Thunderstorm Wind, Maricopa
- When
- January 8, 8:00 PM MST
- Where
- Maricopa County, New River
- Property damage
- $5,000
- Coordinates
- 33.349, -112.491 (the zone’s center; the record gives no point)
The new Mill Avenue Bridge was washed away by the raging Salt River. A large landfill in Mesa was washed away. The Gillespie Dam west of Phoenix was damaged as high water spread throughout low-lying areas. Many roads closed and motorists stranded by flooded dips and washes. Phoenix alone sustained at least $4.2 million in damages from this prolonged period of heavy rains. This January was the wettest January on record with 5.22 inches at the airport. It was also the 4th all- time wettest month. Total rainfall for both December and January was 8.30 inches; this was the greatest ever for any two consecutive months. Arizona experienced its worst flooding in a decade as record rainfall and associated flooding forced many from homes and disrupted business. The Red Cross reported 678 dwellings destroyed or damaged. Early estimates of damage were at least $56 million statewide. A Presidential Federal Disaster Declaration was requested and signed by the President on January 19th. Several storm systems affected the state before the major storm arrived during the night of January 7-8. Significant precipitation of two to three inches were reported in a few sites between Phoenix and the Mogollon Rim. Moist low-level flow was forced upward and resulted in heavy rain and snow in the highest elevations. Periods of heavy rainfall resulted from the interaction of dynamic forcing and convective instability. The most significant flash flood events occurred when convective rains fell on watersheds already saturated from earlier rainfall. Another factor contributing to the unusually high runoffs and associated flooding was snow melt. The snow level during the 6th to the 8th rose to about 8,500 feet, several thousand feet above typical snow levels. In summary, the combination of a northward-displaced subtropical jet, with its abundant moisture supply and associated disturbances, and a southward-displaced polar jet, with its storm track, led to the abnormally wet period from just after Christmas to mid-January.