 Hurricane Marco approachingLouisiana at peak intensity on August 23 | |
| Meteorological history | |
|---|---|
| Formed | August 20, 2020 |
| Remnant low | August 25, 2020 |
| Dissipated | August 26, 2020 |
| Category 1 hurricane | |
| 1-minute sustained (SSHWS/NWS) | |
| Highest winds | 75 mph (120 km/h) |
| Lowest pressure | 991mbar (hPa); 29.26 inHg |
| Overall effects | |
| Fatalities | None |
| Damage | >$35 million (2020USD) |
| Areas affected | Central America, westernCaribbean,Yucatán Peninsula,Gulf Coast of the United States |
IBTrACS /[1] | |
Part of the2020 Atlantic hurricane season | |
Hurricane Marco was the first of twotropical cyclones to threaten theGulf Coast of the United States within a three-day period. The thirteenthnamed storm and third hurricane of the record-breaking2020 Atlantic hurricane season, Marco developed from a fast-movingtropical wave west of theWindward Islands and south ofJamaica on August 20. The fast motion of the wave inhibited intensification initially, but as the wave slowed down and entered a more favorable environment, the system developed into a tropical depression, which in turnrapidly intensified into a strong tropical storm. Due to strongwind shear, Marco's intensification temporarily halted. However, after entering the warm waters of theGulf of Mexico on August 23, Marco briefly intensified into a hurricane, only to quickly weaken later that evening due to another rapid increase in wind shear. Marco subsequently weakened to a tropical depression before degenerating into aremnant low early the next morning. Marco's remnants subsequently dissipated on August 26.
Heavy rains across theYucatán Peninsula caused river rises and flooding throughout the region. One person was indirectly killed inTapachula, Mexico, due to the storm, although this was not included in the official death toll. Impacts in theUnited States were generally minor, as the storm was considerably weakened by the time it impacted the Gulf Coast. Marco did not make landfall, turning parallel to the U.S. coastline, unlike subsequentHurricane Laura.
Extratropical cyclone, remnant low, tropical disturbance, or monsoon depressionAt 00:00 UTC on August 16, theNational Hurricane Center (NHC) began monitoring a westward-movingtropical wave over the Central Atlantic that had the potential for development.[2][3] The disturbance quickly moved westward at a speed over 20 mph (32 km/h), which initially limited its development as it passed through theWindward Islands and into theCaribbean Sea. The system slowed down and gradually organized south of theGreater Antilles on August 19.[4] By 15:00 UTC on August 20, satellite imagery revealed that the wave had developed a well-defined low-level center, prompting the NHC to designate itTropical Depression Fourteen, forming after Tropical Depression Thirteen which would becomeHurricane Laura.[5][6] Post-storm analysis found that the system formed nine hours earlier at 06:00 UTC.[3] At the time the system was located 235 miles (378 km) east of theNicaragua–Honduras border.[5] The storm continued westward towardHonduras, before making a sharp turn northward. Despite favorable conditions, the storm initially failed to intensify, with pulsing convection around a poorly defined center. Eventually, the storm's center became better defined and a small but persistent cluster of convection formed over it. This allowed the depression to intensify, and the NHC upgraded the system toTropical Storm Marco in the northwest Caribbean at 00:00 UTC on August 22.[3] This was the earliest 13th named storm ever recorded in the Atlantic basin, breaking the record set byHurricane Maria of2005 by 11 days.[7]
Marco was able to strengthen quickly as a small system, reaching its initial peak intensity of 65 mph (100 km/h) and 992 mbar (29.29 inHg) just 18 hours after being named,[3] with an almost closed eyewall being observed by Hurricane Hunters.[8][9] Contrary to prior predictions, Marco's track was shifted eastward at the 21:00 UTC advisory on August 22, as the system moved north-northeastward instead of north-northwestward, introducing the possibility of successive landfalls around Louisiana from bothLaura and Marco.[9][10] An increase of southwesterly wind shear brought an abrupt end to the strengthening trend, as Marco moved through theYucatán Channel, with the storm's minimum central pressure rising slightly and the eyewall mostly dissipating as the storm took on a sheared appearance.[11] This weakening period proved to be short-lived, as the shear relaxed somewhat when Marco moved into the warm waters of theGulf of Mexico on August 23. Slow but steady strengthening resumed and data from anotherHurricane Hunter reconnaissance aircraft discovered sustained winds at hurricane strength in the northeastern eyewall.[12] Marco strengthened into a Category 1 hurricane at 12:00 UTC on August 23, and simultaneously reached its peak intensity with 1-minute sustained winds of 75 mph (120 km/h) and a minimum central pressure of 991 mbar (29.26 inHg).[3]
This strengthening proved to be short-lived, however, as upper-level wind shear increased again over the storm.[13] This caused Marco to weaken back to a tropical storm by 00:00 UTC on August 24,[3] and the center of circulation became displaced from the storm's convection.[14] Wind shear continued to plague the system as it turned westward near theLouisiana coastline, and Marco rapidly weakened to minimal tropical storm strength by 18:00 UTC.[15] At 00:00 UTC on August 24, Marco passed just south ofthe mouth of the Mississippi River, with 1-minute sustained winds at 40 mph (65 km/h) and a central pressure of 1,006 mbar (29.71 inHg), although the strongest winds were displaced in convection that was over waters well northeast of the storm's center.[3] Operationally, the NHC said that the storm made landfall here, but that was changed in post-storm analysis because of data from weather stations inSouthwest Pass indicating that Marco stayed offshore.[3][16] Afterward, Marco weakened further and fell to tropical depression intensity just offshore of Louisiana, nearGrand Isle, at 03:00 UTC on August 25, before degenerating into aremnant low three hours later.[3][17][18] The remnant low continued to spin down as it slowly moved westward along the Louisiana coastline, ahead of the approachingHurricane Laura, before opening up into a trough at 00:00 UTC on the next day.[3]
Honduras issued tropical storm watches along its coastline whenTropical Depression Fourteen was designated, before quickly upgrading to warnings hours later.[3] Tropical Storm Watches, and later Tropical Storm Warnings and Hurricane Watches, were also issued for the eastern side of theYucatán Peninsula, as the storm was first predicted to move over the peninsula as a strong tropical storm.[19][20] When Marco moved to the north instead of northwest, a Tropical Storm Warning was issued by theGovernment of Cuba for thePinar del Río Province and theIsle of Youth.[21][22]
Tropical Storm, Hurricane, and Storm Surge Watches were issued inLouisiana,Mississippi, andAlabama when Marco's forecast track shifted significantly eastward on August 22.[23] Many of these watches were upgraded to warnings as the storm continued its approach.[21] In the state ofTexas, thePadre Island National Seashore closed on August 22 in preparation for the hurricane.[24] In Mississippi, mandatory evacuation orders were in place on August 23 at theGulfport andBiloxi marinas and the harbor inLong Beach.[25] All boats were ordered to be moved by sundown that same day.[26] In Gulfport, the fuel dock was closed.[27] However, all the warnings were eventually downgraded and canceled when the storm rapidly weakened as it approached the coast.[21] Six hundred additional resources from were requested fromAlabama Power,Georgia Power, and other power crews to help restoration efforts.[28] Atornado watch was issued for southeast Alabama, theFlorida Panhandle,Southwest Georgia, and United States coastal waters at 20:40 UTC on August 24.[29]
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TheInstituto Meteorológico Nacional of Costa Rica reported that heavy rain from the indirect effects of Marco affected parts of the country for three days. InSanta Cruz,Guanacaste Province, accumulations reached 17.0 in (431 mm), more than twice the average August rainfall of 9.1 in (231 mm). Areas in and around Santa Cruz reportedflooding.[30]
InMexico, an indirect death occurred inTapachula,Chiapas. Despite this, the NHC did not attribute Marco to any deaths in their post-storm report.[3] Rainfall totals were as high as 186.4 millimeters (18.64 cm), with the statesVeracruz,Oaxaca, andChiapas worst affected by heavy rains.[31] In some municipalities ofChiapas, such asTapachula,Escuintla andAcacoyagua, growth of rivers from nearby mountains led to flooding.[32] Losses in Mexico and Costa Rica were estimated byAon to be in the "tens of millions" (USD).[1]
While traversing the Yucatán Channel, Marco brought heavy rain to parts ofPinar del Río Province in Cuba on August 23. The town of Isabel Rubio saw the greatest accumulations at 3.8 in (97 mm) of rainfall.[33] Minor flooding occurred inMantua andSandino. A few trees were uprooted during the storm.[34]
Due to the sheared nature of the storm as it passed just offshore of theUnited States, rain bands extended as far northeast asVirginia. Atornado warning was issued for a storm just northeast ofPanama City, Florida. Another tornado warning was issued for a storm nearCharleston, South Carolina.[35] Numerousspecial marine warnings were also issued due to possiblewaterspouts.[36] However, no tornadoes nor waterspouts were confirmed. Rainfall totals were highest along theFlorida Panhandle, peaking at 13.17 inches (335 mm) nearApalachicola on Monday morning.[3] Several roadways and a hotel were flooded inPanama City Beach that evening as well.[37][38] Heavy rainfall extended much further inland withflash flood warnings being issued as far northeast as theNorth Carolina—Virginia border.[39] Due to Marco being much weaker than anticipated, no wind damage occurred and the peak wind gust from the storm was only 38 mph (61 km/h), which was recorded inPetit Bois Island, Mississippi.[37] The remnants of the storm brought heavy rainfall and flash flooding to SoutheasternOklahoma on August 26 before dissipating.[40] Overall, Marco caused at least $25 million USD in insured losses throughout the impacted areas, as estimated by Aon.[1]
