Southern IL Forecast


 

Hopefully you all enjoyed the sun today. It’s nice to know it still exists after what has seemed like a permanent deck of cloud cover. Speaking of clouds, we’ll likely have some develop in response to a surface ridge moving off to the east promoting southerly flow on the backside. Winds may end up being a little breezy overnight tonight but it should help to moderate temperatures keeping them steady overnight. Area-wide should see temperatures range from 37-42F.

Moving into Saturday, temperatures will warm up to near 60 (56-61) but we’ll also be looking at some rain showers throughout the day. We’ll have the first of several vorticity anomalies slide through the region and it appears as if this feature, along with a cold front, will be enough to generate a band of showers throughout the day. Overall precipitation from this appears to be on the light side with generally around 1/4″ expected. Behind the front, much colder air will filter in and we might be looking at some potential frost overnight Saturday, especially for locations along and north of I-70 where temperatures may fall to 30F. Farther south temperatures will still be in the low 30s but whether or not they fall to the freezing mark is in question. In general, I’m thinking 29-34F for a north to south temperature gradient for southern IL but I’ll have to keep an eye on trends since the timing of the cold front passage along with how dry the air is behind the front in order to fine tune those numbers.

EASTER SUNDAY! As much as I would like to issue a pleasant sunny and 60F, that’s just not going to happen. A tricky high temperature forecast is in play here but given the concern for a band of accumulating snow, I think mid-upper 30s to 40 (35-40) will suffice for now. The potential for accumulating snow should spread across parts of southern IL including the St. Louis metropolitan area as well as Mt. Vernon, and Vandalia, in a west to east band across the state. The GFS/GEM/Euro are all on board with accumulating snow albeit differences in strength in timing exist. The NAM/SREF both come in much lighter placing a wrench in the forecast as has been the case this entire winter. With that being said, I do feel confident enough to believe the snowfall may overcome the mitigating factors enough to suggest light accumulations around 1″ will be possible Sunday. The placement, timing and updated totals will be introduced in updated forecasts as we approach Easter so please check back often in order to have the most up-to-date information. Rain/snow chances will decrease heading into the overnight hours of Sunday with lows ranging from 27-33 (it may be cooler in locations that receives any snow).

The first part of Monday looks to be dry and we’ll see highs in the low-mid 50s (50-56). We might even see some sunshine peak through but again, it will be short-lived. The active pattern we’re in will throw another trough our way. In response, the LLJ will increase throughout the day and we will have precipitation develop along and north of a warm front that will begin lifting north which will bring elevated showers and a few thunderstorms Monday afternoon and Monday night. Temperatures Monday night should stay relatively stable hovering in the upper 40s to around 50 (46-51).

Tuesday will actually start to feel a little like spring with highs dipping into the low 60s across the region. Dew points look to rise into the mid-upper 50s owing allowing surface-based instability to develop in the warm sector. A capped atmosphere that should erode and adequate deep layer shear may also be present which indicates the possibility of a few strong/severe thunderstorms across the region. With this scenario being 4 full days away, a lot can change. At minimum we’ll see rain showers as the cold front swings through but this is your first heads up for the potential for some strong to severe thunderstorms Tuesday afternoon and evening. We will be monitoring trends closely in order to keep you abreast to changes.