 Satellite image of the storm at peak intensity on November 8 | |
| Meteorological history | |
|---|---|
| Formed | November 4, 2011 |
| Dissipated | November 11, 2011 |
| Extratropical cyclone | |
| Highest gusts | 93 mph (150 km/h) onLittle Diomede Island |
| Lowest pressure | 943hPa (mbar); 27.85 inHg |
| Blizzard | |
| Lowest temperature | Wind chill of −17 °F (−27 °C) in Red Dog Dock, Alaska[2] |
| Maximum snowfall or ice accretion | 6.4 in (16 cm) inNome, Alaska[1] |
| Overall effects | |
| Fatalities | 1[1] |
| Damage | At least $24 million[1] |
| Areas affected | Northeast China,North Korea,South Korea,Japan,Alaska,Chukotka |
Part of the2011–12 North American winter | |
TheNovember 2011 Bering Sea cyclone was one of the most powerfulextratropical cyclones to affectAlaska on record. On November 8, theNational Weather Service (NWS) began issuing severe weather warnings, saying that this was a near-record (or record) storm in theBering Sea.[3] It rapidly deepened from 973 mb (28.7 inHg) to 948 mb (28.0 inHg) in just 24 hours before bottoming out at 943 mbar (hPa; 27.85 inHg),[1] roughly comparable to a Category 3 or 4 hurricane. The storm had been deemed life-threatening by many people.[4] The storm had a forward speed of at least 60 mph (97 km/h) before it had reached Alaska. The storm began affecting Alaska in the late hours of November 8, 2011. The highest gust recorded was 93 mph (150 km/h) onLittle Diomede Island.[5] One person was reported missing after being swept into theBering Sea, and he was later pronounced dead.[6][1]
Extratropical cyclone, remnant low, tropical disturbance, or monsoon depressionIn early November 2011, anextratropical cyclone developed over the westernPacific Ocean.[1] Gradually intensifying, the system moved rapidly northeastward at 60 mph (97 km/h) and reached the southernAleutian Islands by November 8, with abarometric pressure estimated at 960 mbar (hPa; 28.35 inHg). Though still intensifying, winds associated with the storm were already estimated in excess ofhurricane-force.[1][7] By 9:00 p.m.AKST, the system had attained a pressure of around 943 mbar (hPa; 27.85 inHg) while it was near theGulf of Anadyr. This made it one of the most powerful storms on record in the region, comparable to the November 1974 storm in Nome, Alaska, which was regarded as "the most severe in Nome in 113 years of record keeping." According to theNational Weather Service (NWS), the system was forecast to have sustained winds of 80 mph (130 km/h) over an area the size ofColorado.[8] After weakening somewhat, the storm crossed theChukotsk Peninsula around 9:00 a.m. AKST on November 9 before moving over theChukchi Sea later that day. Once back over water, the extratropical cyclone turned towards the northwest and was last noted as a 975 mbar (hPa; 28.80 inHg) low on November 10, about 150 mi (240 km) north ofWrangel Island, before dissipating on the next day.[1]
On November 7 and 8, the NWS issued hurricane wind warnings, flood warnings and blizzard warnings for most of Western Alaska. The storm came after almost 7,000 people in theKenai Peninsula lost power in a previous storm the week before.[9] An Alaskan village called Kivalina built a wall to protect waves from flooding the village. The storm was expected to test the walls sturdiness.[4] In case the wall fell down, people who live in Kivalina would be evacuated.[7] Storm surges were expected to be up to 8–10 feet. TheU.S. Coast Guard staged helicopters around the western coast of Alaska in case of any emergencies.[10] People inUnalakleet, Alaska began to board up their windows on November 8.[11] The Alaskan Homeland Security helped villages prepare for the storm.[12]
From November 8, temperatures around Alaska began decreasing. In Anchorage, temperatures the previous day were 18 °F (−8 °C), but temperatures began decreasing to 6 °F (−14 °C) during the afternoon. In Nome, AK, tides had risen up to 7 feet (2.1 m),[13] with waters moving up to bases of people's homes.[14] Windchill temperatures south of Kivalina were −14.1 °F (−25.6 °C) with winds gusting to 70 miles per hour (110 km/h). Many low-lying areas experienced flooding, including Nome.[15]
Across much of western Alaska's coastline, the storm caused widespread erosion andcoastal flooding from a combination ofstorm surge and waves estimated between 30 and 40 ft (9.1 and 12.2 m).[1][7][8] The most significant effects were felt in and around Nome where sea levels rose 8.73 ft (2.66 m) above normal, flooding low-lying areas. The Cape Nome Jetty sustained approximately $500,000 in damage. Although the surge did not over-top theseawall, water from breaking waves washed over and inundated a sewer and water treatment plant. The pumps at the facility were overwhelmed and 165,000 gallons of raw wastewater was discharged into a small harbor. Several other buildings in the area had basement flooding but no significant losses took place. A significant portion of the Nome-Council road was washed out or severely damaged by the storm, and damage was estimated at $24 million. Coastal damage throughout the city of Nome was estimated at $80,000.[1]
The storm caused widespread damage to approximately 37 communities on the Western Alaskan coast. Damage includedcoastal erosion caused bystorm surge, roof and other structural damage to homes and businesses, and loss of heat and electricity.[16]
A fishing vessel was lost in the severe weather after the crew was ordered to abandon ship. The crew was rescued by theUnited States Coast Guard.[17]
Forecasters at the NWS predicted a second strong storm; however, the forecasted storm was not expected to cause as much damage. Other low-pressure areas spawned by this storm were expected to bring heavy rain toBritish Columbia and theWest Coast of the United States.[18] On November 11, 2011, the National Weather Service issued hurricane-force wind warnings and storm warnings for WesternAlaska with coastal flood warnings for theAlaska Peninsula. The second storm attained a minimum central pressure of 954 millibars (28.2 inHg) on November 12, 2011.
On December 22, PresidentBarack Obama issued a disaster declaration due to the large amount of destruction caused by the storm.[19]
Storms analysed below 948 millibars (28.0 inHg) by theNational Weather Service occur on average 5 times per year in the Bering Sea area, where one or two per year see their central pressure drop below 930 millibars (27 inHg).[20] 2011 also saw a low pressure reach 939 mb (27.7 inHg) on April 6, however this storm was less damaging as the wind-field was strongest out to sea.[20]
Strong Bering Sea storms affecting Alaska typically form asEast Asian-northwest Pacific storms, as cold, dry air masses from Siberia meet with mild and moist sub-tropical air masses off the coast of Japan where they canrapidly deepen above theKuroshio Current, before heading towards Alaska.[20] These storms develop in a similar manner to the formation of extratropical cyclones in the North Atlantic, although they tend not to reach the absolute low pressures recorded there, such as 913 mb (27.0 inHg) during theBraer Storm of January 1993.[20]
