The GFS Superensemble!

Thursday, October 13, 2011
1:17 P.M.

When there is a period of pleasant but boring weather like there is right now, I generally look at the GFS Superensemble model for insight into the future. It has the designation of being a "Superensemble" not because it is the most accurate model (it isn't) but because it goes far into the future. It provides charts 384 hours (16 days) out! Although the charts at the end are generally widely inaccurate, a consistent pattern of similar conditions the models super far out may indicate a general pattern that could be developing.

Let's face it. The weather outside right now is nice, but it is far from interesting. Tuesday was incredible. Wednesday was fairly humdrum. And today, there are just some high clouds, with most morning fog burnt off by now. I took a look at the GFS Superensemble model to look into what we could expect the next couple weeks.

10/13/11 12UTC 009HR Fcst Valid Thu 10/13/11 21UTC (NCEP/NWS/NOAA)

300 mb heights, isotachs, and wind (knots)

Sorry if that description seems verbose, I am just trying to get into the habit of specifically citing all the data I get. Basically, this picture represents the jet stream over us right now. You can see a weak ridge over our area that is nudging the jet stream further north, protecting us from any significant rainfall.

10/13/11 12UTC 120HR Fcst Valid Tue 10/18/11 12UTC (NCEP/NWS/NOAA)

300 mb heights, isotachs, and wind (knots)

By next week, the ridge has gotten even bigger! We should see partly cloudy conditions with highs in the 60s early next week.

Models diverge after that. The GFS continues to show this ridge, but the European Model, which is generally more accurate, shows a pretty wet system entering our region.

Ten days later, the GFS shows a zonal flow.

10/13/11 12UTC 240HR Fcst Valid Sun 10/23/11 12UTC (NCEP/NWS/NOAA)

300 mb heights, isotachs, and wind (knots)

At this point, beyond 10 days is completely up for grabs. However, I believe we will see the ridge that the GFS is promising, and then a good soaker like the ECMWF shows in the middle of next week. In other words, I'm following the NWS and tv stations on this one, and you should too!

Have a good one!
Charlie

Latest on Seasonal Forecast

Wednesday, October 12, 2011
11:59 A.M.

Taken from "The International Research Institute for Climate and Society" (IRI)

These models all show the forecast SST for the Nino 3.4 region every month, and you can clearly see that most of the models predict cooler than normal temperatures in Nino 3.4. Cooler SST temperatures in the Eastern Pacific indicate La Nina conditions. Also, the table below shows the individual model outputs, since it can be hard to make out everything on the above chart.

Taken from "The International Research Institute for Climate and Society" (IRI)

The general indication from these models is that this La Nina will be weaker than last year's. However, the NCEP CFS model has been particularly accurate in forecasting La Nina conditions, and it is forecasting some moderate to perhaps strong conditions this winter. I have been looking at the SST in the tropical Pacific (check out my "Tropical Pacific SST" link) and I have noticed that our La Nina has slowly but steadily been strengthening, so I am forecasting tropical Pacific SST anomalies similar to the ones the CFS is showing.

Because a La Nina is expected, the Climate Prediction Center has forecast a wetter and cooler than normal winter for the Pacific Northwest. Below, I show the temperature and precipitation outlooks all the way out to one year. Pay special attention to the winter months though. You can enlarge the pictures by clicking on them.

Temperature

Precipitation

In general, wetter and cooler conditions than normal can be expected in the northern tier of the country, with warmer and drier weather south. Unfortunately, Texas will likely still experience drought conditions.

It would be interesting to study the relationship between ENSO (El Nino Southern Oscillation) and Global Warming. It seems like we haven't had many neutral years lately!

Thanks for stopping by!

Charlie

Heavy Showers

Tuesday, October 11, 2011
2:28 P.M.

Last night, I went walking with some friends around the UW campus just to get a breath of fresh air and get some relief from the plethora of work thrust upon us by our most excellent professors. I knew that showers were in the forecast, but I failed to check the radar imagery before we headed out. There was a light drizzle just outside Lander Hall, but once we got to Red Square, the heavens opened and Red Square turned into Brick Lake. There we were, soaking wet, in the middle of the night, all alone in the middle of campus. I guess everybody else decided to check the radar. Therefore, I dedicate this post to those people who took a drenching stroll with me last night.

Camano Island Radar, 10:22 pm PDT Mon 10 Oct 2011

The radar image above was taken slightly before our walk, and you can see a moderate shower poised to move through. It sure felt heavier than moderate! There were some periods of pretty hefty rain.

Then again, at least we didn't have a super late night! Look at the radar 2 1/2 hours later!

Camano Island Radar, 01:53 am PDT Tue 11 Oct 2011

These periods of rain were associated with a cool and unstable air mass over our area last night. Today, we didn't have prolonged periods of rain, but we had lots of showers. Some of these showers were quite heavy!

4:15 pm PDT Tue 11 Oct 2011

This radar picture, which combines the Langley Hill, Portland, and Camano Island Radars, really shows the showery activity we saw throughout the day. You can see light showers coming in off of the ocean, but when they reach land, they encounter more lift, especially over mountainous areas, and strengthen. You can see a particularly heavy shower southeast of Issaquah, by Tiger Mountain. Look at those reds! It must have been pouring over there.

You can clearly see a lot of showers on the satellite imagery as well. Additionally, all those tight isobars indicate very strong low-level westerly winds. This strong onshore flow leads to lots of orographically enhanced showers. You can see how the Olympics and Cascades have more clouds than normal, but once you get into Eastern Washington, the air sinks, compresses, and warms, inhibiting clouds or precipitation. While the mountains saw inches of rain or feet of snow, Eastern Washington basked under sunny skies.

Visible satellite at 2:30 pm PDT (from NWS)

I recently talked about "unsettled weather" in one of my recent blog posts, and we definitely saw some unsettled weather today. Take a look at a time-lapse video from Red Square today.

Uploaded by KOMOcommunities on October 11, 2011

Showers will still be around on Wednesday, but they will not be as numerous or intense as today's cloudbursts. Thursday will dry, and light rain returns for Friday and Saturday. Next week looks calm and seasonable, and models diverge after that.

Also, I updated my blog format to make it easier to follow, hopefully attracting more viewers!

On the left side, you can subscribe to the blog, follow it by email, share it on twitter or facebook, become an official "follower" (whatever that means), take a look at some of my favorite weather links, and take a look at my archived posts.

On the right side, you can search the blog, check out my total pageviews, look at my popular posts, and look at ALL my posts on this blog under "recent posts!"

Under each individual post, you can also do some more stuff to share my blog. As always, comments are encouraged!

All of these plugins work with the internet browsers I have used, but Chrome works the best, which would make sense, since Blogger is made by Google. Firefox and Internet Explorer also work, but you generally need to refresh the page once for all of the plugins to show. I haven't tried Opera or Safari, but who uses those browsers anyway?

On a side note, I think it is ironic that my most viewed post is about nuclear energy, but I traced some of the links that lead people to my blog and found that a picture from my blog of a nuclear explosion comes up when you google image search "nuclear energy." Clicking on this image will lead you to my "Nuclear Energy" post! Pretty cool stuff.

Thank you for reading! I have to get back to schoolwork.
Charlie Phillips

Storm!

Monday, October 10, 2011
9:34 A.M.

Don't you just love these National Weather Service graphics? It's hard to find one single graphic that has so many explanations and a model picture, but the NWS issues them when there is some sort of significant weather occurring. Pretty awesome!!!

Over the next few days, we will get a fair amount of rain. The graphic above shows the Seattle metropolitan area getting anywhere from around .75 to 1.25 inches of rain from 5 A.M. PDT Monday to 5 A.M. PDT Wednesday. As is generally the case, higher amounts will be found to the south, as there is less rain shadowing from the Olympics there.

This particular system differs from other weather systems that impact us in the autumn and winter because it will give us several periods of rain instead of one long period of rain before the front passes through. Right now, we have a pretty weak front passing through, with most of the rain heading south toward Cape Mendocino. However, the strong jet stream and unstable air behind the front will support the development of numerous small troughs, which will keep the rain going around our area until early Wednesday morning.

Take a look at the current satellite and radar imagery for our area. They don't look too impressive over Washington. The satellite pic was taken at 7 A.M. PDT, and the radar image was taken 2 hours later. I obtained both of these pictures from the NWS' graphical forecast discussion.

However, the GFS models from this morning show a strong jet stream, currently over southern Oregon, lifting northward into our area. Both of the models below are also from the NWS graphical forecast discussion.

Winds at 250 mb - 11 A.M. PDT, Monday, October 10, 2011

Winds at 250 mb - 5 A.M. PDT, Tuesday, October 11, 2011

With a strong jet stream perpendicular to the mountains and numerous rain bands as the result of unstable air behind us, the mountains will see heavy precipitation, the mountains will see some serious snowfall. The snow level is now expected to be around 1,000 feet higher than forecast earlier this week, so the highest passes should be ok, but places above that line will see a dumping. Take a look at the 24 hour snowfall amounts on the volcanoes! Some places on Mt. Rainier could experience a storm total of over 3 feet!

Valid 05:00 pm PDT Tue, 11 Oct 2011 - 36hr Fcst - UW 4km 12z WRF-GFS 24 hour snowfall

Western Washington could also see some thundershowers tomorrow, as the air is very unstable. Instability leads to convection, and convection can lead to thunderstorms.

Thursday looks like the best day to get outside, and rain returns for the weekend. No major storms in sight... for now.

Thanks for reading.

Charlie Phillips

Mountain Snowfall Forecast Gaining More Credibility

Friday, October 7, 2011
11:15 A.M.

Looking at the WRF-GFS models from the UW this morning, I have some good news for winter sports and water supply enthusiasts everywhere! The forecast for significant snowfall in the mountains is gaining more credibility. It isn't a slam dunk, but it definitely is looking more likely after the most recent model runs.

As I stated yesterday, the NWS from Seattle has access to the European (ECMWF or Euro) model, but I do not. The Euro shows heavy snowfall in the mountains above 4,500 feet. The GFS doesn't quite show that yet. However, the most recent runs of the GFS are becoming more in line with the Euro.

First, let's check out the jet stream. This graphic shows the winds at the 300mb level, and you can see that there are strong winds ramming right into Western Washington. Strong jet streams generally give stronger storms, and the orientation of the jet stream in the next couple days is expected to be perpendicular to the Cascades, resulting in favorable orographic enhancement for heavy precipitation!

Valid 05:00 am PDT Tue, 11 Oct 2011 - 96hr Fcst - UW 36km 12z WRF-GFS 300mb isotachs

You can clearly see a strong jet stream flowing right over the Pacific Northwest. The windiest parts of the jet stream could approach 160 knots! 

Now, let's look at the 48 hour precipitation.

Valid 05:00 am PDT Wed, 12 Oct 2011 - 120hr Fcst - UW 12km 12z WRF-GFS 48-hour precipitation

Just to clarify, this graphic shows the precipitation forecast for the past 48 hours, not 48 hours in the future. You can see anywhere from 1 to over 3 inches of liquid precipitation throughout the Cascades, with more at higher elevations. I didn't show the snow graphic because I believe that the GFS is too high with the snow level. Regardless, one inch of rain is generally equal to 10 inches of snow. This ratio will be lower where is is warmer (wet snow) and higher where it is colder (powdery snow), but it is a good benchmark. At face value, we could see snowfall totals of around 30 inches in isolated spots in the Cascades, and maybe even 40 inches at places on the volcanoes. 

Hopefully we will see some heavy duty snow! But even if we don't in the next week, we should see gobs in the winter. La Nina baby!

Thanks for reading,

Charlie