If You Can Hear Thunder, Does That Mean There is Lightning?

Friends say the darndest things...

I don't have the same "drive" to update my blog in the summer as I do in the winter. You've probably noticed. But folks, this last week has been pretty amazing. I can't recall ever seeing a week with as much thunderstorms in the lowlands as this one. And while our Oklahoman summer transplants may scoff at a Pacific Northwest "thunderstorm," I'm still glad they've been around. They add a little excitement to the otherwise humdrum summers of the Pacific Northwest.

What's been causing all these thunderstorms? Well, I'm not the greatest person to ask. They don't occur very often here and I don't know much about them. But what I do know is that from late Thursday to early Saturday, we had a very tight upper level low pressure center essentially stall over our area, and it provided moisture and lift. With moisture and lift, you get convection, and convection creates thunderstorms.

Valid 02:00 pm PDT Fri, 13 Jul 2012 - 9hr Fcst - UW 12z 12km WRF-GFS 500mb absolute vorticity, heights (initialized 5 A.M. Friday the 13th)

It seems like we often get thunderstorms with this type of scenario. We get these low pressure centers that direct warm, humid southerly air off the cascades and allow thunderstorms to travel from the Cascades down into the lowlands. That's right, our weather often comes from the EAST in these scenarios. Definitely a thing to delve deeper into.

The weather for the future? Kinda boring. :/

But if you hear thunder, you can bet your buttons that lightning isn't too far away.

Charlie

Summer Starts July 5th

Wednesday, July 4, 2012

12:06 A.M.

Us meteorologists like to joke that summer starts on July 5th. Well this year, that actually looks like it will be the case. Independence Day won't be bad at all. We'll start off with some clouds in the morning but quickly warm up to around 70 or so. The normal high for this time of year is 74.

And then, right on cue, July 5th rolls around, and we are forecast to hit 74. I think we might squeak out an extra degree, which would put us above average. And we don't just get above average and then fall below it again. We stay above average for as far as the model can forecast.

Valid 05:00 pm PDT Wed, 04 Jul 2012 - 24hr Fcst - UW 00z 36km WRF-GFS 1000-500mb thickness, SLP

Right now, we have a very weak jet stream over us, and this will further weaken throughout tomorrow and eventually cease to exist by Thursday night. After that, the jet stream will shift northward. The model above shows the 1000-500mb thickness. Where the thickness is higher, the temperatures are generally warmer. The temperatures get hot when you go inland!

But as the week progresses, we will warm up even further!

Valid 05:00 pm PDT Tue, 10 Jul 2012 - 168hr Fcst - UW 00z 36km WRF-GFS 1000-500mb thickness, SLP

Look at that! Warm temperatures up and down the Best Coast. Next week will be a great time to go swimming in Lake Washington.

Thanks,

Charlie

Back From The Dead!

My, my my! It certainly has been a long time. Well, I could enamor you with excuses, but I'm not here to justify my actions (or lack thereof).

I'm here to predict the weather.

To say that June has been rather chilly is an understatement. To quote Scott Sistek of KOMO, "Today marked the 20th time in June's first 25 days where temperatures stayed below average." Yeah. It's been pretty bad.


The last several Junes have been pretty darn chilly, and many have dubbed them as "June-uary" because of their unseasonable coolness. This is likely because of La Nina. Although La Nina is dead now, its effects tend to lag on well after the Pacific warms past the La Nina phase. I was down in Portland over the weekend visiting my uncle and a dear friend, and it was pretty wet there. I heard it was even wetter up here in Seattle.

... until we see some summer? Well, if trends are correct, we will start to see summer on July 5th. But the current forecast has a different outlook. It calls for a damp Tuesday, a wet Thursday, and a soaking Saturday, but Wednesday should be nice, Friday should be decent, and once we get into next week, it's cloudy mornings and sunny afternoons as far as the mind can grasp. Perfect summertime weather.

Ahhhhhhhhhh... it feels good to be back on the blog again. Thanks for reading. :)

Charlie

Cascadia Subduction Zone

Monday, April 30, 2012
10:49 A.M.

I know it's been a while since I've posted. Sorry.

I actually haven't been doing a whole lot of weather related things lately. The weather has been pretty boring around here (and it probably will be until October), so I've been focusing on other earth sciences that interest me.

In particular, I've been reading a lot about the Cascadia Subduction Zone. Remember that huge earthquake that occurred last year in Japan? We've got a fault off our coast that bears a lot of similarity to the fault that caused that earthquake and tsunami in Japan last year. I'm sure many of you knew that we live in an earthquake-prone region, especially if you lived through the 2001 Nisqually Earthquake, but I don't know how many of you have really thought about what would happen if we saw an earthquake like the one Japan saw last year.

Huge subduction zone earthquakes like the one in Japan last year and the one in the Indian Ocean in 2004 are called "megathrust earthquakes." Megathrust earthquakes are the most powerful type of earthquakes and completely overshadow all other earthquakes in the amount of energy released. To get an idea of the amount of energy these earthquakes release, take a look at the pie chart below. The three largest earthquakes ever recorded (Sumatra, Alaska, and Chile) make up about half of all the seismic energy released in the past 100 years. The 7.9 earthquake that devastated San Francisco in 1906 is practically invisible on this pie chart.

If a megathrust earthquake were to occur off our coast, many coastal communities would be wiped out from the tsunami and major cities like Seattle and Portland would suffer heavy damage from the earthquake itself. We are not prepared for such a disaster.

I've got to go to class now... I know this isn't the most elegantly written post I've ever created. But it is food for thought.

Charlie

It's Thursday, Thursday.

Thursday, April 5, 2012

9:43 A.M.

Yes, it may not be Friday, and the weekend may actually be two days away, but I'm still pretty darn excited. Besides it being Easter Sunday, which is always in style, the weather is expected to be nicer than it has been in a while. It certainly won't be hot and sunny, but it will be warmer than we've seen in a while. It will definitely be good picnic weather and a great day to go relax in the UW quad. I just can't get enough of how beautiful the cherry blossoms are right now. Of course, I wish there were actual cherries involved, but I'll take cherry blossoms any day.

Before then, we've got some weather to go through. Today could be an interesting day for weather for certain places, because we've got cold air overhead and strong solar insolation. When the sun heats the lower atmosphere, air expands and decreases in density, and these air parcels continue to rise through more dense and colder air in the mid-upper trophosphere. This phenomenon creates towering cumulus clouds, and, if the conditions are right, thunderstorms. The air mass isn't too unstable today, so if there are any thunderstorms, they will be isolated. We could see some beautiful cumulus clouds though.

Cumulus congestus clouds

 Weak cumulonimbus over Seattle

And here's a picture of a supercell thunderstorm. We will not be seeing these today.

Of course, our thunderstorms are a far cry from the thunderstorms seen east of the Rockies at this time of year, but they are interesting nonetheless. There actually was one time where we got some very well developed thunderstorms on the Cascade foothills, but they were still much weaker than storms like the one pictured above. The UW atmospheric sciences department loves this picture.

Ok, now let's get onto our forecast. Chilly with a slight chance of thunderstorms today, especially along the coast. We could see a few showers tomorrow as well, but they will be more isolated and weaker than today.

Then comes the weekend. 

Right now we've got a pretty big trough off our coast, which is directing cool air into our region. 

Valid 05:00 am PDT Thu, 05 Apr 2012 - UW 36km WRF-GFS 1000-500mb thickness, SLP

But look what happens on Saturday. We get a little ridge over our area, which will direct warmer air into our region.

Valid 05:00 pm PDT Sat, 07 Apr 2012 - 60hr Fcst -  - UW 36km WRF-GFS 1000-500mb thickness, SLP

The ridge will strengthen on Sunday before a weak trough moves in on Monday, giving us a chance of showers and thunderstorms.

Enjoy your Thursday!

Charlie