Marine Weather and Tide Forecast for Jacksonville, IL

DISCUSSION
Issued at 228 PM CDT Fri Apr 25 2025

Scattered Convection This Afternoon/Evening

18z/1pm surface analysis shows a slow-moving cold front extending from southern Michigan southwestward into Missouri. While the bulk of the precip that tracked across the area this morning has pushed east of the I-57 corridor and decreased in areal coverage, new convection is beginning to form along the front from just south of Lewistown to near Jacksonville. Given partial sunshine heating temperatures into the lower to middle 70s and surface dewpoints hovering in the 60s, SPC mesoanalysis indicates SBCAPEs have risen into the 1000-1500J/kg range. Weak convergence along the boundary and deep layer shear of less than 30kt will be mitigating factors for vigorous convection: however, think this band of scattered showers and thunderstorms will continue to work its way eastward across the area...generally impacting locations along/south of a Lewistown
to Bloomington
to Hoopeston line between now and about 8-9pm. After that, the showers will push into Indiana and dissipate by late evening.

Windy and Much Warmer Conditions on Monday

As high pressure pushes eastward into the Ohio River Valley, southeasterly return flow will commence on Sunday. Some CAMs suggest a few WAA showers will be possible across the W/SW CWA: however, these will be fighting a dry low-level airmass and will not amount to much even if they do occur. As the high shifts further east and a cold front approaches from the west, a tightening pressure gradient will lead to increasing winds on Monday. The 00z Apr 25 LREF is showing a high probability (60-90% chance) for southerly wind gusts exceeding 30mph everywhere north of the I-70 corridor by Monday afternoon. Both the LREF and NBM indicate a strong signal for wind gusts over 30mph on Monday and in the 25-30mph range into Tuesday as well. With sunshine and strong southerly winds, the 570dm 1000-500mb thickness line is progged to surge northward into the area...supporting Monday afternoon highs in the lower to middle 80s.

Severe Weather Risk Monday Night

The approaching cold front will interact with a highly unstable (GFS SBCAPEs 2000-3000J/kg) and strongly sheared (GFS 0-6km bulk shear greater than 50kt) environment to trigger a line of severe convection across western Wisconsin into Iowa by late Monday afternoon/evening. This convection will then translate eastward into the Illinois River Valley after dark and will likely continue eastward to the I-57 corridor toward dawn Tuesday. While the storms will be undergoing some degree of diurnal weakening, ample wind energy in the environment will keep the risk of at least scattered severe wind gusts alive across a good portion of the KILX CWA The latest SPC outlook highlights locations along/west of a Litchfield to Hoopeston line...and this still looks good based on the latest data.

Severe Weather Risk Tuesday Afternoon/Evening

The big question for Tuesday will be exactly where convection will re-develop ahead of the cold front/outflow boundary during the afternoon. The GFS continues to suggest initiation will be across the heart of central Illinois: however, the 12z ECMWF is showing things setting up a bit further south...perhaps along the I-70 corridor. Will need to keep a close eye on where the storms eventually fire, because deep-layer kinematics associated with the right entrance region of a 110-120kt 300mb jet streak across the Great Lakes will be favorable for significant synoptic lift. In addition, strong convergence along the cold front will support vigorous updrafts and the subsequent risk for large hail and damaging wind gusts from mid-afternoon into the evening.

Barnes

AVIATION
(For the 00z TAFs through 00z Saturday Evening)
Issued at 612 PM CDT Fri Apr 25 2025

MVFR cigs are expected to spread over the central IL terminals from the northwest this evening, lingering into Saturday morning.
Although timing continues to have uncertainty, start of MVFR looks to be anywhere from before 00Z at KBMI to 03Z at KDEC, and end looks to be around 15Z-17Z. Winds N 10-15 kts with gusts around 20 kts this evening, decreasing to 10-12 kts and shifting to NNE overnight.

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ILX WATCHES/WARNINGS/ADVISORIES
None.