© 2019 Terry Swails

SURELY WE CAN DO BETTER...

February 20, 2020

I'm constantly moaning and complaining about the ability of the GFS (the top U.S. forecast model) to keep up with its prime competitor the European. Time and time again it gets beat to the punch by the EURO when it comes to picking up trends and maintaining some degree of consistency in its forecasts. Neither is perfect (and I'm the first to say I'm not) but the verification skill scores of the GFS are far less than the EURO. In fact I saw recently that the GFS was 4th best performing model behind even the Canadian and UKMET. That's hard for me to believe!

 

The reason I bring this up is that last night I mentioned in my post there was a storm threat centered around Tuesday of next week. I was quick to point out that I had my doubts due to the differences between the EURO and GFS. My direct quote below. Note the highlighted sentence at the end of the quote.

Boy was it ever on the wrong scent. This is what last nights GFS showed for snowfall. 31.7" in Waterloo and 37.8" in Marshalltown. I of course didn't put that up knowing full well those amounts were enormously inflated and the ensuing panic they would create. However, I did wonder at the very least of the model had the right idea on the general track and position of some sort of snow band.

Ha! What a joke, this is what the same model showed just 18 hours later.

My point is this, here we are the "quote" strongest country in the world with access to brilliant minds and money and we can't develop a weather model that's reliable or even consistent. The GFS is useless more often than not beyond 3 days. I'm to the point that I only look at the GFS to entertain myself, especially beyond 48 hours. It can put seeds of doubt in your mind that cloud a mans judgement. That's the last thing I need so until I see something dramatically change in the performance of the GFS, I won't give it much credence unless I see the same thing on the EURO. Jeepers creepers, I just had to get that off my chest. Let's go USA, get our model up to speed with the competition.  

 

On to the weather. One thing that's changed the past 24 hours (and to the credit of the GFS) is that the storm both models showed staying south of my area Sunday night and Monday has now trended further north. That allows its precipitation shield to get into at least the southern half of my area which was not the case yesterday. Here's what the 2 models show for total precipitation through Monday. I think the GFS is too far north and far too heavy on amounts.Again, I give the nod to the EURO.

 

The EURO

 

 

The GFS

Where things get much more difficult for the models is how much of this falls as snow. The track is good and precipitation is plentiful so what is the problem. You guessed it, limited cold air. With time the storm may be able to generate its own cold pocket but how soon will make the difference between some slushy accumulations or mainly a cold rain. Overall, I favor rain.

 

For now the EURO which is further south shows this for potential snow totals. Not much for my area

 

The GFS is a little more aggressive but I don't have much faith in this solution. It's likely too wet and far north.

All I can say about this situation Sunday night Monday is that there is higher confidence of rain in the south, but low confidence of any snow and most certainly how much. One of the biggest hurdles we've faced all winter long is how much phasing takes place with the northern and southern branches of the jet stream. The way the winter pattern is aligned makes it hard for models to see that interaction until it's basically in top of the Midwest. I frankly have little faith in any model at this distance but say in earnest the whole scenario could change over the next 24-48 hours depending on the merger and interaction of energy. I would not be surprised if there are tricks to come.

 

The next issue will be what to do with another wave of energy that arrives Tuesday and Tuesday night. This is the one the GFS soiled itself on yesterday. I suspect what happens with the first disturbance will impact how the second evolves so not much sense speculating on that until we have a better handle on number one.

 

Short term, up until Sunday night, the weather looks dry and warmer with time. Thursday will be a very crisp day spent int the teens but a return to southerly winds signals a nice weekend warming trend. Highs Friday will pop into the 30s and by Saturday and Sunday it looks like 40s are back on the board. The sun is getting stronger by the day! Roll weather...TS

I did want to mention that I have another weather school planned for April 4th. This one is called Severe Storms 101. If you want to know more about the ins and outs of severe thunderstorms and how to forecast them this will be a great introductory session. There will be event simulations and a big focus on tornadoes. Some tips on chasing them as well. Aside from that a focus on the 1968 Charles City tornado outbreak, the Parkersburg EF5 of 2008, and the rare Washington, Illinois twister that pounced in mid-November pf 2013. Lots of compelling video and insights presented by 3 meteorologists. Check out the link above to get details and secure your spot or contact carolynswettstone@yahoo.com

 

 

 

 

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