6 July 2020 Severe Weather Alert: 09/07/2020
The Cape Town Weather Office has issued the following severe weather alerts:
HAZARD: Damaging Winds
Alert Level: Advisory
Valid From (SAST): 09/07/20 00h00
Valid To (SAST): 09/07/20 00h00
Strong north-westerly winds(60-75km/h)are expected over the Western Cape on Thursday (9/7/2020) but strong gale (80-100km/h) wind is expected over the Central Karoo, Little Karoo, Cape Winelands, Overberg and coastal regions between Cape Columbine and Cape Agulhas of the Western Cape spreading to Plettenberg Bay by Thursday evening subside by Friday morning.
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 crosswinds 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.
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 stormwater drains. It can occur with prolonged periods 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 floodwater. 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 / 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 watermark.
If the sea recedes exposing rock and sea bed normally not exposed immediately seeks 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.