ONE STEP CLOSER, A MID-DAY UPDATE ON SNOW NEXT WEEK...

February 22, 2020

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ONE STEP CLOSER TO A STORM...A MID_DAY UPDATE!

 

Since yesterday not much has changed with the potential snow system for next week. One minor issue to note is that the system has trended a little further north but so far that does not impact my area other than to bring the heavier snows even further north into northern Iowa. If coming runs continue that trend it could eventually lower amounts some in the south but that would serve to increase them even more in the north. Something to watch.

 

The one model that is handling the system differently is the operational GFS. It takes the upper air support further north and for some reason is slower injecting moisture into the system. It's ensembles look much different and reflect the solutions of the EURO, 12K, and Canadian. I just think the GFS operational is unreliable this winter and so far I see no reason for it to be so far north. Again, a trend to keep an eye on.

 

As for timing, It still seems like this will be a long duration event. Snow should develop Monday night and it could continue into at least Wednesday morning. The EURO has QPF of 1 to 1.5" for much of my area. That's the liquid equivalent which converted to snow ratios of 12 or 13:1 could yield some big results!

 

Today we are a big step closer to reality with this but I won't feel really secure until I see this carry over into Sunday evening. I also want to make mention that models tend to be inflated with regards to moisture and snow totals at this range so they typically are high end. However, even if you knock 3-4" off this would be a high impact event.

 

Confidence is growing that significant snow will occur next week. If we are seeing the same scenario tomorrow at this time it will force the NWS to put out a winter storm watch for much of my area. Again, I don't want to get too far ahead of the game and I stress, there is still time for movement and this is not a slam dunk yet. That said, I think there is high confidence there is going to be a storm. The big question is where is the heart of it centered. What I want to see more of is consistency in the snow location and amounts going forward

 

Here are the raw snowfall numbers from the models. They are not forecasts, just guidance used to formulate them. Here's what I have using the Kuchera method (when possible). It shows ratios that are somewhat higher than 10:1 which is what thermal profiles would suggest.

 

THE EURO

 The Canadian GEM

 The GFS operational...the odd model out!

 The 12K NAM...only out through Tuesday evening. There could be another 12 hours of snow in spots!

 The GFS ensemble...only available in a 10:1 ratio

Data sampling will improve in coming model runs and that could still alter the track and location of the heaviest snow. Later Sunday we should have a pretty good handle on the general specifics. Until then, this is meant to be a heads up that a higher end snow event is a possibility. If things change, and that's still on the table we can always back down. Stay tuned for further updates and revisions. Roll weather...TS

 

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© 2019 Terry Swails