The effects of severe weather are felt every year by many South Africans. To obtain critical weather information, the SAWDOS use voluntary weather observers. These volunteers help keep their local communities safe and informed by providing timely and accurate reports of severe weather to the SAWDOS for publication on the Blog. The SAWDOS is a non-profit organization that renders a FREE COMMUNITY-BASED SERVICE.
Pages
- Home
- SAWDOS1 Twitter South Africa Tweets
- SAWDOS2 Twitter World Wide Tweets
- TrafficSA Twitter Updates
- RSOE Emergency and Disaster Information Service
- USGS Earthquake Monitor
- SA Private WX Stations
- Real-Time APRS WX Station Data
- Disclaimer/Indemnity: SAWDOS
- Articles and Photos: SAWDOS
- About: SAWDOS
- South African Disasters
- Mossel Bay WX Stations
- SA Sea Level Synoptic Chart
- SA Weather Webcams
- YO Weather Prediction
- Mossel Bay Mad Scientist Projects
- Weather Forecast for South Africa
Wednesday, 28 November 2012
SA National Severe Weather Warnings: 28 November 2012 04h00 SAST
Current warning: Eastern Cape Province
Updated: 28/11/2012 05:05:07
Validity: 2012-11-28 to 2012-11-28
Type: Watch. Be prepared
Subject: Fire Danger
Detail: A veld fire danger is expected in places in northwest
Current warning: Free State Province
Updated: 28/11/2012 05:05:07
Validity: 2012-11-28 to 2012-11-28
Type: Watch. Be prepared
Subject: Fire Danger
Detail: A veld fire danger is expected in places in east
Current warning: Northern Cape Province
Updated: 28/11/2012 05:05:07
Validity: 2012-11-28 to 2012-11-28
Type: Warning. Take action
Subject: Extremely hot and humid as well as Fire Danger
Detail: Warning: ---------- 1. Extremely hot conditions are expected over the coast and adjacent interior. 2. Extremely uncomfortable, humid conditions are expected over the coast and adjacent interior Watch: ------ 3. A veld fire danger is expected in places in east.
Current warning: Western Cape Province
Updated: 28/11/2012 05:05:07
Validity: 2012-11-28 to 2012-11-28
Type: Warning. Take action
Subject: Extremely hot and humid
Detail: Warning: ----------- 1. Extremely hot conditions are expected over the West coast district. 2. Extremely uncomfortable, humid conditions are expected over the West coast district.
Current warning: All other Provinces
Updated: 28/11/2012 05:05:07
Validity: 2012-11-28 to 2012-11-28
No warnings nor advisories in effect
Subject: No Alerts
Detail: No Alerts
- SAWS
SA Sea Level Synoptic Chart : 28 November 2012
Possible 24 hour rainfall: South Africa
Fires Across Cape York Peninsula
Summer bushfires near densely-populated areas in southern Australia attract the most public attention, but the continent’s largest and most frequent fires actually occur in the spring in the tropical savannas of northern Australia.
On November 25, 2012, the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite captured this natural-color image of wildfires burning on Cape York Peninsula, the northernmost part of Australia. Smoke plumes from multiple fires are visible streaming west; red outlines indicate hot spots where MODIS detected unusually warm surface temperatures associated with fires.
Three main meteorological variables affect fire behavior: atmospheric humidity, air temperature, and wind strength. On Cape York Peninsula, humidity drops and temperatures rise beginning with the arrival of the dry season in March. By the end of November, grasses and woodland trees in the region have reached their most flammable state. In this case, steady winds (about 20 kilometers/12 miles per hour) have helped sustain fires that were likely started by lightning and human activity.
About half of the savanna woodlands on Cape York Peninsula burn either every year or so, typically late in the dry season. Dried grasses, which receive ample sunshine and rain during the wet season, provide the bulk of the fuel. As the dry season progresses, trees also drop loads of leaves and twigs that help fuel fires. Key grasses and trees in the region include Sorghum, Eucalyptus, and Corymbia.
Despite the frequency of the burning, wildfires on Cape York Peninsula are generally less severe than in southern Australia because fungi, bacteria, and other decomposers that thrive in the region continuously break dried grass and leaf litter down. Fewer decomposers live in southern Australia, making it possible for leaf litter and other fuel to build up for decades and prime the landscape for extremely destructive fires.
On November 25, 2012, the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite captured this natural-color image of wildfires burning on Cape York Peninsula, the northernmost part of Australia. Smoke plumes from multiple fires are visible streaming west; red outlines indicate hot spots where MODIS detected unusually warm surface temperatures associated with fires.
Three main meteorological variables affect fire behavior: atmospheric humidity, air temperature, and wind strength. On Cape York Peninsula, humidity drops and temperatures rise beginning with the arrival of the dry season in March. By the end of November, grasses and woodland trees in the region have reached their most flammable state. In this case, steady winds (about 20 kilometers/12 miles per hour) have helped sustain fires that were likely started by lightning and human activity.
About half of the savanna woodlands on Cape York Peninsula burn either every year or so, typically late in the dry season. Dried grasses, which receive ample sunshine and rain during the wet season, provide the bulk of the fuel. As the dry season progresses, trees also drop loads of leaves and twigs that help fuel fires. Key grasses and trees in the region include Sorghum, Eucalyptus, and Corymbia.
Despite the frequency of the burning, wildfires on Cape York Peninsula are generally less severe than in southern Australia because fungi, bacteria, and other decomposers that thrive in the region continuously break dried grass and leaf litter down. Fewer decomposers live in southern Australia, making it possible for leaf litter and other fuel to build up for decades and prime the landscape for extremely destructive fires.
References
- NAFI. (2012, Nov. 27) North Australia fire information map: Cape York. Accessed Nov. 27, 2012.
- NASA. (2012, Nov. 27) Cape York Peninsula fires. Accessed Nov. 27, 2012.
- Queensland Government. (n.d.) Rural fire service. Accessed Nov. 27, 2012.
- Savannah Explorer. (n.d.) Fire in Australia’s tropical savannas. Accessed Nov. 27, 2012.
Further Reading
- CSIRO. (2012, Oct. 26). Bushfire in Australia. Accessed Nov. 27, 2012.
- Crowley, G.M. (2008, Oct. 9). Changing fire management in the pastoral lands of Cape York Peninsula of northeast Australia. Geographical Research.
NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response Team at NASA GSFC. Caption by Adam Voiland.
- Instrument:
- Aqua - MODIS - NASA
Tuesday, 27 November 2012
SA National Severe Weather Warnings: 27 November 2012 16h00 SAST
Current warning: Eastern Cape Province
Updated: 27/11/2012 15:47:31
Validity: 2012-11-28 to 2012-11-28
Type: Watch. Be prepared
Subject: Fire Danger
Detail: A veld fire danger is expected in places in northwestern Eastern Cape.
Current warning: Free State Province
Updated: 27/11/2012 15:47:31
Validity: 2012-11-28 to 2012-11-28
Type: Watch. Be prepared
Subject: Fire Danger
Detail: A veld fire danger is expected in places in eastern Northern Cape.
Current warning: Northern Cape Province
Updated: 27/11/2012 15:47:31
Validity: 2012-11-28 to 2012-11-28
Type: Warning. Take action
Subject: Extremely hot and humid as well as Fire Danger
Detail: 1. Extremely hot conditions are expected over the coast and adjacent interior of Northern Cape. 2. Extremely uncomfortable, humid conditions are expected over the coast and adjacent interior of Northern Cape. WATCHES: -------- 1. A veld fire danger is expected in places in eastern Northern Cape
Current warning: Western Cape Province
Updated: 27/11/2012 15:47:31
Validity: 2012-11-28 to 2012-11-28
Type: Warning. Take action
Subject: Extremely hot and humid
Detail: 1. Extremely hot conditions are expected over the West coast district. 2. Extremely uncomfortable, humid conditions are expected over the West coast district.
Current warning: All other Provinces
Updated: 27/11/2012 04:59:32
Validity: 2012-11-27 to 2012-11-27
No warnings nor advisories in effect
Subject: No Alerts
Detail: No Alerts
- SAWS
SA Weather Observation: South Africa (27 November 2012)
AraDee Aradna Aniroodh - Storm clouds in Durban, light drizzle with patches of sunshine.
Sunninghill_SA - Possible build up of activity to the East of Sunninghill, Johannesburg
Zs-one Tp Jakes - A lovely day in Cape Town. 27 November 2012. Lekker warm. Clear skies.
Francis Proudfoot Lanham - Beautiful cloud picture taken just now in Edenvale
THE MOUTH - Moon rise over the JHB CBD on a lovely summer evening.
Dee de Souza - Durban harbour this morning, 27 November 2012, 11.33am
Nelso Gomes - Early evening sky
SA National Severe Weather Warnings: 27 November 2012 04h00 SAST
Current warning: Northern Cape Province
Updated: 27/11/2012 04:59:32
Validity: 2012-11-27 to 2012-11-27
Type: Warning. Take action
Subject: extremely hot and extremely uncomfortable
Detail: 1. Extremely hot conditions are expected over the coast. 2. Extremely uncomfortable, humid conditions are expected over the coast.
Current warning: Western Cape Province
Updated: 27/11/2012 04:59:32
Validity: 2012-11-27 to 2012-11-27
Type: Warning. Take action
Subject: extremely hot and extremely uncomfortable
Detail: 1. Extremely hot conditions are expected over the West coast district. 2. Extremely uncomfortable, humid conditions are expected over the West coast district.
Current warning: All other Provinces
Updated: 27/11/2012 04:59:32
Validity: 2012-11-27 to 2012-11-27
No warnings nor advisories in effect
Subject: No Alerts
Detail: No Alerts
- SAWS
Possible 24 hour rainfall: South Africa
Dense Fog over the Missouri and Mississippi Rivers
The day before Thanksgiving is one of the busiest travel days of the year in the United States. But on November 21, 2012, weather posed a challenge for people flying in and out of St. Louis, Missouri. It also posed a challenge for drivers making their morning commutes. Thick fog descended on the city overnight on November 20–21, and on the morning of November 21, visibility was as low as one-sixteenth of a mile (0.1 kilometers), according to news reports.
Fog lingered over the region when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image at 10:45 a.m. local time (16:45 UTC) on November 21. Fog filled the Mississippi River Valley as well as the valleys of the Missouri River and many of its tributaries. Fog extended from Jefferson City in the northwest to Cape Girardeau in the southeast. Situated at the confluence of the Missouri and Mississippi Rivers, St. Louis was engulfed by low clouds.
Fog is simply clouds that have formed at ground level. Like all clouds, fog forms when the local air reaches its dew point—the temperature at which water vapor condenses into tiny droplets. In the autumn, the moisture content of the atmosphere remains relatively high, but nights are cool. Overnight, the ground tends to cool faster than the atmosphere, and air in contact with a cooling, sloped surface will slide down and settle in the valley floor. Because autumn brings longer nights, fog has more time to form and is a fairly common occurrence.
Fog lingered over the region when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image at 10:45 a.m. local time (16:45 UTC) on November 21. Fog filled the Mississippi River Valley as well as the valleys of the Missouri River and many of its tributaries. Fog extended from Jefferson City in the northwest to Cape Girardeau in the southeast. Situated at the confluence of the Missouri and Mississippi Rivers, St. Louis was engulfed by low clouds.
Fog is simply clouds that have formed at ground level. Like all clouds, fog forms when the local air reaches its dew point—the temperature at which water vapor condenses into tiny droplets. In the autumn, the moisture content of the atmosphere remains relatively high, but nights are cool. Overnight, the ground tends to cool faster than the atmosphere, and air in contact with a cooling, sloped surface will slide down and settle in the valley floor. Because autumn brings longer nights, fog has more time to form and is a fairly common occurrence.
-
References
- AccuWeather. (2012, October 16) Mountain valley fog: What causes it? Accessed November 26, 2012.
- Blume, B. (2012, November 21) Dense fog settles over St. Louis, cutting visibility to near zero. CBS St. Louis. Accessed November 26, 2012.
- Department of Atmospheric Sciences. Observed dew point temperature. University of Illinois at Urbana-Champaign.
- Hudson, K. (2012, November 21) Fog affecting Lambert flights on busy Thanksgiving travel day.
- KMOV. (2012, November 21) Dense fog blankets the News 4 viewing area. Accessed November 26, 2012.
NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response Team at NASA GSFC. Caption by Michon Scott.
- Instrument:
- Terra - MODIS
Monday, 26 November 2012
SA National Severe Weather Warnings: 26 November 2012 16h00 SAST
Current warning: Eastern Cape Province
Updated: 26/11/2012 15:12:12
Validity: 2012-11-26 to 2012-11-26
Type: Warning. Take action
Subject: Very rough seas
Detail: 1. very rough seas with heights between 4 and 6m are expected between Plettenberg Bay and Port Alfred.
Current warning: Northern Cape Province
Updated: 26/11/2012 15:12:12
Validity: 2012-11-27 to 2012-11-27
Type: Warning. Take action
Subject: extremely hot and extremely uncomfortable
Detail: 1. Extremely hot conditions are expected over the coast. 2. Extremely uncomfortable, humid conditions are expected over the coast.
Current warning: Western Cape Province
Updated: 26/11/2012 15:12:12
Validity: 2012-11-27 to 2012-11-27
Type: Warning. Take action
Subject: extremely hot and extremely uncomfortable
Detail: 1. Extremely hot conditions are expected over the west coast. 2. Extremely uncomfortable, humid conditions are expected over the west coast.
Current warning: All other Provinces
Updated: 26/11/2012 15:12:12
Validity: 2012-11-26 to 2012-11-26
No warnings nor advisories in effect
Subject: No Alerts
Detail: No Alerts
- SAWS
Photos: Weather Observation: South Africa - 26 November 2012
SAsunshineJHB - Beautiful day in Johannesburg
SAsunshineJHB - The skies above Rosebank. Beautiful
Zs-one Tp Jakes - 26 Nov 2012, a beautiful day in Cape Town. Very few clouds and its getting warm!
SA National Severe Weather Warnings: 26 November 2012 04h00 SAST
Current warning: All provinces in South Africa
Updated: 26/11/2012 05:14:35
Validity: 2012-11-26 to 2012-11-26
No warnings nor advisories in effect
Subject: No Alerts
Detail: No Alerts
- SAWS
Possible 24 hour rainfall: South Africa
Cloud Vortices off St. Helena
St. Helena is a small, rugged volcanic island in the southern Atlantic Ocean. At its highest point, Mount Actaeon, the island rises 818 meters (2,684 feet) above sea level—high enough to affect cloud formation. On November 15, 2012, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image of cloud vortices stretching away from the island to the west-northwest.
When moving air masses encounter an obstacle such as a volcanic island, the wind flow is disrupted. Downstream from the obstacle, von Karman vortices form. These double-row vortices alternate their direction and rotation.
Clouds not only make the von Karman vortices visible to satellites sensors, they also make appealing pictures. Satellite sensors have spotted von Karman vortices around the globe, including sightings off of Guadalupe Island, near the coast of Chile, in the Greenland Sea, in the Arctic, even next to a tropical storm.
Located more than 1,800 kilometers (1,100 miles) west of Africa, St. Helena is as remote as it is rugged. The island was uninhabited when the Portuguese first discovered it in 1502, and became famous centuries later as the final home of Napoleon Bonaparte I of France. He was exiled there in 1815 and died on the island in 1821.
When moving air masses encounter an obstacle such as a volcanic island, the wind flow is disrupted. Downstream from the obstacle, von Karman vortices form. These double-row vortices alternate their direction and rotation.
Clouds not only make the von Karman vortices visible to satellites sensors, they also make appealing pictures. Satellite sensors have spotted von Karman vortices around the globe, including sightings off of Guadalupe Island, near the coast of Chile, in the Greenland Sea, in the Arctic, even next to a tropical storm.
Located more than 1,800 kilometers (1,100 miles) west of Africa, St. Helena is as remote as it is rugged. The island was uninhabited when the Portuguese first discovered it in 1502, and became famous centuries later as the final home of Napoleon Bonaparte I of France. He was exiled there in 1815 and died on the island in 1821.
-
References
- Goddard Earth Sciences, Data and Information Services Center. Science Focus: Von Karman Vortices. Accessed November 16, 2012.
- CIA World Factbook. (2012, November 9) Saint Helena, Ascension, and Tristan da Cunha. Accessed November 16, 2012.
NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response Team at NASA GSFC. Caption by Michon Scott.
- Instrument:
- Terra - MODIS - NASA
Sunday, 25 November 2012
SA National Severe Weather Warnings: 25 November 2012 16h00 SAST
Current warning: All provinces in South Africa
Updated: 25/11/2012 15:00:11
Validity: 2012-11-25 to 2012-11-25
No warnings nor advisories in effect
Subject: No Alerts
Detail: No Alerts
- SAWS
SA National Severe Weather Warnings: 25 November 2012 04h00 SAST
Current warning: Eastern Cape Province
Updated: 25/11/2012 05:04:12
Validity: 2012-11-25 to 2012-11-25
Type: Warning. Take action
Subject: Very rough seas
Detail: 1. Very rough seas with wave height between 4 and 6m is expected along the Eastern Cape coast.
Current warning: Kwazulu Natal Province
Updated: 25/11/2012 05:04:12
Validity: 2012-11-25 to 2012-11-25
Type: Warning. Take action
Subject: Very rough seas
Detail: 1. Very rough seas with wave height between 4 and 6m is expected south of Durban.
Current warning: Western Cape Province
Updated: 25/11/2012 05:04:12
Validity: 2012-11-25 to 2012-11-25
Type: Warning. Take action
Subject: Very rough seas
Detail: 1. Very rough seas with wave height between 4 and 6m is expected between Lamberts Bay and Plettenberg Bay.
Current warning: All other Provinces
Updated: 25/11/2012 05:04:12
Validity: 2012-11-25 to 2012-11-25
No warnings nor advisories in effect
Subject: No Alerts
Detail: No Alerts
- SAWS
Possible 24 hour rainfall: South Africa
Important Notice: Restructuring of the SAWDOS Blog
The SAWDIS/SAWDOS was established on the 8 October 2008 and has grown to one of the best and well known Weather and Disaster Information/Observation Services in the World thanks to the many roll players, the public, the media, organizations and SAWDOS Observers. I always stated and will continue to do so, that the success of the SAWDOS is attributed to those who contributed information, data, photos etc.
It has however become necessary to once again make certain drastic/dramatic changes to the SAWDOS blog. We live in a changing world and unfortunately or fortunately this also apply to the SAWDOS. Several reasons necessitate these changes and I am of the opinion that the reasons must be shared with our readers.
1. The blog format is a fairly old concept and is really time consuming to update. I tried to automate the updating of the blog but unfortunately it has it's limitations.
2. It is alleged that according to the terms of the Digital Millennium Copyright Act (DMCA), that certain content in the SAWDOS blog is alleged to infringe upon the copyrights of others. This is a constant issue that prohibits the SAWDOS to keep the public informed of weather and disasters in South Africa as well as World Wide. Several local newspapers and other sources expressed their dissatisfaction with the fact that SAWDOS uplift articles from their newspapers and re-publish them on the SAWDOS Blog.
3. The founder of the SAWDOS recently received an invitation from the private sector as well as government for assistance relating to disaster risk management and the establishment of an early warning system for insurance companies relating to severe weather in South Africa early in the new year. Negotiations is currently underway and a final decision will be taken in this regard before the end of December 2012. If I do accept the invitations I will have less time available to update the blog.
4. The founder of the SAWDOS also received invitations from two overseas countries to assist in the developing of a Disaster Mitigation for Sustainable Livelihoods Program for a poverty stricken country. I have not taken a decision in this regard. If I do accept the invitations I will have less time available to update the blog.
5. Political intolerance also found it's way into the SAWDOS the past few weeks. As many already know I categorically stated that the SAWDOS is a nonprofit organization that provides a free weather and disaster observation service to people in South African and across the globe. The SAWDOS is not affiliated to any political party, organization, group, forum, movement or for that matter to any other weather or disaster organization in South Africa or abroad. The SAWDOS is non biased towards any race, color, gender, sexual orientation, creed, religion, national, ethnic or social origin. Nor do we endorse any political views of any political party, organization, group, forum, movement or for that matter any other weather or disaster organization in South Africa or abroad. I need to keep an watchful eye on what people tweet and write about as you do get those who enjoy political rhetoric.
6. The founder of the SAWDOS is currently busy with several science and technology projects which will benefit those in distress or experiencing an emergency or disaster situation. Hopefully these "inventions" will assist those in desperate need. These projects will hopefully also promote science and technology so desperately needed in South Africa and for that matter in Africa. I need to spend more time on these projects.
7. "Father Time" does not stand still and old age are creeping up on all of us, that's if you are fortunate enough. I spend and average of 6 hours a day updating the SAWDOS Blog. During severe weather and disaster events the hours can increase to up to 14 hours. I am sure that you will agree that sitting in front of a computer for 14 hours is not healthy and advisable.
8. Availability of free weather and disaster information in South Africa from Government or Semi-Government organizations are becoming more difficult by the day. O, yes it is available but at a fairly stiff price tag and even if you pay you not allowed to share the info or images with the general public. I am sure I do not have to mention the names of the organizations as they are well known and many posts can be found on this blog relating to these money making organizations.
In my opinion the above reasons makes it more and more difficult for me to keep the SAWDOS BLOG relevant, informative and of an educational nature. Many of our readers might have noticed that there was a lack and decline of content in the past month or two. If you look at the old SAWDIS blog you will clearly notice the difference. The SAWDIS Blog contained far more content than the current SAWDOS Blog. I believe that the SAWDOS Blog has come to the end of it's life expectancy in it's current format.
This does not mean it is the end of the road for the SAWDOS. By far not. The SAWDOS is still very much alive and active!! Even more so with the current severe weather we are experiencing in South Africa. Statistics has shown that there is an ever increasing amount of people following the SAWDOS Twitter tweets and joining the SAWDOS Facebook Group. Just in the past two months there were and 80% increase in membership which indicates that people do prefer Twitter and Facebook as a means to get the message out relating to severe weather and disasters.
Twitter and Facebook will in future be used as platforms to get the message out to the public relating to severe weather and disasters.
The SAWDOS Blog will only be used for storing and archive purposes of severe weather and disaster incidents. In the mean time and till the end of December 2012 only the following content will be posted on the SAWDOS Blog:
1. SA National Severe Weather Warnings by SAWS
2. SA Weather Satellite Images by Eumetsat and SAT24
3. GFS Medium Range Forecasts of Vertical Velocity and Precipitation by U.S. National Center for Environmental Prediction (NCEP)
4. Possible 24 hour rainfall for South Africa by 1stweather.com
5. Photos: Weather and Disaster Observation - South Africa
6. Cyclone Warnings and Images by JTWC and CIMSS
7. Satellite Observations by NASA
8. SAWDOS Scientific Projects
It has become necessary to once again make certain changes to the SAWDOS Blog. All other content by all other roll players that has no copyright issues will be published on the SAWDOS Facebook Group Pages.
However SAWDOS Twitter and SAWDOS Facebook Group will remain unchanged.
I trust that these changes will not be to disruptive. I am looking forward to a new weather and disaster observation service on Twitter and Facebook that will hopefully be more informative and technologically driven to provide a better service to our readers and observers.
Please feel free to follow SAWDOS on Twitter at: @SAWDOS1 and join the SAWDOS Facebook Group at: http://www.facebook.com/groups/374316165928426/
As we progress I will point out changes and new features to the benefit of all our readers and observers.
J. Terblanche
Founder: SAWDOS
Mossel Bay
25 November 2012
Subscribe to:
Posts (Atom)

































