Tropical Storm Lee increases winds to 70 miles per hour; close to becoming a hurricane

The Tropical Storm Lee This morning it increased the speed of its maximum sustained winds to 70 miles per hour (mph), which positions it as a strong storm just 5 mph away from becoming the fourth hurricane to form this year in the tropical Atlantic basin.

He National Hurricane Center (NHC, in English) reported in its 11:00 am bulletin that the cyclone was located at latitude 14.1 degrees North and longitude 45.5 degrees West. According to these new coordinates, Lee’s center of circulation is 1,426 miles east-southeast of San Juan and 1,200 miles east of the Leeward Islands.

This new report does not include surveillance or warning products for any territory in relation to this cyclone.

The barometric pressure of the system dropped to 994 millibars (mb) and its translational movement is to the west and west-northwest at a rate of 14 mph, the NHC reported in its bulletin. However, the translational movement of this system should reduce in the coming hours.

Tropical storm-force wind field extends up to 80 miles from the center of circulation, but it should expand as the system intensifies. The strongest winds are concentrated towards the northeast quadrant of the cyclone.

In fact, satellite and microwave images recently showed the formation of an eye that was not yet relatively closed, so the NHC determined to maintain the intensity of a tropical storm, although more strengthened than the last bulletin.

The system looks much more organized and with a better convection structure (area of ​​thunderstorms and thunderstorms), so it is experiencing all the favorable conditions to continue gradual strengthening.

This story is being updated following the latest newsletter, so some details below will be updated soon.

A rapid intensification process is when a tropical cyclone increases the maximum intensity of its sustained winds by at least 35 mph in a 24-hour period, according to the NHC. Although these types of processes are still under scientific study, observations made so far by meteorological experts, including the NHC itself, suggest that they occur whenever the phenomena pass through an area of ​​warm or warmer waters than usual.

Framed in global warming and the impact of climate changethese processes have been recorded mostly in waters of the Gulf of Mexico and the nearby area between the tropical Atlantic and the Caribbean, where the so-called “hot pools” tend to be concentrated, which are those areas where the water surface temperature (SST, in English) exceeds the threshold of 78.8 degrees Fahrenheit (26 degrees Celsius) identified as favorable for cyclone intensification.

What changes has the forecast made?

The only change is limited to an increase in intensity within five days. Although the first NHC forecast for Lee – when it was still a tropical depression – was aggressive, it was not enough to raise all the possibilities of its cyclonic future, since most global and regional models suggested a more powerful phenomenon than anticipated. .

Specifically, the NHC yesterday, Tuesday, estimated Lee’s sustained wind speed at 140 mph (category 4) within five days. However, in its most recent forecast it raised the maximum sustained wind speed of the hurricane to 150 mph next Sunday. In fact, the estimate remains relatively below the projections of some models, which even suggest that it is possible that Lee is a category 5 hurricane.

Category 5 on the Saffir-Simpson wind scale starts at 157 mph.

Is it possible to specify potential impacts in Puerto Rico from now on?

With the current imprecision of the forecast, especially in terms of trajectory, It is not possible to establish with certainty the potential impacts of the hurricane during its passage close to the northeast of Puerto Rico..

In fact, the NHC highlighted that there is a margin of error of between 90 and 125 nautical miles for days 4 and 5 of the trajectory outlined in the 11:00 am bulletin, so any future changes that result in adjustments of trajectory will, in turn, affect the forecast of potential impacts.

If Lee’s movement occurs as suggested by the forecast track at 11:00 am, the cyclone should pass as a powerful Category 4 hurricane 250 to 300 miles northeast of San Juan next Sunday. This estimated range in miles will change as the trajectory is adjusted.

Nevertheless, As it is a hurricane that could be category 4 or 5 during its passage northeast of the local area, it is fair to point out that maritime and coastal conditions will become dangerous, while heavy downpours with thunderstorms could reach the island..

Additionally, the outer bands of the system could generate storm-force winds (at or above 40 miles per hour) as they approach the area.

The strongest impact would be experienced by coastal towns in the northern half of the island, including the northeast and east, due to waves that could rise to over 12 feet in height starting next Saturday, according to the preliminary forecast from the maritime division of the NHC.

When will we have more certainty of the prognosis?

The certainty of the forecast will improve as the cyclone approaches the area and reconnaissance flights begin to collect data. on site (in the place of the cyclone). So far, the forecast conforms to estimates from satellite images and nearby buoys.

In the hurricane hunter aircraft agenda, the NHC stipulated that there is the possibility of assigning a reconnaissance flight of a plane from the 53rd Weather Reconnaissance Squadron of the Reserve United States Air Force (US Air Force, in English) on the night of next Thursday, while a ship from the National Oceanic and Atmospheric Administration (NOAA, in English) would depart on Friday morning.

Since there is no surveillance or warning issued, the next complete bulletin with updated information will go out at 11:00 a.m. and then at 5:00 p.m.

Remember that you should not consume information from unreliable sources (especially on social networks) that propose a unique scenario for Puerto Rico in relation to this phenomenon, because no scenario is certain. This factor is important, since some models simulate the worst scenario of an atmospheric phenomenon and any misinterpretation or visualization of these images without proper analysis can generate despair.

Follow official sources of information such as National Hurricane Center and the National Weather Service (SNM) in San Juan. Additionally, you will find all the details you need in the The Time of The New Day.

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Carlos Tolentino Rosario is a journalist who covers weather, climate change and science, among others. He holds a certification in weather forecasting from the Department of Meteorology and Atmospheric Sciences at Pennsylvania State University (PSU). He is also a member of the American Meteorological Society (AMS).