Sunrise 6:00 AM   Sunset 7:51 PM Moonrise 11:09 PM   Moonset 7:14 AM

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FXUS63 KILX 261057 AFDILX

Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 557 AM CDT Fri Apr 26 2024

KEY MESSAGES

- There will be multiple rounds of showers and thunderstorms today through Monday. Some of the storms could be strong to severe through Sunday (5-15%). Much of the area can expect over 1 inch of rain (50th percentile) through Monday, but localized amounts in the 1.5 to 2 inch amounts are possible particularly west of the Illinois River.

- Warmer and more humid conditions and windy conditions are expected this weekend. Daily highs will be in the upper 70s and lower 80s accompanied by breezy southerly winds gusting 30 to 40 mph at times.

DISCUSSION
Issued at 355 AM CDT Fri Apr 26 2024

Predawn surface map shows 993 mb low pressure over nw KS with its warm front over northeast KS into sw MO and central AR. 1032 mb Canadian high pressure was near Montreal close to the the southern Quebec/Ontario province border and ridging westward over the Great Lakes. An east to ESE flow around this high pressure over CWA was keeping lower dewpoints in the mid 30s to around 40F, with even lower 30s over Lacon, Pontiac and LaSalle/Peru. Not as cool as last night with temps in the mid 40s to upper 40s in central IL and lower 50s in southeast IL. Radar mosaic shows widespread showers and scattered thunderstorms over central and western parts of MO/IA with stronger southerly low level jet west of IL. Also some scattered showers in southern IL south of I-64 and into sw KY and mid TN.

A 925-850 mb warm front to lift ne over central IL during this morning and early afternoon, with a band of showers and isolated thunderstorms lifting ne over CWA Showers to reach far sw CWA by Scott county around or just after sunrise and to the Indiana border by 17Z/noon. Then another wave of showers and a few thunderstorms to move eastward into central IL during this afternoon, especially west of I-57. Low threat of severe thunderstorms this afternoon as air mass does not get that unstable yet, with the stronger instability poised west of IL today and into tonight where slight to enhanced risk over MO and Iowa. SPC day1 outlook has marginal risk of severe storms over much of central and western IL with 5% risk of large hail and damaging winds for mainly this evening. There is a 2% risk of tornadoes west of a Macomb to Jacksonville line. Highs today range from lower 60s from I-74 north to lower 70s along and south of highway 50 in southeast IL. Breezy SE winds develop today with gusts 25-30 mph likely.

Surface low pressure to track ne toward the northern WI and MN border by dawn Saturday, with warm front lifting north of central IL. Low pressure weakens as it moves into eastern Lake Superior by sunset Saturday, while pushing a cold front through central parts of WI/Iowa. Looks like a lull in convection over central/se IL Saturday morning, but a more unstable air mass develops by Saturday afternoon of 1500-2500 j/kg Saturday afternoon, most unstable western/nw CWA where wind shear values nearing 30 kts.
SPC day2 outlook continues slight risk of severe storms along and nw of the IL river Sat afternoon/evening while marginal risk extends as far se as a Danville to Sullivan to Litchfield line.
Main severe wx threats are damaging winds and large hail while 2-5% risk of tornadoes from the IL river west. Greater threat of severe storms Sat and Sat night will still west of IL closer to frontal boundary. Stronger southerly winds develop in warm sector over CWA on Saturday with gusts 30-40 mph and bringing warmer highs in the upper 70s and lower 80s. More humid as well with dewpoints getting into the mid 60s.

Another surface low pressure develops in southeast CO Sat afternoon and eject ne toward the upper MS river valley late Sunday night. This to bring another round of showers and thunderstorms Sunday afternoon and Sunday night. SPC day3 outlook has marginal to slight risk of severe storms over all but far eastern IL during this period, with the slight risk west of Peoria and Springfield. Cold front to push eastward over IL during Monday and likely continues chances of showers and thunderstorms though weaker instability on Monday so lower threat of severe storms than this weekend. Rainfall amounts over 1 inch over much of CWA today through Monday with locally 1.5-2 inch amounts over areas west of the IL river as PW values will be around 1.5 inches at times.
Though any training of thunderstorms could bring over 2 inch amounts of rainfall. Strong southerly winds gusting 30-40 mph on Sunday and even approaching 45 mph north of I-70, with warm highs in the lower 80s with Lawrenceville near 85F. Highs Monday in the mid 70s.

Looks like a brief lull in convection chances overnight Monday night into Tuesday, though could be a little more convection developing later Tue with approaching of next wx system into the upper Midwest. Still mild Tue with sw breezes with highs in the upper 70s to near 80F. Next chance of showers and thunderstorms to be later Wed into Thursday and Wed night as yet another wx system moves over the upper MS river valley and pushing a front into IL.
Highs in the upper 70s to around 80F again on Wed and in the low to mid 70s Thu.

07

AVIATION
(For the 12z TAFs through 12z Saturday Morning)
Issued at 555 AM CDT Fri Apr 26 2024

A band of showers and isolated thunderstorms will lift ne across the central IL airports during this morning, reaching SPI between 13-14Z, PIA and DEC by 15Z and BMI and CMI between 16-17Z. VFR conditions early this morning will deteriorate to MVFR conditions later this morning or midday and continue into tonight. ESE winds 10-15 kts with gusts 18-24 kts early this morning to veer SE and increase to around 15 kts with gusts 22-28 kts this afternoon and turn southerly this evening. Added LLWS between 02-03Z with 2k ft sw winds 45-50 kts.

07

ILX WATCHES/WARNINGS/ADVISORIES
None.

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