Marine Weather and Tide Forecast for Apple River, IL

SHORT TERM /THROUGH TONIGHT/
Issued at 316 AM CDT Wed May 21 2025

A weak low moving along the inverted trof across the area that will allow isolated to scattered showers to persist through sunrise.

After sunrise, the areal coverage of showers will decrease as the lift associated with the low exists the area. However, the persistent low clouds may keep areas of drizzle going across much of the area.

During the afternoon another round of diurnal showers are expected to develop with the arrival of a weak upper level disturbance. Areas north of I-80 look to be the favorable location for any rain showers.

The rain showers that develop during the afternoon will slowly dissipate after sunset. However, the persist weak inverted surface trof across the area is expected to allow isolated rain showers to persist through the night.

LONG TERM /THURSDAY THROUGH TUESDAY/
Issued at 316 AM CDT Wed May 21 2025

Thursday Assessment...very high (>90%) of cooler than normal temperatures.
Medium (40-60%) confidence on isolated showers.

The weak inverted trof remains across the area while another weak upper level disturbance moves through the area. Thus, the morning hours should continue to see plenty of clouds with isolated showers.
As the disturbance exits the area during the afternoon, clouds will slowly break up as the showers slowly dissipate.

Thursday night through Friday night Assessment...medium to high (60-80%) confidence of dry but cooler than normal conditions.

Cool Canadian high pressure slowly builds into the Midwest which will keep temperatures below normal and dry conditions across the area.

Saturday through Tuesday Assessment...Low (<25%) confidence regarding precipitation chances.

The global models (both deterministic and ensembles) differ on the sensible weather. The key factor appears to be the position and strength of the Canadian high pressure.

The deterministic ECMWF/ICON/CMC/UKMET are all dry while the GFS has precipitation due to the GFS position of the high being further north and weaker.

Interestingly, a majority of the ensemble members from the EPS/GEPS/ICON-EPS/GEFS suggest the potential for precipitation. The UKMET GREPS 'suggests' dry.

The forecast thus reflects the wetter solutions/ensembles. There does appear to be some agreement that rain may occur late Saturday afternoon into Sunday morning for areas south of I-80 due to the passage of a storm system.

For the rest of the time period the forecast has a 20 to 40 percent chance of rain.

The important message is that while there is a daily risk of rain, there will be many hours of dry weather.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
Issued at 1236 AM CDT Wed May 21 2025

Widespread IFR/LIFR conditions will persist through 18z/21 across much of eastern Iowa and northern Illinois with scattered showers or areas of drizzle. After 18z/21 CIGS will slowly improve to IFR/MVFR with isolated diurnal SHRA mainly north of Interstate 80. After 00z/22 a very slow improvement to MVFR/VFR CIGS will be seen.

DVN WATCHES/WARNINGS/ADVISORIES
IA...None.
IL...None.
MO...None.