A SLOW SLOG...
A highly amplified weather pattern exists over the Midwest thanks to strong ridges over both the east and west coasts. A stout "sympathetic trough" over the middle of the nation is struggling to move and as such, what you see is what you're going to get the next couple of days. That amounts to a slow slog of clouds, showers, and much cooler temperatures that might even bring some snowflakes Wednesday night or Thursday. Yippee.
The 500mb jet stream flow clearly shows our storm situated between the high latitude ridges occupying the east and west coasts. Without the normal east west push of the westerlies the system is only slowly pushing northeast.
You can also see vast amounts of moisture (indicated by clouds) surging northward from the Gulf of Mexico into the central U.S. trough.
The water vapor loop also shows dry air getting drawn into the storms circulation center situated over Missouri. However, the moist conveyor belt continues to transport moisture into Illinois where it is wrapped around the circulation center and falls as rain (or snow) over my area and the central Midwest.
This 60 hour animation shows the how rounds of vorticity rotate around the upper air low creating bouts of rain and eventually rain or snow showers as the disturbance only gradually spins off to the east. Precipitation won't continuously fall but it will be possible at times for at least the next 48 hours (through Thursday morning). Additionally with the atmosphere fully saturated, cloudy dreary weather prevails the into Thursday night, perhaps some breaks in the clouds then. This 90 hour animation off the EURO shows how clouds could be an issue much of that period until breaking out Saturday morning. It just doesn't look very nice the rest of the week.
So far rain totals have been on the order of 1/4 to 1/2 inch through Tuesday evening. Amounts of at least that much or more is expected before the system departs Thursday.
Here are some model depictions of how much additional rain may fall from Tuesday evening through Thursday mid-day. Some of this has already fell Thursday night.
The 12K NAM
Snow has already been noted in NW Iowa and as temperatures cool aloft, at least snow showers are likely to occur in some areas later Wednesday night and early Thursday. The most likely spot would be west of the Mississippi in Iowa. With the recent warmth little if any accumulation is likely and no travel impacts are currently expected.
Here's a sampling of what models are currently indicating. These are not forecasts and there is quite a bit of variability and I would say it's very low confidence as to whether or not there will be any snow accumulations. Temperatures will be marginal and snowfall rates should be light, two big strikes against much in the way outside of a dusting in the west. Just the same, I do expect some wet flakes to mix in, especially west of the Quad Cities.
The 3k NAM
The 12K NAM
As for temperatures, readings Wednesday morning start around 40 in the NW while from the Quad Cities southeast they should be closer to 50. As the day wears on colder air gets wrapped in and by evening readings will range from the upper 30s north to the low 40s south. Thursday with scattered rain and snow showers, everybody remains cold with highs ranging from 35 to 40 from north to south. Friday won't be any picnic either with highs generally in the low to mid 40s. Friday night a hard freeze is possible with lows in the mid and upper 20s.
The weekend looks to be dry but on the cool side. Highs both days will likely hold around 40 in the far north to the low to mid 40s far south. The trend of cool temperatures is likely to be with us much of the next couple of weeks with the week one departure ending March 30th looking like this.
Week 2 ending April 6th looks like this
Most of the Midwest remains in an active pattern with near to above normal precipitation the next 15 days.
Make no mistake about it, the next couple of days are not what the doctor ordered but that's life in the Midwest, especially in the spring. Have a marvelous hump day and roll weather...TS