- Mar 22, 2023

FUN WITH FIFTIES, THEN SNOW?

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FUN WITH FIFTIES, THEN SNOW

For the second consecutive day, highs around the region made it above 50 degrees. In my world, a 50 degree day anytime December through March is what I call a mild day. Going back to December 1st in the Quad Cities, we have now experienced 16 such days. Ironically, the warmest during that period was a 64 degree day that occurred when you would least expect it, December 29th.

I also noticed that on 4 different occasions we've had back to back 50s but never 3 in a row. Wednesday, we have a chance of ending that streak in some areas with highs that should be close to that 50 degree mark. The EURO shows this for max temps. Look at all those 70s in Missouri, tantalizingly close.

Further inspection of that temperature map indicates a sharp thermal boundary that's established over the southern tip of Iowa. That will be a feature to watch Wednesday into Wednesday night as low pressure rides along it. We'll be on the cool side of the boundary with clouds and easterly winds. There may see some scattered light showers or drizzle at times Wednesday, primarily near and south of I-80. Rain chances increase Wednesday night, especially in the far southeast as the primary forcing ejects northeast along the southern Iowa border. The proximity of the low level jet and retuning moisture will develop showers and elevated thunderstorms. There is a chance of some small hail and heavy downpours in the stronger convection which initiates late evening into the overnight. The K index which measures thunderstorm potential is maximized near and especially south of HWY 34. That's the region likely to see thunderstorms as well as the heaviest rains of a 1/2 inch or more. The north pretty much swings and misses.

Models are still conflicted on how to handle the system with the GFS producing precipitation amounts of 1/10th of an inch or less (little of anything across the north). It seems to be the odd model out with the CAMs and Canadian supporting the EURO with some soakers across the southern third of the region. Here's the suggested rain totals from the EURO and GFS.

THE EURO

The GFS

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Whatever comes of this system, another one is hot on its heels Friday night with evidence to support wet snow in some part of the central Midwest. As is always the case, the track of the disturbance will be the deciding factor as to who the lucky recipient is. Precipitation may start as rain but dynamic cooling should flip it quickly over to snow in the sweet spot. Both the EURO and GFS indicate accumulating snow but differ slightly in the location, again due to the handling of the track. Here's a comparison of the two surface depictions.

The EURO

The GFS

With the EURO further NW with its track it brings a pretty good snow into the NW half of my area

The GFS track further SE keeps us just on the edge.

These late season storms are very tricky to call, especially when transitions are involved and ground temperatures are warm. Unless snow really comes down, much of the accumulations occur on grassy and elevated surfaces. Right now its too early to dissect anything more, just wanted to get it out there that the threat of snow exists for the time being. However, if there is less amplification (certainly possible) in future runs, the whole thing stays south and it's a nothing burger. We have seen that plenty of times.

Remarkably, additional snow chances exist again Monday. As I mentioned yesterday, when the pattern is this noisy models have challenges pegging the energy and intensity within it. That keeps confidence low until you get into that 48 hour window.

One thing I did see that hurt a bit long range was the GFS bringing in a late season Arctic blast the end of March. Get a load of these temperature departures it spit out in the 18z run Tuesday. Those are ugly but they are 9 days out and there is plenty of time for the model to change its heart. Let's hope so!.