Watching Central America (Sun 29 October)

There is a strengthening system just off the coast of Central America that the US National Hurricane Center has started tracking. Tropical Depression Nineteen (EP192023) formed yesterday, and is currently meandering about 470km (290miles) off the coast of El Salvador. The forecast is tricky … here is the TAOS/TC impact map based on this morning’s official forecast:

Click any image to enlarge.

While currently nearly stationary, the system is expected to become a tropical storm later today (and will get the name “Pilar”) while beginning a northeastward motion – towards the coast. Here’s the tricky part: a cold front is approaching the storm, and the expectation is that it will turn the storm back out to sea – but the timing is critical, every hour earlier or later in the arrival of the front will make a difference in both how close the storm gets to the coast, as well as how strong the storm will be. As we saw from Otis last week, the sea surface temperatures are quite warm, which means a lot of energy to draw on, and that means it too could rapidly intensify, although not as likely or strong as Otis was. It would be wise for the coast to prepare for a hurricane to avoid being caught off guard.

The current forecast is for the turn to happen about 100 km (67 miles) off the coast, which is close enough to brings winds and heavy rains – which means flash flooding and mudslides – across El Salvador and western Guatemala. But the track models have that “squashed spider” look, the European Centre Model is closer (60km) than the official forecast, the US GFS model a bit farther (175km off of Guatemala), and the concern is that in all three cases they could be off and the storm will make landfall as a hurricane. Here’s what the track maps look like:

Hopefully we will have a better idea by tonight and early tomorrow, when the storm will be better developed, and the timing clearer. In one sense the details don’t matter too much, there will be heavy rain, flash flooding, and mudslides either way. Fortunately it doesn’t look like the storm will get close enough to add to the misery in Acapulco.

Elsewhere, if you look in the upper right corner of the first map above you will see Invest area AL96, which might briefly, technically become a tropical cyclone as it moves parallel to The Bahamas and out to sea near Bermuda. Most likely just a rain event, at present nothing serious to worry about.

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