Weather Alert: Severe Weather Alerts – High Seas, Heavy Rain & Flooding and Snow – 18 AUgust 2020
The Cape Town Weather office has issued the following severe weather alerts:
Hazard 1: High Seas
Alert Level: Warning
Valid From (SAST): 18/08/20 01h00
Valid To (SAST): 18/08/20 23h00
High seas with wave heights between 6-7m are expected between Cape Agulhas and Plettenberg Bay today (18/08/2020).
Hazard 2: Heavy rain
Alert Level: Warning
Valid From (SAST): 18/08/20 01h00
Valid To (SAST): 18/08/20 15h00
Heavy rain is expected over the eastern parts of the Garden Route district (W-Cape) today (18/08/2020).
Hazard 3: Flooding
Alert Level: Warning
Valid From (SAST): 18/08/20 01h00
Valid To (SAST): 18/08/20 15h00
Flooding is expected over the eastern parts of the Garden Route district (W-Cape) today (18/08/2020).
Descriptions: Snow
Snow is precipitation in the form of flakes of crystalline water ice that fall from clouds. Since snow is composed of small ice particles, it is a granular material.
Precautions: Snow
If driving decrease your speed and leave yourself plenty of room to stop, you should allow at least three times more space than usual between you and the car in front of you. Brake gently to avoid skidding. If your wheels start to lock up, ease off the brake. Even at temperatures above freezing, if the conditions are wet, you might encounter ice in shady areas or on exposed roadways like bridges. 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.
Description: Storm surges
Generally storm surges are a result of strong winds blowing over a large area called a fetch combined with low pressure systems. Dangerous waves or surges may also be caused by storms and/or tsunami’s resulting in widespread coastal damage and loss of life.
Precautions: Storm surges
All recreational beach activities should be suspended. People with beach side properties should be aware of the possibility of being flooded by a rise in sea level and wave surges that could cause damage to their property.
If possible relocate valuable assets to higher ground and be vigilant especially during high tide. If the surge is associated with a Spring High Tide then significant inundation is possible and one should be aware of the times of occurrence of the High tide.
Listen to the radio or TV for warnings and obey the instructions from disaster management officers.
Description: Storm surges / High Seas
Generally heavy seas or damaging waves are a result of strong winds blowing over a large area called a fetch combined with low pressure systems. Long period swells are often very dangerous to tankers as they may literally snap them in half. Dangerous waves or surges may also be caused by storm surges and tsunami’s resulting in widespread coastal damage and loss of life.
In oceanography, a sea state is the general condition of the free surface on a large body of water—with respect to wind waves and swell—at a certain location and moment. A sea state is characterized by statistics, including the wave height, period, and power spectrum. The sea state varies with time, as the wind conditions or swell conditions change.
Precautions: Storm surges / High Seas
Ships should “idle” into the swell and wind so that the bow of the ship always faces the oncoming swell. If in a small sailing vessel reduce the sail area and steer into the oncoming swell. If along the shore-line stay well back from the highest high water mark as Secure all hatches, doors, windows and ports. Secure all loose items in the interior.
Pump the bilge’s dry and keep pumping them dry at regular intervals. Stow away all loose gear and lash down any large items that cannot be stowed. Break out your life preservers and inform your crew that everyone will be putting them on well in advance of their necessity.
Break out emergency gear like flares and first aid kit, sea anchor, safety harnesses, etc.
Check your position and update your course as plotted on your chart. Prepare alternative routes to more protected areas. If you think you will be in for relatively long haul prepare some hot soup, coffee or stew freak waves may run up beyond the normal high water mark.
If the sea recedes exposing rock and sea bed normally not exposed immediately seek higher ground at least 50m above your current position. Do not try swimming or fishing or other marine recreation during these events. Only extremely experienced surfers will temp their fate under these conditions.
Listen to the radio or TV for warnings and obey the instructions from disaster management officers.
Report any severe weather related incidents to the Garden Route District Disaster Management Centre at 044-805 5071.
