Marine Weather and Tide Forecast for Lake Petersburg, IL

SHORT TERM
(Tonight through Friday)
Issued at 216 PM CDT Thu May 22 2025

Widely scattered showers continue to develop along a surface trough across central Illinois this afternoon...with most of the showers confined to locations along/north of I-72. Based on robust diurnal cloud elements seen on 1845z/145pm visible satellite imagery and a consistent signal from the HRRR/RAP, will continue to advertise 20-40 PoPs across the northern two-thirds of the KILX CWA through the afternoon until about 01z/8pm when CAMs indicate the showers will fade away. Despite an end to the showers, think it will take awhile longer for all the Cu to dissipate...so am expecting partial cloud cover to linger until late evening, followed by clear skies and chilly conditions overnight with lows dipping into the lower to middle 40s. The trough axis will drop south of the Ohio River on Friday as high pressure builds in from the northwest. Skies will start out sunny: however, high clouds will increase from the west...with a high overcast expected during the afternoon. The increasing high clouds will mitigate the warming trend somewhat, but highs should still reach the upper 60s and lower 70s.

Barnes

LONG TERM
(Saturday through Next Thursday)
Issued at 216 PM CDT Thu May 22 2025

Thanks to an upper-level blocking pattern across eastern Canada, a prominent trough will remain anchored over the Great Lakes this weekend...which will shunt the primary storm track well to the S/SW of central Illinois. The first wave to approach the region will skirt just south of the area Friday night into Saturday, with much of its associated precip occurring across Missouri into far southern Illinois. The second wave will come into the picture Saturday night into Sunday...with some models suggesting precip may spread a bit further north. The NBM continues to be too aggressive with bringing PoPs northward into central Illinois given the clear southward shift seen most notably on the ECMWF.
Have therefore cut PoPs to confine the highest rain chances to areas south of I-72...and further cuts may be needed if trends continue.

As has been seen by the past few model runs, a third wave expected to approach from the southwest early next week stands the best chance at bringing light showers to nearly all of central Illinois Monday night into Tuesday. Despite all the low rain chances from Saturday night through Tuesday, storm total rainfall will be light...ranging from just a couple hundredths of an inch near I-74 to perhaps as much as 0.25 to 0.50 along/south of a Jacksonville
to Taylorville
to Robinson line. The focus for heavier rains and thunderstorms will stay well to the south across southern Missouri into western Kentucky...where amounts of 3 to 5 inches will be likely.

Temperatures will remain on the cool side through Wednesday: however, there are signs of a warm-up by the end of next week. The 12z GEFS shows a powerful 500mb jet streaking across the Pacific Ocean, eventually digging a significant trough just off the West Coast. As the trough sharpens, downstream ridging will bring higher heights and thus warmer, more typical springtime temps back to central Illinois by next Thursday/Friday.

Barnes

AVIATION
(For the 18z TAFs through 18z Friday Afternoon)
Issued at 1231 PM CDT Thu May 22 2025

MVFR ceilings linger at all terminals except KSPI early this afternoon: however, think cloud bases will diurnally rise to low VFR at all sites after 19z/20z. In addition, isolated showers developing on 1720z/1220pm radar imagery will expand in areal coverage and drop southeastward across the area this afternoon.
Have included VCSH accordingly. HRRR/RAP suggest the showers will dissipate toward sunset, so have ended light precip mention by 01z. After that, skies will become mostly clear tonight into Friday morning...before high clouds increase from the west and create an overcast by Friday afternoon. Winds are still gusting 15-20kt at the I-72 terminals, but have dropped to 10kt or less at both KPIA/KBMI. After a few more hours of gustiness, winds will decrease to less than 10kt across the board by sunset.

Barnes

ILX WATCHES/WARNINGS/ADVISORIES
None.