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This 2020 hurricane season is starting on high bases. It is July 25, already 8 cyclones have been named in the basin and a 9th threat to be named next week. It must be said that the temperature of the water is particularly hot (and again, thanks to the haze of sand in recent weeks for having limited its warming a little!) And that the shear is generally low in the tropical Atlantic. Fortunately, there are still areas of very dry air and sand, which somewhat limits the possibility of reinforcement.
Gonzalo
Despite a very marked weakening and a haphazard organization, Gonzalo maintains a deep convection near his center. It is now a small and weak storm (35 kts) which should not survive very long, always near dry air but in addition with a small shear and especially the interaction with the land. Its hours are counted, but the storm generates heavy rainfalls over Trinidad and Tobago, northern Venezuela and southern Caribbean arc. Severe squalls are likely to cause gusts exceeding 40 kts … So be careful.
Invest 92L
The wave that left Africa this week and was the subject of more or less eccentric forecasts from a few models is now closely followed by the nhc and went to Invest. Many rumors and fake news have circulated on his account in recent hours, as often under these circumstances. We have to believe that people love to scare themselves or scare others… so, let's take stock of what is happening for the moment and what we know… more or less!
92L is currently in a precarious situation with very dry air and sand to its north and a shear quite strong in the south. The wave is struggling to find its way in these conditions that are not really favorable for it. These conditions are expected to last until early next week.
Then, the shear is forecast to weaken and the dry air could dissipate a bit… but this is an extremely delicate forecast and it is difficult to draw any conclusions for next week.
Forecast models and the NHC
As often in the classification of a wave in Invest, the models go a little in all directions and we find options sometimes realistic but sometimes totally irrelevant.
The most aggressive model, with the passage of a Cat. 1 or 2 on the north of the arc, is strangely the GFS who however ignored this wave until yesterday. But it is known to have an initialization bias of Invest with an often disproportionate reaction.In aggressive outings we also have the SHIPS which is a model that incorporates a good deal of statistics which also sees a big strengthening.
We then have a beginning of consensus with the other global models which vary from a low to a storm on the northern half of the arc. For its part the nhc do not get too wet as usual for a Invest, especially if it is faced with a complex environment. They are content to gradually increase the risk of reinforcement but do not venture beyond. And this is by far the most reasonable position!
It should be taken into account that the gross outputs of the models are in no way a forecast. These are trends and estimates that must imperatively be the subject of quality human expertise. I have been saying for several years that the fact that these data are in the public domain poses major problems of interpretation. I often hear people say “Windy has planned ..." or "Windy is the best forecast”… Except that Windy (which is also an excellent site) is planning ABSOLUTELY NOTHING !! it simply renders the raw data of the forecast models graphically, without human intervention. So for common weather in temperate zones, it's perfect because these models are extremely efficient for this kind of thing. But for cyclone forecasting and analysis, we are still far from the mark. One need only look at the disagreements for Gonzalo throughout his Atlantic journey to realize this.
Yes, but 92L, what's going to be?
We are more than 130 hours from a possible passage on the arch ... so very far. In the tropical zone, we have the deadline of less than 48 hours which is not badly controlled, that of 48 to 120 hours which is a mixture of tendency and confidence and that beyond 120 hours which is only of the prospective trend. We are therefore at a time when we can ONLY talk about a trend. Everyone who says anything about this deadline is lying.
However, when all global models initialize a cyclone in an identified area, more often than not it ends up happening. This is the case here so we can reasonably think that a system will emerge in the Atlantic in the coming days. Now, knowing where it will go and at what intensity, it's just impossible. The northern half of the West Indies is tall and between a storm and a Cat. 2 the difference is very important. And tomorrow it is possible that one or 2 models announce a Cat.4 ... and that will not change any of that.
So for the moment, there is nothing else to do but wait to see a little clearer and a strong consensus is established between the models and is confirmed by the nhc. Until then, don't listen to any affirmations. The one who howls wolf every time will necessarily be right one day, like the one who announces a small wave. But in the end, 95 times out of 100… they will be wrong. I rarely react to these deadlines because there is no point.
The risk of a cyclone next week is real and there are clear signs that it will pass over the northern half of the arc or even further north. You have to watch it closely and be vigilant, that's for sure (as always, for that matter). Everything else is just speculation.
To follow the live quantified evolution of Invest 92L is HERE.
Image credits; Tropical tidbits, NHC / Noaa, UW-CIMSS
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