Typhoon Mirinae (Santi) is likely to pass across Luzon in the next 24 hours

The latest track forecasts for Typhoon Mirinae (Santi) suggest that a direct hit on Luzon is now highly likely:
Mirinae is not especially strong in terms of windspeed, but the eTRaP data suggest that rainfall volumes are high (this is the precipitation forecast for the next 24 hours):

The topography of this area is pretty mountainous, and the typhoon will pass close to Manila:

The ground is likely to still be very wet from the two earlier typhoon events, although in these residual soils the drainage rate is probably quite high, so there is probably a higher likelihood of landslides than would normally occur for a typhoon of this size.

Typhoon Mirinae (Santi)

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Once again Luzon in the Philippines is staring down the barrel of a powerful tropical cyclone, Typhoon Mirinae (known locally as Typhoon Santi). The storm is currently forecast to track across the southern part of Luzon on Friday evening:
The 24 hour eTRaP precipitation forecast for the storm suggests that it is, as expected, inducing substantial amounts of precipitation along track:

At the moment the storm is quite fast moving (15 knots) which from a precipitation perspective is probably good news. From a landslide perspective the worry however is that the storm appears likely to induce heavy rainfall in the areas most seriously affected by Typhoons Parma and Ketsana:

Indeed, the similarity between the track of Typhoon Ketsana and the forecast for Typhoon Mirinae is of some concern. Typhoon Ketsana killed at least 460 people.

Animation of Seattle harbour liquefaction failures

Youtube has a rather cool video of an animation of the effects of a large earthquake on the harbour side area of Seattle. The main point is I think to show the effects of the earthquake on the elevated roadway, but it also shows liquefaction failures of the fill behind the sea wall:



Pretty neat - certainly a useful teaching tool.

Just when you thought it was safe to go out in Luzon...

...another potential typhoon appears (Tropical Storm 23):

Unbelievable, although the track error this far out is of course very high.

New atlas of natural disaster threats in the Andes

On Friday the Andean Community of Nations (CAN) (Bolivia, Colombia, Ecuador and Peru) released an atlas of potential natural disasters affecting the countries of that region, which has come out of the PREDECAN project. It presents maps of the distributions of earthquakes, volcanic eruptions, landslides, flooding, frost and drought, with a special emphasis on El Nino / La Nina.

As far as I can tell this atlas is available only in Spanish (not unreasonably of course), but it is available online in its entirety, which is certainly one better than the World Bank hotspots project. Of course I am most interested in the landslides section - and this deserves more than a single post - but for now let me just give an overview of the landslides chapter.

The headline figures in the analysis are that between 1970 and 2007 about 11,000 people were killed and 38,000 homes were destroyed by landslides. About 260 landslides killed more than 20 people and/or destroyed more than 50 houses. El Nino is a key control on the occurrence of slides. The following map presents the distribution of fatal landslides, with the size of the spot representing the number of fatalities in each case. The darker grey area is the zone covered by this study:

The study also presents the results of an analysis of trends of occurrence of larger (20+deaths and/or 50+ homes destroyed) landslide accidents:

Clearly the data suggest that more landslides have occurred since the mid 1980's than before, but this may well be an artifact of the data. Note that since the mid 1990's there is no clear overall trend, although the period in the late 1990s characterised by the large El Nino event is clearly evident in the data. A moderate El Nino event is thought to be developing at present.

Typhoon Lupit stalls off the coast of Luzon

Typhoon Lupit (Ramil) has now stalled off the northern coast off Luzon and is forecast to recurve and to head northwards, whilst weakening as it encounters increasingly cold water over the next few days:

This has been an extremely fortunate outcome, and one that has also exposed the continuing problems with forecasting typhoon tracks. The eTRap forecast for the precipitation over the next 24 hours clearly highlights just how close this storm came to causing substantial rainfall in Luzon:

The threat to Luzon has certainly not gone away completely, but is certainly receding substantially. Luckily, at the moment the storm is also forecast to miss Taiwan as well. Unless there is a dramatic change of direction of the storm this will be my last post on Lupit.

Typhoon Lupit (Ramil) continues to confound!

The behaviour of Typhoon Lupit (Ramil) is becoming increasingly difficult to forecast, primarily because its movement remains quite slow. The latest JTWC track forecast is still suggesting that the track will pass across the northern part of Luzon:
However, the storm is now moving slowly and is likely to continue to do so, which makes forecasting its track much more difficult. The major concern is that the JTWC forecast above suggests that the storm will track across Luzon very slowly, which is very bad news in terms of landslide and flood generation. However, some forecast models (such as the GFS model) suggest that the slow movement may allow the regional air pattern to change, which could cause the storm to recurve and head to the north, which would spare Luzon. This remains quite unlikely, but would be very fortunate indeed. On the other hand, some other forecasts suggest a more southerly track than the JTWC one.

The storm itself is now quite weak (only a category 2), but may well strengthen a little over the next few hours. This suggests that if the storm does come ashore the major issue will be the rainfall rather than the winds / storm surge. The eTRaP data, which forecasts rainfall for the next 24 hours, indicates the intensity of the rainfall associated with this storm (NB the scale is in inches, 1 inch = 25.4 mm):

The satellite imagery suggests that the outer edge of the storm (i.e. the high level cloud) has just about reached the Luzon coast, although the main part of the storm is still quite some distance away:


If the storm does come ashore then an interesting site to keep an eye on might be that of a professional extreme weather photographer, John Edds, who is out there and is blogging on the preparations that the local people are taking. You can view his report here.