West Coast Bomb Cyclone: ​​These areas may be affected by flooding and power outages today, Thursday 21 November.

Officials are warning residents of Northern California, Oregon and Washington to prepare for flooding and power outages as “bomb cycloneis moving across the region and more storms are expected over the weekend. The storm has already begun to impact Washington, where more than 300,000 King County residents were without power. Power lines were less affected in Northern California, where more than 20,000 residents in Lassen, Humboldt and Siskiyou counties were without power.. According to the National Weather Service, bomb cyclone is an extremely powerful low-pressure system that must drop more than 24 mb (0.71 in Hg) in 24 hours.

Atmospheric river over California

The storm is bringing an atmospheric river to California that has already begun and is expected to continue through Friday, dumping 6 to 12 inches of rain on the Golden State as the ground struggles to absorb all the moisture that has fallen so far. These conditions pose many risks, and the NWS is already warning that because the ground can’t support the weight of precipitation, the potential for landslides and “hazardous flooding” increases. The NWS advises drivers to avoid all unnecessary travel and, if you must drive during a storm, to try to get information about road closures in advance.

How to Stay Up to Date with Weather Warnings from the NWS

Because warnings issued by the NWS can change quickly, we’ve put together a quick guide to find those related to this storm as it passes and is replaced by another storm over the weekend that will impact Oregon and Washington more than California.

When it comes to flooding, there are four main warnings:

Flood Warning (FLW)

“In terms of hydrology, this is an NWS message informing the public of flooding along larger rivers where there is a serious threat to life or property. A flood warning usually contains river level (level) forecasts.”

Flood Watch

“Issued to advise the public and cooperating agencies that current and evolving hydrometeorological conditions are such that there is a risk of flooding, but its occurrence is neither certain nor imminent.”

Flash Flood Warning

“Issued to inform the public, emergency management authorities and other cooperating agencies that flash flooding is occurring, imminent or highly probable.”

Flash Flood Watch

“Issued to indicate current or developing hydrologic conditions that are favorable to flash flooding in and near the watch area, but its occurrence is neither certain nor imminent.”

Source: National Weather Service: Glossary.

Flood advisories – stay informed

In addition to these four, the weather agency may also issue a flood warning, which warns residents in a particular area where the risk has not reached a level that requires a warning, but officials still want people to be prepared in case conditions change. These recommendations apply in all California from Napa Valley to Humboldt County. For those living along the coast, the latest coastal flood advisories can also be found in the Coastal Flood Information section. Because these are guidelines only, those affected should be checked regularly to ensure there is no change in risk level.

Flood Watch: Be Prepared and Aware

Because these warnings are issued when flooding may occur, it is important to have a plan in place if you are in a low-lying area or in an area where erosion may occur during heavy rain.

A flood warning is currently in effect throughout the area. Northern California, including Lake Shasta, North Sacramento Valley, Central Sacramento Valley and surrounding foothills. Northwestern California, including Del Norte, Humboldt, Trinity and Mendocino counties.. Three to six inches of rain are expected in these areas, but some counties in the foothills and mountains could see up to ten inches. This level of rain creates the risk of flash floods, landslides, and flooding of cities and roads, for which residents should be prepared.

V N.Orth Bay and coastal regions of the state covering Marin, Sonoma and Napa counties.A flood watch was also issued as two to six inches of rain were forecast. More rain is possible at higher elevations. Residents should be aware of road closures, as well as the risks of stream, river and town flooding depending on where they live.

In Southern Oregon, a flood watch operates near areas close to South Fork Coquille River at Myrtle Point, where heavy rainfall may cause the river to overflow.

Finally, a flood watch is in effect for Mason County in Washington until Friday evening as rain may cause rivers, creeks and creeks to overflow.

Flood warnings: Avoid unnecessary travel and heed government advice.

As mentioned earlier, these alerts are sent when flooding occurs or a threat is imminent. The most current list can be found on the NWS website.

In Siskiyou County, California, a flood warning will remain in effect until Friday evening. The area has already received two to six inches of rain, with another three to seven inches expected. Flooding is expected in Mount Shasta City, Weed, Callahan, Tennant and surrounding areas.

Also in Southwest Oregon and Northern California covering Coos, Curry, Jackson, Josephine counties, residents have already seen one to six inches of rain, with another three to seven inches expected. Flooding is expected in low-lying areas and rivers and streams will move out of their traditional channels.

Residents are advised that an evacuation order may be issued.