Closing of Mossel Bay Weather Observation Blog (14 May 2015)

Need I say anything?  I have decided to close this blog with immediate effect.  For several weeks I have been struggling to update this blog via my ADSL Internet subscription.  My ADSL line has been so sporadic that it is not worthwhile to continue this blog.  The ADSL line would just die at any time and then come back a day or two later.  No use in contacting Telkom as we all know by now that it takes hours to get a service from their call centre.

Many of our readers should by now have noticed that very little real time weather observation posts were posted to the Blog.  Only a few weather prediction posts were daily added. Weather is a real time "product".  No use to try and update a blog after severe weather has already occurred.    I have therefor decided that I cannot render a competent weather observation service due to Telkom ADSL downtime and Eskom power issues.  I looked at several other options but due to the lack of funding and high costs it is not worth while to go the more expensive route seeing that I personally bear all the costs to upkeep this Blog.

It is my belief that if you render a service to a community then it must be done properly and effectively.  You cannot render a "half-baked" service especially when it comes to severe weather where lives might be in danger.  I am sure many will understand that either you run a good service or no service at all, there is no in between service.

I would like to thank all those roll players who through the years allowed me to publish many a article, prediction, weather forecast etc.  Your inputs are highly appreciated.

Finally: To all our readers:  "I am sure that you will find other more useful weather sites to browse. Herewith a few sites that might come in handy."

http://oiswww.eumetsat.org/IPPS/html/MSG/RGB/AIRMASS/index.htm
http://earthobservatory.nasa.gov/
http://www.1stweather.com/metrocast/george/index.shtml
http://www.weathersa.co.za/home/specialised
http://www.weather-forecast.com/locations/Mossel-Bay/forecasts/latest#forecast-part-0

PLEASE NOTE:  I will still run the MSBWXB Twitter account where I will post real time Weather and Disaster related observations, information and reports for the Southern Cape and Little Karoo via my I-Phone.

Regards

Johan Terblanche
Founder: MSBWX Blog, SAWDOS and SAWDIS Blogs
Mossel Bay - South Africa
12 May 2015

This MMS was sent by MTN:

ADSL once again down this morning in Heiderand, Mossel Bay. Limited weather updates as a result.

#Calbuco Ash on the Move

In late April 2015, Calbuco volcano in southern Chile spewed at least 210 million cubic meters (7,420 million cubic feet) of ash and rock during two explosive eruptions. A third eruption, reported to have occurred on April 30, added to the volume of material that already blanketed the landscape.

A significant amount of Calbuco’s ejecta came to rest in neighboring Argentina. But some of that material didn’t stay put for long. On May 3, 2015, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired the above image of ash resuspended in the atmosphere—that is, it was picked up by low-level winds like debris in a dust storm. Calbuco (not pictured) is located about 100 kilometers (60 miles) southwest from the lower-left corner of this image.

The resuspension of volcanic ash is not a new phenomenon. For example, satellites have observed wind-blown ash during the 2010 eruption of Eyjafjallajökull volcano in Iceland, and also from old, loose volcanic deposits from past eruptions in Alaska. Resuspended airborne ash, while not fresh from its volcanic source, can still pose a hazard to aircraft by clogging up engines.

Other ejecta from Calbuco moved north toward Villarrica—another volcano in Chile that has seen renewed activity in 2015. On April 27, 2015, the Operational Land Imager (OLI) on Landsat 8 acquired the image below, which shows a small steam or ash plume rising from Villarrica. But the brown, airborne material surrounding the volcano, and presumably some of the brown material on its flanks, is from Calbuco, located about 220 kilometers (140 miles) to the south.

• References and Related Reading

• BBC News (2015, April 24) Calbuco volcano blankets towns in Chile with ash. Accessed May 7, 2015.
• NASA Earth Observatory (2015, March 12) Eruption of Villarrica Volcano.
• NASA Earth Observatory Eruption of Eyjafjallajökull Volcano, Iceland.
• NASA Earth Observatory Villarrica Volcano Awakens.
• NASA Earth Observatory (2003, September 23) Volcanic Ash Over Kodiak Island, Alaska.
• WIRED (2015, April 30) Third Explosive Eruption at Chile’s Calbuco. Accessed May 7, 2015.

NASA image courtesy Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC. Landsat 8 image by Jesse Allen, using Landsat data from the U.S. Geological Survey. Caption by Kathryn Hansen.

Instrument(s): 

Aqua - MODIS

Landsat 8 - OLI

#Weather and #Disaster #Observations Western Cape : 10 May 2015 04h00 SAST - MSBWXB

SEVERE WEATHER ALERTS:
 
WARNINGS: -----Nil

WATCHES: ------Nil

SPECIAL WEATHER ADVISORIES: -------Nil

MOSSEL BAY REAL TIME WEATHER OBSERVATION:  

06h00 -  8/8 Cloud.  No Wind.  12 Deg/C. Light drizzle at times.

WEATHER FORECAST: WESTERN CAPE: 

Cloudy along the south coast at first, otherwise partly cloudy and cool but warm over the western interior where it will be fine. The wind along the coast will be moderate to fresh easterly to south - easterly becoming strong in places along south - western coasts. The expected UVB sunburn index:Moderate

DISASTER OBSERVATION: WESTERN CAPE: Nil

For real live updates follow @MSBWXB on Twitter. 

- MSBWX + SAWS

1 – 3 Day #WeatherForecast Summary: #SouthernCape / #GardenRoute Area - Weather-Forecast

Mossel Bay 1 – 3 Day Weather Forecast Summary:  Some drizzle, heaviest during Sun morning. Warm (max 22°C on Tue afternoon, min 15°C on Mon morning). Wind will be generally light.
  
George 1 – 3 Day Weather Forecast Summary: Some drizzle, heaviest during Sun morning. Warm (max 22°C on Tue afternoon, min 15°C on Mon morning). Wind will be generally light.

Knysna 1 – 3 Day Weather Forecast Summary:  Mostly dry. Warm (max 21°C on Tue afternoon, min 16°C on Mon morning). Wind will be generally light.

Plettenberg Bay 1 – 3 Day Weather Forecast Summary: Mostly dry. Warm (max 21°C on Tue afternoon, min 16°C on Mon morning). Wind will be generally light.

Oudtshoorn 1 – 3 Day Weather Forecast Summary:   Mostly dry. Warm (max 23°C on Tue afternoon, min 15°C on Sun morning). Wind will be generally light.

Riversdale 1 – 3 Day Weather Forecast Summary: Some drizzle, heaviest during Sun morning. Warm (max 25°C on Tue afternoon, min 15°C on Sun night). Wind will be generally light.

- Weather Forecast.com

#WeatherSatellite Image South Africa: 10 May 2015 05h00 SAST - SAT24 -Eumetsat

Image: SAT24 (Click on image for larger view.)

Latest Sea Level #SynopticChart South Africa: 9 May 2015 18:00 - SAWS

Image: SAWS (Click on image for larger view.)

Possible 24 Hour #Rainfall #Prediction South Africa - 1stweather

Image: 1stweather (Click on image for larger view.)

This MMS was sent by MTN:

ADSL line down this morning in Heiderand, Mossel Bay. This blog will not be updated today.

Cloudy Earth - #Africa

Decades of satellite observations and astronaut photographs show that clouds dominate space-based views of Earth. One study based on nearly a decade of satellite data estimated that about 67 percent of Earth’s surface is typically covered by clouds. This is especially the case over the oceans, where other research shows less than 10 percent of the sky is completely clear of clouds at any one time. Over land, 30 percent of skies are completely cloud free. 

 

Earth’s cloudy nature is unmistakable in this global cloud fraction map, based on data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite. While MODIS collects enough data to make a new global map of cloudiness every day, this version of the map shows an average of all of the satellite’s cloud observations between July 2002 and April 2015. Colors range from dark blue (no clouds) to light blue (some clouds) to white (frequent clouds).

There are three broad bands where Earth’s skies are most likely to be cloudy: a narrow strip near the equator and two wider strips in the mid-latitudes. The band near the equator is a function of the large scale circulation patterns—or Hadley cells—present in the tropics. Hadley cells are defined by cool air sinking near the 30 degree latitude line north and south of the equator and warm air rising near the equator where winds from separate Hadley cells converge. (The diagram here illustrates where Hadley cells are located and how they behave.) As warm, moist air converges at lower altitudes near the equator, it rises and cools and therefore can hold less moisture. This causes water vapor to condense into cloud particles and produces a dependable band of thunderstorms in an area known as the Inter Tropical Convergence Zone (ITCZ).

Clouds also tend to form in abundance in the middle latitudes 60 degrees north and south of the equator. This is where the edges of polar and mid-latitude (or Ferrel) circulation cells collide and push air upward, fueling the formation of the large-scale frontal systems that dominate weather patterns in the mid-latitudes. While clouds tend to form where air rises as part of atmospheric circulation patterns, descending air inhibits cloud formation. Since air descends between about 15 and 30 degrees north and south of the equator, clouds are rare and deserts are common at this latitude.

Ocean currents govern the second pattern visible in the cloudiness map: the tendency for clouds to form off the west coasts of continents. This pattern is particularly clear off of South America, Africa, and North America. It occurs because the surface water of oceans gets pushed west away from the western edge of continents because of the direction Earth spins on its axis.

In a process called upwelling, cooler water from deep in the ocean rises to replace the surface water. Upwelling creates a layer of cool water at the surface, which chills the air immediately above the water. As this moist, marine air cools, water vapor condenses into water droplets, and low clouds form. These lumpy, sheet-like clouds are called marine stratocumulus, the most common cloud type in the world by area. Stratocumulus clouds typically cover about one fifth of Earth’s surface.

In some of the less cloudy parts of the world, the influence of other physical processes are visible. For instance, the shape of the landscape can influence where clouds form. Mountain ranges force air currents upward, so rains tend to form on the windward (wind-facing) slopes of the mountain ranges. By the time the air has moved over the top of a range, there is little moisture left. This produces deserts on the lee side of mountains. Examples of deserts caused by rain shadows that are visible in the map above are the Tibetan Plateau (north of the Himalayan Mountains) and Death Valley (east of the Sierra Nevada Range in California). A rain shadow caused by the Andes Mountains contributes to the dryness of the coastal Atacama Desert in South America as well, but several other factors relating to ocean currents and circulation patterns are important.
Note because the map is simply an average of all of the available cloud observations from Aqua, it does not illustrate daily or seasonal variations in the distribution of clouds. Nor does the map offer insight into the altitude of clouds or the presence or absence of multiple layers of clouds (though such datasets are available from MODIS and other NASA sensors). Instead it simply offers a top-down view that shows where MODIS sees clouds versus clear sky.

Since the reflectivity of the underlying surface can affect how sensitive the MODIS is to clouds, slightly different techniques are used to detect clouds over the ocean, coasts, deserts, and vegetated land surfaces. This can affect cloud detection accuracy in different environments. For instance, the MODIS is better at detecting clouds over the dark surfaces of oceans and forests, than the bright surfaces of ice. Likewise thin cirrus clouds are more difficult for the sensor to detect than optically thick cumulus clouds.

• References

• King et al, (2012, April 30) Spatial and Temporal Distribution of Clouds Observed by MODIS Onboard the Terra and Aqua Satellites. IEEE Transactions on Geoscience and Remote Sensing.
• NASA Earth Observations Cloud Fraction. Accessed May 7, 2015.
• NCAR/UCAR Climate Data Guide Cloud Observations from MODIS. Accessed May 7, 2015.
• Wood, R. (2012, August) Stratocumulus Clouds. Monthly Weather Review, 140 (8) 2373-2433.
• University Corporation for Atmospheric Research Clouds and Cloud Formation. Accessed May 7, 2015.

NASA Earth Observatory images by Jesse Allen and Kevin Ward, using data provided by the MODIS Atmosphere Science Team, NASA Goddard Space Flight Center. Caption by Adam Voiland, with information from Steve Platnick and Tom Arnold.

Instrument(s): 

Aqua - MODIS

#Weather and #Disaster #Observations Western Cape : 8 May 2015 04h00 SAST - MSBWXB

SEVERE WEATHER ALERTS:
 
WARNINGS: Extremely high fire danger conditions are expected in places over the Central Karoo.

WATCHES: ------Nil

SPECIAL WEATHER ADVISORIES: -------Nil

MOSSEL BAY REAL TIME WEATHER OBSERVATION:  

06h00 -  4/8 Cloud.  No Wind.  13 Deg/C. No Rain.

WEATHER FORECAST: WESTERN CAPE: 

Evening fog along the west coast, otherwise fine and warm but cool along the south west coast. The wind along the coast will be Moderate to fresh east to south easterly. The expected UVB sunburn index: Moderate

DISASTER OBSERVATION: WESTERN CAPE: Nil

For real live updates follow @MSBWXB on Twitter. 

- MSBWX + SAWS

1 – 3 Day #WeatherForecast Summary: #SouthernCape / #GardenRoute Area - Weather-Forecast

Mossel Bay 1 – 3 Day Weather Forecast Summary:  Mostly dry. Warm (max 26°C on Fri afternoon, min 16°C on Sat night). Wind will be generally light.
  
George 1 – 3 Day Weather Forecast Summary: Mostly dry. Warm (max 26°C on Fri afternoon, min 16°C on Sat night). Wind will be generally light.

Knysna 1 – 3 Day Weather Forecast Summary:  Mostly dry. Warm (max 25°C on Fri night, min 16°C on Sat night). Wind will be generally light.

Plettenberg Bay 1 – 3 Day Weather Forecast Summary: Mostly dry. Warm (max 25°C on Fri night, min 16°C on Sat night). Wind will be generally light.

Oudtshoorn 1 – 3 Day Weather Forecast Summary:   Mostly dry. Warm (max 27°C on Fri afternoon, min 15°C on Sat night). Wind will be generally light.

Riversdale 1 – 3 Day Weather Forecast Summary: Mostly dry. Warm (max 28°C on Fri afternoon, min 15°C on Sun morning). Wind will be generally light.

- Weather Forecast.com

#WeatherSatellite Image South Africa: 8 May 2015 05h00 SAST -Eumetsat

Image: Eumetsat (Click on image for larger view.)

Latest Sea Level #SynopticChart South Africa: 7 May 2015 18:00 - SAWS

Image: SAWS (Click on image for larger view.)

Possible 24 Hour #Rainfall #Prediction South Africa - 1stweather

Image: 1stweather (Click on image for larger view.)

Mapping Forest Loss with Landsat

With at least one image of every location on Earth per season for 43 years, the Landsat data archive contains more than 50 trillion pixels. So how could you put all of that imagery to use in discovering and monitoring subtle changes on Earth? One answer lies in the clouds—cloud computing, that is.

Since the 1990s, University of Maryland geographers and remote sensing specialists Matthew Hansen and Sam Goward have been mapping changes in Earth’s land cover. “We wanted to know the impact of disturbance—harvesting, thinning, fires, storms—things that lead to changes in forests,” said Goward. “Every time you disturb a forest, it restarts the growth cycle, and when you do that, you impact the carbon cycle. Very few forests make it through a full growth cycle because of disturbances, but no one knows the patterns or how they impact the carbon cycle.”

For years, Goward and Hansen worked with low-resolution data, but disturbance happens on a small scale that demands something like the 30-meter resolution of Landsat satellites. The trouble was, researchers had to pay for every Landsat scene, and it was simply too cost-prohibitive to consider a global map. “We did the science we could afford,” Goward said, “not the science we wanted to do.”

Then in 2008, the game changed. Landsat data was made freely available on the World Wide Web. “We then knew we could make a global map,” Hansen said, “but we didn’t have the computing power yet.” While attending an international meeting about deforestation and forest disturbance, he was introduced to Rebecca Moore, a computer scientist and mapping researcher at Google.

Hansen saw an opportunity. “Their computing expertise fit perfectly with our geographic knowledge. So we ported our code for mapping forests to the Google system.”

In just a few days, Google applied the University of Maryland analysis code to 700,000 Landsat scenes, discarding cloudy pixels and keeping clear pixels. They reviewed the remaining sequence of pixels and assigned a flag to each—was it forested or not? The analysis noted the date that forests were cleared or the date when they had grown-in enough to be counted as forest again. The entire process took one million hours on 10,000 central processing units. Moore noted: “The analysis would have taken 15 years on a single computer.”

Above you will find a small sample of that forest-mapping effort. The maps show forest changes near the Congo River in central Africa as observed by Landsat between 2000–2013. Different colors represent the years in which forest parcels changed; in most cases, the change was deforestation.

The maps by Hansen and colleagues agree with other research on deforestation that says anywhere from 53 to 72 Teragrams of stored carbon (mostly trees) were removed from the Democratic Republic of the Congo (DRC) from 2000–2010). Most of the forest losses were due to cut-and-burn agriculture where small plots of land were cleared for subsistence farming or for the use of wood for fuel.

“The patterns of deforestation are clustered around areas of high human population density, which in the DRC tends to be along the major navigable waterways linking people and resources to the capital, Kinshasa,” said Glenn Bush, a researcher at the Woods Hole Research Center. “The pattern of deforestation clearly outlines the main body and tributaries of the Congo river.”
Developing countries like the DRC typically do not have current national forest inventories, if they have any at all. Maps like the Hansen-led effort provide a global standard for mapping, while also filling a void for nations and institutions.

“In a world of scarce resources, there are distinct tradeoffs in costs and benefits of land use, and whether to conserve or convert forest to cropland,” Bush said. “Map-based images are perhaps one of the most succinct means of helping policymakers digest complex ideas of social and economically driven environmental change.”

Armed with their data-rich maps, Hansen and colleagues would like to someday create a global forest loss alert system. The team is also working to develop tools to distinguish the causes of forest change—sich as fire, mechanical removal, disease, storms—from afar.

“We have a globally consistent, locally relevant map product that can be used in a variety of applications: estimating emissions from deforestation, modeling biodiversity, assessing protected areas, and studying forest and human health,” Hansen said. “We plan to move our record forward and backward where Landsat has a sufficiently rich archive of data.”

To learn more about forest mapping and other uses of the massive Landsat archive, read our latest feature: Big Data Helps Scientists Dig Deeper.

• References

• Hansen, M. et al. (2013) High-Resolution Global Maps of 21st-Century Forest Cover Change. Science, 342 (6160) 850–853.
• NASA Earth Observatory (2015, March 26) Big Data Helps Scientists Dig Deeper.
• NASA Earth Observatory (2013, November 16) New Map Yields Better View of Forest Changes.
• NASA Earth Observatory (2012, January 9) Seeing Forests for the Trees and Carbon.
• Tyukavina, A. et al. (2013) National-scale estimation of gross forest aboveground carbon loss: a case study of the Democratic Republic of the Congo. Environmental Research Letters, 8 (4) 044039.
NASA Earth Observatory maps by Joshua Stevens using global forest change data from Hansen et al./UMD. Caption by Mike Carlowicz and Holli Riebeek.

Instrument(s): 

Model

Landsat 8 - OLI

#Weather and #Disaster #Observations Western Cape : 7 May 2015 04h00 SAST - MSBWXB

SEVERE WEATHER ALERTS:
 
WARNINGS: -----Nil

WATCHES: ------Nil

SPECIAL WEATHER ADVISORIES: -------Nil

MOSSEL BAY REAL TIME WEATHER OBSERVATION:  

06h00 -  Clear Skies.  No Wind.  11 Deg/C. No Rain.

WEATHER FORECAST: WESTERN CAPE: 

Partly cloudy along the south coast at first otherwise fine wa rm but cool along the coast. The wind along the coast will be moderate to fresh east to south - easterly The expected UVB sunburn index: Moderate

DISASTER OBSERVATION: WESTERN CAPE: Nil

For real live updates follow @MSBWXB on Twitter. 

- MSBWX + SAWS

1 – 3 Day #WeatherForecast Summary: #SouthernCape / #GardenRoute Area - Weather-Forecast

Mossel Bay 1 – 3 Day Weather Forecast Summary:  Mostly dry. Warm (max 24°C on Fri afternoon, min 14°C on Thu morning). Wind will be generally light.
  
George 1 – 3 Day Weather Forecast Summary: Mostly dry. Warm (max 24°C on Fri afternoon, min 14°C on Thu morning). Wind will be generally light

Knysna 1 – 3 Day Weather Forecast Summary:  Mostly dry. Warm (max 23°C on Fri morning, min 15°C on Thu morning). Mainly fresh winds.

Plettenberg Bay 1 – 3 Day Weather Forecast Summary: Mostly dry. Warm (max 23°C on Fri morning, min 15°C on Thu morning). Mainly fresh winds.

Oudtshoorn 1 – 3 Day Weather Forecast Summary:   Mostly dry. Warm (max 27°C on Fri afternoon, min 13°C on Thu morning). Wind will be generally light.

Riversdale 1 – 3 Day Weather Forecast Summary: Mostly dry. Warm (max 27°C on Fri afternoon, min 12°C on Thu morning). Wind will be generally light.

- Weather Forecast.com

#WeatherSatellite Image South Africa: 7 May 2015 05h00 SAST -Eumetsat

Image: Eumetsat (Click on image for larger view.)

Latest Sea Level #SynopticChart South Africa: 6 May 2015 18:00 - SAWS

Image: SAWS (Click on image for larger view.)