National Situation Update: Tuesday, January 11, 2005

Storms Continue in the West – But Relief Will Soon Arrive

In the West -- A large low pressure system centered along the West Coast since last Friday has produced extensive heavy rainfall, snowfall and high winds over large portions of the West, especially Southern California and the Sierra Madre Mountain Range. Southern California received 4-10 inches of rainfall in the coastal areas and areas in the foothills and mountain regions received over 10 inches of rain.

In the higher elevations of the West, winter storm warnings are widespread, posted for the mountains of northern California, the Sierra Nevada, the mountains of Southern California (above 7,000 feet), the higher ranges of southern Nevada, the mountains of Utah and the ranges in western Colorado.

The good news is that the National Weather Service predicts dry weather to follow in most parts of the West beginning on Tuesday night.

California -- A Pacific Storm is expected to bring more rain to northern California on Monday evening and to Southern California on Tuesday. The storm will bring heavy snow to the higher elevations of the Sierra Madres. Areas near Lake Tahoe, have already received well over 200 inches of snow in the last two weeks. On Monday in Ventura County, California a major mudslide in La Conchita sent mud and debris into approximately 15-20 homes. According to FEMA Region IX, the mudslide caused two fatalities and 50 injuries with search and rescue efforts continuing. Flooding and damage to Highway 101 is hampering rescue efforts as emergency crews are responding to the mudslide. Local and state officials are evacuating the affected area.

Further inland, communities downriver of Piru Lake are receiving voluntary evacuation instructions as the lake approaches capacity and spillways become overwhelmed. The lake’s watershed includes areas of the Piru Fire, one of ten wildfires of the 2003 Firestorm (DR-1498-CA). Piru Lake is receiving ten times as much runoff as it can release and the county hydrologist has predicted an overflow. Evacuation notices were issued to approximately 1,800 residents in the area where approximately 200 homes are immediately threatened. Local officials have opened a shelter at the Piru Elementary School.

A major gasoline supply pipeline from Southern California that provides approximately 40% of fuel consumed in the state is threatened after erosion from the recent storms has exposed a section of the pipeline, prompting a shutdown until repairs are completed. A 3-5 day supply of fuel reserve is available. Flooding in some rural areas has isolated residents in Mohave and Yavapi Counties(AZ). The National Weather Service forecasts approximately 2 additional inches of rain on Tuesday when the storm will pass and dry weather will prevail.

Arizona -- Strong Pacific storms have continued to bring widespread heavy rain to Arizona. For the first time in seven years, virtually every river in Arizona is flowing with water. Winter storms for the past two weeks have provided significant rain and snowmelt. The additional rainfall this past weekend has added to water levels throughout the state that have been very low for decades due to long-term drought conditions and increased groundwater usage by a growing population. However, the recent storms have also caused flooding, highway and road closures, damage to some residences, and evacuations requiring public shelters in several counties.

Other Parts of the West -- On Tuesday light rain is forecast for the Pacific Northwest. A cold front will move into Montana Tuesday night bringing possible blizzard conditions. (Region IX Report, The Washington Times, National Weather Service)

National Situation Update: Sunday, January 9, 2005

California Weather-Related Threats and Concerns

Latest trends in satellite and computer models suggest that a very moist flow from the subtropics will persist across Southern California through Tuesday, January 11, 2005 morning. As a result of this system and the forecasted position of the jet stream and its steering winds, periods of moderate to heavy rain can be expected through early Tuesday.

A cold upper level low pressure system will linger off the Pacific Northwest coast through Monday, January 10, 2005 before pushing across northwest California Monday night. Snow accumulation will moderate over much of the area as snow levels gradually rise to 2000 to 3000 feet through Sunday night. As the upper low pushes inland, rain and snow will increase across northwest California through Monday night.

The additional expected rainfall has the potential to cause serious flooding problem through California west of the mountains. Flash flooding is possible along small streams and in low lying areas. Street and roadway flooding is likely in normally flood prone areas. Significant rises are expected on the area’s main rivers and their tributaries.

It presently appears that an increase in coverage and intensity will occur tonight evening, Sunday during the day, and again Monday night. Regardless, the persistent south to southwesterly low level flow will yield efficient and continuous rainfall over the coastal ranges, foothills, and south facing slopes of the mountains. The heavy rain on already saturated ground will coincidentally increase the flash flood potential as fast-moving water in rivers, creeks, and streams could quickly exceed their banks and mud slides and rock slides are expected with this rain especially in steep terrain or in and below previously burned areas. The US Geological Survey (USGS) has issued a landslide advisory for Southern California.

Total rain amounts each day could be in excess of one inch in the coastal and valley areas with three to six inches on the coastal mountain slopes below the snow level. Larger amounts are likely on southwest facing mountain slopes. In addition, the rains of the last few weeks have filled the aquifers underlying the San Diego and San Luis Rey Rivers. This will result in a quicker response and greater flows in the channels if heavy rainfall should develop. As a result, river flood warnings may be needed by early Sunday morning.

In Southern California, the snow level will be around 6000 feet in the warm southwesterly flow. Several feet of snow are likely to accumulate above 6500 feet. Total rainfall accumulations from this wet pattern through Tuesday could be locally to near six inches in the coastal and valley areas and 12 to 24 inches on some west facing mountain slopes.

A National Weather Service winter storm warning above 1500 feet continues through midnight Monday, January 10, 2005 for elevations above 1500 feet in the mountains of interior California. Snow levels will be near 1000 feet on Saturday tonight, then will rise to 1500 to 2000 feet by Sunday evening. As the showers continue five to nine inches of new snow is expected through Sunday above 1500 feet. Showers will likely taper slightly by early Monday while another two to four inches of snow is expected above 2000 feet. An additional six to ten inches of new snow is then expected to fall through Monday night.

The higher elevations, especially above 2500 feet, will experience periods of strong winds through Sunday night. As much as eight feet of snow was expected through Tuesday in the northern Sierra Nevada. Wind gusts on some mountaintops reached 160 mph. (National Weather Service)

California

The State of California EOC is open and active and will operate 24/7 until at least Sunday evening. The EOCs in San Bernardino, Los Angeles and Monterrey Counties are active on a 24/7 basis. Local Emergency Response elements are active and mitigating the effects of local events as they occur.

All immediate response requirements are being met at the local and state level. FEMA Region IX has detailed two Liaison Officers to the California EOC for the duration of the storm event. No request for Federal assistance has been received.

Highway I-5 is closed north of Castaic, California in the area known as the Grapevine and on Highway 18 near Running Springs, over 100 cars remain stranded as snow piled up three to four feet deep along a 15-mile stretch of highway between the Snow Valley ski resort and Big Bear. Rescue operations, including emergency response to medical problems such as hypothermia and chest pains, are underway through the California Department of Transportation using tracked vehicles to retrieve the snowbound motorists in the mountains about 90 miles east of Los Angeles.

In Southern California, the debris catch basins in San Bernardino adjacent to the burned areas are filling up raising concerns about mud/debris flows and Highway 101 is being monitored for landslide activity in the Gaviota area. The San Diego River is expected to rise above flood stage Sunday morning. Very high tides, in excess of seven feet, along the coast will limit the flow of the drainage basins and sluiceways.

Fast-moving water in rivers, creeks, and streams could quickly exceed their banks and mud slides and rock slides are expected in steep terrain or in and below previously burned areas. The US Geological Survey (USGS) has issued a landslide advisory for Southern California.

In central California, Napa and Marin Counties north of San Francisco were particularly hard hit, with floods closing highway exits and swamping parked cars.

In northern California, while the impact of the storm systems has not reached predicted levels, there is some concern about the levees in Solano County given that the Twitchell Island levee overtopped last night.

Up to four feet of snow fell overnight in the Sierra Nevada around Lake Tahoe, ski areas reported Saturday. These amounts came on top of as much as four feet of snow that was deposited on parts of the area on December 30, 2004.

Interstate 80, which crosses the Sierra and links Sacramento, California, to the Reno-Tahoe, Nevada area, was closed for 13 hours between Friday and Saturday, January 7-8, 2005, and two other major Sierra highways (US 50 over Echo Summit and Highway 88 over Carson Pass) remained closed. (Region IX, and Various Media Sources)

Arizona

With more storms expected to move into and through the southwest, emergency workers around Arizona are bracing for possible flooding.

Weather forecasts call for up to a half-foot of precipitation in northern Arizona by early next week and about 1.5 inches of rain in the Phoenix metropolitan area.

In northern Arizona, where storms are expected to hit hardest, significant amounts of heavy wet snow is expected in the alpine regions where the snow pack is already is very deep.

The State Emergency Operations Center has been activated and will remain operational 247 through Friday, January 14, 2005.

State, local, and nongovernmental disaster planners met Friday, January 7, 2005 to develop flood plans, evacuation plans and routes, identify potential evacuee shelters, and to place disaster volunteers on standby.

In a declaration Friday, January 7, 2005, Navajo Nation President Joe Shirley Jr. said foul weather had made roads impassable and cut off tribal members from food and medical supplies on the reservation. There have been numerous requests for emergency aid and livestock feed and many families are without electricity or phone service and have reported a shortage of food, wood and water.

All immediate response requirements are being met at the State and local level. No request for Federal assistance has been received. (Various Media Sources)