Hurricane Marco (2020)

Storm Active: August 20-25

Around August 10, another tropical wave moved off the coast of Africa. Initially, atmospheric conditions did not favor development and the system did not produce much thunderstorm activity as it traversed the tropical Atlantic. It was only upon approach to the Lesser Antilles around August 16 that it showed signs of organization. The wave produced some rain for the islands as it passed into the Caribbean the next day, but its fast forward speed kept these rains short-lived. A broad low pressure center formed in association with the wave on the 18th. As the system neared the southwestern edge of the subtropical ridge, its forward motion slowed and allowed some more consolidation. Very deep convection blossomed late on August 19 and Tropical Depression Fourteen formed the next morning.

The depression had a curious structure that day, featuring a warm spot on satellite imagery near what appeared to be a mid-level circulation even though surface and aircraft reconnaissance data indicated a surface low further south. The storm did not intensify over the next day, thanks in part to land interaction with Honduras, which Fourteen passed very close to overnight. Feeling the influence of a trough over the Gulf of Mexico, the depression turned rather sharply toward the north and slowed down during the morning of August 21. Outflow from the same trough lay some sinking air over Fourteen, limiting convective activity.

Interestingly, the storm began to build a central dense overcast that evening "from scratch," building an expanding core over the next day. Late in the evening (early on the 22nd UTC time), it strengthened into Tropical Storm Marco. This once again marked a new record for earliest "M" storm, this time surpassing a tie between Maria of 2005 and Lee of 2011, which both formed on September 2. Note that in the second case, though Lee wasn't technically an "M" storm, it was still the thirteenth tropical storm-strength cyclone of the season, in light of the unnamed tropical storm that was identified in post-season analysis. Marco sat atop the highest ocean heat content in the Atlantic, and tapped into it on the 22nd, strengthening rapidly into a strong tropical storm.

Defying forecasts, Marco traveled north-northwest most of the day. Instead of hitting the Yucatan Peninsula, it passed east, in between Cuba and Mexico. In fact, of the two landmasses, only the western tip of Cuba received tropical storm conditions as the storm passed. The storm entered the Gulf of Mexico, where very warm ocean waters and high relative humidity prevailed. As Marco moved north-northwest closer to the trough mentioned earlier though, wind shear steadily increased out of the southwest. As a result, the satellite presentation looked a little "squashed" in the southwest quadrant. The storm fought it off on August 23 enough to strengthen to a category 1 hurricane, reaching its peak intensity with 75 mph winds and a pressure of 991 mb.

But the shear was relentless and increased to over 30 knots that evening, causing the storm to begin to decouple. This began a period of rapid weakening and Marco lost its brief hurricane status. All convection was displaced from the center overnight, so that even though the center was headed toward the Louisiana coastline, that state received almost no rain! The heavy rain that did occur was from the displaced thunderstorms over the Florida panhandle and coastal Alabama. By the afternoon of the 24th, Marco was a weak tropical storm. The center of circulation turned abruptly westward and made landfall near the mouth of the Mississippi river that evening. The weakening vortex paralleled the Louisiana coastline overnight as Marco weakened to a tropical depression, and then a remnant low early on August 25. This low dissipated within a day as Hurricane Laura approached from the southwest.

The above image shows Marco near peak intensity. Notice the straight line cloud formations to the north and the strong winds pushing them toward the northeast. These upper-level winds are what caused Marco to rapidly weaken before landfall.

Despite forming in the Caribbean, Marco took a path that resulted in relatively few land impacts.

Hurricane Laura (2020)

Storm Active: August 19-29

During mid-August, a huge tropical wave traversed the African Sahel, producing massive amounts of rain in west Africa. This impressive feature emerged over the Atlantic on August 15 and moved quickly westward. The system organized only slowly, hampered primarily by its own large size and competing regions of vorticity on the eastern and western edge of the disturbance. Ultimately, convective activity dissipated in the eastern blob and the western end won out. On August 19, the circulation became defined enough to designate the system Tropical Depression Thirteen.

By that time, the depression was moving rapidly west-northwestward and contending with a bit of dry air to the west. This kept development slow in an otherwise favorable environment with warm air and low shear. During the afternoon of August 20, it became evident that multiple low-level swirls existed in the system as one was ejected northwestward out around of the convective canopy. That swirl ultimately dissipated and the center was hard to locate overnight. Nevertheless, thunderstorm coverage increased some the next day as the depression approached the Leeward Islands. Aircraft reconnaissance found tropical storm force winds during the morning of the 21st, prompting an upgrade to Tropical Storm Laura. Laura was the new earliest "L" storm and surpassed the record of Hurricane Luis, which formed on August 28, 1995 (00:00 August 29 in UTC time).

Despite the upgrade, Laura was disheveled on satellite imagery as its bands brought rain to the northeasternmost Caribbean islands. Some improvement to its structure took place overnight and thunderstorm activity became much more widespread. On August 22, instead of no apparent center, there were two: a low-level one moving on a more southerly track south of Puerto Rico, and a mid-level one which crossed the island and ultimately emerged north of it that afternoon. This separation prevented Laura from strengthening quickly, but its winds nevertheless increased to 50 mph that day. On the other hand, the large-scale circulation of Laura was very vigorous and barely slowed down as it went directly across Hispaniola beginning that evening.

Torrential rainfall occurred in both Haiti and the Dominican Republic over the next day, leading to widespread flooding even though Laura was still moving around 20 mph toward the west-northwest. The cyclone deepened a bit more during the afternoon of August 23 as it emerged over water briefly and began to move close to eastern Cuba. A bit of wind shear out of the north pushed some drier land air into the northern semicircle as Laura passed over the waters between Cuba and Jamaica overnight. During the day of the 24th, the structure began to improve again. The storm moved back over land in western Cuba that evening, but it wasn't long until it emerged into the Gulf of Mexico. Even as it exited land, an inner core began to develop.

Steady strengthening commenced once Laura was over water; it became a hurricane the morning of the 25th. It was still moving west-northwest fairly quickly (though slower than before) and so the main difficulty was moistening the slightly drier air mass it was moving into. Thus the storm had the most difficulty closing an eyewall on the western side. Cold cloud tops eventually wrapped all the way around the center that afternoon. That evening, Laura began an extreme bout of rapid intensification. The storm's outflow became more pronounced and its banding more symmetric overnight as it strengthened to a category 2 hurricane. An eye appeared early on August 26 and Laura became the first major hurricane of the season. It also made a turn toward the northwest as it felt the influence of a trough to the north.

The eye cleared out and became more circular in the afternoon as the ring of cold cloud tops around it widened. Soon, the storm reached category 4 status and completed an increase in winds of 65 mph over a period of 24 hours. At the same time, outer bands swept across the Gulf coast of Louisiana and neighboring states, bringing strong winds and isolated tornadoes. Laura's intensity finally leveled out that evening just before landfall, with winds of 150 mph and a minimum central pressure near 938 mb. Just after midnight local time, the eye came ashore in southwestern Lousiana, bringing tremendous storm surge and wind. Its landfalling windspeed of 150 mph was the highest recorded for a Louisiana hurricane since 1856! Even Katrina had lower winds, though its pressure was lower and storm surge higher. In addition, the inundated area was primarily marshland and much less populated than the area Katrina had impacted 15 years prior.

Laura quickly weakened over land and lost hurricane status during the morning of August 27. Later that day, it moved northward into Arkansas. By this time, the radar presentation had degraded significantly. The system weakened to a tropical depression that evening and began a turn toward the east. It brought rain to Ohio Valley and ultimately the southern part of the mid-Atlantic, but impacts were minor. Laura became post-tropical early on August 29 and soon sped eastward into the open Atlantic.

The above image shows Laura at category 4 intensity on August 26.

Laura passed over nearly all of the Greater Antilles as a tropical storm without significant weakening. Once it was over warm waters, it became one of the fastest intensifying Gulf of Mexico hurricanes on record.

Tropical Storm Kyle (2020)

Storm Active: August 14-16

On August 13, thunderstorm activity associated with a broad area of low pressure near the North Carolina coastline showed some evidence of spin on radar imagery, though heavy rain remained offshore. Surprisingly, the disturbance quickly gained organization: the center of circulation moved offshore overnight and convection developed near the center of circulation. Some easterly shear kept the developing vortex a little tilted, but the system was strong enough to be designated Tropical Storm Kyle that afternoon. At that time, it was accelerating east-northeastward away from the coastline. Kyle continued piling on the named storm records for 2020; it was the earliest "K" storm, replacing Katrina of 2005, which formed on August 24 of that year.

The system was not very organized, as the center remained west of any thunderstorm activity. Further, upper-level winds caused the circulation to elongate east to west. Despite these difficulties, the warm Gulf Stream waters fueled some stronger sustained winds overnight, bringing them to 50 mph. Wind shear continued to increase and Kyle began extratropical transition that afternoon. The vorticity was so stretched out that additional deep convection overnight could not stall this transformation. The storm lost tropical status early on August 16. Within a few days, the remnants of Kyle merged with another extratropical low. The combined system strengthened explosively over the northeast Atlantic on August 18 and ultimately brought gale force winds to western Europe.

The above images shows Kyle just after classification as a tropical storm on August 14.

Despite forming close to land, Kyle moved quickly out to sea and did not have any impacts on land as a tropical cyclone.

Tropical Storm Josephine (2020)

Storm Active: August 11-16

On August 8, another member of the train of tropical waves exited Africa. It moved more slowly to the west than its July predecessors that became named storms; this is typical as trade winds lessen toward the end of summer. The next day, a broad low-pressure center formed. The disturbance surrounding the low was rather large and the center itself was initially elongated. Gradually, it overcame these obstacles and developed a concentrated blob of thunderstorm activity. By late on August 10, its only issue was wind shear out of the east, resulting in convection displaced north and west. Some new blow ups near the center on August 11 remedied this enough for the system to be classified Tropical Depression Eleven that afternoon.

Nighttime brought with it more thunderstorm activity, but there was little evidence of banding features until the morning of the 12th, when a spiral band developing looping outward north and east from the center. At the same time, wind shear lessened, but the storm had trouble maintaining persistent convection. Overnight, it turned west-northwest, and on August 13 was upgraded to Tropical Storm Josephine, the new earliest "J" storm. It claimed that record from Jose of 2005, which was named on August 22. Despite the upgrade, the storm spent most of the next couple days as a formless blob of convection. Also, the center likely reformed to the north during the day of August 14, sending the storm on a more northwest trajectory in the short-term.

Josephine made its closest approach to the Lesser Antilles on August 15, but it stayed far enough north that there were minimal impacts, especially since the storm had little rain in its southwest quadrant. Wind shear increased even more that day and set the storm on a weakening trend. During the morning of August 16, it was downgraded to a tropical depression, and shortly after it degenerated into a trough of low pressure. The remnants of Josephine brought some rain to Bermuda a little while after.

Josephine was a relatively small cyclone, shown above on August 13.

The tropical storm traveled over warm ocean waters its whole lifetime, but strong wind shear prevented significant strengthening and ultimately caused Josephine's demise.

Tropical Depression Ten (2020)

Storm Active: July 31-August 1

On July 29, a tropical wave moved off Africa, but unlike its predecessors, made little westward progress. Almost immediately, the system had a pronounced spin, but there was little thunderstorm activity north of the center. The disturbance drifted north-northwestward over the next few days and gradually became more organized. With a new flare up of central convection, the system became Tropical Depression Ten east of the Cape Verde islands.

Overnight, the depression made its closest approach to the islands, but it was small enough that it brought only a few showers to the easternmost part of Cape Verde. By August 1, the system was encountering cooler water and more stable air. Thunderstorm activity waned and the shallow system turned left toward the west. That night, the depression dissipated.

The above images shows the exposed center of Tropical Depression Ten on July 31 with a bit of thunderstorm activity off to the west-northwest.

Tropical Depression Ten was small and short-lived; it did not affect land.

Hurricane Isaias (2020)

Storm Active: July 29-August 4

On July 23, a large tropical wave exited Africa. It was perhaps the first of the season to really punch a hole in the dry Saharan air layer (SAL) to its north. The disturbance passed south of the Cape Verde Islands and pushed rapidly westward. Within a few days, the wave had a huge area of vorticity associated with it, but was highly disorganized. It's often the case that larger systems take longer to consolidate, and this was no exception. Though it developed a broad low pressure center, no well-defined center of circulation appeared for several days. At its fast clip, the outer rain bands of the tropical wave began to affect Barbados by July 28. By that time, tropical storm force winds were already occurring to the north of the center.

Overnight, the low passed over the Windward Islands at a remarkable 25 mph clip, bringing strong wind and heavy rains to nearly all the Lesser Antilles during that period due to its large size. As far as internal dynamics were concerned, the system was still struggling. Instead of a well-defined center of circulation, there was only a sharp trough axis oriented southwest to northeast, with competing mid-level vortices and convection clusters at each end. The large-scale cyclonic spin helped to turn the axis toward south to north on the 29th, but the system was still a mess on satellite imagery. It was only that evening that a new central area of thunderstorm activity formed atop a clear center and Tropical Storm Isaias was born, already packing 50 mph sustained winds. Not only did Isaias become the new earliest "I" storm (previous record-holder: Irene of 2005, which was named on August 7), but it also brought the number of named storms in July 2020 to 5, also tying an Atlantic record held by 2005.

Beginning later that day, the storm brought significant flooding and mudslides to Puerto Rico, the Dominican Republic, and some of the surrounding isles. The low-level center soon made landfall along the southern coast of the Dominican Republic, but the overall circulation was so large that the land encounter did not significantly disrupt the system. In fact, at the same time, a mid-level circulation moving east to west parallel to the northern coast became better defined. Soon, the surface center reformed under the nascent vortex and strengthening resumed. This is not to say interaction with Hispaniola did not affect Isaias at all: the central overcast became a bit separated from the eastern and southern portions of the circulation by a few tongues of drier air. Nevertheless, the detached bands pulled an immense amount of tropical moisture northward into the storm that fueled intense thunderstorms as well as the system's further development.

Overnight, Isaias moved northwestward into the Bahamas and strengthened into a category 1 hurricane. Some struggles with dry air caused the storm to level off in intensity on the 31st. Overnight, it peaked in intensity with 85 mph winds. The minimum pressure was 987 mb. Meanwhile, it continued northwestward at a fairly quick speed under the continuing influence of the neighboring subtropical ridge. During the morning of August 1, Isaias's center passed directly over Andros Island; around the same time, dry air, pushed into the circulation by upper-level winds out of the southwest, completely overcame the storm. A totally exposed center of circulation moved west-northwestward off of the island and nearly all convection was left on the other side of a north-south wall of low-humidity air. This caused Isaias to weaken back to a tropical storm that afternoon.

The storm continued to battle back, however, and convection blossomed again that evening. This sort of fluctuation continued, though less extreme, through the next few days. The shear persisted throughout and Isaias was not quick vertically stacked even thunderstorm activity was on the upswing: the mid-level center remained east of the low-level one. Fortunately for Florida, the system moved north-northwestward paralleling the coastline, and shear meant that the west half of the circulation was almost dry. Impacts to the state were confirmed to a few bad squalls. Late on August 2, the storm began to accelerate northward as it felt a cold front approach the U.S. east coast.

During the day of August 3, the interaction of the front with Isaias changed the shape of the storm: it took on the characteristic comma shape of a cyclone entering the mid-latitudes and the heaviest rainfall now fell northwest of the center. The outer bands of Isaias swept across South Carolina through the evening as the center approached. The inner core also recovered a bit from the latest intrusion of dry air and managed to build a more complete eyewall on radar. This resulted in the storm regaining hurricane strength.

Baroclinic forces (which are the mechanism by which non-tropical systems strengthen) also contributed to the intensification of Isaias: an anomalous jet stream out of the south fed unusually strong winds into the cyclone's eastern side a few thousand feet above ground. This phenomenon slowed the storm's weakening during and after landfall. Moreover, some of the winds mixed down to ground level, bumping up Isaias's intensity and matching its peak of 85 mph winds and a pressure of 988 mb. It maintained this through landfall just north of the Carolina border just before midnight. Isaias joined Bertha, Cristobal, Fay, and Hanna to become the earliest fifth named storm landfall in the United States on record.

By this time, the storm had begun to accelerate in earnest. On August 4, its forward speed exceeded 30 mph toward the north-northeast and it weakened back to a tropical storm. Nevertheless, rainfall totals of 3-6 inches (with isolated higher totals) were common along the storm track through the Carolinas and up the mid-Atlantic though Virginia, inland Maryland, and eastern Pennsylvania. Sporadic tornadoes broke out on the system's east side nearer to the coast. Isaias moved over the interior northeast and became post-tropical that evening. The remnant system brought rain and wind as far north as southern Quebec before dissipating.

The above image shows Isaias after achieving hurricane status for the first time on July 31st.

After moving across the tropical Atlantic as a tropical wave for nearly a week, Isaias was finally named in the Caribbean.

Hurricane Hanna (2020)

Storm Active: July 22-27

During the third week of July, a tropical wave moving through the Caribbean began to exhibit thunderstorm activity near its northern end over the Greater Antilles. Due to land interaction and wind shear, the disturbance did not develop further for the next few days. Around July 21, a broad surface low formed in the Florida straits, bring scattered storms to much of the eastern Gulf region and Florida. It slowly consolidated over the next day, ultimately becoming Tropical Depression Eight late on July 22.

A ridge over the southern U.S. kept the depression moving west-northwestward across the open Gulf of Mexico, though at a slow forward speed. On July 23, Eight's structure improved drastically and the central pressure dropped, but winds lagged behind. It wasn't until late that night that the storm was upgraded to Tropical Storm Hanna. Hanna added to the growing list of records set by its predecessors, becoming the earliest "H" storm. The previous record-holder was Harvey of 2005, which formed on August 3 of that year (not to be confused with the devastating Hurricane Harvey of 2017, which retired the name). At the time of naming, Hanna had vigorous convection in the southern and eastern semicircles, but the northwest struggled some with dry air. This led to the formation of a curious mid-level eye feature, even with the cyclone still a minimal tropical storm! The mid-level center was not yet vertically aligned with the surface circulation due to a bit of wind shear, so Hanna wasn't quite ready to strengthen more rapidly.

On July 24, the storm turned more to the west and filled in more in the northwest quadrant, leading to faster intensification. On top of extremely warm ocean waters, these favorable factors were enough to boost Hanna to hurricane status by the morning of July 25. By that time, tropical storm conditions were affecting the south Texas coastline, and a large eye became increasingly evident on satellite and radar imagery. Hanna's central pressure dropped steadily through the afternoon despite increasing proximity to land. It reached its peak intensity as a high-end category 1, with 90 mph winds and a central pressure of 973 mb, just before landfall in south Texas.

As it made landfall, Hanna took a dive to the west-southwest, angling towards northern Mexico. It weakened to a tropical storm and soon crossed the international border, but maintained an impressive radar signature throughout the next day. By the afternoon of the 26th, the storm weakened to a tropical depression. The next day it weakened to a remnant low and dissipated over the mountains of northern Mexico.

The above images shows Hanna at landfall in south Texas.

Hanna's slow track through the western Gulf of Mexico allowed it ample time to strengthen into a well-organized category 1 hurricane.

Tropical Storm Gonzalo (2020)

Storm Active: July 21-25

Around July 17, a tropical wave associated with a monsoonal trough of low pressure near the equator entered the Atlantic from the east. To its north, plentiful dust-laden air still streamed westward off of the Saharan desert over the ocean. For the first part of July, this Saharan air layer (SAL) contributed to a very dry tropical Atlantic and stifled the season's early tropical waves. This wave, however, stayed low in latitude and produced persistent shower activity as the trade winds guided it westward.

There was an elongated area of enhanced vorticity associated with the system for a few days, but no single circulation center. Some spin became apparent early on July 20, when a surface low formed. Though the circulation became better defined by the evening, thunderstorm activity was still a bit spotty and winds remained lackluster. The system entrained more moisture from the inter-tropical convergence zone (ITCZ) to the south on July 21, and strengthened a little, earning the designation Tropical Depression Seven late that afternoon. Organization steadily increased overnight, and the storm became Tropical Storm Gonzalo during the morning of July 22. Following in the footsteps of earlier storms of the 2020 season, Gonzalo was the earliest ever seventh named storm, beating out Gert of 2005, which formed July 24 of that year.

The steering pattern near Gonzalo was quite simple: a strong subtropical ridge to its north kept it traversing the 10°N parallel at a gradually increasing speed. Environmental factors were more mixed, however. Ocean temperatures were quite warm and wind shear was fairly low, but the SAL lurked to the north and the system was fighting dry air. That day, Gonzalo lost some of its outer banding features even as the inner core improved and it strengthened some. The small cyclone peaked at 65 mph winds and a pressure of 997 mb that night, but the central dense overcast promptly collapsed a few hours later as dry air invaded Gonzalo. The storm ejected a blob of convection to the west, but the circulation was nearly bare apart from that by the morning of the 23rd, leading to some weakening.

A small shield of thunderstorm activity made a comeback later that day, once again covering the center of circulation, but the weakening trend continued throughout the next couple of days as the central pressure rose. Meanwhile, Gonzalo's westward motion had hastened, making it more difficult for the cyclone to maintain a closed circulation. During the morning of July 25, Gonzalo made landfall in Trinidad as a minimal tropical storm and weakened to a tropical depression shortly after. Land interaction further sealed the cyclone's demise and what was left of the circulation dissipated that afternoon. Though fast moving, Gonzalo brought heavy rain to portions of the southern Windward Islands and northern Venezuela. After dissipation, the remnant tropical wave continued west-northwestward through the eastern Caribbean.

The above images shows Gonzalo over the open tropical Atlantic. Despite warm waters, dry air and stable air eventually overwhelmed the small cyclone.

Gonzalo took an unusually southern track, ultimately affecting South America.

Tropical Storm Fay (2020)

Storm Active: July 9-11

On July 4, a disturbance that had brought heavy downpours to Louisiana dipped southward into the Gulf of Mexico. Though a surface low formed over water, it was weak and moved northeast back over land without any tropical development. Over the next few days, it moved inland across Georgia and South Carolina. By July 8, the broad circulation began to feel the approaching Atlantic waters and generated large areas of thunderstorm activity offshore. By that evening, the system had moved over the ocean just off the border of the Carolinas, but it lacked organization.

The morning of July 9 saw the formation of a surface vortex, but convection still lay off to the northeast of the center, precluding tropical cyclone development. It wasn't until a new center of circulation took over under the thunderstorms near Cape Hatteras that afternoon that the system became organized enough to be classified. Aircraft data indicated the presence of tropical storm force winds east of the center, so the disturbance was designated Tropical Storm Fay. Upon formation, Fay continued the streak of broken records by becoming the earliest "F" storm recorded. The previous record was Tropical Storm Franklin of 2005, which formed on July 21.

While over the northern edge of the Gulf Stream, Fay managed to develop deeper convection that night, resulting in some modest strengthening. Soon, however, the center moved over colder waters and dry air invaded the circulation, displacing thunderstorm activity away from the center to the north or southeast. Fay reached a peak intensity of 60 mph winds and a pressure of 998 mb during the morning of July 10 as it approached the mid-Atlantic coastline. Well before landfall, heavy rains spread across the northeast. That afternoon, the cyclone's center crossed the coast in southern New Jersey. Once inland, Fay decayed rapidly and lost tropical characteristics by early on July 11 over New England. Later that day, the vortex was absorbed by another system approaching from the west.

The above image shows Fay a few hours before landfall in New Jersey. The cyclone had taken on a "hybrid" appearance between tropical and subtropical, with comparatively little cloud cover near the center of circulation.

Fay took a rather unusual track up the east coast: rather then veering east, it moved nearly due northward during its time as a tropical cyclone.

Tropical Storm Edouard (2020)

Storm Active: July 4-6

On July 3, a low pressure system formed along a stationary front northeast of the Bahamas. Though atmospheric conditions were only marginally favorable, the small system managed to organize quickly and become Tropical Depression Five the next morning. Sandwiched between a ridge to the south and a trough to the north, the depression was steered rapidly east-northeastward. Very early on July 5, Five passed Bermuda, making its closest approach just northeast of the island. Thunderstorm activity at the time was minimal, however, so the island experienced little more than gusty winds and showers.

There was a resurgence of deep convection that evening and winds increased to tropical storm force, prompting the naming of Tropical Storm Edouard. With this upgrade, Edouard became the earliest "E" storm ever in the Atlantic, surpassing 2005's Hurricane Emily, which was named on July 11. The cyclone did not have much time as a tropical storm, however, as it accelerated northeast and began extratropical transition on July 6. By late that afternoon, the still vigorous system had merged with a nearby frontal boundary roughly 500 miles southeast of Newfoundland.

Edouard was a fast-moving and short-lived storm that took a typical track northeastward across the subtropical Atlantic.

The above image shows the track of Edouard, including the progress of its extratropical remnant across the ocean toward Europe.