Summary of Atmospheric River Events from Dec. 26 2022 to January 17 2023

I recently wrote a series of posts about the atmospheric river events that occurred in California in late December 2022 into early January 2023 (see my posts starting with December 30th and ending with January 13th). A couple of days ago, I knew that I wanted to find some summary precipitation totals covering all the atmospheric river events starting from December 26, 2022. I was not surprised that I was having difficulty finding such maps and data. I know that National Weather Service River Forecast Centers might have access to or help me find the maps and data that I was looking for. I called the NWS California-Nevada River Forecast Center (CNRFC). I talked to Brett Whitin, P.E., a Service Hydrologist with the California-Nevada River Forecast Center. Brett was very helpful and we have been in touch over e-mail as I worked on this article. The graphics he obtained for me and his assistance over e-mail helped to make this post possible. Thank-you Brett!

I told Brett what that I was looking for something similar to the Total Precipitation Map for December 24th to January 10th for California done by The Weather Prediction Center using data from the AHPS Precipitation Analysis. Brett took the time to spend a few minutes with me on the telephone, saying that he would send me some graphics over e-mail.  

The first graphic that Brett sent me is prepared by the Center for Western Weather and Water Extremes. This graphic is one of my favorites. The graphic refers to the water year 2023. I know that the USGS uses a water year from October 1 through September 30. The current water year is from October 1, 2022 through September 30, 2023. I asked Brett about the Water Year he said “We (at the CNRFC) go by water year instead of calendar year because our dry season is really summer through early fall.  So to capture a wet season, we go by Oct 1 through Sep 30 of the following year as our water year.” 

Center for Western Weather and Water Extremes

A couple of things leaped out at me when I look at the graphic shown above. That is, the 24 atmospheric rivers are broken down by strength and by region. The map shows the strength scale and more importantly for our purposes where “each atmospheric river was strongest over the coast.” While I have been focusing in my blog on the atmospheric rivers that impacted California, I was aware that the atmospheric rivers may have impacted Oregon and Washington, with both states seeing rain and/or snow from these events.However,  my focus here is on California.

Moving on to total precipitation, when I went to The Weather Prediction Center’s twitter page on January 19th, I noticed that they updated the Total Precipitation Map to reflect the period from December 26th through January 17th, I took a screen shot of their tweet which I share below along with a direct link to the tweet. Note the listing of selected precipitation totals especially the top four, an incredible amount of rain. Of interest are the sites that had a record for the 23 day period: Oakland, San Francisco International Airport, and Stockton.

Screenshot taken on January 20, 2022 from NWS Weather Prediction Center Tweet on precipitation totals

I don’t want to leave out the snowfall from these atmospheric rivers. See the following map for snowfall totals which include snow fall totals for selected sites, note the area on pink that received over 15 feet of snow. 

Screenshot taken on January 20, 2023 from NWS Weather Prediction Center's Tweet on snowfall totals

Brett and I spent  a little time talking about the importance of showing rainfall departures from normal precipitation. He assisted me by sending me the two graphics that I will share below. The first map shows the percent of normal annual precipitation for the period from December 26 to January 11th. While this map ends at January 11, 2023 and does not go through January 17th, it does depict the impacts of the heavy rainfall over the 16 day period in California, especially in southern California. If I am able to obtain a similar map for the period from December 26th to January 17th I will share it in a later post.

The  final map Brett sent me shows the 90-day percent precipitation, created on January 18th. Brett clarified that this map depicts the 90-day percent of normal precipitation for the 90 day period. I am drawn to the areas in Central and southern California in blues and purples showing at least 200 percent of normal precipitation fell during the 90-day period. 

I hope that the graphics that I have shared here, with the help of Brett Whitin, have given you an overview of the extraordinary amounts of rain and snow that fell over parts of California during the atmospheric rivers that occurred from December 26 through January 17. If I get updated versions of any of these graphics, I will share them in a later post.

In closing, I want to mention two sites that Brett told me about that I think some of you might be interested in exploring. I mentioned the Center for Western Weather and Water Extremes earlier. I was interested in their work on atmospheric rivers including but not limited to their scale characterizing the strength of atmospheric rivers, atmospheric river forecasts, interactive maps, and atmospheric river aerial reconnaissance. The second site he pointed me to is the California Data Exchange Center, the CDEC is under the umbrella of the California Department of Water Resources. The CDEC has a wealth of information that some of you might be interested in including but not limited to data for river basins and individual rivers, current and monthly precipitation data for river basins, climate and hydrology, water quality, water supply and burn areas. For example, if I wanted to find information about a particular river in California, I would explore the CDEC site in addition to the 

NWS California-Nevada River Forecast Center (CNRFC).

The "strange yellow orb" aka the sun makes an appearance

Direct link to video from Time-Lapse Photography

I do not think my use of the phrase "the strange yellow orb" (aka the sun) is unique to me. My use of this phrase goes back over 30 years ago when my Dad was still alive and we in the Mid-Atlantic along with New England (where my Dad was living) had several days of cloudy weather along with rain. He called me up and told me that he had a strange yellow orb in the sky, had I seen it? I said yes, and we both laughed. 

I am in process of working on a post for Friday about the effects of the recent atmospheric rivers in California. I don't know about today, but I know that yesterday, Tuesday January 17, the"strange yellow orb" made an appearance at least in some parts of California.

And we in New Jersey are seeing the "strange yellow orb" today. While we have had some cloudy and rainy days recently, it is along the lines of a normal rainy weather, nothing extraordinary.

In closing, I would not be a child of the 60s if I did not share the Beatles song "Here Comes the Sun"

Direct link from The Beatles

Atmospheric River Events in the Western U.S.: January 13th update

I continue to follow the forecasts for more atmospheric river events in California. I'll get to that in a moment, but first I want to share a nice report that a friend sent to me from NBC 7 in San Diego on how the Air Force is aiding in forecasting atmospheric rivers. The report from NBC7 may be found here. As sometimes I could not get the embed code for the video to work, but the video is less than three minutes and is worth watching. 

The Weather Prediction Center posted a graphical forecast for two atmospheric river events, one tomorrow, January 14th and the second on January 16th.

The active pattern for the West continues with another strong atmospheric river set to bring heavy precipitation to CA this weekend. Heavy rainfall producing flooding and heavy mountain snow producing dangerous travel conditions are expected. The latest Key Messages are below. pic.twitter.com/Oi8brDGJQs

— NWS Weather Prediction Center (@NWSWPC) January 13, 2023

Atmospheric River Events in the Western U.S.: January 11th update

 I begin todays post on the atmospheric rivers by sharing excerpts from the Short Range Forecast Discussion issued by the NWS Weather Prediction Center  on January 11th at 3AM EST where they discussed an atmospheric river forecasted to impact northern California and other areas of the pacific northwest on January 11th through January 12th.

Short Range Forecast Discussion

NWS Weather Prediction Center College Park MD

300 AM EST Wed Jan 11 2023

Valid 12Z Wed Jan 11 2023 - 12Z Fri Jan 13 2023

...Next Atmospheric River event to impact northern California today, spreading up the Pacific Northwest coast on Thursday...

Following another day of heavy precipitation and gusty winds across California, the storm system associated with the recent unrelenting series of atmospheric river events has moved well inland and is currently bringing mountain snows across the Intermountain West and into much of the central Rockies.  Meanwhile, an enormous cyclone rotating well off the West Coast will bring the next round of heavy precipitation and gusty winds today, this time targeting northern California.  Unlike the recent atmospheric river events, this upcoming event is forecast to impact areas farther north from northern California and up the coast of the Pacific Northwest through the next few days.  The heaviest rains are expected to impact northwestern California through the next couple of days with a few inches of rain possible.  By later on Thursday, the threat of heavy rain will reach the Olympic Peninsula where a few inches of rain is possible as well.

As I wrote yesterday, January 10th, I was speechless and saddened by the devastating impacts of the January 9th and 10th atmospheric river event in much of California. I did my best to try to peruse affected NWS Weather Forecast Offices that were impacted by this atmospheric river focusing on debris flows on wildland fire burn scars. I focused on the following four NWS Forecast Offices:

• NWS Forecast Office Los Angeles CA
• NWS Forecast Office San Francisco Bay Area CA
• NWS Forecast Office Sacramento CA
• NWS Forecast Office Hanford/San Joaquin Valley CA

From what I could see from following these Weather Forecast Offices and conversations with Meteorologists from three of the four aforementioned Weather Forecast Offices, I knew that they were working hard providing various forecasts, watches and warnings including but not limited to flash flood warnings, high wind warnings, and thunderstorm warnings. I also knew that they were monitoring burn scars in the forecast area for possible impacts from flash flooding and debris flows. Perhaps I am missing, something which is always possible, but I am not aware of any major damage from flash flooding and debris flows in or near recent burn scars. If I later become aware of such damage to burn scars, I will make another post. The Weather Prediction Center issued a storm summary on January 10th with an update on the then current situation in areas impacted by the atmospheric river, it may be found here (and I hope that this link will stay active), they report that the event which began on January 9th was coming to end and provided some snow fall and rain totals with some snow fall totals of over three feet and some rainfall totals over ten inches. Wind gusts are also included in that report with a number of reports of peak wind gusts of over 70 mph. 

According to a January 11th report on CNN 17 people have died and flood watches are continuing on January 11th affecting as many as 5 million people in California. As I write this, the CNN article also reports on the efforts to find a five-year boy who was swept from his mother's arms during the floods, damage to cars, destroyed homes, and a forecast for the next few days in the Pacific Northwest.

Here is a map from the Weather Prediction Center of rainfall that fell in California from December 24, 2022  through January 10, 2023.

As another Atmospheric River impacts the West, here's a look at the total precipitation from 12/24 - 1/10 across California. The excessive precipitation has resulted in many floods and even some mudslides, so be sure to protect yourself from the dangers presented by flooding. pic.twitter.com/2YZIwWtxQY

— NWS Weather Prediction Center (@NWSWPC) January 10, 2023

I referred to coverage by the Weather Channel (with photos) and excellent coverage by the Capital Weather Gang of the Washington Post  in my January 10th article, if you are interested in reading those articles see my January 10th articles for the direct links. I subscribe to the New York Times where I have been following their coverage of the atmospheric river events in California. I read an excellent article just this morning, January 11th, in their live coverage under storm damage where they included photos and videos of four towns impacted by flood waters, with a map showing you where these towns are located. They also mapped out flooded roads and mudslides as well as river and stream flooding. As someone who is not intimately familiar with California geography I appreciated the maps and I hope you do as well. I am hopefully gifting you today's New York Times article with videos, photos, and maps of damage from the California storms (free access through January 20, 2023).

I continue to keep all those affected by these devastating atmospheric rivers and those yet to come in my thoughts and prayers. With a special shout out to the National Weather Service Weather Forecast Offices and the River Forecast Centers and all the first responders.

Atmospheric River Event in Western U.S.: Thoughts on January 10th

I was busy this morning sitting at my local auto dealership's service department waiting while my car was being serviced. It was not until early this afternoon that I was able to find out what has been going on in much of California after last nights atmospheric river event, see my January 9th article for more information. For example. I checked out the coverage on the Weather Channel, specifically their January 10th article with updates on the storm as well as a photo gallery.

Matthew Cappucci, Andrew Jeong, and Scott Dance from the Washington Post's Capital Weather Gang continue to report on the storms in California in a January 10th article, "California storm triggers more floods, tornado warnings as death toll climbs."

I have to admit that after looking at a lot of articles and photos reporting on the loss of life, flooding  damaging houses, rock slides and mud flows closing roads, power outages, on going evacuations, etc. that I am feeling a bit overwhelmed and at a loss for words. I am reflecting on what to say tomorrow. I write this to let y'all know that I am paying attention to the atmospheric rivers affecting much of California. I offer my thoughts and prayers to all affected by today's atmospheric river event and those over the last few days. I'd like to thank the Meteorologists at the NWS Weather Forecast Offices in Hanford/San Joaquin Valley, San Francisco and Sacramento who took a few minutes out of their busy day to talk to me about the atmospheric river event affecting their forecast area, helping me to get a clearer idea of what is going on as I prepare to write tomorrow's article.

Note: I subscribe to the Washington Post and as a subscriber I can gift ten articles a month for ten days free access (which will run out on January 20th). It is my intention to use one of my gift articles to share the January 10th article by Cappucci, Jeong, and Dance with you so you don't have to worry about a paywall. I hope this works out.

Atmospheric River Event in Western U.S.: January 9th Update

January 9, 2:50 PM EST

From the National Weather Service Forecast Office Los Angeles

Residents near recent burn areas are advised to monitor local weather, news, and https://t.co/qVlkZ3gRPO for up-to-date information.

Gather loved ones, pets, supplies, and important documents in the event of an Evacuation Order by local authorities.

— Ready Los Angeles County (@ReadyLACounty) January 9, 2023

#WEATHER: An evacuation warning has been issued for residents in the Lake Hughes and Kings Canyon areas due to the threat of mudflows in recent burn areas. https://t.co/u0fH9psrJm

— KCAL News (@CBSLA) January 9, 2023

Flash Flood Warning including Santa Maria CA, Santa Barbara CA and Lompoc CA until 4:45 PM PST pic.twitter.com/MeHGXYDAP2

— NWS Los Angeles (@NWSLosAngeles) January 9, 2023

January 9, 6:30 AM EST

I continue posting about the forecast atmospheric river event in California on January 9 through January 11th, see my post of January 8th where I first posted on this forecasted atmospheric event. If you are affected by the forecasted atmospheric river events or just want more information on a specific area please go the relevant NWS Weather Forecast Office for more information. Please heed any warnings and evacuation orders. Go to your local emergency management office for information on any warnings and evacuation orders that might affect you. Turn around don't drown

The Weather Prediction Center issued a short range forecast discussion on January 9th including a discussion of these forecasted atmospheric river events, I am copying the portion of the WPC discussion pertinent to California:

Short Range Forecast Discussion

NWS Weather Prediction Center College Park MD

300 AM EST Mon Jan 09 2023

Valid 12Z Mon Jan 09 2023 - 12Z Wed Jan 11 2023

...Two major episodes of heavy precipitation expected to impact California today and Tuesday...

Two major episodes of heavy rain and heavy mountain snow are expected to impact California in quick succession during the next couple of days in association with two of the more energetic and moisture-laden parade of cyclones that are aiming directly for California.  The heavy precipitation episode currently streaming into central California is expected to be the more robust of the two, resulting in heavy rainfall totals of 3-5 inches near the coast.  The second episode will quickly arrive on Tuesday with amounts slightly less heavy, but impacting locations farther south into southern California.  The Sierra Nevada will likely see heavy snow exceeding 6 feet across the higher elevations before the snow tapers off Wednesday morning.  The cumulative effect of successive heavy rainfall events will lead to additional instances of flooding. This includes rapid water rises, mudslides, and the potential for major river flooding. Susceptible terrain and areas near recent burn scars will be most at risk for debris flows and rapid runoff. For the higher terrain of the Sierra Nevada, extremely heavy snow and intense snowfall rates are anticipated to make travel very dangerous to impossible at times, including the potential for road closures. The amount of additional accumulating snow on top of an already well built snowpack is likely to increase the threat of avalanches and strain infrastructure. Gusty winds are also expected to spread onshore with the approaching system and could lead to the threat of downed trees and power outrages. The combination of saturated soil and gusty winds could exacerbate the tree damage threat. Residents and visitors across this region are advised to check their local forecast, never drive across flooded roadways (Turn Around Don't Drown!), and have both an emergency kit and evacuation plan in place.

To review, take a look at this graphic (I first posted this on December 30th) that explains what an atmospheric River on the west coast USA is. 

Obtained on December 30, 2022 from https://www.noaa.gov/stories/what-are-atmospheric-rivers

One of the reasons why I started posting on the atmospheric river events is because of the risk of debris flows on recent wildfire burn scars. For more information on the danger flooding rains pose to burn scars, see my January 6th post. Two NWS Weather Service Forecast Offices, San Francisco/Monterey and Los Angeles are warning that heavy rain may lead to debris flows on recent burn scars. See the graphic images below for more information. If you live near any of these burn scars or other burn scars not mentioned, please pay special attention to any evacuation orders.

obtained on January 9, 2023, 6 AM EST from NWS Forecast Office Los Angeles

obtained on January 9, 2023, 6AM EST from NWS Forecast Office San Francisco CA

Two other National Weather Service Forecast Offices in Sacramento and Hanford/San Joaquin Valley CA are expecting heavy rainfall from this forecast atmospheric river event. See the graphic images below.

obtained on January 9, 2023, 6AM EST from NWS Forecast Office Sacramento CA

obtained on January 9, 2023, 6AM EST from NWS Forecast Office Hanford/San Joaquin Valley CA

Atmospheric River Event in Western U.S.: January 8th Update

 

Obtained on January 8, 2022 at 7:20 AM EST from the Weather Prediction Center's Facebook Page

I would like to thank a Meteorologist friend in California for giving me the heads up about the atmospheric river event forecast for early this coming week (January 9 -11).  I am very thankful for the graphic update on this atmospheric river event that I shared above as they talk about the entire state of California making it  easier to write this post. At my Meteorologist friend's suggestion, I have been following the following these National Weather Service Forecast Offices in California:

• NWS Forecast Office Los Angeles
• NWS Forecast Office San Joaquin Valley/Hanford
• NWS Forecast Office Sacramento
• NWS Forecast Office San Francisco Bay Area

I am going to continue to follow these four Weather Forecast Offices but may won't post updates from each office, at least for now. 

Those of you reading this while this before, during, or just after this latest atmospheric river event forecast for January 9 through 11 with local interests might want to follow one of these four NWS Forecast Offices and follow your local emergency management office for emergency updates. Please heed any evacuations and take any Weather Emergency Alerts (WEA) that you may get on your smart phones seriously. Remember, turn around and don't drown.

I won't to close by mentioning a good article on the Washington Post that dated January 6th by Matthew Cappucci. Mr. Cappucci is a Meteorologist for the Washington Post's Capital Weather Gang. Cappucci's article has the following headline "California’s not done. Three more atmospheric rivers are on the way. The strips of deep tropical moisture are deluging the state, causing flood concerns and mountain snows." I enjoyed reading Cappucci's article, finding the article very informative. He writes about what an atmospheric river is, including a graphic. He says in part:

Atmospheric rivers are narrow filaments of tropical moisture that can stretch thousands of miles or more. They’re often only a couple hundred miles wide, but may be transporting more than a billion pounds of moisture overhead every second. Much of that moisture remains as water vapor or condensate in the form of cloud cover, but some falls as rain or snow. Unsurprisingly, precipitation totals can climb quickly.

Most atmospheric rivers carry the bulk of their moisture a mile or so above the ground. That’s why the greatest totals of rain or snow are usually found in the higher elevations. Additionally, moist air forced up the mountains frequently cools to its dew point, becoming saturated and ridding itself of excess moisture in the form of heavy precipitation.

I will be keeping all who may be affected by the upcoming atmospheric river event in California in my thoughts and prayers. 

Note: I subscribe to the Washington Post and as a subscriber I can gift ten articles a month for ten days free access (which will run out on January 18th). It is my intention to use one of my gift articles to share Cappucci's January 6th article with you so you don't have to worry about a paywall. I hope this works out.

Atmospheric River Event in Western U.S.: January 6th Update

Hint, if you are using the Firefox browser and can not see the graphics on this post, you will need to turn off tracking protection temporarily to view this post or use another browser. Other browsers may have tracking protection or add ons that might block these graphics. And if you are your cell phone, turn your phone to landscape mode. 

I have been writing recently about the ongoing atmospheric river events (ARE) in California, see for example my January 4th post. I had some questions about the most recent ARE in California, specifically the rainfall totals. I turned to social media accounts from a couple of agencies within the National Weather Service because of their good science, easy to understand graphics with important commentary. For today's article I was looking for a map that I could share with you and I found one on the NWS Weather Prediction Center's twitter page, it was not shared on Facebook. This map (prepared on January 5th) depicts where the highest rainfall totals occurred in darker shades oranges and reds. The lighter amounts are in various shades of green and yellow.

Here are the precipitation totals so far for the series of atmospheric rivers affecting California that began on December 26, 2022. We will add to these totals in the next couple weeks as additional systems are expected. For more data, visit https://t.co/6wTyTSKPbx pic.twitter.com/yNSGtQuFE4

— NWS Weather Prediction Center (@NWSWPC) January 5, 2023

I know that heavy rainfalls, especially on already saturated soils can lead to debris flows on recent burn scars. As I write this I do not know if there have been any debris flows on burn scars, but there may well be some that I do not know about. In any event, I found the following graphics from the National Weather Service IMET Office's Facebook page  dated January 4, 2023 illustrating the danger from debris flows on burn scars. If you click on each image you should be able to see a larger image.

Finally I suspected that there would be more ARE's in the forecast for California. I found this forecast from the NWS Weather Prediction Center, it is in a nice graphic from a January 5th post on the NWS Weather Prediction Center's Facebook page. AREs are forecast for this weekend and again on Monday. If you live in one of the affected areas, please check with your local NWS Weather Forecast Office for the latest forecast and any warnings; get emergency alerts from your local emergency management office, and check your local media outlets for their coverage. Please, please heed any evacuation orders. Turn around don't drown.

Atmospheric River Event in Western U.S.: January 4th & 5th Update

January 5th, 3:28 PM

I was not surprised to see a report a January 4th report from CBS Sacramento -- with thanks to my friends from NJFFS Section B10 for sharing the video today -- about the concern that there may be debris flows from this atmospheric river event that could impact recent burn scars. In addition, there will be road closures and high winds could lead to power outages. Rock slides and road washouts remain a concern

Direct link to video from CBS Sacramento on YouTube

January 5th, 9:32 AM EST

I woke up today with news from Fox Weather of the atmospheric river event overnight on January 4th to 5th, two more people have died, including an infant, see this January 5th article from Fox Weather for more information. See also this article (with ongoing updates) from NBC Bay Area and a January 5th update from CapRadio (NPR afflilate) in Sacramento. Flood and high wind warnings continue in northern California along with power outages. The Governor has issued a state of emergency for California.

I am sharing more graphics from the Weather Forecast Office in Sacramento, CA

Obtained on January 5, 2023 from the Weather Forecast Office in Sacramento, CA

Obtained on January 5, 2023 from the Weather Forecast Office in Sacramento, CA

 

January 4th, 8:02 AM EST

I am following up on the post I wrote yesterday on the forecasted atmospheric river event on January 4th and 5th in California. I have been following the Weather Forecast Office in Sacramento, CA, and I understand that this atmospheric river event will impact other areas in California outside of the Sacramento area. I will be posting updates to this atmospheric river event to this post.

I went to the webpage for the WFO in Sacramento to get an update on their forecast, I saw this graphic, that I am sharing below. Note the concern for debris flows in recent burn scars.

Obtained on January 4, 2023 from the Weather Forecast Office in Sacramento, CA

Another Atmospheric River Event for the West Coast USA on Jan 4th and 5th

the

Obtained on January 3rd at 10:45 AM EST from the National Weather Service Sacramento

Another atmospheric river event is forecast to impact California tomorrow (January 4th) and Thursday (January 5th). I again am focusing on the Sacramento area following up on my original post of December 30th and my follow-up post on January 2nd.

Here is an excerpt from the Forecast Discussion from the Weather Forecast Office (WFO) Sacramento on January 3rd at 3:25 AM PST for the current period (January 3rd through January 6th). Because the Weather Service updates the links to the Forecast Discussion, while I will cite where I obtained the Forecast Discussion, the link is likely to be outdated by the time you look at the link. This is because of the way that the National Weather Service updates each WFO Forecast Discussion.

A more potent weather system is forecast to impact NorCal  early morning Wednesday and continues through Thursday night which will bring very strong winds, heavy rain and mountain snow. This  storm taps into a moderate to strong Atmospheric River (AR). Therefore, another round of moderate to heavy precipitation is expected with more flooding concerns. Precipitation forecasts for the midweek storm continue to be around 2 to 3 inches possible in the Central Valley with 3 to 6 inches or more of liquid precip in the foothills and mountains. Based on latest guidance, a band of precipitation will move up from the southwest early morning Wednesday, with widespread rainfall expected for the morning commute. The heaviest rainfall is expected to be Wednesday afternoon and overnight. With already saturated soils, and rivers, creeks and streams already running high from the end of the year's heavy precipitation, additional heavy rain will likely lead to additional flooding concerns. Minor to moderate flooding is possible on area rivers and streams, as well as urban flooding.As such, a Flood Watch was issued, and will be in effect early Wednesday through Friday morning. Even though rainfall will be winding down Friday morning, flooding impacts can remain several hours (and even days) after the heaviest rainfall occurred. Reminder, if you encounter flooded roadways, Turn Around, Don't Drown! Be sure to be extra cautious when driving at night, when it may be difficult to see flooded roadways. (obtained on January 3rd, 10:45 AM EST from the National Weather Service Sacramento, Forecast Discussion for January 3, 2022 at 3:25 AM PST)

Follow-up: West Coast USA Atmospheric River Event Jan 1 update

I want to follow-up on my December 30th post reporting on the December 31, 2022 to January 1 2023 Atmospheric River Event (ARE) on the west coast of the United States. In my December 30th post, I focused on the Sacramento California area, understanding that this ARE impacted other areas of California. I want to begin by reminding everyone about the importance of following your local emergency management agency and signing up to receive alerts. In addition, your local Weather Forecast Office of the National Weather Service provides warnings such as flash flood warnings that you may receive on your smart phones, known as Wireless Emergency Alerts. 

I begin by sharing a screen shot I took of the Sacramento California area from Apple Maps on my iMac. I hope that I captured some of the areas that were severely impacted by the flooding rains that hit the Sacramento area this past weekend. I normally save images from Google Earth when I want to show a map of an area that I am referring to in this blog. In this case, I wanted to show CA Highway 99 on a map and it was easier to take a screen shot from Apple Maps to show you some of the highways. Sections of CA Highway 99 were among the roads and highways that were flooded over the weekend. Evacuations were ordered in the Point Pleasant area (south of Sacramento) on January 1st. As I write this on January 2nd, I am uncertain if this evacuation order is still in place. 

Three day rainfall totals for the three days ending on January 1st ranged from 1.5 inches to over 9 inches (see the video below), with snow in the higher elevations. More rain is forecast for later this week (January 2 through 7). The storm resulted in power outages.

Sacramento CA area, screenshot from Apple Maps

The National Public Radio affiliate in Sacramento, CapRadio, has a nice report on the Sacramento Storm on January 1st (but no video). I like to see images and videos so I am embeding a video from KCRA in Sacramento (January 1, approximately 5:30 PM PST), it is over 16 minutes that I thought that some of you might find useful. I got a lot out of this video because I wanted an overview of the heavy rain fall and resultant flooding over the weekend. I got this from watching the entire video. Of course, the shots of the flooding will mean more to those of you who are familiar with the area.

For those who are short of time and have specific concerns here are some approximate time points in the video in minutes:seconds:

• 5:12 current weather report and precipitation totals
• 6:48 flooding
• 10:28 power outages
• 14:47 weather forecast 

Direct link from KCRA on YouTube

Atmospheric River Event on West Coast (December 31 2022 to January 1 2023)

Rain and snow came to portions of the west coast of the United States earlier this week caused by Atmospheric Rivers and are forecast to occur this coming weekend. What are atmospheric Rivers, this document ,"What are Atmospheric Rivers" by NOAA provides some of the meteorology behind atmospheric rivers, they say in part:

Atmospheric rivers are relatively long, narrow regions in the atmosphere – like rivers in the sky – that transport most of the water vapor outside of the tropics. These columns of vapor move with the weather, carrying an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River. When the atmospheric rivers make landfall, they often release this water vapor in the form of rain or snow. Although atmospheric rivers come in many shapes and sizes, those that contain the largest amounts of water vapor and the strongest winds can create extreme rainfall and floods, often by stalling over watersheds vulnerable to flooding. These events can disrupt travel, induce mudslides and cause catastrophic damage to life and property. A well-known example is the "Pineapple Express," a strong atmospheric river that is capable of bringing moisture from the tropics near Hawaii over to the U.S. West Coast.

Take a look at this graphic that explains what an atmospheric River on the west coast USA is. 

Obtained on December 30, 2022 from https://www.noaa.gov/stories/what-are-atmospheric-rivers

I first got wind of the atmospheric river that occured on the west coast USA from this Washington Post article by Matthew Cappucci on December 27th, Cappucci reports in part:

The West Coast, ordinarily known for being parched and drought-stricken, is facing a barrage of atmospheric rivers — plumes of deep tropical moisture known for bringing heavy rain and snow. Parts of coastal California, including the Bay Area, are under flood watches, initial signs from the first of several atmospheric rivers set to drench the West in the days ahead.

Weather alerts — for heavy rain in the lowlands, and snow and wind in the mountains — blanket most of central and Northern California. Coastal and central Oregon and Washington are largely under flood watches and high wind warnings, with winter storm warnings in the Cascades and Columbia River Basin.

I am interested in these forecasted atmospheric rivers because I know how much the drought-stricken west coast needs rain. While I doubt that this atmospheric river event will be a drought buster, any precipitation will help. I understand that the atmospheric river event, see for example the graphic below from the Sacramento Weather Forecast Office of the National Weather Service will take place over a couple of days possibly bringing from one to nine inches depending on location:

Obtained on December 30, 2022 from https://www.weather.gov/sto/

Here is what I hope is a good link from KCRA in Sacramento with this weekend's wet weather forecast, forecasting an atmospheric river event.

It seems like this upcoming atmospheric river event will be over a couple of days, which hopefully will minimize any detrimental effects on recent wildfire burn scars.