Arizona has been affected by hurricanes on numerous occasions. Usually, these storms originate in the eastern Pacific Ocean, make landfall in the Mexican states of Baja California or Sonora, and dissipate before crossing into the United States. Thus, in most cases, it is only the tropical cyclones' remnant moisture that produces heavy rainfall—and in some occasions, flooding—in portions of Arizona. However, approximately every five years, a tropical cyclone retains sufficient strength to enter the state as a tropical storm or a tropical depression. Arizonans can expect indirect flash floods caused by the remnants of tropical cyclones to occur about every two years. [1]
Tropical cyclones in Arizona are not common, since the predominant wind pattern steers most storms that form in the Eastern Pacific either parallel or away from the Pacific coast of northwestern Mexico. As a result, most storms that could affect Arizona are carried away from the United States, with only 6% of all Pacific hurricanes entering US territory. [2] Not all Arizona hurricanes originate from the Pacific Ocean, however; in July 2008 an Atlantic hurricane named Hurricane Dolly produced rainfall in the eastern portion of the state, and another Atlantic storm reached Arizona as a tropical depression. Many, but not all, of these systems also impacted California.
Despite their rarity, hurricanes are among Arizona's most significant weather makers. In years when Arizona is affected by a tropical cyclone, these can be responsible for up to 25% of the rainfall in areas along the Colorado River. Arizona hurricanes are also responsible for torrential rains in localized areas, with the state's 24-hour rainfall record—11.97 inches (304 mm) of precipitation [3] —occurring during Hurricane Nora's landfall in 1997. The heavy rainfall can trigger extensive flash floods, such as the ones produced by the remnants of Tropical Storm Octave in 1983, or the lingering moisture from Tropical Storm Emilia in 2006.
Month | Number of storms |
---|---|
June | |
July | |
August | |
September | |
October |
Tropical cyclones are not common over Arizona, but on average, a tropical storm or a tropical depression enters the state approximately every five years. However, indirect flash floods caused by the remnants of tropical cyclones are more common, as they tend to occur about every two years. [1]
Storms that approach the southwestern United States, and by extension Arizona, generally form closer to the Mexican shoreline than average, making them more likely to recurve northwards under the influence of an approaching trough. These troughs tend to extend farther to the south during the latter part of the Pacific hurricane season, in the period between late August and early October. These pronounced troughs thus produce a synoptic-scale flow that is conducive to steering hurricanes towards the southwestern United States. [4]
The infusions of tropical moisture from Arizona-bound tropical cyclones can be a significant portion of the rainfall in the region. In years when hurricanes approach Arizona, eastern and northern portions of the state receive on average 6–8% of the monsoon-season precipitation from tropical systems and their remnants. This percentage rises towards the southwestern corner of the state, which can receive up to a quarter of its monsoon-season rainfall from tropical cyclones. [4]
Tropical storms are one of Arizona's main sources of rainfall, as they infuse the monsoon over the southwestern United States with moisture, producing large-scale floods in occasions. [5] However, all of the storms that have impacted Arizona have formed in the latter parts of the Pacific hurricane season, and only storm remnants have affected the state before August. [2]
Category | m/s | knots | mph | km/h |
---|---|---|---|---|
5 | ≥ 70 | ≥ 137 | ≥ 157 | ≥ 252 |
4 | 58–70 | 113–136 | 130–156 | 209–251 |
3 | 50–58 | 96–112 | 111–129 | 178–208 |
2 | 43–49 | 83–95 | 96–110 | 154–177 |
1 | 33–42 | 64–82 | 74–95 | 119–153 |
TS | 18–32 | 34–63 | 39–73 | 63–118 |
TD | ≤ 17 | ≤ 33 | ≤ 38 | ≤ 62 |
Storm | Peak intensity | Season | Intensity | Date [6] |
---|---|---|---|---|
Unnamed [7] | Unknown | 1921 | Remnant low | August 20, 1921 |
Unnamed [8] | Unknown | 1921 | Tropical depression | September 30, 1921 |
Unnamed [6] | Unknown | 1926 | Remnant low | September 20, 1926 |
Unnamed [6] | Unknown | 1927 | Remnant low | September 7, 1927 |
One [9] | Category 1 [9] | 1929 | Tropical depression | June 30, 1929 |
Unnamed [10] | Unknown | 1935 | Tropical storm | August 22, 1935 |
Unnamed [11] | Tropical storm [12] | 1951 | Tropical storm | August 3, 1951 |
Unnamed [11] | Category 1 [12] | 1958 | Tropical storm | October 6, 1958 |
Claudia [6] | Tropical storm [12] | 1962 | Tropical storm | September 25, 1962 |
Tillie [10] | Tropical storm [12] | 1964 | Remnant low | September 9, 1964 |
Emily [11] | Category 1 [12] | 1965 | Remnant low | September 6, 1965 |
Kirsten [13] | Tropical storm [12] | 1966 | Remnant low | September 29, 1966 |
Katrina [6] | Category 1 [12] | 1967 | Tropical storm | August 29, 1967 |
Hyacinth [11] | Tropical storm [12] | 1968 | Tropical depression | August 20, 1968 |
Pauline [14] | Category 1 [12] | 1968 | Remnant low | October 3, 1968 |
Norma [6] | Tropical storm [12] | 1970 | Remnant low | September 4, 1970 |
Irene-Olivia [15] | Category 3 [12] | 1971 | Remnant low | October 1, 1971 |
Joanne [6] | Category 2 [12] | 1972 | Tropical storm | October 4, 1972 |
Kathleen [6] | Category 1 [12] | 1976 | Tropical storm | September 10, 1976 |
Liza [16] | Category 4 [12] | 1976 | Remnant low | October 2, 1976 |
Doreen [6] | Category 1 [12] | 1977 | Tropical storm | August 13, 1977 |
Heather [6] | Category 1 [12] | 1977 | Tropical depression | October 4, 1977 |
Octave [6] | Tropical storm [12] | 1983 | Tropical storm | September 28, 1983 |
Norbert [17] | Category 4 [12] | 1984 | Tropical depression | September 25, 1984 |
Polo [18] | Category 3 [12] | 1984 | Remnant low | October 3, 1984 |
Raymond [11] | Category 3 [12] | 1989 | Tropical depression | October 5, 1989 |
Boris [19] | Category 1 [12] | 1990 | Remnant low [19] | June 11, 1990 |
Lester [11] | Category 1 [20] | 1992 | Tropical storm | August 22, 1992 |
Hilary [21] | Category 3 [12] | 1993 | Remnant low | August 27, 1993 |
Flossie [22] | Category 1 [12] | 1995 | Remnant low | August 11, 1995 |
Ismael [11] | Category 1 [12] | 1995 | Remnant low | September 15, 1995 |
Nora [6] | Category 4 [12] | 1997 | Tropical storm | September 25, 1997 |
Frank [23] | Tropical storm [12] | 1998 | Remnant low | August 9, 1998 |
Isis [24] | Category 1 [12] | 1998 | Remnant low | September 5, 1998 |
Olivia [25] | Tropical storm [12] | 2000 | Remnant low | October 11, 2000 |
Juliette [26] | Category 4 [12] | 2001 | Remnant low | October 3, 2001 |
Ignacio [27] | Category 2 [12] | 2003 | Remnant low | August 25, 2003 |
Marty [11] | Category 2 [12] | 2003 | Remnant low | September 22, 2003 |
Javier [28] | Category 4 [12] | 2004 | Remnant low | September 20, 2004 |
Emilia [29] | Tropical storm [12] | 2006 | Remnant low | July 25, 2006 |
John [30] | Category 4 [12] | 2006 | Remnant low | September 5, 2006 |
Henriette [31] | Category 1 [12] | 2007 | Remnant low | September 6, 2007 |
Dolly [16] | Category 2 [12] | 2008 | Remnant low | July 28, 2008 |
Julio [32] | Tropical storm [12] | 2008 | Remnant low | August 25, 2008 |
Jimena [33] | Category 4 [12] | 2009 | Remnant low | September 5, 2009 |
Norbert [34] | Category 3 [35] | 2014 | Remnant low | September 8, 2014 |
Odile [36] | Category 4 [37] | 2014 | Remnant low | September 17, 2014 |
Newton [38] | Category 1 [39] | 2016 | Remnant low | September 7, 2016 |
Rosa [40] | Category 4 [41] | 2018 | Tropical depression | October 2, 2018 |
Sergio | Category 4 | 2018 | Tropical depression | October 13, 2018 |
Hilary | Category 4 | 2023 | Tropical depression | August 20, 2023 |
Precipitation | Storm | Location | Ref. | ||
---|---|---|---|---|---|
Rank | mm | in | |||
1 | 344.4 | 13.56 | Unnamed 1951 | Crown King | [42] |
1 | 305.1 | 12.01 | Nora 1997 | Harquahala Mountains | [16] |
2 | 304.8 | 12.00 | Octave 1983 | Mount Graham | [16] |
3 | 289.6 | 11.40 | Norma 1970 | Workman Creek | [42] |
4 | 210.8 | 8.30 | Heather 1977 | Nogales | [16] |
5 | 209.8 | 8.26 | Unnamed 1926 | Hereford | [42] |
6 | 178.6 | 7.03 | Unnamed 1939 | Wikieup | [42] |
7 | 178.1 | 7.01 | Doreen 1977 | Yuma Valley | [16] |
8 | 177.8 | 7.00 | Javier 2004 | Walnut Creek | [16] |
9 | 166.9 | 6.57 | Newton 2016 | Rincon Mountains | [43] |
10 | 158.8 | 6.25 | Norbert 2014 | Tempe 3.1 WSW | [42] |
Several of these tropical cyclones have caused deaths or heavy property damage, usually due to flooding caused by rain.
Records of tropical cyclones in the East Pacific before 1950 are sparse, but there were still several storms that produced rainfall over Arizona in this period.
The 1980s saw destructive tropical cyclones pass through the state, as was the case with the previous decade.
During the 1990s, several tropical systems affected Arizona even after losing all tropical characteristics. However, two hurricanes survived long enough to reach Arizona while still considered tropical systems.
The last decade saw no storms reach Arizona while retaining tropical characteristics; however, numerous remnant lows caused heavy rainfall and flooding throughout the state.
Hurricane Kathleen was a Category 1 Pacific hurricane that had a destructive impact in California. On September 7, 1976, a tropical depression formed; two days later it accelerated north towards the Baja California Peninsula. Kathleen brushed the Pacific coast of the peninsula as a hurricane on September 9 and made landfall as a fast-moving tropical storm the next day. With its circulation intact and still a tropical storm, Kathleen headed north into the United States and affected California and Arizona. Kathleen finally dissipated late on September 11.
Tropical Storm Grace was a weak tropical storm that struck Texas in the 2003 Atlantic hurricane season. The eleventh tropical depression and the seventh tropical storm of the season, Grace was also the weakest storm of the season. On August 30 the storm developed from a long-track tropical wave in the western Gulf of Mexico. Grace remained disorganized throughout its lifetime due to an upper-level low to its west. The weak storm moved northwestward and made landfall on southeastern Texas. Grace quickly weakened over land, and dissipated on September 2 as it merged into a cold front.
Hurricane John was a Category 4 hurricane that caused heavy flooding and extensive damage across most of the Pacific coast of Mexico in late August through early September 2006. John was the eleventh named storm, seventh hurricane, and fifth major hurricane of the 2006 Pacific hurricane season. Hurricane John developed on August 28 from a tropical wave to the south of Mexico. Favorable conditions allowed the storm to intensify quickly, and it attained peak winds of 130 mph (210 km/h) on August 30. Eyewall replacement cycles and land interaction with western Mexico weakened the hurricane, and John made landfall on southeastern Baja California Sur with winds of 110 mph (180 km/h) on September 1. It slowly weakened as it moved northwestward through the Baja California peninsula, and dissipated on September 4. Moisture from the remnants of the storm entered the southwest United States.
Tropical Storm Emilia was a rare tropical cyclone that affected the Baja California Peninsula in July 2006. The sixth tropical depression and fifth tropical storm of the 2006 Pacific hurricane season, it developed on July 21 about 400 miles (640 km) off the coast of Mexico. It moved northward toward the coast, reaching peak winds of 65 mph (105 km/h) before turning westward and encountering unfavorable conditions. Emilia later turned to the north, passing near Baja California as a strong tropical storm. Subsequently, the storm moved further away from the coast, and on July 27 it dissipated.
Tropical Storm Marco was the only tropical cyclone to make landfall on the United States during the 1990 Atlantic hurricane season. The 13th named storm of the season, Marco formed from a cold-core low pressure area along the northern coast of Cuba on October 9, and tracked northwestward through the eastern Gulf of Mexico. With most of its circulation over the western portion of Florida, Tropical Storm Marco produced 65 mph (105 km/h) winds over land. However, it weakened to a tropical depression before moving ashore near Cedar Key. The cyclone combined with a cold front and the remnants of Hurricane Klaus to produce heavy rainfall in Georgia and the Carolinas. After interacting with the nearby Hurricane Lili, Marco continued northward until being absorbed by a cold front on October 13.
Hurricane Isis was the only hurricane to make landfall during the 1998 Pacific hurricane season. The ninth tropical storm and sixth hurricane of the season, Isis developed on September 1 from an interaction between a tropical wave and a large surface circulation to the southwest of Mexico. It moved northward, striking the extreme southeastern portion of the Baja California peninsula before attaining hurricane status in the Gulf of California. Isis made landfall at Topolobampo in the Mexican state of Sinaloa on September 3, and quickly lost its low-level circulation. The remnants persisted for several days before dissipating over the U.S. state of Idaho on September 8.
Hurricane Lester was the first Pacific tropical cyclone to enter the United States as a tropical storm since 1967. The fourteenth named storm and eighth hurricane of the 1992 Pacific hurricane season, Lester formed on August 20 from a tropical wave southwest of Mexico. The tropical storm moved generally northwestward while steadily intensifying. After turning to the north, approaching the Mexican coast, Lester attained hurricane status. The hurricane reached peak winds of 85 mph (137 km/h) before making landfall on west-central Baja California. The system weakened while moving across the peninsula and then over northwestern Mexico. Not long after entering Arizona, Lester weakened to a tropical depression, and degenerated into an extratropical low on August 24, 1992, over New Mexico. The storm's remnants later merged with the remnants of Hurricane Andrew and another frontal system on August 29.
Tropical Storm Barry was a rapidly forming tropical cyclone that made landfall on Florida, United States, in early June 2007. The second named storm of the 2007 Atlantic hurricane season, Barry developed from a trough of low pressure in the southeastern Gulf of Mexico on June 1. It tracked rapidly northeastward, reaching peak winds of 60 mph (97 km/h) before weakening and making landfall near Tampa Bay as a tropical depression. Barry quickly lost tropical characteristics after wind shear removed much of the convection, and early on June 3, it completed the transition into an extratropical cyclone. The extratropical remnants tracked up the East Coast of the United States, and were absorbed by a larger extratropical cyclone on June 5.
Hurricane Paine was the sixteenth tropical storm and eighth hurricane of the fairly active 1986 Pacific hurricane season; moisture from the system contributed to one of the most significant flooding events in Oklahoma history. Paine formed on September 28 off the southeast coast of Mexico. It moved around a ridge, later turning to the north and brushing the Baja California Peninsula. By that time, Paine had attained peak winds of 100 mph (160 km/h), but it weakened slightly before hitting the Mexican state of Sonora. The remnant moisture combined with a cold front to produce heavy rainfall in the South Central United States.
Tropical Storm Octave was considered the worst tropical cyclone in the history of Arizona. The nineteenth tropical cyclone and fifteenth named storm of the 1983 Pacific hurricane season, the origins of Tropical Storm Octave were from a tropical disturbance that formed south of the Gulf of Tehuantepec on September 23, 1983. Steered by a deep layer high over Mexico, the disturbance moved west for four days before becoming a tropical depression on September 27 off the southwest coast of Mexico. Over an area of warm sea surface temperatures, it was able to quickly strengthen to peak winds of 50 mph (85 km/h), through wind shear prevented much further development. By September 30, Octave was accelerating to the northeast, steadily weakening due to cooler waters. That day it weakened to tropical depression status, and on October 2, Octave dissipated.
Hurricane Joanne was one of four tropical cyclones to bring gale-force winds to the Southwestern United States in the 20th century. A tropical depression developed on September 30, 1972. It then moved west northwest and intensified into a hurricane on October 1. Hurricane Joanne peaked as a Category 2 hurricane, as measured by the modern Saffir-Simpson hurricane wind scale (SSHWS), October 2. Joanne then slowed and began to re-curve. Joanne made landfall along the northern portion of the Baja California Peninsula as a tropical storm. The tropical storm moved inland over Sonora on October 6 and was believed to have survived into Arizona as a tropical storm. In Arizona, many roads were closed and some water rescues had to be performed due to a prolonged period of heavy rains. One person was reportedly killed while another was electrocuted. A few weeks after the hurricane, Arizona would sustain additional flooding and eight additional deaths.
Hurricane Heather was one of the worst tropical cyclones to affect Arizona on record. The sixteenth tropical cyclone, eighth named storm, and fourth hurricane of the 1977 Pacific hurricane season, it began as a tropical disturbance off the west coast of Mexico on October 3. The next day, October 4, it developed into a tropical depression and then turned to the northwest. It was soon upgraded to Tropical Storm Heather. On October 5, Heather became a hurricane, and later that day its winds peaked at 85 mph (137 km/h). Heather began to turn north-northwest around this time. By October 6, it was re-designated a tropical storm. Moving north, Heather continued to weaken over cooler waters, and on October 7, the final advisory was issued, downgrading Heather to a tropical depression.
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