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What Is ALERT?
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San
Diego County Flood Warning System ALERT systems are used around the
world to provide real-time flood warning to local communities at risk from
flooding threat. ALERT is an acronym that stands for Automatic Local Evaluation in Real-Time. An ALERT
system is characterized by its real-time nature, accomplished by the
instantaneous transmission of weather events primarily by radio transmission,
and to a lesser extent by satellite, telephone, and cell phone transmission.
Changes in rainfall, stream, weather and lake levels throughout San Diego
County are transmitted by radio to mountaintop repeaters, which in turn relay
the transmission to our Weather Center in Kearny Mesa. In Kearny Mesa, the data
are also relayed by internet to the National Weather Service (NWS) in San
Diego. This data is received by ALERT computers which check the data for
validity, check against established warning criteria for that data, update
any displayed maps, then place the data into a
database. If any warning criteria are met, the computers will put out a
visible warning and assemble a text message to warn appropriate emergency
staff. In San
Diego County, a partnership has evolved between the Flood Control District
(FCD), the NWS, and the County Office of Emergency Services (OES). The FCD is
responsible for the maintenance and operation of the ALERT Flood Warning
System. When flooding conditions develop, the FCD evaluates the flooding
potential presented by the ALERT data and advises the NWS and OES on possible
flooding in the County. The NWS will complete the assessment of flooding
potential using their resources and will issue a forecast update, special
weather statement, flash flood watch, or flash flood warning. OES will pass
along the NWS warnings and watches to relevant agencies within San Diego
County and will coordinate Disaster Relief Operations whenever necessary. Because of its nature, the ALERT system can monitor anything that provides a contact closure, a voltage range of 0-5 volts, or a current range of 4-20 mA. This makes it ideal not only to provide real-time flood warning, but can also monitor water resource parameters such as: winds, temperature, humidity, barometric pressure, groundwater levels, soil moisture, fuel moisture, water temperature, water quality, and evaporation. ALERT field transmitters with control capability can also perform physical functions such as activating low water crossing flood warning gates and signals, raising flood control barriers, or setting off warning sirens. |
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