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Author: Marlene Nqumse

Severe Weather Alert

A Severe Weather Alert was issued by the Cape Town Weather Office as follows:

Hazard: Heavy Rain
Alert Level: Advisory
Valid From (SAST): 10/03/19 – 00h00
Valid To (SAST): 11/03/19 – 00h00

An intense cut-off low is expected to affect the Western Cape on Sunday into Monday. The public is advised that heavy rain and flooding is expected over the Garden Route, Overberg District and Breede River Valley.

Hazard: Flooding
Alert Level: Advisory
Valid From (SAST): 10/03/19 – 00h00
Valid To (SAST): 11/03/19 – 00h00

An intense cut-off low is expected to affect the Western Cape on Sunday into Monday. The public is advised that heavy rain and flooding is expected over the Garden Route, Overberg District and Breede River Valley.

Hazard: Damaging Winds
Alert Level: Advisory
Valid From (SAST): 10/03/19 – 00h00
Valid To (SAST): 11/03/19 – 00h00

An intense cut-off low is expected to affect the Western Cape on Sunday into Monday. Strong to gale force winds are also expected along the south and south-western coastal areas on Sunday into Monday.

Description: Strong damaging winds

Strong damaging winds often occur along coastal regions, but also often occur during thunderstorm activity. These winds are sudden and can cause much damage.

Precautions:  Strong damaging winds

Stay indoors where possible away from the windows that open towards the severe winds. Be aware of the following: – sudden cross winds if traveling especially between buildings, fallen trees or power lines and flying debris.
Small boats must stay away from the open sea and seek the shelter of a harbour, river estuary or protected bay.
Parked aircraft should be pointed into the direction of the wind and secured Listen to the radio or TV for warnings and obey the instructions from disaster management officers.

Description: Flooding / Heavy Rain

Flooding occurs when water overflows its normal channels such as streams and storm water drains. It can occur with prolonged period of rain, with continuous heavy falls or in the form of flash floods which are usually associated with severe thunderstorms. Heavy rain may also result in river flooding causing damage downstream to areas that may receive no rainfall at all during the flooding event.

Precautions: Flooding / Heavy Rain

If possible stay indoors and off the roads, avoid crossing rivers and swollen streams where water is above your ankles. If trapped in flooding in a vehicle, abandon it and climb to higher ground. In buildings, move valuables to a safe place above the expected flood level. Switch off electricity at the supply point to the building. In rural areas protect/relocate animals to a safe place on higher ground. Abandon your home immediately if evacuation is recommended, before access is cut off by flood water.  NEVER drive on a road covered by water. You do not know how deep it is or if the road has been washed away. If the vehicle stalls, leave it immediately and seek higher ground. Be especially cautious at night when it’s harder to recognize flood dangers. Listen to the radio or TV for warnings and obey the instructions from disaster management officers.

Upwelling events and fish wash outs explained

The beach is constantly changing, every day will be different.  Sometimes the beach seems empty with very little lying along the high water mark but generally there will be bits of driftwood, soft sponges or hard coral, redbait polyps, shark egg cases and of course bits and pieces of shell. But every now and again something unusual happens, either a rare find or sometimes lots and lots of things wash out at the same time.

Mass washout events of invertebrates and fish species occur intermittently both across our beaches and over time. Until fairly recently these events may have gone relatively unnoticed. However, today an unusual event is quickly advertised through facebook and other online media.

The most recent event in the Garden Route included the washout of relatively high numbers of fish.

Two days prior to wash out we experienced strong and sustained easterly winds.  Driving along the coastline this wind starts to cause the inshore surface waters to move away from the coastline which in turn starts to pull up colder deeper water to the surface.  The easterly winds essentially drive a very large and effective water pump. If the water temperature drops quickly, fish are unable to adapt and are stunned by the cold water. Stunned and unable to swim they then wash ashore.

Although a natural event which provides plenty of easy food for many seabirds and beach scavengers, satellite derived wind data shows that since the early 1990’s the intensity and variability of upwelling along the south coast has increased with potential implications for marine life.

Changes in wind patterns and water temperature have the potential to impact the productivity and species composition of plankton which in turn can influence the abundance of small pelagic fish (e.g. sardines, anchovies) with consequences for larger predators (both fish and bird). In addition an increase in upwelling will increase the offshore movement of surface waters and along with it fish larvae drifting southwards from the more easterly spawning grounds may well be lost.  Ultimately the consequences of increased upwelling are likely to be complex and variable.

During the February upwelling a number of species washed up along the coastline but our surveys of the event indicated that the majority of the fish impacted were juvenile red tjor tjor, santer and maasbanker. Of these santer are an important species within the ski-boat linefishery and we will have to wait and see if this upwelling event will have impacted catch rates in 3 to 4 years when these fish would have been large enough to catch.

Article written by SANParks marine ecologist, Kyle Smith

Severe Weather Alert

A Severe Weather Alert was issued by the Cape Town Weather Office as follows:

Hazard: Veld Fire Conditions
Alert Level: Warning
Valid From (SAST): 06/03/19 – 10h00
Valid To (SAST): 06/03/19 – 18h00

WARNING:  Expected in places over the Central Karoo and Little Karoo (Western Cape) tomorrow (Wednesday).

Description: Dangerous veld/bush fire conditions

Whenever there are prolonged periods of little and no rain coupled with warm dry winds, veld or bush fires can easily be sparked and will spread rapidly in strong winds.

Precautions: Dangerous veld/bush fire conditions

Do not make fires in the open and/or leave fires unattended. Do not throw cigarette butts out of cars or in the open veld.  Do not throw bottles in the veld as they can magnify the sun’s rays and start fires. Prepare and maintain fire breaks in controlled manner. In the case of a large fire, report it immediately and move away from the area to let the professionals deal with it. Never throw water onto a fire started by an electrical fault or fires started by oil or paraffin lamps. In this case sand or a blanket should be used to smother the fire. Listen to the radio or TV for warnings and obey the instructions from disaster management officers.