Weather Blog

When storms don't follow the script

When storms don't follow the script
We've been saying all along to expect some surprises as this incredibly complex pattern of two weather systems move through Thursday and Friday, but now it's even getting more... complex.

The second storm due in Thursday night is now looking much stronger and not exactly where the models through it'd be.  This adds a whole lot more uncertainty to the forecast because the computers now are basing their projections on incorrect information. Here is where the storm is as of 4 p.m. on satellite:

And here is the model output for 4 p.m. (actually, both major models looked nearly identical, so just showing on here:)

Note I put the red "L" on the model output where the storm actually is. Also note the satellite shows a clearly defined low pressure center now -- the comma shaped swirl is the tell-tale sign. But the forecast model doesn't have it developed that well at all.

This means the storm is likely stronger than we thought (or at least, stronger than the models thought it'd be today. Remember earlier this week, they did have this storm stronger) It also means it might take a different track.

With an anticipated southerly track, that could be the whammy to bring cold air from the north combined with the moisture from the storm to bring snow to Seattle. It's still very uncertain, and read the weather story on our home page for more information, but this shows the challenges we face as forecasters when the storms don’t follow the script.

(And also the extra-special challenge that unlike the East Coast, we don't have anyone living to our west to take accurate and frequent observations to see how the storm is developing.  I'd like to see the folks in, say, Baltimore try and forecast if all you had was a satellite image, reports from a few truckers as they moved down the freeway (to simulate moving ships at sea), and maybe what the weather is like in Cincinnati and Detroit but nowhere else nearby, to simulate the sporadic buoy reports we get. Every other city would have to be in the dark -- no observations, no radars, no phone call to your aunt in Cleveland to cheat. And that's what it's like here in Seattle :) )

I'll keep peeking in through the night to see what's new.