STIR ME UP BUTTERCUP...

A gigantic storm system is parked over the Midwest and it's spinning like a top. I mean this thing is really wound up. Imagine vigorously stirring a glass of water with a straw and then pulling it out...you get that swirl in the glass until the energy dissipates. That's exactly the process our atmosphere is going through. The storm is going to spin and wobble in a limited space until it weakens and runs out of steam (in this case swirl).

Here you can see the closed circulation at 500mb gyrating slowly through the region, essentially feeding on itself. That's a classic bowling ball.

The satellite reveals a cold front extending from Lake Superior to northeast Texas. Ahead of it in the warm sector, showers and thunderstorms are active. Under the upper air low in Wisconsin, cold unstable air with rain and snow showers is pouring into the Midwest. We've entered the cold sector and that's the type of weather we'll be dealing with the rest of the work week.

Note the difference in temperatures around the central U.S. Wednesday afternoon with warmth surging into the east and cold air spilling in behind the storm center on gusty W/NW winds to the west.

That cold air really gets established the next 24-48 hours and you can see by Friday temperatures are way below normal over the entire central third of the nation. These are the departures the GFS indicates around noon Friday.

Look at the wind chills we'll deal with all day Friday. There are down in the 20s. Ugh...no thanks!

The air is becoming very cold aloft and at this time of year that means steep lapse rates and plenty of instability. Throw in a couple spikes of vorticity and the stage is set for showers to develop Thursday that are likely to continue on a hit and miss basis into Friday. Even more fun, the showers are likely to mix with and change to snow at some time Thursday night and Friday. Accumulations are not expected to amount to much but a few spots, especially in the north could pick up a dusting mainly on grassy and elevated surfaces. Closer to HWY 20 in my far northern counties, 1/2 to 1" of snow is a possibility. I look for those types of amounts to be localized and few and far between.

On the animation below, you can see over a 60 hour period the scattered rain and snow showers wrapping around the upper air center which is slowly drifting E/SE. You can even see banding which is where the heavier snows are more apt to fall.

Total precipitation from the showers the next couple of days is relatively light, 1/10 to 2/10ths of an inch through Friday. Here's what models are indicating for amounts.

The EURO

The GFS

The 3k NAM

Once again when it comes to snowfall, it's minimal but most areas will see snow showers at some time Thursday night or Friday. A few could even sneak into the north as early as Thursday afternoon. Here's a sampling of what models are suggesting for accumulations.

The GFS

The EURO

The 3k NAM

The HRRR

Friday night the system is finally kicked east and temperatures will make a weekend recovery going from the range of 45-50 north to south Saturday, to 55-60 Sunday. Saturday looks dry and so does most of Sunday. The GFS tries to scare up a few showers Sunday afternoon but so far the EURO remains dry.

NEXT STORM UP...

The next storm enters the que Sunday night with rain chances indicated Monday through Wednesday. The tricky aspect of next week is determining the position of a front that is forecast to vacillate near the area the entire period. The EURO is furthest north indicating highs all three days in the 70s over the southern half of the area. The GFS is further south with the boundary and cooler, although it too gets highs to 70 on Wednesday. This is a tricky set-up as lake enhanced cool air off Lake Michigan may have something to say about how far north the front gets. Convection from Thunderstorms along the front may also hinder the northward movement of the boundary until the system ejects out of the Plains Wednesday.

Needless to say the set-up is quite complex and we may not know for a couple more days how this plays out. However, next weeks storm should be loaded with moisture that's pooled along a stout thermal gradient. Instability will be significant in some part of the Midwest and the potential is there for locally heavy rains and perhaps severe weather. Certainly this looks to be another potent spring storm with the ability to generate significant weather. There's plenty of time to work out the details in coming days.

With that, I close the book on another post. Have an excellent day and roll weather...TS