Monday, October 29, 2012

A Record-Breaking Storm

Monday, October 29, 2012
3:06 P.M.

19 years old, and Spongebob is still my favorite cartoon. 

It seems like everywhere I go, people are talking about Hurricane Sandy. Most of what I'm seeing are Facebook posts from people on the West Coast praying for the health and safety of those affected by this massive storm. Some posts are from people who are experiencing the onslaught of the storm. Other posts juxtapose Sandy with other topics, such as the presidential debate or global warming. And of course, there is the occasional egotistical braggart who feels they need to tell the world how sunny and warm the weather is at their locale.

Sonja Breda, one of my good friends who is a freshman at Bryn Mawr in Pennsylvania, updated her status as "I have to say that I love radical weather, so I have been really enjoying watching Sandy's progression as I sit drinking tea with my pals, watching tree branches fly past our windows." Sounds like my kind of woman!!! On the other hand, I asked my friend Alex Dyring, who I thought was living in Boston, what the weather was like there, and he said "I actually live in Spain right now although I'd be happy to give you a report of my sunny day today." And of course, my good friend Nicholas Efthimiadis commented " It's very windy today... We've been so focused on Sandy, we forgot about our own weather." I agree, it has been a tad breezy. But it has been nothing like the East Coast.

Here's the latest satellite image of Sandy, and below that is a video that show's Sandy's development. I believe the loop approximately shows the last ~48 hours up to the time of the latest satellite image below.

NASA GOES 13 Satellite - Valid 2232 UTC, October 29, 2012

video

As of 2:00 PDT, Sandy was a category one hurricane located at 38.8 N and 74.4 W. It was heading WNW at 28 mph, has maximum sustained winds of 90 mph, and has a pressure minimum of 940 millibars. At some point, the pressure may dip below 940 millibars. Simply incredible. To put things in perspective, the Columbus Day Storm, which was by far the most powerful windstorm to ever strike the West Coast, only got down to 960 millibars. The record for the lowest pressure recorded north of Cape Hatteras is 946 millibars, and was recorded on Long Island during the New England Hurricane of 1938. I'm not sure if this record has been broken, but there is a good chance it will be.

There are, well, a trillion things about Sandy that make it different than your typical hurricane, but I'll just name a few. First off, it is exceptionally large. The Saffir-Simpson Hurricane Scale rates hurricanes based on their central pressure, not wind speed. Since Sandy is so large, the wind is spread out over a huge area, but it isn't as strong as it would be if Sandy was a more compact cyclone. Hurricane Charley, which hit Florida as an extremely strong category four hurricane in 2004, had a minimum pressure of 941 millibars. So to say that Sandy is "just a category one" is misleading. It still has extremely high winds, and the large size of the storm helps to create a storm surge that has already inundated parts of the East Coast.

Second off, the thing that makes Hurricane Sandy different from your typical hurricane is that it is undergoing a transition to an extratropical cyclone. I mentioned this in my previous blog post on Friday, but it is the singular thing that makes this storm so unique. You regular readers of my blog know the whole spiel that I've given numerous times... tropical and extratropical cyclones are extremely different. Tropical cyclones form over warm water where there are minimal horizontal temperature gradients in the atmosphere, and they derive their energy exclusively from the ocean's warmth. Their warmest temperatures are at their core, and they have no fronts. Extratropical cyclones, on the other hand, typically have their coolest temperatures at the core, as the counterclockwise flow (in the Northern Hemisphere) brings cold air originating from the poles right into their low pressure center. Hurricanes and extratropical storms are often called warm and cold core systems, respectively.

What Sandy is doing is undergoing a transition from a warm core storm to a cold core storm. Take a look at some of the pictures below, and you'll see what I'm talking about.

Disclaimer: I got the idea of showing these pictures from Cliff Mass' blog, because I thought he did a good job at explaining it. These are not the exact same pictures and aren't even from the same model run. These are from the Monday, October 29 12z HWRF model and are the charts at 850 mb. They show the geopotential heights (contours, 30m interval), temperatures (color fill, 2 Celsius interval), and wind vectors (m/s).
6 hour forecast

Six hours after the initialization (which was at 12z this morning, so this is chart models the storm as it was several hours ago), the storm has its warmest air at its core, and looks pretty darn symmetrical.

12 hour forecast

Six hours later though, its symmetry is starting to fade and it is getting cooler at the center. Most hurricanes weaken when their warm cores die, but this storm is special because it is actually strengthening off of the horizontal temperature gradients across latitudes. It has a ton of energy and moisture and the gradients are very sharp, so it undergoes explosive cyclogenesis.

18 hour forecast

Six hours after that, the process continues. The warm air at the center is being replaced by cold air.  You can  see the nice "hook" shape, this is due to the occluded front wrapping around the center of the low. This is called the "bent-back occlusion" and is a hallmark of strong extratropical storms.

24 hour forecast

24 hours after the initialization, the process is essentially complete. No more warm air in the center. Cooler air continues to flow in. By this point, the storm is starting to weaken, because the horizontal temperature gradients are weakening due to the evolution of the fronts, but it'll still be strong nonetheless.

The third main thing that makes this storm unique is the fact that it is causing blizzard conditions in the Appalachian Mountains. The National Weather Service is calling for up to three feet of snow in the southern Appalachians above 3,000 feet! That's some crazy stuff right there. You usually don't associate tropical systems with snow. But folks, this is no ordinary storm.

AP Photo/Robert Ray - Snow in the mountains of West Virginia - 10/29/12

I've seen a lot of headlines dubbing this storm the "Superstorm." What makes this storm any more super than other storms? In my opinion, it's just the most incredible, rare, meteorological setup. Hurricane Katrina was way stronger than this storm. But Hurricane Katrina didn't undergo an extratropical transition, and New Orleans did not receive any snow from this storm. This storm, whether it's just known as the "Superstorm," the "Frankenstorm," "Sandy," or something else, is a meteorologists' fantasy. 

That being said, my heart goes out for everyone who is affected by this storm, whether they are riding it out on the East Coast, or they are praying for somebody else who is. Please stay safe.

One more thought... there are some fake photos going around. 



The theme seems to be various types of horrendous weather the Statue of Liberty. If you want the most accurate information and photos available, well, you know where to find it.

;)
Charlie

Friday, October 26, 2012

The "Frankenstorm" of 2012

Friday, October 26, 2012
2:51 P.M.

Hi everybody. I just finished a hectic week. Two midterms. A ton of homework. I even finished an entire package of Omega-Three gummy bears from Costco. Maybe it's a stress thing.

But honestly, the thing that made this week the most hectic, was this.

video

This, my friends, is a wonderful satellite image that shows the evolution of Hurricane Sandy. I'm not sure where the loop starts, but I believe it starts at 22:15 UTC October 24 and ends at 18:46 UTC October 26. The loop is a composite image of very high resolution infrared imagery at night and visible imagery during the day. On October 24, when the storm legitimately looked like a hurricane, there were some serious signs that it could impact the U.S. One model (the ECMWF) was bringing it straight into New York City as a 950 mb megastorm. The other model, the GFS (which is the model I use the most and the model that the UW uses to initialize their WRF forecasts), showed the storm weakening and harmlessly moving out to sea. One thing I like to do on this blog is give people advanced warnings of historic storms that may be in the making. However, I just didn't have the time to do so.

I did, however, let some East Coast friends know that a potentially historic storm could be heading their way. I told them it probably wouldn't happen, but that it might, and it could be very serious if it does.

Before I show you the models and give you all a heart attack, let's look at some of the atmospheric and oceanographic conditions that have contributed to the formation of this once-in-a-lifetime storm. And no, folks, I am not exaggerating. 





For any tropical system to form, water temperatures need to be hot. Take a look at the pictures above. The top one is from "My Fox Hurricane." And no, these water temperatures are not conservative estimates (props to all of you who got that joke.) They are real measurements from buoys. The picture below is taken from satellites, and it shows the sea surface temperatures throughout the Western Atlantic basin. They are hot. The standard "rule of thumb" for hurricane formation is that they need water that is greater than 80 degrees Fahrenheit do a depth of at least 150 feet. If you take a look at the SSTs measured by the buoys above, they are well above 80 degrees. And the satellite picture shows that these warm temperatures extend up the East Coast thanks to the Gulf Stream. The water temperatures off the northern East Coast are up five degrees Fahrenheit above normal, and Sandy is predicted to perfectly follow the Gulf Stream, picking up more steam (literally) and becoming more powerful in the process. See the picture below for a map of the SST anomalies as of October 25. This picture was taken from NOAA's Office of Satellite Data Processing and Distribution.



But if you look at the last satellite image (below), the storm doesn't really look like a hurricane. It doesn't have an "eye" and is rather asymmetrical. It looks more like a mid-latitude cyclone than a hurricane.


Why is this? The storm is clearly over warm enough waters to be a hurricane. The answer, my fellow meteorological connoisseurs, is because of strong horizontal temperature gradients in the mid-latitudes. In terms of temperature, the transition from autumn to winter is much quicker than the transition from winter to spring. Even though the air temperatures to the northwest of this storm aren't incredibly cold, they contrast sharply with the tropically influenced temperatures to the southeast. This temperature difference forms fronts. Just a little meteorological 101 here... fronts are boundaries between two different types of air masses. And the air masses on either side of this storm are very different indeed.

I have a detailed blog post I wrote last (2011) summer about the differences in tropical storms vs. extratropical storms. I highly recommend reading it here.

This is clearly shown in the models. Take a look at the 18z GFS 500mb vorticity and height model below. Don't worry if you don't know what it means... just follow my lead and look at what I'm telling you to look at.


See that super red thingy over the Western Atlantic? That's Sandy. Pretty obvious. But now, look to the northwest of Sandy. See that big "trough" in the 500mb height level? It looks like a V. That represents colder air coming down from Canada. This chart is valid 00 UTC Monday October 29, and is 54 hours out.

And then, something extraordinary happens.


This image is valid 30 hours later, at 06 UTC on the 30th. Look at how far the trough has come, and look at how there is the slim line stretching all the way up into northern Canada connected to Sandy. That line represents increased vorticity at the 500mb level, which is simply defined as "the tendency for an air parcel to spin." High levels of vorticity are associated with foul weather and moving air parcels. What this diagram shows is how much cold, Canadian air Sandy is drawing into itself. This contrast between air masses will help transition Sandy from a tropical cyclone, which is built on a uniform mass of warm humid air, to a mid latitude cyclone, which gets its strength from horizontal temperature and humidity differences. As you can see in this picture, the differences will be absolutely massive, and this will lead to the formation of an extremely powerful storm.

I've got to head to a band practice now, but I will be extremely active on this blog and I will post more model forecasts in the future. As of now, it looks like a 940-950 mb cyclone will hit somewhere between North Carolina and Massachusetts, with 80 mph sustained winds on the coast and a very large gale-force wind field that will extend for hundreds of miles. Areas to the northwest of the storm will experience blizzard conditions, and areas along the immediate coast will experience a storm surge of at least 10 feet, nearly a foot of rain, and insane amounts of wind. This storm has already killed 42 people, and it will inevitably kill some more and cause billions of dollars of damage.

If you have any relatives or know anybody on the East Coast, WARN THEM NOW and let them know that the strongest extratropical storm they may ever see will be upon them in several days.

Stay safe.
Charlie

Thursday, October 25, 2012

WeatherOn!

Thursday, October 25, 2012
8:52 P.M.

I am more than pleased to announce the beginning of my career at WeatherOn, which is the website and brainchild of Tanner Petersen, a FRESHMAN (in high school!) who lives in Marysville. Tanner is an incredibly talented, determined, and ambitious young man. Shannon O'Donnell, of Komo 4 News, once called Tanner "The hardest working kid on this side of the Mississippi!" Well, there's one thing wrong with this statement. He's the hardest working kid on both sides of the Mississippi. He has extensive knowledge of HTML programming and web design, well beyond his years. And he's pretty darn good at forecasting the weather as well.

The thing is that anybody can really forecast the weather. It's not that difficult. It's probably the only job where you can be wrong on a consistent basis and not get fired. But web programming, that's a completely different story. That takes a whole bunch of hard work. I may seem like I know a lot about the weather (and to be fair, I do), but when it comes to programming, I know less than Bill O'Reilly knows about tides. I've only taken an introductory Java class, and I had to take it twice. It's really hard stuff! And the fact that Tanner is able to create a very complex website shows that he is extremely dedicated and intelligent. I mean, you can even get weather alerts from him by texting "ALERTS" to  (805) 419-9229 and you will get automated text messages whenever interesting or potentially stormy weather comes through the region. So while I may be good at throwing out entertaining pictures, adding some personality in my blog, and forecasting snow (I actually have a really good track record on that), I don't know squat about computer programming, and Tanner is an absolute genius.

Weather websites are becoming more and more common, descriptive, diverse, and thorough.  And if you look at all the weather websites out there... the Weather Underground is a great one, Accuweather is hit or miss, and of course looking at the models, they became known because of people who have a thirst for knowledge, are familiar with computers, and most importantly, are extremely dedicated and hard working. People like Tanner Petersen.

How did Tanner get started? Here's a brief history.

from chuckgoolsbee.org - December 22, 2008

In 2008, Tanner witnessed the legendary snow storm of 2008. All of you Seattlelites should remember this one. But as hard as Seattle was hit, Marysville was hit even harder. Take a look at the sheer amount of snow on that post! I'm pretty sure that picture was taken in Marysville, but I'm not positive. After this, Tanner started writing little five-day forecasts for his friends and family, and hung them around the house for all to see. He was in 5th grade at the time. And he was already making nifty little graphics, like the one below. He named his fledgling company "Tanner's Local Weather." There was no website at this time though.

Pretty groovy!



On September 2, 2010, Tanner's Local Weather went public on Facebook. Check out the 5-day forecast above. This was Tanner's very first forecast! And yes, he designed the graphics all by himself.


In November of 2010, Tanner finally got his very own website up! At first, it was called TLWofficial.webs.com. This was a huge step for Tanner. Look at that beautiful website. It was officially changed to TannersLocalWeather.com on September 19, 2011.


By 2011, Tanner's Local Weather was improving in many ways. Tanner was getting better at forecasting, and the graphics were just getting prettier and prettier.



Another HUGE step came in 2012, when Tanner completely redesigned the website. Just when you thought it couldn't get any better, it did. The picture explains itself. The new website is a work of art.


In August of 2012, Tanner released a mobile version of his site. How he did this, I have no idea. But he did, and it's awesome. I have a ghetto phone, so I can't access the website, but all you people who are up to date with today's technology can access the site from your iPhone, Nexus, etc.



VERY recently (October 12), TannersLocalWeather.com became WeatherOn.net. Tanner was trying to go for a more universal domain name to truly establish himself as a viable organization in the weather cyberspace world.

So professional!

And here's the cool part. On October 17, Tanner hired me as the very first employee at WeatherOn! I am now the official long range blogger for WeatherOn. I will continue to post on this blog, including the occasional long range outlook, but the posts on WeatherOn will not be found on this blog. They are exclusive to WeatherOn.net, and that is the only place you will find them. You wanna contact me? No problem. Tanner made me a business card too. :)


This kid is the real deal. I'll start posting long range forecasts soon. I have a midterm tomorrow and two next week, but I'll get one in before the weekend. And remember, you can ONLY find them on WeatherOn.net. 


Additionally, on November 1st, Tanner and I will jointly release our winter outlook for the 2012-2013 season. It will cover the ENTIRE US, with a little more attention paid to our corner of the country.

I cannot give Tanner enough praise. He's so dedicated, and he's also extremely nice. I look forward to developing WeatherOn into the best site in can be. And trust me, at the rate it is going, it's going to become a major, worldwide known site. We won't stop until it does.

Oh yeah, a category 4 hurricane/winter blizzard could hit the East Coast. I'll blog about that tomorrow. But for now, a siesta, and then, back to studying.

Take it easy, and visit http://www.weatheron.net/!

Charlie

Friday, October 19, 2012

Sequim: Is It Really That Sunny?

Friday, October 19, 2012
11:03 A.M.

Happy Friday everyone!!!

Everybody talks about the Sequim rain shadow is the driest place in Western Washington, and for good reason. It is. They only get around 16 inches of rain each year, as they are northeast of the Olympics, and since the winter flow is generally from the southwest, especially during heavy rain events, the air descends off the Olympics, warms, and dries when it gets to Sequim. There is actually a type of native cactus that grows in Sequim. And even more impressive, they have a law that outlaws bad weather. I believe it was passed in 1995. Check this out!

"Sequim Municipal Ordinance 95-009, Section 2.1, "prohibits weather conditions that are detrimental to the enjoyment of activities within the city."

Mayor Bill Thomas sent a draft letter to Seattle TV weather forecasters saying "While watching your weather report . . . I noticed you placed your stinking little clouds . . . directly over Sequim while you were discussing Seattle weather. These folks are hardcore. Thomas also said "we'll be closely watching foreigners from Port Angeles and Port Townsend." The penalty for weather conditions that are detrimental to the enjoyment of activities within the city? Somebody proposed the idea of Bermuda shorts in the article I read, which can be found here. In the words of Thomas, "Hey, we're famous for our sunny weather, and we want to keep it that way." 

Sequim likes to brag about their rain shadow, but how much bragging rights do they really have? Let's take a look at the visible satellite picture over Washington right now.

12:00 pm PDT Fri 19 Oct 2012 - GOES West 1km Washington visible satellite

Sequim? Completely overcast. Why? Well, the flow over our area is from the west, not the southwest. When the flow is from the west, the Olympics do not block the flow over Sequim, and they get the same cloudy weather like the rest of Western Washington. Right now, the "rain shadow" is over Seattle due to the westerly flow, but alas, there is no cloud shadow to be found west of the Cascades.

But check out Eastern Washington, particularly on the east slopes of the Cascades. It is very sunny there! Thick clouds and lots of precipitation at and west of the Cascade crest, but once you get to Cle Elum and points east, it is completely sunny, except for a few orographically enhanced clouds over the higher terrain over there. Once you go further east, you get cloudy again. 

The east slopes of the Cascades are the sunniest place in Washington. My family owns some property in the Teanaway Valley, and a couple years back, some NYC businessman had a plan to build the world's largest solar power plant there, which would generate 75 megawatts of electricity. I'm usually all for clean energy, but I was actually against this solar plant simply because it would substantially lower the value of our property there. A lot of the other partners we shared the land with protested on the premise that the Teanaway Valley is NOT the sunniest place in Washington. After all, it gets over twice the amount of rain as nearby Ellensburg. So a lot of the partners turned to me to make a report showing how there are way sunnier places in Washington than the Teanaway Valley.

Unfortunately, I had to give them the cold hard facts. The Teanaway Valley is the best place in Washington to build a huge solar reserve. It is close to I-90, so energy can be distributed easily, and it is the sunniest place in Washington. Eastern Washington can be thought of as a "bowl," since it is surrounded by the Cascades, the Okanogan Highlands to the north, the Rockies to the far east, and the Blue Mountains to the southeast. In the Columbia Basin, cold air collects at the surface and creates an inversion, with low stratus clouds and fog often shrouding the basin in the winter. The east slopes of the Cascades are high enough that they are out of this inversion, but they still receive the drying effects of being on the lee side of the Cascades. In fact, even when there is no inversion, they are often still sunnier than Eastern Washington because the air sinks at a faster rate on the east slopes of the Cascades, so it is harder for clouds to form. Just take a look at the satellite picture above!

And yes, it is easier for moisture to make it over to Cle Elum than it is to Ellensburg, but rainfall doesn't necessarily translate into sunshine.

I was also looking at the radar images, and I found some pretty cool ones. They really show how strong the orographic lifting is right now over the Cascades and how much precipitation is falling on the windward sides of them. Check this picture out.

14:23 pm PDT Fri 19 Oct 2012 - UW composite radar image

Wow! Tons of precip over the Cascades, and zip once you get a couple miles east of the crest. Also, there's a pretty hefty convergence zone to our north. Convergence zones are really cool, and often occur simultaneously with the heavy orographically-enhanced precipitation over the Cascades, because they both occur in a post frontal, westerly flow off the Pacific.

Ok, one more thing. I took a look at the 12z WRF-GFS model this morning, and was astounded by the amount of snowfall forecast over the Cascades. Check this out.

Valid 05:00 pm PDT Sat, 20 Oct 2012 - 36hr Fcst - UW 12km 12z WRF-GFS 24-hour snowfall

Previous forecasts by the NWS had 3-8 inches of snow in the Cascades with a snow level at 3000 feet. Judging by this model, the Cascades above 2000 feet could see 18-30 inches of snow. That is a huge jump, and I'm not quite sure what to make of it, but I think we will see substantially more snow than previously forecast. I'm taking the middle road, forecasting 1-2 feet above 2,500 feet. 

One thing's for sure. If we get a ton of snow, I'm changing my Facebook profile picture to a cam of the snow at Snoqualmie Pass. It's been far too long since I've seen snow on that road.

Have a good one!
Charlie

Thursday, October 18, 2012

A Well-Defined Front

Thursday, October 18, 2012
6:52 P.M.


I just got done with a physics midterm, my first midterm of the autumn 2012 quarter! It went decently well, although there was one question involving a inclined plane, two weighted objects, tension, kinetic friction, and a whole bunch of gnarly stuff where I was supposed to find the angle (θ) of the inclined plane.


I'm pretty sure I got the wrong answer... I didn't have enough time to completely go through and figure it out. But now that I think about it, there's no wonder I didn't get the right answer. The test question was flawed. They weren't specific enough, and they left a lot of crucial information up to individual interpretation. They didn't specify what material the plane was made out of. What if the plane was made out of slick memory foam? The angle would decrease the closer the block got to the angle. What if the whole plane-block system was actually 20,000 leagues under the sea? This would strongly counteract the force of gravity, add immense pressure, and would involve making sophisticated calculations we haven't learned yet. What if the figurative incline, is, as I am talking, slowly falling into the supermassive black hole at the center of the Milky Way? This would stretch out the plane, so the angle that students would have calculated would have been different depending on what time during the test they completed the problem, since the angle would have been a function of time. The angle would have been larger if the student did the calculation early in the test, and it would have been smaller if they had rushed an answer at the last minute, since the plane would be more oblong. What if the kinetic friction by the block on the plane was so great that it caused the plane, now hypothetically made out of balsa wood, to catch on fire? Then there wouldn't be an angle to calculate! 

Alright, enough of the flippant excuses. I've got more midterms to study for. But infinitely more important, I have weather to talk about.

Valid 18:50 PDT, Thu 18 Oct 2012

Take a look at how well-defined that front is! This front is the leading edge of a system that will dump a brief dose of heavy rain over our area. How much rain are we talking here? Quite a bit, actually, anywhere from 0.5 to 1 inch in the lowlands from 5 P.M. Thursday to 5 P.M. Friday. The picture below is from UW's ultra-high resolution 4/3 km WRF-GFS model. I love this model because it allows me to see how much the rainfall varies with our topography.

Valid 05:00 pm PDT Fri, 19 Oct 2012 - 36hr Fcst - UW 4/3km 12z WRF-GFS 24-hour precip

Just for a comparison, look at the 12km resolution chart from the same model run and time below.

Valid 05:00 pm PDT Fri, 19 Oct 2012 - 36hr Fcst - UW 4/3km 12z WRF-GFS 24-hour precip

It gets the general idea, but it isn't as precise as the 4/3 km version, and it's a whole hell of a lot less pretty to look at. For a true meteorological buff, the UW's 4/3 WRF-GFS is not just a great tool for forecasting, but it's eye candy too.

Let's take a look at the timeline for this rain. As I write this sentence, it is 7:47 P.M. Let's see what this morning's 4/3 WRF-GFS model run predicts for one-hour rainfall from 7-8 P.M. tonight.

Valid 08:00 pm PDT Thu, 18 Oct 2012 - 15hr Fcst - UW 4/3km 12z WRF-GFS 1-hour precip

The rain that's passing through here right now (see above) will be out of here by 11 P.M (see below).



Valid 11:00 pm PDT Thu, 18 Oct 2012 - 18hr Fcst - UW 4/3km 12z WRF-GFS 1-hour precip

Another shot of rain comes in Friday morning. This one will be even briefer, lasting only an hour or two.

 Valid 11:00 am PDT Fri, 19 Oct 2012 - 30hr Fcst - UW 4/3km 12z WRF-GFS 1-hour precip

After this wave passes through, we will get cool and showery. A large upper-level trough in the jet stream will slide into our area, and direct cool, unstable, northwesterly flow over our area. We won't have much in the way of lift, so I wouldn't expect any convective activity to be too widespread, but the environmental lapse rates will be high (meaning there is a sharp decrease in temperature with altitude), so we will see some convection.

Valid 05:00 am PDT Sat, 20 Oct 2012 - 48hr Fcst - UW 36km 12z WRF-GFS 500mb vorticity, heights

The awesome thing about this trough is that it will direct cooler air into our region, and all the mountain passes, even Snoqualmie, will see their first snow of the season. In fact, the National Weather Service just issued a "Special Weather Statement" addressing the first mountain snowfall of the season. Nothing major, but hopefully the first snow of a very snowy season for the ski resorts.

Peace and love.
Charlie

Monday, October 15, 2012

Cold in the Extended?

Monday, October 15, 2012
10:42 A.M.

Folks, let me just start out by saying that the Seahawks game yesterday was incredible. Especially since I would have lost all my hair had the Hawks come up short to the Patriots via a bet with a New Englander. Now, normally, I wouldn't care about losing my hair (free haircut, right?), but after looking at the models, I'm pretty glad the Hawks won. It is about to get COLD here in October, and I don't know if my body has quite adapted to the change yet, so I need all the extra hair on my head that I can get. Nevertheless, I am still extremely excited, because if the long-range models turn out to be correct, we will get an early start to our skiing season, and it's been far too long since I've been on the slopes.

For now, though, we've got some weather to go through.


This picture above was taken from the Seattle National Weather Service's graphical forecast discussion, and it shows the storm we will be dealing with today currently off our coast. This storm will move quickly through the area and give us a brief shot of heavy rain and a good deal of wind to boot. In fact, we currently have a low-end wind advisory over our area for 5 P.M. tonight to 5 A.M. Tuesday morning. Below is the exact wording of the advisory.


URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE SEATTLE WA
958 AM PDT MON OCT 15 2012

...VERY WINDY CONDITIONS THIS AFTERNOON AND TONIGHT...

.A RAPIDLY MOVING FRONTAL SYSTEM WILL MOVE THROUGH WESTERN
WASHINGTON TONIGHT. SOUTHERLY WINDS AHEAD OF THE FRONT WILL
INCREASE OVER THE COAST AND NORTHWEST INTERIOR TO 20 TO 30 MPH
WITH GUSTS TO 50 MPH BEGINNING THIS AFTERNOON. THE WINDS WILL
CONTINUE INTO THE EVENING HOURS. OVER THE REST OF THE INTERIOR
WINDS WILL INCREASE AFTER THE FRONT PASSES THIS EVENING AND LAST
THROUGH THE NIGHT. WINDS WILL BE IN THE 20 TO 30 MPH RANGE WITH
GUSTS TO 45 MPH.

WAZ504-505-507>509-511-512-514-515-152330-
/O.EXB.KSEW.WI.Y.0027.121016T0000Z-121016T1200Z/
SOUTHWEST INTERIOR-EAST PUGET SOUND LOWLANDS-EVERETT AND VICINITY-
SEATTLE/BREMERTON AREA-TACOMA AREA-HOOD CANAL AREA-
LOWER CHEHALIS VALLEY AREA-EASTERN STRAIT OF JUAN DE FUCA-
WESTERN STRAIT OF JUAN DE FUCA-
958 AM PDT MON OCT 15 2012

...WIND ADVISORY IN EFFECT FROM 5 PM THIS AFTERNOON TO 5 AM PDT
TUESDAY...

THE NATIONAL WEATHER SERVICE IN SEATTLE HAS ISSUED A WIND
ADVISORY...WHICH IS IN EFFECT FROM 5 PM THIS AFTERNOON TO 5 AM
PDT TUESDAY.

* SOME AFFECTED LOCATIONS...SEATTLE...EVERETT...BREMERTON...
  OLYMPIA...TACOMA...CHEHALIS...PORT ANGELES.

* TIMING...THIS AFTERNOON THROUGH THIS EVENING.

* WIND...SOUTHWEST WINDS WILL INCREASE TO 20 TO 30 MPH WITH GUSTS
  TO 45 MPH LATE THIS AFTERNOON. WINDS WILL CONTINUE INTO THE LATE
  NIGHT HOURS.

* IMPACTS...STRONG SOUTHERLY WINDS WILL PRUNE DEAD BRANCHES FROM
  TREES. FALLING BRANCHES MAY RESULT IN LOCAL POWER OUTAGES AT
  TIMES. SOME WEAKENED TREES COULD FALL IN THE WIND. MOST TREES
  STILL HAVE SOME OR ALL OF THEIR LEAVES...WHICH WILL HEIGHTEN THE
  IMPACT OF THE WIND ON THE TREES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WIND ADVISORY IS ISSUED WHEN SUSTAINED WINDS OF 30 TO 39 MPH OR
GUSTS OF 45 TO 57 MPH ARE LIKELY.

&&

$$


As you can see, we are on the very low end of the wind advisory, with gusts to 45 mph and sustained winds of 20 to 30. I have a feeling that if this storm occurred in December, a wind advisory would not be issued. The reason why it is being issued here is because many of the trees still have their leaves on them, and they also have a bunch of dead branches that haven't been blown off by previous storms because, well, there haven't been any. A closer look at the UW's high resolution 4km WRF-GFS shows us that the winds won't be anything to really worry about. Of course, relative to this past summer, it will probably feel like a hurricane out there.

Valid 05:00 pm PDT Mon, 15 Oct 2012 - 12hr Fcst - UW 4km 12z WRF-GFS 10 meter wind, SLP

The above picture shows the wind as predicted at 5 P.M. Pretty decent winds on the coast and San Juans, but nothing here.

Valid 11:00 pm PDT Mon, 15 Oct 2012 - 18hr Fcst - UW 4km 12z WRF-GFS 10 meter wind, SLP

Later in the night, we will get a surge of wind down the Strait, but again, we won't see much wind in the Seattle metropolitan area. If I was the National Weather Service, I would not be issuing a wind advisory based on these models. Of course, I'm not the National Weather Service, so for now, a wind advisory remains in effect.

Precipitation-wise, this storm will be lighter than the one we just saw because it will move through our area at a higher velocity (to use a term from the intro physics class I am taking this quarter). I'd expect 24-hour totals of a quarter to a half inch of rain in the Western Washington lowlands, but the Olympics and Cascades could see two to three inches. Not enough to cause flooding, but enough to make the Skokomish River come close.

Valid 05:00 am PDT Tue, 16 Oct 2012 - 24hr Fcst - UW 4km 12z WRF-GFS 24 hour precip

After this guy rolls on through, we will be dry for a couple days, and then we'll have another storm come through our area on Friday. This one could deliver a bit more wind and a bit more rain. It seems as though autumn is making up for lost time.

Valid 05:00 am PDT Fri, 19 Oct 2012 - 96hr Fcst - UW 12km 12z WRF-GFS 24 hour precip

But it is into next week that things start to get rather interesting.

Forecast retrieved from Brian Schmit's "16-Day GFS Extraction" Program

Of course, you have to take these direct extraction things with a grain of salt. Earlier runs had Seattle in the low 30s for four straight days. This is because the resolution on these global models is very low, and it doesn't account for the local moderating effects of the Pacific Ocean, and also because the forecast is in the extremely far extended. It is very useful for picking up patterns in the models though. They have been consistent with this pattern, and at this point, I'm definitely forecasting snow in Snoqualmie Pass next week. 

Have a nice day!
Charlie

Saturday, October 13, 2012

Terrible Tempest the Twelfth

October 12, 2012
4:18 P.M.


As promised, I'll give you guys a brief overview of the Columbus Day Storm of 1962 since it has been 50 years since it happened. Unfortunately, I had a seizure before the presentation and was still in the ER when the presentation started. Trust me, I tried to convince those hospital techs, but they like to be careful. I'm quite alright; I do have epilepsy and I have had a string of seizures over the past two weeks, but apart from a sore tongue, I am fine. Hopefully, my neurologist will figure out what has changed and change my meds accordingly so I can stop having so many seizures and start going to weather events.

However, the good thing is that I do know a good bit about the Columbus Day Storm. It is, without a doubt, the most intense storm to strike the Pacific Northwest since the arrival of European settlers, and could be the most powerful extratropical windstorm to ever strike the United States since 1776.

The Columbus Day Storm was a freak of nature - an outlier - a singularity in severe Pacific Northwest weather events. It was by far the strongest wind event to ever hit our area, and it was the earliest as well. November, especially around Thanksgiving, and early December are the times when the Pacific Northwest is stormiest. How is it then, that our strongest storm occurred in early October?

Well, the key here is understanding how tropical moisture gets entrained in the Westerlies. In October, ocean temperatures in the western Pacific Ocean are still very warm, and very strong supertyphoons can still form. The Columbus Day Storm actually started life as a typhoon - Typhoon Freda - over the western Pacific Ocean. As the typhoon degenerated and lost its tropical characteristics, it still retained a massive amount of warm air and moisture. This parcel of air was carried west across the Pacific Ocean all the way to the Californian coast, but once it was off there, the air associated with typhoon Freda collaborated with a 170+ knot jet stream in the upper atmosphere to promote cyclogenesis and form a storm of the likes we had never seen before.

From Christopher C. Burt's "Wunderblog"


After this storm formed, it raced up the Pacific Northwest shoreline. And folks, when I say "raced," I am not exaggerating. After forming, the storm itself moved to the NNE at 40 miles per hour. This, combined with a minimum pressure of 960 millibars, the proximity of the low to the coast, and an extremely tight pressure gradient, made the Columbus Day Storm a step ahead of any storm seen before or since with respect to wind velocity.



Folks, nothing has even come close. This map (see photo credit above) shows three of the Pacific Northwest's biggest windstorm: the Columbus Day Storm, the November 14, 1981 storm, and the December 12, 1995 storm. The 1981 and 1995 storms were actually deeper, but they were a far cry from the Columbus Day Storm in terms of wind speed. Why was there so much discrepancy in the power of winds from three similarly-deep lows?

There were a variety of factors that made the Columbus Storm so windy, but three big ones were:

A.) How swiftly moving the storm was (this contributed to extremely fast pressure rises and falls which accentuated the strength of the wind)

B.) How compact the storm was. Whereas many extratropical cyclones are spread out over a very wide area, the Columbus Day Storm was pretty small in terms of area. Of course, it traveled over a huge area, so the damage was widespread, but the actual radius of the storm was fairly small.

C.) How closely it paralleled the shoreline. The Columbus Day Storm was much closer to the Pacific Northwest than the November 14, 1981 storm and the December 12, 1995 storm. The only exception is that the December 1995 storm actually came within the same distance to Seattle as the Columbus Day Storm, but the December 1995 storm was much bigger (this does NOT mean more powerful) in terms of area, so the pressure gradients were less intense.

From Wolf Read's "The Storm King" Website

Take a look at the December 12, 1995 storm. This storm was at least 5 mb deeper than the Columbus Day Storm, but it was much bigger, moved slower, and was further away from the coastline for most of the duration of its life.

Here's some satellite info of the November 1981 storm. Satellites weren't too high-resolution back then, but it can give you an idea of what the atmosphere looked like over the Pacific Northwest on that day.


From Wolf Read's "The Storm King" Website

Sadly, there is not satellite data for the Columbus Day Storm, but we do have some surface maps that show the incredibly compact nature of the storm. This surface map was completed in 1966 by Lynott and Cramer, and I found it on Cliff Mass' blog. It shows the storm at peak intensity, which was around 3 P.M. that fateful Friday.


Finally, no storm presentation is complete without me giving you a map of the actual winds that were witnessed, so here is a beautiful map of all the gusts in knots compiled by Wolf Read. To convert to miles per hour, multiply by 1.15.


If I ever get my hands on a video from Cliff's presentation, I will listen to it, and relay what I have learned back to you. Until then, you'll have to make due with this.

Charlie