impacting a terminal, VFR conditions are expected through the period. Deubelbeiss && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$