Wednesday, February 11, 2015

Challenging Forecast

We have a difficult forecast on our hands next week. You may have noticed that we are mentioning the chance of some wintry weather on Monday and Tuesday. We hope to gain more confidence in the forecast as we get within 3-4 days out, but as we watch it from 5 days out... It's challenging! Here are my thoughts, as of now:

  • Wintry weather will probably happen, but amounts and type are still in question.
  • Forecast largely depends on the track of the low pressure.
  • If the low tracks south, we could see a decent winter storm.
  • If the low tracks north, we may start as a wintry mix and switch to plain rain.
Let me explain the differences between a low that tracks north and one that tracks south. First, let me show you the "colder" setup which would lead to travel problems in Region 8. This is the evening data from the GFS for Tuesday morning:
In the above image, the surface low is tracking south of us and leaves us on the "cold side" of the storm. If this happened, we would see some freezing rain, sleet, and snow.

Here's the problem though. The next round of data that came in from the GFS through the overnight shows a different setup. I'll call it the "warmer setup":
In the above image, the surface low is tracking north of us and leaves us on the "warm side" of the storm. If this happened, we would see freezing rain or sleet at the start, but change to plain rain by Monday afternoon into Tuesday. 

As a forecaster, we can't hop on every change, in every model run. Our forecast would change by 20 degrees, every 12 hours. We have to look at the setup, look at other models, look at overall global pattern, etc to forecast what will happen.

We are going to keep "wintry mix" in the forecast for now, but I'm really leaning toward a warmer solution, based mainly on the pattern, the trend this winter, and something we call the "Arctic Oscillation". When the AO looks to stay "positive" or "neutral", we typically are warmer. It shows a little dip to negative early next week, so we need to stay on our toes, but this may be a storm that starts with a little wintry weather on Monday morning and switches to plain ole rain through the day. 

Stay tuned!


Nikki Adams said...

I vote for snow.

Anonymous said...

My vote goes for an apocalyptic ice storm.

Teisa said...

Plz SNOW...!!!!!!!

Anonymous said...

I hope it stays warmer. I hate winter.