Tuesday, February 28, 2017
Monday, February 27, 2017
Surprise Snowstorm in Seattle
It was quite a surprise for many as heavy snow started falling in Seattle around 6:30 AM this morning. The National Weather Service did talk about the potential for rain and snow showers, but the this morning the snow was quite substantial with .5-2.5 inches around Seattle and neighboring communities.
What happened?
An area of particularly heavy precipitation that pushed the snow level to sea level.
When I went out to get the newspaper at 6:30 AM it was actually raining, but as the precipitation intensity increased, snow started mixing in, followed by big wet flakes.
The Camano Island radar shows the culprit (see below): a small area of heavy showers (yellow is moderate intensities). The precipitation is being enhanced over central Puget Sound due to convergence (air coming together) in the lee of the Olympic Mountains (a weak Puget Sound Convergence Zone).
The freezing level at 5:30 AM was at roughly 1300 ft, but near-freezing temperatures were found down to around 500 ft. As a rule of thumb, the snow level (the level at which all snow from aloft melts) is roughly 1000 ft below the freezing level. So we were close,
As the snow aloft melted, it cooled the air below (it takes heat to melt the snow!), causing the freezing and snow level to be pushed lower. The descending snow level quickly reached the surface, resulting in snow accumulating on grass, building, and even the roads (which were above freezing). Beautiful big flakes.
Why were the snowflakes so big? Because at marginal temperatures at or near freezing snowflakes are more "sticky" and they tend to form large aggregates of smaller snowflakes.
Roads should improve and daytime solar heating will ensure that temperatures rise by early afternoon. But there are some more showers moving in that could cause some snow showers. And there is another chance of significant snow later this afternoon as a Puget Sound Convergence Zone forms north of the city (see snowfall forecast for the 3-hr ending 4 PM).
___________________
The Northwest Weather Workshop
And don't forget...if you want to attend the big weather meeting of the year...the Northwest Weather Workshop on March 3-4 in Seattle...you have to register before. The agenda and more information (including how to register) is found here: http://ift.tt/1kGl4aC
from Cliff Mass Weather Blog http://ift.tt/2l4LhHH
What happened?
An area of particularly heavy precipitation that pushed the snow level to sea level.
When I went out to get the newspaper at 6:30 AM it was actually raining, but as the precipitation intensity increased, snow started mixing in, followed by big wet flakes.
The Camano Island radar shows the culprit (see below): a small area of heavy showers (yellow is moderate intensities). The precipitation is being enhanced over central Puget Sound due to convergence (air coming together) in the lee of the Olympic Mountains (a weak Puget Sound Convergence Zone).
The freezing level at 5:30 AM was at roughly 1300 ft, but near-freezing temperatures were found down to around 500 ft. As a rule of thumb, the snow level (the level at which all snow from aloft melts) is roughly 1000 ft below the freezing level. So we were close,
Why were the snowflakes so big? Because at marginal temperatures at or near freezing snowflakes are more "sticky" and they tend to form large aggregates of smaller snowflakes.
Roads should improve and daytime solar heating will ensure that temperatures rise by early afternoon. But there are some more showers moving in that could cause some snow showers. And there is another chance of significant snow later this afternoon as a Puget Sound Convergence Zone forms north of the city (see snowfall forecast for the 3-hr ending 4 PM).
___________________
The Northwest Weather Workshop
And don't forget...if you want to attend the big weather meeting of the year...the Northwest Weather Workshop on March 3-4 in Seattle...you have to register before. The agenda and more information (including how to register) is found here: http://ift.tt/1kGl4aC
from Cliff Mass Weather Blog http://ift.tt/2l4LhHH
Surprise Snowstorm in Seattle
It was quite a surprise for many as heavy snow started falling in Seattle around 6:30 AM this morning. The National Weather Service did talk about the potential for rain and snow showers, but the this morning the snow was quite substantial with .5-2.5 inches around Seattle and neighboring communities.
What happened?
An area of particularly heavy precipitation that pushed the snow level to sea level.
When I went out to get the newspaper at 6:30 AM it was actually raining, but as the precipitation intensity increased, snow started mixing in, followed by big wet flakes.
The Camano Island radar shows the culprit (see below): a small area of heavy showers (yellow is moderate intensities). The precipitation is being enhanced over central Puget Sound due to convergence (air coming together) in the lee of the Olympic Mountains (a weak Puget Sound Convergence Zone).
The freezing level at 5:30 AM was at roughly 1300 ft, but near-freezing temperatures were found down to around 500 ft. As a rule of thumb, the snow level (the level at which all snow from aloft melts) is roughly 1000 ft below the freezing level. So we were close,
As the snow aloft melted, it cooled the air below (it takes heat to melt the snow!), causing the freezing and snow level to be pushed lower. The descending snow level quickly reached the surface, resulting in snow accumulating on grass, building, and even the roads (which were above freezing). Beautiful big flakes.
Roads should rapidly improve and the daytime solar heating will ensure that temperatures rise. But there are some more showers moving in that could cause some snow showers. And there is another chance of significant snow later this afternoon as a Puget Sound Convergence Zone forms north of the city (see snowfall forecast for the 3-hr ending 4 PM).
___________________
The Northwest Weather Workshop
And don't forget...if you want to attend the big weather meeting of the year...the Northwest Weather Workshop on March 3-4 in Seattle...you have to register before. The agenda and more information (including how to register) is found here: http://ift.tt/1kGl4aC
from Cliff Mass Weather Blog http://ift.tt/2l4LhHH
What happened?
An area of particularly heavy precipitation that pushed the snow level to sea level.
When I went out to get the newspaper at 6:30 AM it was actually raining, but as the precipitation intensity increased, snow started mixing in, followed by big wet flakes.
The Camano Island radar shows the culprit (see below): a small area of heavy showers (yellow is moderate intensities). The precipitation is being enhanced over central Puget Sound due to convergence (air coming together) in the lee of the Olympic Mountains (a weak Puget Sound Convergence Zone).
The freezing level at 5:30 AM was at roughly 1300 ft, but near-freezing temperatures were found down to around 500 ft. As a rule of thumb, the snow level (the level at which all snow from aloft melts) is roughly 1000 ft below the freezing level. So we were close,
Roads should rapidly improve and the daytime solar heating will ensure that temperatures rise. But there are some more showers moving in that could cause some snow showers. And there is another chance of significant snow later this afternoon as a Puget Sound Convergence Zone forms north of the city (see snowfall forecast for the 3-hr ending 4 PM).
___________________
The Northwest Weather Workshop
And don't forget...if you want to attend the big weather meeting of the year...the Northwest Weather Workshop on March 3-4 in Seattle...you have to register before. The agenda and more information (including how to register) is found here: http://ift.tt/1kGl4aC
from Cliff Mass Weather Blog http://ift.tt/2l4LhHH
Sunday, February 26, 2017
Too Warm
While the passes are getting hammered with snow right now (chains required at Snoqualmie), the lower atmosphere is too warm to get snow down to near sea level. Snow is being reported at higher stations (e.g., Paine Field in Everett) and over NW Washington, but around Seattle it is nearly all rain.
Peter Benda sent a picture at his house at 1170 feet near Bellevue...about 1.5 inches there.
Light snow around Bellinghan
The snow level is around 400-500 feet now around Puget Sound.
We knew the temperatures were marginal, with the predicted precipitation intensities sufficient to bring the freezing and snow levels down to a few hundred feet.. However, the precipitation has been lighter and thus the atmosphere stayed warmer near the surface.
The latest radar (7AM) show only light precipitation and the back edge of the front is already crossing the coast. Just a few light showers offshore and most of those are going to the southeast.
Well, at least everyone was warned about this possibility.
from Cliff Mass Weather Blog http://ift.tt/2mrVCtV
Peter Benda sent a picture at his house at 1170 feet near Bellevue...about 1.5 inches there.
And you pick up snow on I 90 east of Issaquah.
Light snow around Bellinghan
The snow level is around 400-500 feet now around Puget Sound.
We knew the temperatures were marginal, with the predicted precipitation intensities sufficient to bring the freezing and snow levels down to a few hundred feet.. However, the precipitation has been lighter and thus the atmosphere stayed warmer near the surface.
The latest radar (7AM) show only light precipitation and the back edge of the front is already crossing the coast. Just a few light showers offshore and most of those are going to the southeast.
Well, at least everyone was warned about this possibility.
from Cliff Mass Weather Blog http://ift.tt/2mrVCtV
Too Warm
While the passes are getting hammered with snow right now (chains required at Snoqualmie), the lower atmosphere is too warm to get snow down to near sea level. Snow is being reported at higher stations (e.g., Paine Field in Everett) and over NW Washington, but around Seattle it is nearly all rain.
Peter Benda sent a picture at his house at 1170 feet near Bellevue...about 1.5 inches there.
The snow level is around 400 feet now.
We knew the temperatures were marginal, with the predicted precipitation intensities sufficient to bring the freezing and snow levels down to a few hundred feet.. However, the precipitation has been lighter and thus the atmosphere stayed warmer near the surface.
The latest radar (7AM) show only light precipitation and the back edge of the front is already crossing the coast.
Well, at least everyone was warned about this possibility.
from Cliff Mass Weather Blog http://ift.tt/2mrVCtV
Peter Benda sent a picture at his house at 1170 feet near Bellevue...about 1.5 inches there.
And you pick up snow on I 90 east of Issaquah.
The snow level is around 400 feet now.
We knew the temperatures were marginal, with the predicted precipitation intensities sufficient to bring the freezing and snow levels down to a few hundred feet.. However, the precipitation has been lighter and thus the atmosphere stayed warmer near the surface.
The latest radar (7AM) show only light precipitation and the back edge of the front is already crossing the coast.
Well, at least everyone was warned about this possibility.
from Cliff Mass Weather Blog http://ift.tt/2mrVCtV
Saturday, February 25, 2017
Marginal Lowland Snow, Again.
Folks... this is getting tiring. Another situation in which lowland temperatures are marginal for snow, making the forecast exquisitely difficult and elevation dependent. With rapidly increasing day length and strengthening sun, we are almost out of the lowland snow season (which is really over by March 8-10th).
Later tonight and tomorrow morning, an upper level (500 hPa) trough of low pressure will pass over the Northwest, producing upward motion and precipitation (see forecast map for 10 AM tomorrow).
Associated with upper trough will be a surface low, that will be along the Washington coast. The trouble is that temperatures are not that cold over the region and there is not a good push of cold air out of British Columbia.
So what are the model's saying? Well, the super high-resolution UW WRF model is predicting a few inches of snowfall over central Puget Sound by 4 PM Sunday (keep in mind that snow DEPTH would be less). Lots of snow in the Cascades (1-1.5 ft). But it is spotty and less near the water.
The vaunted European Center model for the same period? Less snow near sea level, with increasing amounts (few inches) towards the Cascade foothills. Somewhat different details though.
What about the ensemble (any model) forecasts? A lot of uncertainty, with varying amounts. The ensemble average is about 1.25 inches in Seattle and 2.00 inches at Paine Field in Everett.
So what is the bottom line? Precipitation will start tonight around 10PM-midnight and will continue until mid-morning. Above 400 feet, there will be a few inches of wet snow, increasing with higher elevation. Below that, it will be a mixed bag. Perhaps .5-1 inch near sea level, increasing to a few inches as one goes higher.
But please not there is a lot of uncertainty. Sea level could be all rain or get 3-4 inches.
Later in the day, temperatures will warm into the 40s with onshore flow behind the low and warming by the sun. So driving conditions will improve rapidly.
from Cliff Mass Weather Blog http://ift.tt/2lW0Ws5
Later tonight and tomorrow morning, an upper level (500 hPa) trough of low pressure will pass over the Northwest, producing upward motion and precipitation (see forecast map for 10 AM tomorrow).
Associated with upper trough will be a surface low, that will be along the Washington coast. The trouble is that temperatures are not that cold over the region and there is not a good push of cold air out of British Columbia.
But we do have cool air over us now, with the freezing level around 1300 ft. The snow level is generally about 1000 ft below that, so snow could fall to 300 ft. And precipitation can cool the atmosphere, thus bringing wet snow to sea level.
So what is the bottom line? Precipitation will start tonight around 10PM-midnight and will continue until mid-morning. Above 400 feet, there will be a few inches of wet snow, increasing with higher elevation. Below that, it will be a mixed bag. Perhaps .5-1 inch near sea level, increasing to a few inches as one goes higher.
But please not there is a lot of uncertainty. Sea level could be all rain or get 3-4 inches.
Later in the day, temperatures will warm into the 40s with onshore flow behind the low and warming by the sun. So driving conditions will improve rapidly.
from Cliff Mass Weather Blog http://ift.tt/2lW0Ws5
Marginal Lowland Snow, Again.
Folks... this is getting tiring. Another situation in which lowland temperatures are marginal for snow, making the forecast exquisitely difficult and elevation dependent. With rapidly increasing day length and strengthening sun, we are almost out of the lowland snow season (which is really over by March 8-10th).
Later tonight and tomorrow morning, an upper level (500 hPa) trough of low pressure will pass over the Northwest, producing upward motion and precipitation (see forecast map for 10 AM tomorrow).
Associated with upper trough will be a surface low, that will be along the Washington coast. The trouble is that temperatures are not that cold over the region and there is not a good push of cold air out of British Columbia.
So what are the model's saying? Well, the super high-resolution UW WRF model is predicting a few inches of snowfall over central Puget Sound by 4 PM Sunday (keep in mind that snow DEPTH would be less). Lots of snow in the Cascades (1-1.5 ft). But it is spotty and less near the water.
The vaunted European Center model for the same period? Less snow near sea level, with increasing amounts (few inches) towards the Cascade foothills. Somewhat different details though.
What about the ensemble (any model) forecasts? A lot of uncertainty, with varying amounts. The ensemble average is about 1.25 inches in Seattle and 2.00 inches at Paine Field in Everett.
So what is the bottom line? Precipitation will start tonight around 10PM-midnight and will continue until mid-morning. Above 400 feet, there will be a few inches of wet snow, increasing with higher elevation. Below that, it will be a mixed bag. Perhaps .5-1 inch near sea level, increasing to a few inches as one goes higher.
But please not there is a lot of uncertainty. Sea level could be all rain or get 3-4 inches.
Later in the day, temperatures will warm into the 40s with onshore flow behind the low and warming by the sun. So driving conditions will improve rapidly.
from Cliff Mass Weather Blog http://ift.tt/2lW0Ws5
Later tonight and tomorrow morning, an upper level (500 hPa) trough of low pressure will pass over the Northwest, producing upward motion and precipitation (see forecast map for 10 AM tomorrow).
Associated with upper trough will be a surface low, that will be along the Washington coast. The trouble is that temperatures are not that cold over the region and there is not a good push of cold air out of British Columbia.
But we do have cool air over us now, with the freezing level around 1300 ft. The snow level is generally about 1000 ft below that, so snow could fall to 300 ft. And precipitation can cool the atmosphere, thus bringing wet snow to sea level.
So what is the bottom line? Precipitation will start tonight around 10PM-midnight and will continue until mid-morning. Above 400 feet, there will be a few inches of wet snow, increasing with higher elevation. Below that, it will be a mixed bag. Perhaps .5-1 inch near sea level, increasing to a few inches as one goes higher.
But please not there is a lot of uncertainty. Sea level could be all rain or get 3-4 inches.
Later in the day, temperatures will warm into the 40s with onshore flow behind the low and warming by the sun. So driving conditions will improve rapidly.
from Cliff Mass Weather Blog http://ift.tt/2lW0Ws5
Friday, February 24, 2017
Thursday, February 23, 2017
Why has California Been Wet and Washington State Cool This WInter
It has been a remarkable winter so far, very different in character from the previous winter seasons. During the past 90 days, the southwest US, and particularly California and Nevada, have been MUCH wetter than normal. Some locations have had over 400% of normal precipitation! Western Washington has been a bit drier than normal.
So what his interesting north-south pattern and why has it been so persistent?
Well, the proximate cause is easy. There has been a persistent area of low pressure over the eastern Pacific west of northern California to Washington. The following figure shows the anomaly (difference from normal) of the height the 500 hPa pressure surface (around 18,000 ft) for the past 90 days. There is an amazing negative anomaly (purple color) signifying lower than normal heights (or equivalently low pressure).
Storm after storm has brought low heights/pressures along the northern West Coast.
Such a persistent trough or low along the northern West Coast causes the jet stream to be pushed south into California, instead of its normal position coming into the Pacific Northwest (the jet stream, a current of strong winds tends to follow the outer periphery of the trough). Troughs are associated with colder than normal air. So with the jet moving south into California, CA get more precipitation (since the southern of the trough is associated with upward motion), while cold air is found over the Northwest.
But why is the trough found over the northern West Coast? Good question. If you look at the pattern of the height anomalies, you will notice a wave-like pattern, with alternating high and low heights. This pattern is associated with something called Rossby waves in the atmosphere (they are names after a famous meteorologist Carl Gustav Rossby). Think about throwing a rock into a big pond, with waves radiating away from the rock.
So what is the analog for a rock in the atmosphere? What is disturbing the atmosphere causing waves to propagate over the Pacific Ocean and north America?
Lots of thunderstorms over the Maritime Continent- places like Borneo, New Guinea, Indonesia, and the adjacent islands.
Here is a measure of the amount of thunderstorms that we can observe from space--called Outgoing Longwave Radiation (OLR) for the same 90 day period. To be more specific, this shows the anomaly (or difference) from normal. Where values of OLR are low, there are more high clouds from thunderstorms. You can see a big negative anomaly over the Maritime continent and SE Asia.
Thunderstorm are like rocks to the atmosphere, greatly perturbing the wind, temperature, and humidity fields. That in turn generates atmospheric waves that can cause localized weather anomalies like we have seen on the West Coast.
But why is there a big thunderstorm anomaly with lots of thunderstorms over SE Asia and the Maritime Continent? That is probably due to the La Nina of last winter, which wass associated with stronger trade winds that push warm water into the western Pacific. And why is there La Nina? Because of a natural oscillation in the tropical Pacific.
Enough questions! But perhaps there is one more. Will it snow over the lowlands on Sunday? The latest model runs suggest some light snow is possible (see snowfall prediction for the 24 ending 4 PM Sunday). Temperatures are marginal, but where there is some elevation and greater precipitation rates, snow may reach to near sea level. More on Saturday.
___________________
The Northwest Weather Workshop
And don't forget...if you want to attend the big weather meeting of the year...the Northwest Weather Workshop on March 3-4 in Seattle...you have to register before. The agenda and more information (including how to register) is found here: http://ift.tt/1kGl4aC
from Cliff Mass Weather Blog http://ift.tt/2kT24NL
For temperatures over the same period, Washington and Oregon have been much cooler than normal (particularly east of the Cascade crest), while California close to normal.
So what his interesting north-south pattern and why has it been so persistent?
Well, the proximate cause is easy. There has been a persistent area of low pressure over the eastern Pacific west of northern California to Washington. The following figure shows the anomaly (difference from normal) of the height the 500 hPa pressure surface (around 18,000 ft) for the past 90 days. There is an amazing negative anomaly (purple color) signifying lower than normal heights (or equivalently low pressure).
Storm after storm has brought low heights/pressures along the northern West Coast.
Such a persistent trough or low along the northern West Coast causes the jet stream to be pushed south into California, instead of its normal position coming into the Pacific Northwest (the jet stream, a current of strong winds tends to follow the outer periphery of the trough). Troughs are associated with colder than normal air. So with the jet moving south into California, CA get more precipitation (since the southern of the trough is associated with upward motion), while cold air is found over the Northwest.
But why is the trough found over the northern West Coast? Good question. If you look at the pattern of the height anomalies, you will notice a wave-like pattern, with alternating high and low heights. This pattern is associated with something called Rossby waves in the atmosphere (they are names after a famous meteorologist Carl Gustav Rossby). Think about throwing a rock into a big pond, with waves radiating away from the rock.
So what is the analog for a rock in the atmosphere? What is disturbing the atmosphere causing waves to propagate over the Pacific Ocean and north America?
Lots of thunderstorms over the Maritime Continent- places like Borneo, New Guinea, Indonesia, and the adjacent islands.
Here is a measure of the amount of thunderstorms that we can observe from space--called Outgoing Longwave Radiation (OLR) for the same 90 day period. To be more specific, this shows the anomaly (or difference) from normal. Where values of OLR are low, there are more high clouds from thunderstorms. You can see a big negative anomaly over the Maritime continent and SE Asia.
But why is there a big thunderstorm anomaly with lots of thunderstorms over SE Asia and the Maritime Continent? That is probably due to the La Nina of last winter, which wass associated with stronger trade winds that push warm water into the western Pacific. And why is there La Nina? Because of a natural oscillation in the tropical Pacific.
Enough questions! But perhaps there is one more. Will it snow over the lowlands on Sunday? The latest model runs suggest some light snow is possible (see snowfall prediction for the 24 ending 4 PM Sunday). Temperatures are marginal, but where there is some elevation and greater precipitation rates, snow may reach to near sea level. More on Saturday.
___________________
The Northwest Weather Workshop
And don't forget...if you want to attend the big weather meeting of the year...the Northwest Weather Workshop on March 3-4 in Seattle...you have to register before. The agenda and more information (including how to register) is found here: http://ift.tt/1kGl4aC
from Cliff Mass Weather Blog http://ift.tt/2kT24NL
Why has California Been Wet and Washington State Cool This WInter
It has been a remarkable winter so far, very different in character from the previous winter seasons. During the past 90 days, the southwest US, and particularly California and Nevada, have been MUCH wetter than normal. Some locations have had over 400% of normal precipitation! Western Washington has been a bit drier than normal.
So what his interesting north-south pattern and why has it been so persistent?
Well, the proximate cause is easy. There has been a persistent area of low pressure over the eastern Pacific west of northern California to Washington. The following figure shows the anomaly (difference from normal) of the height the 500 hPa pressure surface (around 18,000 ft) for the past 90 days. There is an amazing negative anomaly (purple color) signifying lower than normal heights (or equivalently low pressure).
Storm after storm has brought low heights/pressures along the northern West Coast.
Such a persistent trough or low along the northern West Coast causes the jet stream to be pushed south into California, instead of its normal position coming into the Pacific Northwest (the jet stream, a current of strong winds tends to follow the outer periphery of the trough). Troughs are associated with colder than normal air. So with the jet moving south into California, CA get more precipitation (since the southern of the trough is associated with upward motion), while cold air is found over the Northwest.
But why is the trough found over the northern West Coast? Good question. If you look at the pattern of the height anomalies, you will notice a wave-like pattern, with alternating high and low heights. This pattern is associated with something called Rossby waves in the atmosphere (they are names after a famous meteorologist Carl Gustav Rossby). Think about throwing a rock into a big pond, with waves radiating away from the rock.
So what is the analog for a rock in the atmosphere? What is disturbing the atmosphere causing waves to propagate over the Pacific Ocean and north America?
Lots of thunderstorms over the Maritime Continent- places like Borneo, New Guinea, Indonesia, and the adjacent islands.
Here is a measure of the amount of thunderstorms that we can observe from space--called Outgoing Longwave Radiation (OLR) for the same 90 day period. To be more specific, this shows the anomaly (or difference) from normal. Where values of OLR are low, there are more high clouds from thunderstorms. You can see a big negative anomaly over the Maritime continent and SE Asia.
Thunderstorm are like rocks to the atmosphere, greatly perturbing the wind, temperature, and humidity fields. That in turn generates atmospheric waves that can cause localized weather anomalies like we have seen on the West Coast.
But why is there a big thunderstorm anomaly with lots of thunderstorms over SE Asia and the Maritime Continent? That is probably due to the La Nina of last winter, which wass associated with stronger trade winds that push warm water into the western Pacific. And why is there La Nina? Because of a natural oscillation in the tropical Pacific.
Enough questions! But perhaps there is one more. Will it snow over the lowlands on Sunday? The latest model runs suggest some light snow is possible (see snowfall prediction for the 24 ending 4 PM Sunday). Temperatures are marginal, but where there is some elevation and greater precipitation rates, snow may reach to near sea level. More on Saturday.
___________________
The Northwest Weather Workshop
And don't forget...if you want to attend the big weather meeting of the year...the Northwest Weather Workshop on March 3-4 in Seattle...you have to register before. The agenda and more information (including how to register) is found here: http://ift.tt/1kGl4aC
from Cliff Mass Weather Blog http://ift.tt/2kT24NL
For temperatures over the same period, Washington and Oregon have been much cooler than normal (particularly east of the Cascade crest), while California close to normal.
So what his interesting north-south pattern and why has it been so persistent?
Well, the proximate cause is easy. There has been a persistent area of low pressure over the eastern Pacific west of northern California to Washington. The following figure shows the anomaly (difference from normal) of the height the 500 hPa pressure surface (around 18,000 ft) for the past 90 days. There is an amazing negative anomaly (purple color) signifying lower than normal heights (or equivalently low pressure).
Storm after storm has brought low heights/pressures along the northern West Coast.
Such a persistent trough or low along the northern West Coast causes the jet stream to be pushed south into California, instead of its normal position coming into the Pacific Northwest (the jet stream, a current of strong winds tends to follow the outer periphery of the trough). Troughs are associated with colder than normal air. So with the jet moving south into California, CA get more precipitation (since the southern of the trough is associated with upward motion), while cold air is found over the Northwest.
But why is the trough found over the northern West Coast? Good question. If you look at the pattern of the height anomalies, you will notice a wave-like pattern, with alternating high and low heights. This pattern is associated with something called Rossby waves in the atmosphere (they are names after a famous meteorologist Carl Gustav Rossby). Think about throwing a rock into a big pond, with waves radiating away from the rock.
So what is the analog for a rock in the atmosphere? What is disturbing the atmosphere causing waves to propagate over the Pacific Ocean and north America?
Lots of thunderstorms over the Maritime Continent- places like Borneo, New Guinea, Indonesia, and the adjacent islands.
Here is a measure of the amount of thunderstorms that we can observe from space--called Outgoing Longwave Radiation (OLR) for the same 90 day period. To be more specific, this shows the anomaly (or difference) from normal. Where values of OLR are low, there are more high clouds from thunderstorms. You can see a big negative anomaly over the Maritime continent and SE Asia.
But why is there a big thunderstorm anomaly with lots of thunderstorms over SE Asia and the Maritime Continent? That is probably due to the La Nina of last winter, which wass associated with stronger trade winds that push warm water into the western Pacific. And why is there La Nina? Because of a natural oscillation in the tropical Pacific.
Enough questions! But perhaps there is one more. Will it snow over the lowlands on Sunday? The latest model runs suggest some light snow is possible (see snowfall prediction for the 24 ending 4 PM Sunday). Temperatures are marginal, but where there is some elevation and greater precipitation rates, snow may reach to near sea level. More on Saturday.
___________________
The Northwest Weather Workshop
And don't forget...if you want to attend the big weather meeting of the year...the Northwest Weather Workshop on March 3-4 in Seattle...you have to register before. The agenda and more information (including how to register) is found here: http://ift.tt/1kGl4aC
from Cliff Mass Weather Blog http://ift.tt/2kT24NL
Wednesday, February 22, 2017
Tuesday, February 21, 2017
How to Create a Winter Sanctuary With “Hygge” — The Danish Concept
Did you know that Denmark is the happiest country in the world? One might as how they do that? How are the constituently the happiest country in all of the world? Of course, there are many factors to this, but one factor my be the concept of “Hygge”.
Hygee (pronounced hue-gah) is a Danish concept and word that means “a feeling or mood that comes from taking genuine pleasure in making ordinary, every day moments more meaningful, beautiful, or special”. You can apply this concept in your very own home, or in other places in your life.
For instance, interior specialists Baytree Interiors help people personalize their homes in order to fit in with this concept. Rustic materials, cozy textures throughout the home, soft furnishings, and a simple, neutral colour scheme keeps the home looking like a soft, winter wonderland. In this way, you can bring the little joys of winter right into your home. By doing that, you can appreciate the little things about winter and the cold (something the people living in Denmark are quite used to), and thus apply Hygge.
Another way to help bring in some winter appreciation into your home is considering the lighting. Using lamps and candles — especially in the evenings — can help bring a beautiful ambiance into the home that you can’t get from most overhead lighting.
On top of bringing this concept into your personal home, can also do this for a wedding! Garden weddings can be great, and if it’s too cold in the inter, you can bring the concept inside. With rustic furniture that brings the aspects of the cozy winter inside to your reception or wedding ceremony. Soft lighting from candles helps, too, bring in the warm atmosphere from the cold. A wedding colour scheme that includes pale colours, or red and green to remind you and your guests about the beautiful world that is right outside the exit doors. With blankets, or cloth gloves for your wedding favors, too. All of these things can help bring in this feeling, and create even a more relaxing, romantic atmosphere.
Hygge is all about using the little things in life to bring more joy into your life and the life of the people around you. What do you think? Do you like the concept of Hygge? Do you plan to try to use it in your own home, or maybe at something like a big wedding? Whatever you do, just remember to invest effort in to what you already have.
from Home Design Ideas | Interior Design Ideas And Architcture http://ift.tt/2lJ7p9P
How to Create a Winter Sanctuary With “Hygge” — The Danish Concept
Did you know that Denmark is the happiest country in the world? One might as how they do that? How are the constituently the happiest country in all of the world? Of course, there are many factors to this, but one factor my be the concept of “Hygge”.
Hygee (pronounced hue-gah) is a Danish concept and word that means “a feeling or mood that comes from taking genuine pleasure in making ordinary, every day moments more meaningful, beautiful, or special”. You can apply this concept in your very own home, or in other places in your life.
For instance, interior specialists Baytree Interiors help people personalize their homes in order to fit in with this concept. Rustic materials, cozy textures throughout the home, soft furnishings, and a simple, neutral colour scheme keeps the home looking like a soft, winter wonderland. In this way, you can bring the little joys of winter right into your home. By doing that, you can appreciate the little things about winter and the cold (something the people living in Denmark are quite used to), and thus apply Hygge.
Another way to help bring in some winter appreciation into your home is considering the lighting. Using lamps and candles — especially in the evenings — can help bring a beautiful ambiance into the home that you can’t get from most overhead lighting.
On top of bringing this concept into your personal home, can also do this for a wedding! Garden weddings can be great, and if it’s too cold in the inter, you can bring the concept inside. With rustic furniture that brings the aspects of the cozy winter inside to your reception or wedding ceremony. Soft lighting from candles helps, too, bring in the warm atmosphere from the cold. A wedding colour scheme that includes pale colours, or red and green to remind you and your guests about the beautiful world that is right outside the exit doors. With blankets, or cloth gloves for your wedding favors, too. All of these things can help bring in this feeling, and create even a more relaxing, romantic atmosphere.
Hygge is all about using the little things in life to bring more joy into your life and the life of the people around you. What do you think? Do you like the concept of Hygge? Do you plan to try to use it in your own home, or maybe at something like a big wedding? Whatever you do, just remember to invest effort in to what you already have.
from Home Design Ideas | Interior Design Ideas And Architcture http://ift.tt/2lJ7p9P
La Nina is Dead. Can El Nino Be Far Behind?
I have sad news for all of you.
La Nina is dead. Done. Finished. Terminated. The final word came out a week ago, provided by the august U.S. Climate Prediction Center (see below).
And it appear that we have a better than even chance of moving back into the El Nino pattern again, a configuration that leads to generally less snow over the Pacific Northwest.
To track the oscillation between La Nina, Neutral conditions, to El Nino and back again, meteorologists follow the sea surface temperatures (SST) in tropical Pacific. As I have noted in past blogs, this variation, also called El Nino Southern Oscillation (ENSO), represents a sloshing of the warm water in tropical Pacific. When the water sloshes towards the west we have El Nino, when it sloshes to the east, La Nina. You can think of the tropical Pacific as a giant bathtub.
To get a handle on what the sloshing is up to, meteorologists follow the SSTs for a few areas in the tropical Pacific (the Nino 4, Nino 3.4, Nino 3 and Nino 1+2 areas). The figure below shows their locations.
The general approach is to track the SST anomalies (differences from normal) for these areas, with Nino 3.4 being probably the most popular. When Nino 3.4 has a warm anomaly greater than +.5C we have El Nino, an anomaly of -.5C or less, La Nina. Near zero, a neutral or La Nada period.
Here are the latest graphs of SST anomalies. Viewing the Nino 3.4 graph, you can see we had a weak La Nina for a while, but now temperatures are slightly on the warm side---we are in neutral conditions and probably have been for a few months.
The main U.S. seasonal model, CFSv2, is run as an ensemble (many forecasts). Although there is a lot of uncertainty, most runs are heading towards El Nino.
Let me stress that ENSO forecasts made mid-winter have been notoriously bad. Skill for the upcoming year increases substantially by summer.
One thing you can be sure about: with our reservoirs in decent shape and a near normal snowpack, the water situation in the NW looks excellent for this summer. And with California soaked this winter and its reservoirs filled, vegetable/fruit prices should be more modest than in past years.
from Cliff Mass Weather Blog http://ift.tt/2kTOzsb
La Nina is dead. Done. Finished. Terminated. The final word came out a week ago, provided by the august U.S. Climate Prediction Center (see below).
And it appear that we have a better than even chance of moving back into the El Nino pattern again, a configuration that leads to generally less snow over the Pacific Northwest.
To track the oscillation between La Nina, Neutral conditions, to El Nino and back again, meteorologists follow the sea surface temperatures (SST) in tropical Pacific. As I have noted in past blogs, this variation, also called El Nino Southern Oscillation (ENSO), represents a sloshing of the warm water in tropical Pacific. When the water sloshes towards the west we have El Nino, when it sloshes to the east, La Nina. You can think of the tropical Pacific as a giant bathtub.
To get a handle on what the sloshing is up to, meteorologists follow the SSTs for a few areas in the tropical Pacific (the Nino 4, Nino 3.4, Nino 3 and Nino 1+2 areas). The figure below shows their locations.
The general approach is to track the SST anomalies (differences from normal) for these areas, with Nino 3.4 being probably the most popular. When Nino 3.4 has a warm anomaly greater than +.5C we have El Nino, an anomaly of -.5C or less, La Nina. Near zero, a neutral or La Nada period.
Here are the latest graphs of SST anomalies. Viewing the Nino 3.4 graph, you can see we had a weak La Nina for a while, but now temperatures are slightly on the warm side---we are in neutral conditions and probably have been for a few months.
What about the future? The Climate Prediction Center provides a nice graphic of past and predicted SST anomalies from many different ENSO forecasting systems (see below). Forget La Nina. Some of the model stay in neutral territory, but half move toward El Nino.
The main U.S. seasonal model, CFSv2, is run as an ensemble (many forecasts). Although there is a lot of uncertainty, most runs are heading towards El Nino.
Digesting all of the this information, the Climate Prediction Center is going for neutral conditions continuing into spring, but equal chances of moving toward El Nino by midsummer, and a tendency towards El Nino by fall.
Let me stress that ENSO forecasts made mid-winter have been notoriously bad. Skill for the upcoming year increases substantially by summer.
One thing you can be sure about: with our reservoirs in decent shape and a near normal snowpack, the water situation in the NW looks excellent for this summer. And with California soaked this winter and its reservoirs filled, vegetable/fruit prices should be more modest than in past years.
from Cliff Mass Weather Blog http://ift.tt/2kTOzsb
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