Southern Illinois 5-Day Forecast 1/18-1/22


18Z GFS forecast depiction of precipitation moving through our area Sunday night into Monday morning.

I was a couple degrees too low on my forecast high temperatures for today in the northern part of my viewing as WAA (warm air advection) has begun. Temperatures in the southern part of the forecast region near Mount Vernon and Paducah are on track to verify with the recent snowpack keeping temperatures cooler but fear not, the snow will be gone in the next couple of days as temperatures continue to climb into the weekend. Friday night into Saturday morning suggests the potential for fog development as warm air is moving over the still relatively cool ground. I will have more details on that possibility tomorrow when I get a handle on the amount of snow remaining in the southern part of the forecast area and how warm temperatures rise. I currently expect Saturday to remain dry but Saturday night I think there is a small chance of widely scattered showers as moisture from the Gulf of Mexico begins to surge north ahead of a low pressure system that will arrive Sunday. I do believe the entire forecast area will remain in the warm sector for the entirety of the event Sunday night into Monday morning and it looks like we’ll hear our first clap of thunder with this event as well but right now uncertainty remains too high to believe any severe weather potential exists. As for precipitation, forecast models are fairly consistent painting between 0.5-0.75″ of precipitation. In the next day or two I will work to pin down a more precise time frame for the arrival of the main precipitation shield and QPF (quantitative precipitation forecast) totals. The system of interest still hasn’t completely been sampled by our upper air network and until it is, variations in timing, intensity and QPF  will continue to exist. 

St. Louis and Surrounding Areas:

1/18 Tonight

Lows: 22-26 °F

Clear

Precip: 0-5%

1/19 Friday

Highs 48-52 °F

Sunny

Precip: 0-5%

 

Friday Night

Lows: 30-35 °F

Mostly Clear

Precip 0-5%

1/20 Saturday

Highs 48-53 °F

Mostly Sunny

Precip: 5-10%

 

Saturday Night

Lows: 38-42 °F

Mostly Cloudy

Precip: 5-10%

1/21 Sunday

Highs 55-60 °F

Mostly Cloudy

Precip: 30%

 

Sunday Night

Lows: 41-45 °F

Showers Likely

Precip: 70%

1/22 Monday

Highs 44-48 °F

Showers Early

Precip: 60%

 

Monday Night

Lows 28-32 °F

Mostly Cloudy

Precip: 10-20%

Mount Vernon and Surrounding Areas:

1/18 Tonight

Lows: 19-24 °F

Mostly Clear

Precip: 0-5%

1/19 Friday

Highs 40-44 °F

Sunny

Precip: 0-5%

 

Friday Night

Lows: 28-33 °F

Mostly Clear

Precip 0-5%

1/20 Saturday

Highs 44-49 °F

Partly Cloudy

Precip: 10%

 

Saturday Night

Lows: 37-42 °F

Mostly Cloudy

Precip: 20%

1/21 Sunday

Highs 52-57 °F

Mostly Cloudy

Precip: 30%

 

Sunday Night

Lows: 42-47 °F

Mostly Cloudy

Precip: 70%

1/22 Monday

Highs 47-52 °F

Showers Early

Precip: 60%

 

Monday Night

Lows 29-33 °F

Mostly Cloudy

Precip: 10-20%

Paducah and Surrounding Areas:

1/18 Tonight

Lows: 16-21 °F

Mostly Clear

Precip: 0-5%

1/19 Friday

Highs 36-41 °F

Sunny

Precip: 0-5%

 

Friday Night

Lows: 28-33 °F

Mostly Clear

Precip 0-5%

1/20 Saturday

Highs 44-48 °F

Mostly Cloudy

Precip: 10%

 

Saturday Night

Lows: 40-44 °F

Mostly Cloudy

Precip: 20%

1/21 Sunday

Highs 55-59 °F

Mostly Cloudy

Precip: 30%

 

Sunday Night

Lows: 44-48 °F

Mostly Cloudy

Precip: 70%

1/22 Monday

Highs 53-58°F

Showers Early

Precip: 60%

 

Monday Night

Lows 30-34 °F

Mostly Cloudy

Precip: 10-20%