A cold front moved into the northwestern Caribbean on 9
November, followed by an abnormally strong high pressure system
which dominated the eastern United States. The front became
nearly stationary and interacted with a series of westward moving
tropical waves.
The Intertropical Convergence Zone (ITCZ) became
active in the southwestern Caribbean as monsoonal southwesterly
flow from the eastern Pacific reached the area. As early as 13
November, surface analysis showed a weak low pressure area just
north of Colombia and, by the next day, there was a well-defined
but broad low-level circulation between Jamaica and Honduras. At
that time, the system did not meet the criteria for tropical depression
status because the convection was not concentrated nor
organized near a center
of circulation. In fact, there were
several smaller centers of circulation embedded within a much
larger system. The broad area of low pressure drifted northward
for a couple of days, and in combination with a high pressure
system over the United States, produced gale force
winds over Florida, Cuba, the Bahamas and the Gulf of Mexico.
The convection gradually became organized south of Jamaica
and a post-analysis of the surface and reconnaissance aircraft
data indicates that the system became a tropical depression at
1800 UTC November 16. The poorly-defined tropical depression
moved generally southward and encountered a much better upper-level
environment for strengthening. It became a tropical storm
at 0600 UTC 19 November and then moved on a slow east-northeast
track. Marco briefly reached hurricane
status at 0600 UTC 20 November with maximum winds of 65 knots and a minimum
pressure of 983 mb. Thereafter, Marco was hit by strong upper-level
westerlies and weakened rapidly to a tropical depression at 1800
UTC 23 November. It was then located just to the southeast of
Jamaica.
Once a middle-level ridge rebuilt over the Bahamas and Florida,
Marco turned toward the west and west-northwest and regained
tropical storm strength. The tropical cyclone
was south of the western tip of Cuba when it interacted with a cold front and
dissipated by 1800 UTC 26 November. The remnants of Marco drifted
southward and produced heavy rains over Honduras and Belize.
Marco was characterized by its numerous intensity
fluctuations. For several consecutive days, Marco became
disorganized during the afternoon when the low-level center was
practically exposed and there was an increase in the central
pressure. This was followed by a significant redevelopment of the
convection and a drop in pressure during the nights and early
mornings. These fluctuations could be attributed to the
interaction of Marco with a series of fast moving shortwave
troughs and ridges observed on water vapor imagery. These
features increased and relaxed the shear while moving through the
area.
Marco was upgraded to a hurricane based on a 63-knot 1-min sustained wind reported by a U.S. Navy ship. Shortly thereafter, a reconnaissance plane reported a minimum pressure of 983 mb and 1-sec wind of 89 knots. This was a significant pressure drop of 11 mb in 1 h and 40 minutes. During that flight, the crew reported a volatile center structure with severe turbulence, extreme rainfall and hail. Satellite images showed very cold convective tops at that time. During the early morning flight of 22 November, the reconnaissance plane observed another pressure drop from 996 to 985 mb in about 2 hours, and a 5 n mi diameter eye. The vessel PFAS reported sustained winds of 56 knots and a pressure of 1007.5 mb at 1200 UTC 25 November. This observation was used to operationally upgrade Marco to a tropical storm for the second time.
Marco never hit land but its large circulation brought heavy rains to Central America and Hispaniola. These rains produced floods and mud slides causing at least eight deaths. The interaction of Marco during its developing stage with a strong high over the U.S. resulted in gale force winds which produced beach erosion along the east coast of Florida.