October 2009 North American storm complex

October 2009 North American storm complex

Infrared satellite loop of the system off the coast of the Western United States
Storm type:	Coastal storm
Formed:	October 11, 2009
Dissipated:	October 15, 2009
Maximum amount:*	23 in (580 mm) at Mammoth Mountain Ski Area 21.34 in (542 mm) of rain in Monterey County, California
Damages:	$18.8 million (2009 USD)
Fatalities:	2 total
Areas affected:	Western and Central North America
^* Maximum snowfall or ice accretion

The October 2009 North American storm complex was a powerful non-tropical cyclone, associated with the remnants of Typhoon Melor that brought extreme amounts of rainfall to California. The system started out as a weak area of low pressure, that formed north of Typhoon Melor's remnants, late on October 11, in the Gulf of Alaska. The system then absorbed Melor's remnants quickly, which resulted in the system strengthening significantly off-shore, before moving southeastward to inpact the West Coast of the United States, beginning very early the next day.

Impact

California

The storm system, formerly considered to have been Melor, became one of the most intense storms to impact the state of California during October on record. Numerous locations recorded rainfall in excess of 10 in (250 mm) in a 24-hour span, with a maximum of 21.34 in (542 mm) falling at Mining Ridge, Monterey County.^[1] This amount surpassed the previous rainfall record from a tropical cyclone or its remnants in the state by nearly 7 in (180 mm). Hurricane Kathleen in 1976 held the record prior to Melor, producing a maximum of 14.76 in (375 mm) at San Gorgonio.^[2] In San Francisco, an all-time record was set of 2.49 in (63 mm) in a 24-hour span, greater than any other total since records began in 1849. At higher elevations, significant amounts of snow fell; exact totals are not known, but estimated to be at least several feet. Strong winds also accompanied the record rainfall. Hurricane-force wind gusts, recorded up to 87 mph (140 km/h), were associated with Melor's remnants. Similar winds were likely felt in higher elevations, resulting in blizzard conditions. Although the rainfall was record-breaking, it significantly helped to alleviate one of California's worst droughts on record, spanning several years.^[1] At San Marcos Pass, rainfall from the storm surpassed the all-time record October rainfall in a single day, with 10.31 in (262 mm) falling at the pass.^[3]

In areas near San Francisco, hundreds of car accidents occurred due to wet roads and high winds. On the Richmond Bridge, a tractor-trailer was blown on its side, landing on a passing car; however, the two passengers of the car and the truck driver were uninjured. This accident resulted in all east-bound lanes on the bridge being shut down from 3:00 pm to 5:30 pm. The California Highway Patrol stated that they received over 3,000 calls during the first half of the day concerning accidents, against the normal 1,000 calls during an entire day without rain. A crash in the Caldecott Tunnel, requiring emergency repairs to the structure, led to a temporary closure and creating more traffic issues. A three car collision on state Highway 1 resulted in the death of one person. The section of the highway near the crash was shut down for near four hours also. Over 200 accidents occurred throughout the day around San Francisco due to the storm.^[4]

Throughout the Santa Cruz Mountains, several roads were closed due to flooding. Along Swanton Road, emergency officials issued a mandatory evacuation of 60 residents due to the flooding. Schools in San Lorenzo Valley were closed for the day due to the rising waters. Some residents were trapped by waters reaching a depth of 6 ft (1.8 m), leading to emergency rescues. High winds resulted in major air traffic delays, with officials noting average delays of three or more hours.^[4]

At the height of the storm, more than 35,000 residences were without power initially due to heavy rains; however, wind eventually worsened power issues as branches began to fall on power lines. A transmittion emergency was declared on the evening of October 12 as a 500,000 volt power line was blown down.^[4] In northern portions of the state, winds exceeding 80 mph (130 km/h) left hundreds of thousands of people without power and sparked several power line fires. The storm was described as "just phenomenal" by meteorologists.^[5] In response to the storm, flood disaster agencies allocated 20,000 sandbags for immediate deployment. All state and emergency operation centers in the state we activated on October 14 and support from electric companies in Arizona and Nevada was received to assist in power restoration.^[6]

Other states

In Oregon, the remnants of Melor brought heavy rains and high winds to many areas. Maximum rainfall associated with the system was around 1 in (25 mm), making the remnants of Melor the third known tropical cyclone, or remnants of a cyclone, to impact state.^[2][7] Minor effects were recorded in terms of damage: one rockslide took place on Highway 101 and large swells affected the coastline.^[7] In mountainous areas of Nevada, the storm produced upwards of 1 ft (0.30 m) of snow and winds over 50 mph (80 km/h). Several accidents took place on slick roadways during the storm; however, no fatalities or major injuries were reported. The highest winds were likely at the peaks of the Sierra mountains, forecasted to reach 140 mph (230 km/h), equivalent to a strong Category 4 hurricane. At least 2 in (51 mm) of rain fell along the foothills of the mountains, making the remnants of Melor one of the wettest former tropical cyclones to impact the state of Nevada.^[2][8] In Minnesota, a region rarely affected by the remnants of tropical cyclones,^[9] received moderate rainfall from the former typhoon. On October 14 and 15, the remnants of Melor affected the state, with estimated rainfall totals peaking at 0.85 in (22 mm).^[10] By the end of October 15, the storm complex was absorbed by a neighboring extratropical storm, as the storm complex neared the East Coast of the United States.

See also

Tropical cyclones portal

• 2009 Pacific typhoon season
• 1962 Columbus Day storm - Associated with the remnants of Typhoon Freda. It caused the lowest pressure every measured in Oregon to be recorded.
• East Asian snowstorms of 2009-2010
• December 2009 North American snowstorms

References

1. ^ ^{a b} Jeff Masters (2009-10-14). "Thirsty California soaks up Melor's Deluge". Weather Underground. http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1350. Retrieved 2009-10-14. 
2. ^ ^{a b c} David M. Roth (2009). "Tropical Cyclone Rainfall for the West". Hydrometeorological Prediction Center. http://www.hpc.ncep.noaa.gov/tropical/rain/tcwest.html. Retrieved 2009-10-17. 
3. ^ Eric Lindberg (2009-10-15). "Heavy rains hit mountains, cause little damage". Daily Sound. http://www.webcitation.org/5kb1FbkOj. Retrieved 2009-10-17. 
4. ^ ^{a b c} KTVU (2009-10-13). "Storm Winds Blow Big Rig Over On Richmond Bridge". Fox Reno News. http://www.foxreno.com/news/21271107/detail.html. Retrieved 2009-10-15. 
5. ^ Mike Hazelwood (2009-10-15). "Storm causes some road flooding in Tulare". Visalia Times-Delta. http://www.visaliatimesdelta.com/article/20091015/NEWS01/910150314/Storm+causes+some+road+flooding+in+Tulare. Retrieved 2009-10-15. ^{[dead link]}
6. ^ Staff Writer (2009-10-14). "National Situation Update: Wednesday, 2009-10-14". Federal Emergency Management Agency. http://www.fema.gov/emergency/reports/2009/nat101409.shtm. Retrieved 2009-10-17. 
7. ^ ^{a b} Arwyn Rice (2009-10-14). "Typhoon’s remnants drop inch of rain on South Coast". Curry Pilot. http://www.currypilot.com/20091014114014/News/Local-News/Typhoons-remnants-drop-inch-of-rain-on-South-Coast. Retrieved 2009-10-15. ^{[dead link]}
8. ^ Associated Press (2009-10-13). "Storm brings snow to Sierra, rain, wind to Reno". Mercyury News. http://www.mercurynews.com/news/ci_13552163. Retrieved 2009-10-15. ^{[dead link]}
9. ^ David M. Roth (2009). "Tropical Cyclone Rainfall for the Midwest". Hydrometeorological Prediction Center. http://www.hpc.ncep.noaa.gov/tropical/rain/tcmidwest.html. Retrieved 2009-10-17. 
10. ^ Paul Douglas (2009-10-14). "Japanese typhoon makes Minnesota rain". Minnesota Post. http://www.minnpost.com/pauldouglas/2009/10/14/12472/japanese_typhoon_makes_minnesota_rain. Retrieved 2009-10-15.