June 18, 2020 Global Cyclones update

The tropics are eerily quiet

Tropics — ghost town 👻

There really isn’t much to talk about in the global tropics including the Atlantic and Pacific. Normally there is something going on by middle-June like a hurricane in the Eastern Pacific off the coast of Mexico or a Typhoon east of the Philippines. But nope, it is a ghost town. The suppression of tropical cyclones in the Pacific actually makes sense with an oncoming La Nina and may be a symptom of the transition of the atmospheric state to La Nina. Time will tell. Of course the Atlantic is very active during La Nina summer and autumn.

The best place to see some tropical cyclone action is in the Eastern Pacific and the National Hurricane Center is watching the basin in the next 5-days with a 20% yellow hatching. So they are not too excited.

ECMWF ensemble storm tracks

As part of my research a long time ago at Florida State, I applied storm trackers to various weather model forecast and climate (reanalysis) data. So, when I finally got access to the ECMWF suite — which costs upwards of $250K/year — I took many of my research codes and ideas and applied them to the operational weather model data. The ensemble storm tracks or spaghetti are one of my favorite maps.

• 51-ensembles or scenarios of the same model (1 control + 50 perturbed)

• 15-days of forecast data every 6-hours

• storm tracks are color coded by the mean sea-level pressure (MSLP) at the point

Note, that the Eastern Pacific tropics indeed have “some” tracks. But the Western Pacific is mostly empty and the Atlantic is devoid of activity as well.

But, take a look at the other cyclones e.g. non-tropical or extratropical cyclones around the world. Right now, the Southern Hemisphere circumpolar storm tracks are roaring. The central pressure of these storms is typically quite deep and significantly deeper relative to the average Northern Hemisphere winter-time storm. In the summer, there are certainly still North Pacific and North Atlantic non-tropical storms but they are usually rather weak with gale force winds.

Sahara Dust Layer (SAL)

Everyone is watching the SAL coming off of Africa heading for the Caribbean and then the Gulf of Mexico.

I got curious about the magnitude of this SAL event so I downloaded the 1981-2019 historical data from NASA’s reanalysis called MERRA-2. I am in the process of generating a climatology now. And, with the real-time GEOS-5 model, I am confident I can put the current SAL outbreak into historical context.