Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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567 FXUS63 KILX 130825 CCA AFDILX Area Forecast Discussion National Weather Service Lincoln IL 325 AM CDT Mon May 13 2024 .KEY MESSAGES... - Showers and storms are expected (70-90% chance) mainly this afternoon through Tuesday afternoon. Coverage/potential of >1.0" rainfall is lowering. There is a 20-40% chance for more than an inch of rainfall in any one location. The widespread amounts now look to be in the 0.50-0.75 inch range. - Another system will bring rain to the area Thursday into Friday, with a 40-50% chance of rainfall amounts up to a half inch south of I-72. && .DISCUSSION... Issued at 325 AM CDT Mon May 13 2024 IR satellite loops are showing the upper level low over western Kansas and progressing slowly eastward. Synoptic scale lift is gradually increasing ahead of low as far east as north-central Missouri/south-central Iowa, where showers and a few storms are expanding in coverage. Southerly flow today will encourage modest low level moisture advection, to help overcome the dry sub-700mb airmass in place early this morning. Due to the dry antecedent air, the development of more widespread showers in central IL looks to begin this afternoon, when instability params indicate narrow MLCAPE as high as 1500 J/kg in the RAP soundings. Shear profiles remain marginal for strong storms, with 0-6km bulk shear at 25kts. However, a few supercells may develop per the elongation of straight hodographs with time this afternoon. Isolated hail and strong wind gusts could develop, but overall potential of severe weather is low. Given the patchy nature of the storm coverage, a few locations could see over 1.5" and others less than 0.5". The best chances of widespread showers looks to be this afternoon into evening, with that area shifting to south of I-72 on Tuesday afternoon. The consensus of ensemble guidance is still indicating a break in the rain mid-week in response to ridging at the surface and aloft across Illinois. That break will coincide with some cooler temps, with Wed morning lows in the upper 40s north of I-72. Showers and isolated storms return Thursday through Friday, with the highest potential (50-65% chance) Thursday afternoon into evening. Instability looks marginal with 500 J/kg MUCAPE amidst 0-6km shear up to 25kts. Potential of severe weather is quite low. A bright spot in the extended is for high temps to return to the lower 80s Saturday and Sunday, despite 20-30% chance for showers to bubble up each day. Shimon && .AVIATION... (For the 06z TAFs through 06z Monday Night) Issued at 1133 PM CDT Sun May 12 2024 VFR conditions to prevail into midday Monday, though ceilings will be steadily lowering as a storm system approaches. While a few showers are possible as early as 15Z, most will be during the afternoon and evening. Main period for potential thunder appears during the mid to late afternoon. A few storms may linger into early evening from KPIA-KCMI, though this is less certain, and will not be mentioned at this time. A rapid expanse of lower ceilings is expected in the afternoon, and most sites should be MVFR by about 21-22Z. Ensemble guidance suggests ceilings may dip below 1,000 feet late in the period, with about a 30-50% chance at this point. Geelhart && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$