© 2019 Terry Swails

BLINDED BY OPTIMISM...

March 14, 2018

Last Thursday I showed you numbers off the GFS and EURO that indicated March 16th (this Friday) had the ear marks of a healthy warm-up. Both major models at some point were showing highs that ranged from the 60s to low 70s. I generally don't like to advertise such a big warm-up but I did for 2 reasons. One, as I mentioned in one of my posts, nearly every March sees a 60 degree day and in many years a 70 degree day. In other words, it's not unusual to get toasty. Two, both models showed the potential warmth so there was consistency to back the climatology. Here's what the GFS showed for March 16th.

The GFS was even warmer 2 days later when it had a 74 on the 18th. That projection came out only 3 days ago. 

What did I say after I saw the above numbers? That I felt good about our chances for a coming warm-up. However, knowing it was early in the game and how fickle March can be I did caution this...a direct quote from my post.

 

"This early in the game I would not get caught up in the numbers (especially the GFS which could easily be inflated) but the consistency in the models leads to early confidence in a couple warm few days around March 16th That's in line with the statistics which show 15 out of the past 16 Marches in Cedar Rapids have had a 60 degree day. 9 of the 16 have had a 70 and 2 have had 80 degree" temperatures".

 

Well, as you probably figured this is going somewhere and that "somewhere" is the wrong direction. Sunday night signs were showing that the warmth was fading and by Monday forecasters all over the Midwest were slicing and dicing away. Today, the whole set-up has vanished and now the GFS is forecasting a high on Friday of 35. 

How does that happen? How do you go from the 70s to the 30s? Clearly something changed. Probably the biggest factor was initialization of data in the models. As the event drew closer more accurate and detailed data was ingested into the forecasts. Once this happened it became clear that the southern stream of the jet was going to be more dominate than the northern branch. Instead of a strong system passing to the north, less phasing was depicted and the primary energy was shown tracking much further south. Instead of warm southerly winds, east to northeast breezes would feed much cooler air into the majority of the Midwest. Game over, a bust for any big warm-ups.

 

Moving on, this southern stream pattern looks to hold into next week. 2 systems embedded within the flow will not only keep it chilly, they will threaten rain or snow. The first disturbance should keep most of its precipitation shield near or south of I-80 Friday night or Saturday morning. That said, the latest trends have been inching the system north so there is uncertainty on the precise track. The GFS really made a jump north Tuesday afternoon showing this for total precipitation. 

It even breaks out some snow. 

I have serious doubts about anything the GFS is showing as its been having all sorts of problems lately. I am more inclined to believe the EURO which has been leading the way and is far more consistent and further south. However, even it has shown a slight shift north. It has this for total precipitation.

And this for snow. 

The second disturbance I mentioned looks stronger and further north. It also has enough cold air available that accumulating snow could be a problem for some on Monday. We'll cross that bridge in more detail tomorrow when data and consistency should be better. Meantime, Wednesday will be a warmer day but we'll have to wait for any of those 60-70 degree temps. I was blinded by optimism. Back to the drawing board. Roll weather...TS

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