PDC Weekly Global Flood Survey: February 9, 2012

Figure 1. PDC Global Hazards Atlas displaying 7 day precipitation accumulation and PDC Integrated Active Hazards.

According to the February 9, 2012 NOAA prediction, the current La Nina episode has peaked, and the oceanic and atmospheric patterns now reflect weak-to-moderate strength. A transition from the recent mature La Nina towards neutral conditions will occur during the March through May 2012 period.  ENSO (EL Nino Southern Oscillation) neutral conditions refer to those periods when neither El Nino nor La Nina is present. These periods often coincide with the transition between the two events. During ENSO-neutral periods the ocean temperatures, tropical rainfall patterns, and atmospheric winds over the equatorial Pacific Ocean are near the long-term average.

During La Nina episodes rainfall is often enhanced across the western Pacific, Indonesia and the Philippines and is nearly absent across the eastern equatorial Pacific. Elsewhere, wetter than normal conditions tend to be observed during December-February over northern South America and southern Africa, and during June-August over southeastern Australia. Drier than normal conditions are generally observed along coastal Ecuador, northwestern Peru and equatorial Africa during December, January and February, and over southern Brazil and central Argentina during June, July, and August. As we move into the upcoming neutral conditions, precipitation around the globe will likely tend back towards the average in general. This Map shows typical conditions during La Nina in February.

There are several areas around the globe that have experienced flooding events during the past week, a few of which include parts of Australia, Fiji (See Figure 1), and Mozambique (See Figure 4) .

Precipitation & Flooding: Pacific

Figure 2. PDC Global Hazards Atlas focused on the Pacific and displaying 7 day precipitation accumulation and PDC Integrated Active Hazards.

As was the case last week, and as is often the case during a typical La Nina period, we see a fairly extensive swath of precipitation extending from the southwest to the northeast across the northern latitudes of the Pacific. (see Figure 2)  The bulk of this rainfall runs along the main storm track of the mid-latitudes, generally under the polar jet stream between 30 and 50 degrees north latitude. The Hawaiian Islands remained south of this rainfall, although a precipitation-bearing cold front did bring some slight relief from the very dry conditions that have prevailed much of the 2012 winter.

In the southern Pacific, there was a much thinner swath of rainfall that moved in a west to east direction offshore from generally around the Philippine Islands. This precipitation was associated with the inter-tropical convergence zone, where the northeast and southeast trades meet; near, or slightly to the north of the equator. This area was well south in latitude from the Hawaiian Islands…extending to near Columbia in South America.

A third, and by far the heaviest swath of precipitation in the Pacific, extended from the Bismarck Sea into the Solomon Sea and Solomon Islands, then southeast into Vanuatu and Fiji.  This swath of precipitation brought substantial rainfall to American Samoa, Niue, Tonga and the Pitcairn Islands as it progressed towards southern South America. An active tropical cyclone (Typhoon Jasmine – 10P ) near New Caledonia added to the significant precipitation in this area.

Flooding in Fiji and Vanuatu: According to Reliefweb, the US Government is supporting Fiji Relief Efforts. The U.S. is assisting the people of Fiji by responding to the recently declared state of emergency in the western parts of the main island, Viti Levu, caused by the severe flooding of homes, towns and villages. Vanuatu also experienced flooding when tropical cyclone 10P (Jasmine) moved by just to the south of the island group bringing heavy rainfall.

 Precipitation & Flooding: Americas

Figure 3. PDC Global Hazards Atlas displaying 7 day precipitation accumulation and PDC Integrated Active Hazards.

Taking a look at North America (see Figure 3) a wide gap of generally dry conditions is evident from the west coast across the Rocky Mountains. Moderate to heavy rainfall fell over the northern part of Central America, the western Gulf of Mexico and across the central United States. The better part of this rainfall missed the exceedingly dry areas of Texas.  The eastern United States missed the bulk of this rainfall, although southern Florida did have light to moderately heavy rainfall at times.

Again, and as is often the case during a La Nina episode, South America received moderately heavy rainfall from just south of Columbia across the Amazon, and into much of Brazil.  Rainfall tapered off during the last seven days south of Bolivia to near Paraguay. The heaviest precipitation in South America was focused over the area from Uruguay southwest towards Argentina…focused largely over the heavily populated areas around Buenos Aires.

Flooding in Paraguay: According to REDLAC (The Risk Emergency Disaster Working Group for Latin America and the Caribbean), Paraguay has been affected by both drought and flooding. While the drought has been a major problem, rains this last week have affected many communities.

Precipitation & Flooding: Africa

Figure 4. PDC Global Hazards Atlas displaying 7 day rainfall accumulation across Africa

The PDC Global Hazards Atlas shows a large area of precipitation extending through southern Africa and eastward into the Indian Ocean…as was the case last week (see Figure 4).  Precipitation has been locally heavy at times, especially from Angola to Zambia and Mozambique, and then southward through Namibia, Zimbabwe and Botswana to South Africa. Mozambique continues to experience flooding with ongoing rainfall delaying response and recovery efforts.

Meanwhile, a developing tropical storm in the south Indian Ocean (12S), is headed towards Madagascar. The hope of all involved in the area, is that this tropical cyclone won’t cross the Mozambique Channel, and bring even more flooding rainfall to Mozambique. The PDC Global Hazard Atlas above shows this storm.

Flooding in Mozambique:  Rescue workers, including the British Red Cross in Mozambique, are in support of widespread flooding that has affected the country since January 2012. The floods have affected more than 8,000 households. According to The National Disaster Management Institute, at least 20 people have died thus far.

Looking Ahead

Over the next week PDC will be monitoring areas of high precipitation and keeping a close eye on flooding across the globe.  Currently PDC is monitoring significant flood events in the following areas: Australia, Bolivia, Fiji, Mozambique, Paraguay, southern United States, and Vanuatu.

For the most up-to-date information on these flood events and all-hazards, download the free PDC Disaster Alert mobile app for iOS and Android devices.