is 13:1, meaning of snow melts down to of water. The El Niño-Southern Oscillation affects the precipitation distribution, by altering rainfall patterns across the West, Midwest, the Southeast, and throughout the tropics. During the summer, the Southwest monsoon combined with Gulf of California and Gulf of Mexico moisture moving around the subtropical ridge in the Atlantic Ocean bring the promise of afternoon and evening thunderstorms to the southern tier of the country as well as the Great Plains. Equatorward of the subtropical ridge, tropical cyclones enhance precipitation (mostly from August to October) across southern and eastern sections of the country, as well as Puerto Rico, the United States Virgin Islands, the Northern Mariana Islands, Guam, and American Samoa. Over the top of the ridge, the jet stream brings a summer precipitation maximum to the Great Lakes. Large thunderstorm areas known as mesoscale convective complexes move through the Plains, Midwest, and Great Lakes during the warm season, contributing up to 10% of the annual precipitation to the region. Extremes In northern Alaska, tundra and arctic conditions predominate, and the temperature has fallen as low as . On the other end of the spectrum, Death Valley, California once reached , officially the highest temperature ever recorded on Earth. On average, the mountains of the western states receive the highest levels of snowfall on Earth. The greatest annual snowfall level is at Mount Rainier in Washington, at ; the record there was in the winter of 1971–72. This record was broken by the Mt. Baker Ski Area in northwestern Washington which reported of snowfall for the 1998–99 snowfall season. Other places with significant snowfall outside the Cascade Range are the Wasatch Range, near the Great Salt Lake and the Sierra Nevada, near Lake Tahoe. Along the coastal mountain ranges in the Pacific Northwest, rainfall is greater than anywhere else in the continental U.S., with Quinault Ranger Station in Washington having an average of . Hawaii receives even more, with measured annually, on average, at the Big Bog, in Maui. Pago Pago Harbor in American Samoa is the rainiest harbor in the world (because of the 523 meter Rainmaker Mountain). The Sonoran Desert in the southwest is home to the driest locale in the US. Yuma, Arizona, has an average of of precipitation each year. Extreme highs Extreme lows Overall average(s) Natural disasters and effects Because of contrasting air masses, the Great Plains, the