| Tropical storm (SSHWS) | |
|---|---|
 Tropical Storm Boris just after landfall in Guatemala. | |
| Formed | May 29, 2020 |
| Dissipated | May 31, 2020 |
| Highest winds | 70 mph (115 km/h) |
| Lowest pressure | 999 mbar (29.50 inHg) |
| Fatalities | 44 |
| Damage | >$500 million |
| Areas affected | Costa Rica, El Salvador, Guatemala, Mexico |
| Part of the 2020 Pacific hurricane season | |
| Category 1 hurricane (SSHWS) | |
|---|---|
 Hurricane Dolly on approach to Louisiana. | |
| Formed | June 1, 2020 |
| Dissipated | June 11, 2020 |
| Highest winds | 75 mph (120 km/h) |
| Lowest pressure | 987 mbar (29.15 inHg) |
| Fatalities | 30 |
| Damage | $300 million |
| Areas affected | Mexico, United States (specifically Louisiana) |
| Part of the 2020 Atlantic hurricane season | |
Tropical Storm Boris and Hurricane Dolly were two tropical cyclones that developed from the same entity in late-May and early-June. Both tropical cyclones caused widespread damage and fatalities in Mexico, and Central America in the case of Boris.
Tropical Storm Boris formed in the Eastern Pacific on May 29, 2020, and moved north-northwest while quickly intensifying. It made landfall in Guatemala near the Port of San Jose just under hurricane intensity. After moving inland, the low-level center dissipated while the mid-level center persisted, eventually leading to the formation of Tropical Depression Four-L in the Bay of Campeche on June 1.
Four-L quickly intensified into Tropical Storm Dolly, did a loop in the Bay of Campeche, and then paralleled the western coast of the Yucatan Peninsula, weakening due to land interaction. It continued to intensify as it moved away from land and eventually reached hurricane intensity on June 7. Dolly was a Category 1 hurricane for 12 hours before shear began to affect the system. It made landfall in Louisiana as a 65 mph tropical storm, and weakened slowly inland. Dolly was declared a remnant low by the National Hurricane Center on June 11, and advisories were handed to the National Weather Service.
With Boris relating to the genesis of Dolly, it was the first time that an Eastern Pacific cyclone had regenerated into another tropical cyclone in the Atlantic since [placeholder until pre-2020 seasons are made]. Dolly was also the first June hurricane in the Atlantic since [placeholder until pre-2020 seasons are made], and one of the earliest June hurricanes on record as well. Dolly also broke the record for earliest "D" named storm on record after it was given a name on June 2, shattering the record by [placeholder] in [placeholder year].
Meteorological history[]
Map plotting the track and intensity of Tropical Storm Boris, according to the Saffir-Simpson scale.
A very broad and weak low pressure developed near Trinidad and Tobago on May 25 and quickly moved into northern South America the following day. The National Hurricane Center took notice of this system as it interacted with the ITCZ overland and marked it as an area of interest in the Eastern Pacific, as conditions in the Caribbean were too hostile for development there. Once the disturbance entered the Eastern Pacific, it began to quickly organize. On May 28, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert (TCFA) for the system. At 00:00 UTC on May 29, the system had organized sufficiently to become Tropical Depression Two-E. It did not take long for the depression to intensify into a tropical storm. Less than six hours after designation, ASCAT passes detected winds of gale-force. Following this revelation, the National Hurricane Center promptly upgraded Two-E to Tropical Storm Boris at 06:00 UTC May 29. Throughout the day, Boris continued to organize while it developed outflow and colder cloudtops as it neared landfall in Guatemala. Boris developed a nascent eye around 02:00 UTC on May 30. The National Hurricane Center responded quickly to this development and upgraded Boris to a 70 mph (110 km/h) tropical storm. As Boris was nearing landfall, its eye feature vanished and the system seemed to be deteriorating under the influence of the Guatemalan coast. Boris made landfall as a 65 mph tropical storm and quickly began to weaken inland. At this point, the National Hurricane Center recognized the possibility of tropical cyclogenesis in the Bay of Campeche from the remnants of Boris. The system continued to weaken as it move inland, with the low-level center dissipating over central Guatemala.
Map plotting the track and intensity of Hurricane Dolly, according to the Saffir-Simpson scale.
The mid-level center and general convective activity associated with Boris continued north and northwest into the Bay of Campeche where it redeveloped into Tropical Depression Four-L at 00:00 UTC June 1. The system executed an anti-cyclonic loop as it strengthened into Tropical Storm Dolly. Dolly made an uncomfortably close pass to Cuidad del Carmen in Mexico on June 3 - 4, initially peaking just under hurricane status. The system weakened briefly to a tropical depression as it paralleled the western coast of the Yucatan Peninsula. Twelve hours after initially weakening, Dolly strengthened back into a tropical storm and began to quickly organize as it moved north. It was much broader and larger than it was previously in the Bay of Campeche, and as a result convective blowups surrounding Dolly's center began to form into a solid eyewall. Recon aircraft entered the system as the eye began to form and confirmed the existence of hurricane-force winds in the developing eyewall, and the National Hurricane Center subsequently upgraded it to Hurricane Dolly on June 8. It began to deteriorate after peaking, with part of the southern eyewall eroding due to hostile conditions in the Gulf of Mexico. It made landfall as a 60 mph tropical storm southwest of Paul J Rainey Wildlife Refuge and Game Preserve and promptly began weakening over Louisiana. Dolly became a tropical depression over north Louisiana and continued deteriorating as it moved inland, delivering heavy rain across nearby states. Dolly was declared a remnant low by the National Hurricane Center at 12:00 UTC on June 11, but the National Weather Service continued monitoring the system as it moved into the Midwest. Dolly's extratropical remnants moved out into the open-Atlantic on June 14, only to merge with an oncoming front that had delivered severe thunderstorms to the Northeastern United States the day prior.
Preparation[]
Tropical Storm Boris[]
The National Hurricane Center's rainfall forecast for Tropical Depression Two-E (which would become Tropical Storm Boris the next advisory) at 00:00 UTC on May 29, 2020.
In advance of Tropical Storm Boris, tropical storm watches and warnings were put into effect along the coast of Guatemala. At formation as Two-E, the National Hurricane Center and the Government of Guatemala expected tropical storm conditions as early as the morning of May 30 depending on how much the system grew. Rainfall totals were anticipated to be extremely devastating as well, especially if Boris became larger or stronger than anticipated. Initial forecasts called for up to 24 inches (610 mm) of rain along the Guatemalan coast as the system came ashore. Further north, forecasts up to 20 inches (508 mm) spread across the Yucatan Peninsula while the majority of Belize was forecasted to receive anywhere from 2 to 4 inches (51 to 102 mm) of rainfall. Widespread evacuations were put in place as the storm approached, and emergency services were ready to begin water rescues should conditions warrant them.
Hurricane Dolly[]
As the remnants of Boris redeveloped into TD Four-L in the Bay of Campeche, tropical storm watches and warnings were immediately put into place in areas in the southern portion of the bay. As Dolly executed the aforementioned anti-cyclonic loop, it exacerbated the excessive amount of rainfall produced by Tropical Storm Boris and its remnants/Dolly's precursor. Prior to formation, total rainfall totals were upwards of 24 inches, similarly to Boris. The only difference was that Dolly would not make landfall so rain bands would simply lash the coastal areas of the Bay of Campeche until the system moved away. Preparations for Dolly were rushed and hard to execute because of Boris-Dolly's remnants being in close vicinity and causing disruptions. Landslides and flash flooding made it difficult for emergency disaster assistance to arrive in preparation for Dolly's anticipated slow movement.
The NHC's cone for advisory #27 for Dolly, which was upgraded to a hurricane at this time. Note the hurricane warnings stretched along the Louisiana coast.
In the United States, Dolly's cone encompassed Louisiana's coast and disaster assistance acted fast. Faced with the looming threat of a near-hurricane or hurricane landfall in June, cities such as New Orleans and Lafayette began to prepare. A state of emergency was put into effect for the state of Louisiana on June 7 as Dolly continued to intensify and while it was expected to strike as a hurricane in a few days' time. A hurricane watch amongst storm surge, flash flood, and tropical storm warnings were put into place as Dolly intensified into a hurricane. These alerts continued along the path of the storm until it degenerated into a remnant low, when the only alerts still in place were flash flood watches and warnings issued by the National Weather Service.
Impact[]
Tropical Storm Boris[]
Total rainfall totals from Tropical Storm Boris, from the formation of its precursor to the moment the remnants of Boris became a disturbance in the Atlantic basin.
Initial rainfall forecasts for Boris failed as the system grew increasingly larger and stronger. Despite weakening slightly at landfall, Tropical Storm Boris continued to grow on radar and move inland at a snail's pace. Heavy rain bands overtook much of the coast from eastern mainland-Mexico, lower portions of the Yucatan Peninsula, and almost all of El Salvador. Boris delivered torrential rains along the coast of Mexico to extreme western Nicaragua. The maximum recorded rainfall total was recorded in Iztapa, Guatemala, just above 36 inches (3 ft, 914.4 mm) of rain.
In the country of El Salvador, no rainfall totals below 7 inches (178 mm) were recorded, leading to flash flooding and landslides widespread throughout the country. Maximum rain totals in the country topped off between 25 to 30 inches (635 to 762 mm).
Belize and Honduras saw impacts from rainfall, flash flooding, and landslides, but much lesser than areas closer to Boris' landfall location. In Belize, maximum rainfall recorded was between 10 to 15 inches (254 to 381 mm). Honduras recorded a peak of 20 to 25 inches (508 to 635 mm) near the border of El Salvador.
Hurricane Dolly[]
Total rainfall totals from Hurricane Dolly, from the formation of its precursor to the moment it became a remnant low over Arkansas.
The remnants of Tropical Storm Boris/the precursor to Hurricane Dolly only expanded the extent of the agonizing rainfall for Mexico and Central America. Tropical Storm Dolly's slow movement during its first peak in the Bay of Campeche along the coast of Mexico delivered almost 46 inches (1,168 mm) of rain in cities such as Cuidad del Carmen. The highest rainfall total across the region as Tropical Storm Dolly rode the coast was recorded in Carmen, Campeche, Mexico, located near Laguna de Términos, with 45.86 inches (1164.844 mm) of rain. Rainfall was extremely high in this region due to Dolly's core remaining just offshore as it essentially traced the coastline. Dolly moved extremely slowly along the coast as well, so the allotted time for rainfall was unexpectedly extended. The onshore push from the Bay of Campeche combined with torrential rainfall proved disastrous for the region, and 24 fatalities were recorded in the Yucatan and nearby areas from flash flooding and heavy rain.
In the United States, impacts were less extreme than forecast due to Dolly's weakening before landfall. Regardless of Dolly's intensity at landfall, it delivered between 15 to 20 inches (381 to 508 mm) of rain along the southeastern coast of Louisiana. Much of Hurricane Dolly's impacts were focused on the right half of the system, with heavy rain spreading to areas along the Alabama-Mississippi border. Storm surge, flash flooding, and heavy rain all came together in a large combination of water rescues and few levee failures. Much of the city of New Orleans lost power due to the flooding and heavy rain that moved ashore as Dolly made landfall roughly 130 miles (209 kilometers) southwest. As Dolly moved inland, convection waned on the right half, lessening the heavy rain and focusing it more on the rapidly deteriorating core of the tropical cyclone. Power was recovered late at night on June 9 into the early morning hours of June 10.
Dolly continued moving north into areas like Arkansas, Missouri, and Tennessee, delivering less rainfall than it did as it moved into coastal Louisiana, but producing life threatening tornadoes on the right quadrants of the tropical cyclone, particularly as it was post-tropical from June 11 onwards. Many of the fourteen confirmed tornadoes along Dolly's path were officially rated as EF0, while two of them were EF1s. These caused localized damage as many tornadoes were short-lived.
Aftermath[]
Collectively, Tropical Storm Boris and Hurricane Dolly caused a total of at least $800 million along the entity's path. Boris' heavy rainfall, landslides, and flash flooding in vulnerable Central America & Mexico totaled more than $500 million in damages. It is considered one of the worst tropical cyclones to strike the area in recorded history. Hurricane Dolly exacerbated the effects in Central America, while instigating worse conditions in Campeche because of its slow movement. The United States managed to fare better than others, with a quick disaster response and limited power outages.
Despite a massive trail of destruction between the two tropical cyclones, the names Boris and Dolly were not requested for retirement at the World Meteorological Organization's joint 42nd and 43rd Sessions of the RA IV Hurricane Committee on March 13, 2020.
Gallery[]
Tropical Storm Boris[]
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Hurricane Dolly[]
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