This article is about extratropical cyclones. For tropical cyclones, see Rapid intensification.

The Braer Storm of January 1993 explosively deepened to a

record low of 913 mbar (hPa)

GKHJVHGVSH CFYCMBXKDIHJCFHXVN BCXMKXDIJFDHXCVNB 004DSLKDSJCHFXN BMFGDCFXHVCKFHGHDEFKVLB

VMNBCDSHYDESFDVK t $125 billion in late August 2005, particularly in the city of New Orleans and its surrounding area. It is tied

d
with Hurricane Harvey as being the tages, uprooted

deep atmospher
ic convection as
it trekked across
the tropical
eastern Atlantic.
With time,
showers and
thunderstorms
began to
increase within
the wave,
although no
distinct
circulation
center was
detected. Early
[1]

on October 1,
the National
Hurricane
Center (NHC)
began to
monitor the
tropical wave
moving into
the Eastern
Caribbean for
potential tropical
cyclogenesis. [3]

As the system
moved across
the Lesser
Antilles,
thunderstorm
activity
fluctuated,
inhibited from
development by
moderate vertic
al wind
shear and dry
air intrusion. At
18:00 UTC on
October 4,
analysis
of satellite
imagery and sc
atterometer dat
a found a well-
defined
circulation
center
sustaining
sufficiently-
organized deep
convection,
marking the
formation of
Tropical
Depression
Twenty-Six
about 100 mi
(170 km) south
of Kingston,
Jamaica.
Convection
continued to
increase after
formation, but
was initially
confined to the
southern portion
of the circulation
due to northerly
wind shear.
Once the shear
lessened on
October 5,
convection
became more
symmetric
around the
center, and the
system
strengthened to
become
Tropical Storm
Delta by
12:00 UTC that
day about
150 mi (240 km)
south-southwest
of Montego Bay,
Jamaica. [1]
While
accelerating
west-
northwestward
over the
Western
Caribbean
along a
building subtropi
cal ridge to its
north and
northeast, Delta
commenced a
phase of rapid
intensification o
ver ideal
environmental
conditions
encompassing
warm seas, low
wind shear, and
high levels of
moisture aloft,
becoming a
Category 1
hurricane 12
hours after
being named.
[1]
As it finally
began to turn
northwestward
early on
October 6, Delta
reached
Category 2
status just nine
hours later at
09:00 UTC, bef
[4]

ore becoming a
Category 3
major hurricane
three hours later
at 12:00 UTC.
[1]
Delta's
intensification
was described
as the fastest in
a 24-hour
period
since Hurricane
Wilma of 2005. [5]

The storm was

characterized
as a very
symmetric and
compact system
as a
pinhole eye beg
an to form. At
[6]

15:20 UTC,
an NOAA
hurricane
Hunter aircraft
indicated that
the storm's 1-
minute
sustained wind
speed was at
130 mph
(210 km/h),
making Delta a
Category 4
hurricane. Delt
[7]

a intensified
from a tropical
depression to
Category 4
hurricane in just
over 36 hours,
breaking the
record of 42
hours
that Hurricane
Keith set
in 2000. Meas
[8]

ured at 4
nautical miles
(4.6 mi; 7.4 km)
in width, the eye
was slightly
larger than the
smallest eye
ever observed
in Hurricane
Wilma in 2005. [9]
 Delta nearing its secondary peak intensity east of Texas on
October 8

Delta attained
its peak
intensity by
18:00 UTC
with maximum
sustained
winds of
140 mph
(220 km/h) and
a barometric
pressure of
953 mbar
(28.14 inHg).
Delta had
intensified by
105 mph
(165 km/h) in
over 36 hours,
which only four
other tropical
cyclones had
been able to
achieve since
the satellite era.
At this time,
Delta exhibited
its pinhole eye
surrounded by
very intense
deep
convection. Its
[1]

pressure was
unusually high
for a storm this
strong, which
indicated that
Delta's
circulation did
not extend as
far into the
upper troposphe
re as would be
expected for a
storm of its
intensity.
Additionally, the
storm's eye was
barely visible on
visible satellite
imagery,
although it was
seen
on microwave
images. Delta
did not keep this
intensity for very
long as an
increase in mid-
level wind
shear and dry
air entrainment
significantly
disrupted
Delta's small
core, and the
storm abruptly
weakened with
its banding
features becomi
ng less defined
and its eye
completely
disappearing. [10]

The storm
accelerated
northwestward
and at around
05:45 UTC on
October 7,
made landfall at
Puerto
Morelos, Quinta
na Roo, Mexico,
as a high-end
Category 2
storm with
winds of
110 mph
(180 km/h). It
subsequently
weakened some
more as it
moved over
the Yucatán
Peninsula and
into the Gulf of
Mexico as a
Category 1
hurricane. The
storm remained
well-organized
throughout its
passage over
the peninsula,
situating over
conducive
atmospheric
and oceanic
conditions; as
such, Delta
again
intensified. [1]

Satellite
imagery
revealed
a central dense
overcast as the
system
gradually
intensifies into a
Category 2
hurricane at
06:00 UTC of
October 8.
[11]
Delta steadily
became more
organized, with
an eye
occasionally
becoming
evident on
satellite imagery
and a lowering
minimum
central pressure
as it turned
northward
ahead of an
approaching tro
ugh to its
northwest. Del
[12]
ta regained
Category 3
status by
18:00 UTC
about 230 mi
(370 km) south
of the Texas–
Louisiana
border. Early on
October 9, Delta
attained its
secondary peak
intensity with
sustained winds
of 120 mph
(195 km/h) and
a central
pressure of
953 mbar
(28.14 inHg).
The storm held
the intensity
overnight until
an increase of
southwesterly
wind shear and
a decrease
in ocean
heat weakened
it over the
northern Gulf of
Mexico into a
Category 2
hurricane at
18:00 UTC. As
an asymmetrical
storm, Delta
made another
landfall
near Creole,
Louisiana at
23:00 UTC with
winds of
100 mph
(155 km/h).
After that, Delta
began to
weaken more
rapidly,
dropping to
Category 1
status an hour
after landfall at
00:00 UTC on
October 10 and
a tropical storm
six hours later.
It accelerated
northeastward
and transitioned
into
an extratropical
cyclone over W
estern
Mississippi by
18:00 UTC. The
system
continued to
weaken and its
circulation
broadened
through the day
on October 11,
and by 00:00 on
October 12, it
opened into
a trough of low
pressure over
the southeaster
n United States.
[1]
Preparations
[edit]

Cayman Islands and Cuba

Hurricane Zeta

[edit]

Main article: Hurricane Zeta

Category 3 hurricane (SSHWS)

Duration October 24 – October 29

Peak intensity 115 mph (185 km/h) (1-min);

970 mbar (hPa)

The interaction of a tropical wave and a midlevel trough led to the formation of Tropical Depression Twenty-Eight on October 24
near Grand Cayman. It quickly intensified into Tropical Storm Zeta, and reached hurricane status on October 26. That day, Zeta
made landfall near Ciudad Chemuyil, Quintana Roo, with winds of 85 mph (135 km/h). After weakening to a tropical storm inland,
Zeta moved offshore of the northern coast of the Yucatán Peninsula about 11 hours later. On October 28, it reattained hurricane
status as it turned northward. Zeta peaked later that day at 21:00 UTC when it became a Category 3 major hurricane with maximum
sustained winds of 115 mph (185 km/h) and a minimum barometric pressure of 970 mbar (29 inHg), as it made its second landfall
near Cocodrie, Louisiana. Zeta steadily lost strength after landfall, weakening to a tropical storm over Alabama at 06:00 UTC on
October 29, before transitioning into a post-tropical cyclone over central Virginia by 18:00 UTC that day, while moving rapidly
northeastward. Early on October 30, Zeta's remnants dissipated east of the mid-Atlantic U.S. coast.[45]

Heavy rain in Jamaica caused a landslide that killed two people after demolishing a home in Saint Andrew Parish. Zeta left roughly
$15 million in damage on the island.[45] Strong winds and rain caused flooding and

The emergency response from federal, state, and local governments was widely criticized, leading to the resignation of Federal
Emergency Management Agency (FEMA) director Michael D. Brown and New Orleans Police Department (NOPD)
superintendent Eddie Compass. Many other government officials faced criticism for their responses, especially New Orleans
mayor Ray Nagin, Louisiana governor Kathleen Blanco, and President George W. Bush. However, several agencies, such as
the United States Coast Guard (USCG), National Hurricane Center (NHC), and National Weather Service (NWS), were commended
for their actions, with the NHC being p

" a "maritime, cold season event".[10][12]

In early 2023 in the North Atlantic, fourteen wind events out of twenty that had reached hurricane-force, underwent bombogenesis,
the process that creates a bomb cyclone, according to National Oceanic and Atmospheric Administration (NOAA).[16] NOAA said that
bombogenesis "occurs when a midlatitude cyclone rapidly intensifies, dropping at least 24 millibars over 24 hours."[16]

Formation
[edit]

Baroclinic instability has been cited as one of the principal mechanisms for the development of most explosively deepening
cyclones.[17] However, the relative roles of baroclinic and diabatic processes in explosive deepening of extratropical cyclones have
been subject to debate (citing case studies) for a long time.[18] Other factors include the relative position of a 500-hPa trough
and thickness patterns, deep tropospheric frontogenetic processes which happen both upstream and downstream of the surface
low, the influence of air–sea interaction, and latent heat release.[19]

Regions and motion

[edit]

Absorbing the remnants of a powerful tropical cyclone can trigger

explosive cyclogenesis

The four most active regions where extratropical explosive cyclogenesis occurs in the world are the Northwest Pacific, the North
Atlantic, the Southwest Pacific, the South Atlantic and the Eastern Pacific. [20]

In the Northern Hemisphere the maximum frequency of explosively deepening cyclones is found within or to the north of the
Atlantic Gulf Stream, the Kuroshio Current in the western Pacific,[10] and in the eastern Pacific. In the Southern Hemisphere it is
found with Australian east coast lows above the East Australian Current, which shows the importance of air-sea interaction in
initiating and rapidly developing extratropical cyclones.[21]

Explosively deepening cyclones south of 50°S often show equator-ward movement, in contrast with the poleward motion of most
Northern Hemisphere bombs.[19] Over the year, 45 cyclones on average in the Northern Hemisphere and 26 in the Southern
Hemisphere develop explosively, mostly in the respective hemisphere's winter time. Less seasonality has been noticed in bomb
cyclogenesis occurrences in the Southern Hemisphere.[19]

Other uses of "weather bomb"

[edit]

The term "weather bomb" is popularly used in New Zealand to describe dramatic or destructive weather events. Rarely are the
events actual instances of explosive cyclogenesis, as the rapid deepening of low pressure areas is rare around New Zealand. [22]
[23]
This use of "bomb" may lead to confusion with the more strictly defined meteorological term. In Japan, the term bomb cyclone (爆弾
低気圧, bakudan teikiatsu) is used both academically and commonly to refer to an extratropical cyclone which meets the
meteorological "bomb" conditions.[24][25]

The term "bomb" may be somewhat controversial. When European researchers protested that it was a rather warlike term, Fred
Sanders, the coauthor of the paper which introduced the meteorological usage quipped: "So why are you using the term 'front'?" [26]

See also
[edit]
 Weather portal

 Cyclogenesis, extratropical cyclones

 Extratropical cyclone, formation
 Notable non-tropical pressures over the North Atlantic
 Superstorm
References
[edit]

1. ^ Jump up to:a b "Fierce 'weather bomb' batters Britain". The Telegraph. 9 December 2011. Archived from the original on 9 December
2011. Retrieved 21 March 2013.
2. ^ "The worst storm in years?". Met Office Blog. 28 January 2013. Retrieved 21 March 2013.
3. ^ Edwards, Tim (10 December 2014). "Weather bomb: the storm phenomenon brewing over Britain". The Week. London, United
Kingdom: Dennis Publishing. Retrieved 21 November 2024.
4. ^ O'Hanlon, Larry (25 February 2013). "Look out -- 'meteorological bomb' is on the way!". NBC News. Retrieved 21 March 2013.
5. ^ Jump up to:a b Williams, Jack (20 May 2005). "Bomb cyclones ravage northwestern Atlantic". USA Today. Retrieved 22 March 2013.
6. ^ Feltman, Rachel (3 January 2018). "What the heck is a bomb cyclone?". Popular Science. Retrieved 6 January 2018.
7. ^ "Ryan explains Bomb Cyclogenesis". WBRZ News 2 Louisiana. Archived from the original on 12 April 2013. Retrieved 21 March 2013.
8. ^ Freedman, Andrew (1 March 2013). "Meteorological bomb explodes over New England". Washington Post. Archived from the original on
December 24, 2013. Retrieved 21 March 2013.
9. ^ Rodman, Kristen (23 January 2014). "What is Bombogenesis?". Accuweather. Retrieved 31 January 2014.
10. ^ Jump up to:a b c d e f Sanders, Frederick; Gyakum, John R (1980). "Synoptic-Dynamic Climatology of the 'Bomb'". Monthly Weather
Review. 108 (10): 1589–606. Bibcode:1980MWRv..108.1589S. doi:10.1175/1520-0493(1980)108<1589:SDCOT>2.0.CO;2.
11. ^ Chelsea Harvey (November 10, 2014). "Here's What Caused The 'Bomb Cyclone' That's About To Freeze The Northern US". Business
Insider. Retrieved October 8, 2017.
12. ^ Jump up to:a b "Bomb". American Meteorological Society. Glossary of Meteorology. 20 February 2012. Retrieved 27 December 2023.
13. ^ Jump up to:a b "The Bomb". blog.ametsoc.org. 27 October 2010. Retrieved 21 March 2013.
14. ^ MacDonald, Bruce C; Reiter, Elmar R (1988). "Explosive Cyclogenesis over the Eastern United States". Monthly Weather
Review. 116 (8): 1568–86. Bibcode:1988MWRv..116.1568M. doi:10.1175/1520-0493(1988)116<1568:ECOTEU>2.0.CO;2.
15. ^ Baker, Laura (2024). Sting Jets in Extratropical Cyclones (Ph.D.). University of Reading.
16. ^ Jump up to:a b "What is bombogenesis?". US Department of Commerce and National Oceanic and Atmospheric Administration. n.d.
Retrieved 27 December 2023.
17. ^ Weng, H. Y.; Barcilon, A. (1987). "Favorable environments for explosive cyclogenesis in a modified two-layer Eady model". Tellus
A. 39A (3): 202–214. Bibcode:1987TellA..39..202W. doi:10.1111/j.1600-0870.1987.tb00301.x.
18. ^ Fink, Andreas H.; Pohle, Susan; Pinto, Joaquim G.; Knippertz, Peter (2012). "Diagnosing the influence of diabatic processes on the
explosive deepening of extratropical cyclones" (PDF). Geophysical Research Letters. 39 (7):
n/a. Bibcode:2012GeoRL..39.7803F. doi:10.1029/2012GL051025. Retrieved 2 June 2013.
19. ^ Jump up to:a b c Lim, Eun-Pa; Simmonds, Ian (2002). "Explosive Cyclone Development in the Southern Hemisphere and a Comparison
with Northern Hemisphere Events". Monthly Weather Review. 130 (9): 2188–2209. Bibcode:2002MWRv..130.2188L. doi:10.1175/1520-
0493(2002)130<2188:ECDITS>2.0.CO;2.
20. ^