AFTERNOON-OVERNIGHT: Clouds and sun are in place this morning across zones 6 and 7. There are some rain to the northwest associated with a cold front to the west and northwest of the forecast area.
Through the morning hours’ clouds will continue to build and rain will develop southward along the front. By 12-1 PM rain will be moving to the east and northeast into western portions of zones 6 and 7.
Rain and a few t’storms will continue moving to the east and northeast across Illinois this afternoon. By 4-5 PM the cold front and rain looks to be situated across east central Illinois.
By 7-8 PM this evening some scattered rain and storms will be continuing across zones 6 and 7 in Illinois.
Through the overnight any precipitation in place will start to fade as we lose what instability we will gain. So while a few showers will remain possible through the overnight, coverage will be less.
Lows tonight will be in the mid to upper 50’s across Illinois.
WEDNESDAY: We will likely start Wednesday out with a few showers across zone 6. However, these will be hit and miss, and very light in nature so I’m not expecting any problems out of those.
Highs on Wednesday will be in the mid 60’s west to mid 70’s east. Winds will be gusty at times, with 25-35 mph gusts out of the south/southeast possible.
Through the day a cold front will approach from the west. As it does, rain and thunderstorms will develop along the front. Storm timing looks like 3-5 PM Wednesday afternoon for initial rain/thunderstorm development.
By 9-10 PM Wednesday evening the surface cold front will be located across eastern Missouri and very western portions of Illinois. Ahead of the front scattered rain and storms will be ongoing across the zones.
By 3-4 AM Thursday morning the front will be pushing through Illinois. As it does the main threat for rain and storms will shift eastward across the very eastern portions of the forecast area and into Indiana.
I am not expecting much, if any, severe weather with the storms that roll through the area. Both winds aloft and instability look pretty weak. If some pockets of greater instability could interact with storms and the increased low-level jet late in the afternoon/evening Wednesday a few strong to possibly low-end severe storms will be possible. However, I’m not anticipating any significant severe weather.
Regarding new rainfall totals, I think .25-.50” will likely be close to the average accumulation across the zone forecast area through Thursday morning. However, the areas that get under the heavier storms will see much more. Areas of 1-1.5” will be likely, with some 1.5-2” reports possible locally.
Lows Wednesday night into Thursday will be in the low 50’s west to upper 50’s east.
THURSDAY: The cold front will move to the east of the forecast area through early Thursday morning taking most of the precipitation with it.
While there could be some showers leftover early in the daytime hours, mostly dry conditions are expected through the day. It is even possible as we see some of the sinking air behind the system that sunshine gets through during the afternoon hours.
Highs on Thursday will be in the mid 60’s to low 70’s. Gusty winds will remain possible behind the front on Thursday. Some winds gusts of 25 mph will be possible.
By later in the evening Thursday there will be a secondary cold front we will be watching move in from the northwest. By 7-8 PM the front looks to be in place across zone 7. Moisture looks pretty meager ahead it, so if any precipitation does form it will be light in nature.
Through the evening the front will continue pushing to the south and southeast across Illinois. By 10-11 PM it will be located across zone 6 along with some scattered light rain showers too.
THURSDAY NIGHT – FRIDAY: An area of low pressure will remain in the area through at least Thursday night. Right now, there is a large spread in models regarding the timing and placement of the low.
The NAM places the low to the south of the forecast area. This location would allow for better chances of rain to continue through the day on Friday, escpeciall across southern portions of the forecast area.
The CMC exits the low my early to mid-afternoon. However, this solution would likely allow scattered rain showers and perhaps a storm to develop across the area.
The GFS and EURO models do exit the low much quicker paving way to a mostly dry Friday. The GFS would suggest the rain completely ends by early Friday morning, while the EURO keeps a few isolated showers in the forecast. We will continue to watch the models and trends over the next few days.
Highs on Friday will be in the low 60’s north to around 70 south.
LONG-RANGE(WEEKEND): Overall the weekend is looking very nice as an rea of high pressure builds into the region behind the end of the week weather system. This will allow for more sunshine and mostly dry conditions.
Highs this weekend will warm into the mid 60’s to mid 70’s Saturday. Highs on Sunday look to top out in the upper 60’s to possibly near 80 in locations!