In recent days, the news of a climate forecast for the Caribbean has circulated, highlighting the presence of heat waves in island areas such as Cuba. This has uncovered alarms and concerns among readers.
We are not going to delve into this subject, since the excellent article by Orfilio Peláez, published in Granma in 2018, "No heat wave" clarifies some doubts by Dr. Ramón Pérez, a researcher at the Climate Center of the Institute of Meteorology, when Faced with a similar concern, in this case in a month of July, the debate on the matter arose.
However, it is an excellent opportunity to continue talking about April, which, as we mentioned in a previous installment of Blast 340, is usually characterized by very hot days. So much so that the fourth month of the calendar holds the lead for the greatest number of absolute records in the country's weather stations, although April is not exactly one of the first months that Cubans would think of when we think of high temperatures.
Interesting figures
Of the absolute records reported in the 68 meteorological stations that the country has, 44 have been reported from the year 2000 to 2021, of which 2015 and 2020 stand out with 15 values each. In both cases, the month of April also led the way, although in the case of 2015 there was a little more parity between that month and July, with 8 and 5 records respectively.
The trend of rising temperatures has meant that few records recorded more than 30 years ago have "survived" to the present. Only 12 stations (less than 20%) maintain absolute values since before 1991: the oldest records that are still in force belong to the Cabo San Antonio stations in Pinar del Río, with 37.5 degrees Celsius since June 29, 1958 and the one located near the city of Sancti Spíritus, which on August 28, 1952 reported 38.5 degrees Celsius. A large number of the current stations were established in the second half of the 1960s and even some in the 1990s. Although this data should not have any influence on the warming trend in recent decades, it is necessary to clarify it so that readers know that all data series do not have the same length.
April 2020, to raise the thermometers
The fourth month of 2020, in addition to marking the beginnings of the fight against the covid-19 pandemic, was established as perhaps one of the hottest (if not the hottest) in history, if we take into account the number of records that have been set. They broke up that year.
During that stage, as we already mentioned, 13 of the 15 absolute records of that year were reported, almost all specifically on days 10, 11 and 12, with five, two and five respectively. Three of them above 39 degrees: Veguitas with 39.7, Indio Hatuey with 39.3 and Jucarito with 39.2, reported on April 12, coincidentally in these three locations the previous day the historical marks had already been broken, for which reason for the second day in a row.
It is necessary to clarify that we are only talking about absolute records, taking into account that on those dates monthly records were also reported and "broken" on several occasions—some of them also consecutively—in some stations, that is to say that although they were not it exceeded the absolute maximum, it was the hottest April day in the stored data.
For example, on April 9, 2020, no absolute record was reported, but 26 measurements exceeded 35 degrees Celsius and the Palo Seco station in Guáimaro, Camagüey, reported 38.0 degrees, equaling its absolute record... which is also from April.
What was special about the 12th for these values to be reached? First let this satellite image from that day, recorded at 2:36 pm, illustrate. It is a composite image of the visible spectrum, very similar to what a human observer would see.
The almost complete absence of cloudiness is evident, even at that time, a time of day when the presence of some clouds is common, which although they do not produce rain, block solar radiation. This abundant radiation for a longer time, favors the increase in temperatures, combined with another factor: persistent winds from the south, especially in the western region. The latter, although not completely discernible to an untrained eye, can be inferred from the way in which the sparse cloudiness is organized over the Caribbean Sea, to the south of western Cuba, describing thin lines of clouds that are oriented in an almost vertical position with respect to the image, that is, from south to north.
It is added to this situation that it occurred for the second day in a row, that is, this heat was "accumulating" in successive days up to this maximum point.
I personally remember the hot southerly wind, similar to what it feels like to be near an air conditioner that dissipates heat. A personal thermometer, placed in the window, in that flow of hot wind marked more than 35 degrees Celsius.
Curiously, in that same image, some plumes of smoke are visible, coming from fires in the vegetation, at points located almost all in the center of the country. Another topic that we also discussed previously in this space.
That is to say that April, although in the insular tropics we do not suffer the consequences of heat waves as in the continental zones, is a month of heat, records and contrasts. It is not at all unusual that we can experience days of great insolation and excessive heat, followed by heavy rains and then low temperatures on consecutive days, something for which only the long-awaited visit of a cold front is necessary.