Tropical Storm Patricia (2009)
Encyclopedia
Tropical Storm Patricia was a short-lived tropical cyclone
that briefly affected parts of Baja California Sur
before rapidly degenerating over water. Developing from a tropical wave
that traversed the Atlantic Ocean during September 2009, Patricia was first classified as a tropical depression on October 11 several hundred miles south of the Baja California Peninsula
. The system quickly intensified into a tropical storm as it tracked in a general northward direction. By October 12, Patricia attained its peak intensity with winds of 60 mph (95 km/h) and a minimum barometric pressure of 996 mbar (hPa; 29.41 inHg). The following day, increasing wind shear
and unfavorable conditions caused the storm to rapidly weaken. By the morning of October 14, Patricia had degenerated into a non-convective
remnant low pressure area
near the southern coastline of Baja California Sur
. The remnants of the storm peristed until October 15, at which time they dissipated over open waters.
Although the center
of Patricia did not impact land, the outer bands
caused significant rainfall in portions of western Mexico. In Sonora
, up to 240 mm (9.4 in) of rain fell, leading to significant flooding that left 600 people homeless. Other Mexican states received similar impact. Overall, the effects of Patricia were minor and resulted in no loss of life.
that moved off the west coast of Africa on September 23, 2009. Two days later, Tropical Depression Eight developed from the wave over the eastern Atlantic Ocean
. The depression tracked northwestward, while the wave continued a steady westward track. By October 6, the system crossed Central America
and entered the eastern Pacific Ocean
. Gradual development took place over the following several days with widespread, scattered convection
consolidating around a developing area of low pressure
. On October 11, a well-defined circulation had formed and the National Hurricane Center
(NHC) estimated that it developed into a tropical depression roughly 405 mi (650 km) south-southeast of the southern tip of Baja California Sur
.
Several hours later, the system further strengthened into a tropical storm and was named
Patricia. The low-level circulation
became embedded within very deep convection and further intensification was anticipated. Patricia tracked north-northwest in a region of low to moderate wind shear
, under the steering currents of a strong ridge of high pressure
to the east and a trough
located northwest. Although over warm sea surface temperature
s, relatively stable air prevented substantial intensification. By the late morning of October 12, the overall extent of cloud cover had increased but the center became less defined, described as "sloppy" by NHC forecaster Todd Kimberlain. Later that day, Patricia attained its peak intensity as a moderately strong tropical storm with winds of 60 mph (95 km/h) and a minimum barometric pressure of
996 mbar (hPa; 29.41 inHg).
The storm maintained this intensity for several hours as its central dense overcast remained intact despite increasing wind shear. However, the NHC stated that there was a 20% chance of the storm becoming a hurricane within 24 hours based on climatological factors and the average forecast intensity errors. However, this did not take place. The combination of moderate wind shear and a stable environment caused Patricia to rapidly weaken on October 13. The storm's cirrus
outflow
became weak in all directions and convection diminished. Later that day, convective developed ceased to occur as the storm neared the south tip of Baja California Sur
. Early on October 14, Patricia degenerated into a remnant low pressure area
, bypassing tropical depression status, roughly 30 mi (50 km) south of the Baja California Peninsula. The remnant low turned westward and tracked over open waters before dissipating on October 15.
for areas along Baja California Sur
between La Paz and Santa Fe. The following day, the watch was upgraded to a tropical storm warning for areas between Buenavista and Agua Blanca. However, the storm's rapid decay on October 14 allowed the watches and warnings to be discontinued. Officials in the threatened region began preparing by closing schools and opening 159 shelters on October 12. The Civil Protection Department was prepared to evacuate residents in low-lying area if necessary. Resorts and hotels cancelled all outdoor activities and brought all loose objects indoors. The city of Los Cabos was placed under a state of emergency
as flooding rains were forecast to impact the area. Ports in the region were also shut down due to rough seas.
The storm's quick deterioration led to significantly less impact than anticipated. High waves affected the coastlines of Baja California Sur, Sinaloa and Nayarit. Parts of Sinaloa
also recorded heavy rainfall from Patricia, peaking at 184.5 mm (7.3 in) in Higuera de Zaragoza. Subsequent flooding was reported in 12 municipalities in the state, resulting in the evacuation of 3,000 people. Officials also closed elementary schools throughout the affected area due to the anticipation of flood waters. In southern Sonora
, rainfall up to 240 mm (9.4 in) led to widespread flooding. Officials reported that 181 people sought refuge in shelters. Additionally, relief agencies supplied 500 people with food during the storm. A total of 2,272 hectares (5,614 acres) of agricultural land was inundated by flood waters. Roughly 815 people were left homeless in the wake of the storm, 600 of whom were in Sonora.
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
that briefly affected parts of Baja California Sur
Baja California Sur
Baja California Sur , is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Before becoming a state on October 8, 1974, the area was known as the South Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises...
before rapidly degenerating over water. Developing from a tropical wave
Tropical wave
Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which move from east to west across the tropics causing areas of...
that traversed the Atlantic Ocean during September 2009, Patricia was first classified as a tropical depression on October 11 several hundred miles south of the Baja California Peninsula
Baja California Peninsula
The Baja California peninsula , is a peninsula in northwestern Mexico. Its land mass separates the Pacific Ocean from the Gulf of California. The Peninsula extends from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south.The total area of the Baja California...
. The system quickly intensified into a tropical storm as it tracked in a general northward direction. By October 12, Patricia attained its peak intensity with winds of 60 mph (95 km/h) and a minimum barometric pressure of 996 mbar (hPa; 29.41 inHg). The following day, increasing wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
and unfavorable conditions caused the storm to rapidly weaken. By the morning of October 14, Patricia had degenerated into a non-convective
Atmospheric convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to...
remnant low pressure area
Low pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...
near the southern coastline of Baja California Sur
Baja California Sur
Baja California Sur , is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Before becoming a state on October 8, 1974, the area was known as the South Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises...
. The remnants of the storm peristed until October 15, at which time they dissipated over open waters.
Although the center
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
of Patricia did not impact land, the outer bands
Rainband
A rainband is a cloud and precipitation structure associated with an area of rainfall which is significantly elongated. Rainbands can be stratiform or convective, and are generated by differences in temperature. When noted on weather radar imagery, this precipitation elongation is referred to as...
caused significant rainfall in portions of western Mexico. In Sonora
Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....
, up to 240 mm (9.4 in) of rain fell, leading to significant flooding that left 600 people homeless. Other Mexican states received similar impact. Overall, the effects of Patricia were minor and resulted in no loss of life.
Meteorological history
Tropical Storm Patricia originated from a tropical waveTropical wave
Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which move from east to west across the tropics causing areas of...
that moved off the west coast of Africa on September 23, 2009. Two days later, Tropical Depression Eight developed from the wave over the eastern Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
. The depression tracked northwestward, while the wave continued a steady westward track. By October 6, the system crossed Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
and entered the eastern Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. Gradual development took place over the following several days with widespread, scattered convection
Atmospheric convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to...
consolidating around a developing area of low pressure
Low pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...
. On October 11, a well-defined circulation had formed and the National Hurricane Center
National Hurricane Center
The National Hurricane Center , located at Florida International University in Miami, Florida, is the division of the National Weather Service responsible for tracking and predicting weather systems within the tropics between the Prime Meridian and the 140th meridian west poleward to the 30th...
(NHC) estimated that it developed into a tropical depression roughly 405 mi (650 km) south-southeast of the southern tip of Baja California Sur
Baja California Sur
Baja California Sur , is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Before becoming a state on October 8, 1974, the area was known as the South Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises...
.
Several hours later, the system further strengthened into a tropical storm and was named
Tropical cyclone naming
Tropical cyclones have officially been named since 1945 and are named for a variety of reasons, which include to facilitate communications between forecasters and the public when forecasts, watches, and warnings are issued. Names also reduce confusion about what storm is being described, as more...
Patricia. The low-level circulation
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
became embedded within very deep convection and further intensification was anticipated. Patricia tracked north-northwest in a region of low to moderate wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
, under the steering currents of a strong ridge of high pressure
High pressure area
A high-pressure area is a region where the atmospheric pressure at the surface of the planet is greater than its surrounding environment. Winds within high-pressure areas flow outward due to the higher density air near their center and friction with land...
to the east and a trough
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.Unlike fronts, there is not a universal symbol for a trough on a weather chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked...
located northwest. Although over warm sea surface temperature
Sea surface temperature
Sea surface temperature is the water temperature close to the oceans surface. The exact meaning of surface varies according to the measurement method used, but it is between and below the sea surface. Air masses in the Earth's atmosphere are highly modified by sea surface temperatures within a...
s, relatively stable air prevented substantial intensification. By the late morning of October 12, the overall extent of cloud cover had increased but the center became less defined, described as "sloppy" by NHC forecaster Todd Kimberlain. Later that day, Patricia attained its peak intensity as a moderately strong tropical storm with winds of 60 mph (95 km/h) and a minimum barometric pressure of
996 mbar (hPa; 29.41 inHg).
The storm maintained this intensity for several hours as its central dense overcast remained intact despite increasing wind shear. However, the NHC stated that there was a 20% chance of the storm becoming a hurricane within 24 hours based on climatological factors and the average forecast intensity errors. However, this did not take place. The combination of moderate wind shear and a stable environment caused Patricia to rapidly weaken on October 13. The storm's cirrus
Cirrus cloud
Cirrus clouds are atmospheric clouds generally characterized by thin, wispy strands, giving them their name from the Latin word cirrus meaning a ringlet or curling lock of hair...
outflow
Outflow (meteorology)
Outflow, in meteorology, is air that flows outwards from a storm system. It is associated with ridging, or anticyclonic flow. In the low levels of the troposphere, outflow radiates from thunderstorms in the form of a wedge of rain-cooled air, which is visible as a thin rope-like cloud on weather...
became weak in all directions and convection diminished. Later that day, convective developed ceased to occur as the storm neared the south tip of Baja California Sur
Baja California Sur
Baja California Sur , is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Before becoming a state on October 8, 1974, the area was known as the South Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises...
. Early on October 14, Patricia degenerated into a remnant low pressure area
Low pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...
, bypassing tropical depression status, roughly 30 mi (50 km) south of the Baja California Peninsula. The remnant low turned westward and tracked over open waters before dissipating on October 15.
Preparations and impact
Several hours after Patricia was classified as a tropical storm on October 12, the National Hurricane Center issued a tropical storm watchTropical cyclone warnings and watches
Warnings and watches are two levels of alert issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone of tropical storm or hurricane intensity. They are notices to the local population and civil authorities to make appropriate...
for areas along Baja California Sur
Baja California Sur
Baja California Sur , is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Before becoming a state on October 8, 1974, the area was known as the South Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises...
between La Paz and Santa Fe. The following day, the watch was upgraded to a tropical storm warning for areas between Buenavista and Agua Blanca. However, the storm's rapid decay on October 14 allowed the watches and warnings to be discontinued. Officials in the threatened region began preparing by closing schools and opening 159 shelters on October 12. The Civil Protection Department was prepared to evacuate residents in low-lying area if necessary. Resorts and hotels cancelled all outdoor activities and brought all loose objects indoors. The city of Los Cabos was placed under a state of emergency
State of emergency
A state of emergency is a governmental declaration that may suspend some normal functions of the executive, legislative and judicial powers, alert citizens to change their normal behaviours, or order government agencies to implement emergency preparedness plans. It can also be used as a rationale...
as flooding rains were forecast to impact the area. Ports in the region were also shut down due to rough seas.
The storm's quick deterioration led to significantly less impact than anticipated. High waves affected the coastlines of Baja California Sur, Sinaloa and Nayarit. Parts of Sinaloa
Sinaloa
Sinaloa officially Estado Libre y Soberano de Sinaloa is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 18 municipalities and its capital city is Culiacán Rosales....
also recorded heavy rainfall from Patricia, peaking at 184.5 mm (7.3 in) in Higuera de Zaragoza. Subsequent flooding was reported in 12 municipalities in the state, resulting in the evacuation of 3,000 people. Officials also closed elementary schools throughout the affected area due to the anticipation of flood waters. In southern Sonora
Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....
, rainfall up to 240 mm (9.4 in) led to widespread flooding. Officials reported that 181 people sought refuge in shelters. Additionally, relief agencies supplied 500 people with food during the storm. A total of 2,272 hectares (5,614 acres) of agricultural land was inundated by flood waters. Roughly 815 people were left homeless in the wake of the storm, 600 of whom were in Sonora.
See also
- 2009 Pacific hurricane season2009 Pacific hurricane seasonThe 2009 Pacific hurricane season was an active event in the annual cycle of tropical cyclone formation, due to a moderate El Niño, unlike the 2009 Atlantic hurricane season, which was relatively quiet. The season officially started on May 15 in the eastern Pacific, and on June 1 for the central...
- Timeline of the 2009 Pacific hurricane seasonTimeline of the 2009 Pacific hurricane seasonBelow is the Timeline of the 2009 Pacific hurricane season, documenting all the storm formations, strengthening, weakening, landfalls, extratropical transitions, as well as dissipation. The 2009 Pacific hurricane season officially began on May 15, 2009, and will last until November 30. For...