On Wednesday afternoon, I posted this on social media:
“-Putting numbers in a forecast more than a few days out is a recipe for flip-flopping and changing forecasts with each new run of the models. 4-8″ becomes 6-10″ becomes 3-6″ becomes 6-10″, etc etc. We would rather you hear as few numbers as possible so that our message is clear. The closer we are to an event, the less likely it is that the forecast will have to change much. ”
In some ways, I didn’t follow my own credo. This storm was coming on a weekend and by Thursday, I felt it was time to give people a firm idea of what to expect. We should have waited until Friday.
Our initial forecast was for 5-10″. We are getting 2-5″. So, what happened? Why are we getting less snow?
This storm was supposed to come in 2 “waves”. The first one, the one we are getting this morning, followed by a second, heavier wave tonight and Monday morning. Here’s this morning’s radar:
The reason for the lower amounts is that the 2nd wave is not going to get pulled northeast like originally expected.
Essentially, the “northern feature”, a trough of low pressure moving through the Great Lakes, was supposed exhibit some “pull” on the southern feature…lifting it somewhat north. BUT, the northern feature ended up moving too fast to give the southern one a lift. The southern feature missed it’s ride, basically. So, it is moving more due east.
Getting the interactions of these things right was key to getting the forecast right. The southern feature did not get onto the mainland US until yesterday, so the models had a hard time figuring this out. And therefore, humans were fooled.
Our forecast could have been worse! Thursday morning we were staring at models that looked like this: Yup, that’s the European model, usually one of our better models, predicting a FOOT of snow in parts of the Valley.
Some well-known national weather companies had us getting 6-12″ and for a time and I saw a map that had the Valley in a “10”+” band for a while. So our 5-10″ forecast was actually sort of conservative.
The lesson for forecasters? In very, VERY complex situations like this one…it’s best to wait until you are within 48 hours of an event before making a snow accumulation forecast. It is tough to abide by this, especially when it is coming on a weekend. And it’s 2014, so social media “buzz” builds to a fever pitch, even a WEEK or more ahead of a possible storm. There is pressure to make a statement, to get your forecast “out there”.
There is a reason why we are vague and non-committal when viewers, family members, neighbors, pets, etc. start asking us “how much you thinking” about a storm that’s more than a couple or few days away. It’s not because we ENJOY being coy. It’s because weather forecasting is complicated. Things change. The atmosphere is so complex it boggles the mind. It’s because these types of things can and do (and always will) happen.
Just know this, I (along with Jess and Mike) are on it. When it’s obvious changes are needed, we start making them. Bad forecasts don’t stay bad for long. Take a look back at my tweets, Facebook postings, etc. My train of thought is on there.
Winter can end any time now!