RAI / Odette

As most of you will have picked up by now, Pagasa is warning of a named storm that might very well develop into a dangerous typhoon, and is predicted to reach Negros by 11 am Friday morning.
Details are rather scarce so far, but if the predicted trajectory holds it should make landfall in Negros in the Tanjay general area, about 50 km north of Dumaguete.
According to windy.com, we might be spared the worst of the winds in Dumaguete, although they might still reach a sustained 60 km/h or so, with gusts going a fair bit higher.
Although the winds will probably do extensive damage to the electricity infrastructure and to light materials huts (which is bad enough already),
I think the amount of expected rain will be a bigger concern, and possibly more dangerous.
Windy.com predicts a grand total of 270 mm of rain for Dumaguete for the next 5 days, with the bulk falling between 6 am and 3 pm on friday. I suspect such an amount of rainfall may very well cause extended flooding.

 

Update:
The predicted trajectory for the storm has moved somewhat to the North; the center is now suspected to make landfall in the La Libertad area, which is around 100 km from Dumaguete.

 

After it scores a direct hit on Cebu City.

For those who want to see the updated forecast, here is the rain forecast on Windy.com for Friday at 4 AM:
https://www.windy.com/-Rain-thunder-rain?rain,2021121621,10.341,123.875,9

This typhoon is forecasted to have little wind but lots of rain.
https://www.windy.com/?2021121621,10.341,123.875,9

 

The projected trajectory keeps shifting further north for now; the storm is now predicted to hit northern Cebu and hit Negros a bit North of San Carlos, or about 130 km from here (as the crow flies).
Obviously that means we won't see really heavy winds here in Dumaguete, although windy.com still shows possible gusts up to 70 km/h. Predicted precipitation is similarly (much) lower at 85 mm.
It's still early though, forecasts can still change.

 

I've been using the US Navy JTWC site for many years and found it to be very accurate

https://www.metoc.navy.mil/jtwc/jtwc.html

 

There are two significant mathematical weather models in use. The US funded GFS model and the European funded ECMWF model. There are others that do not get as much funding and are not as accurate. The US Navy uses the US funded GFS model.

Both of these models (and others) are available for viewing on Windy.com Look in the lower part of the screen often the lower left depending which view you are in.

 

I found a map of the accumulated rainfall during Washi/Sendong in 2011.
It shows that the Dumaguete area got around 100 mm back then. I wasn't here in 2011, so no idea if there was extensive flooding then; all I know is there was a bridge destroyed and the concrete path in the Casaroro canyon got badly messed up.
The current storm is now expected to drop around 140 mm in Dumaguete (the forecast path has shifted back to the south a bit, center of the storm is now expected to hit Negros in the Guihulngan area around 3 am on Friday).

 

As the typhoon passes North of us, the Cuernos de Negros mountain range will shield us from much of the wind that will be coming from the West. I am hoping it will reduce the rainfall we receive too.

Although the mathematical models predict the general effect of the local geography, They are not fine enough to predict the specific effect of local geography. As you can see from the image attached the model predicts light winds (green) around and to the West of Dumaguete. This is because of the mountains and the wind direction.


The ECMWF model shows Dumaguete out of the wettest zone getting 140 mm of rain. The GFS model shows Dumaguete in the wettest zone. (205 mm) So 6 to 8 inches of rain. This is a lot in a few hours.

 

Extremely intense lightning is predicted in the Dumaguete area. Make sure you disconnect all electrical devices. Unplug them from the wall outlet and disconnect any antenna or network cables.