Western Railroad Discussion > Atmospheric River coming to California

The weather service is close to predicting with certainy that California may be hit with a powerful atmospheric river later in the week. This juicy storm will be pulling in tropical moisture leading to a high snow level of 10,000 feet.  This could get very interesting with the quick snowmelt in the Sierras leading to torrential flooding.  Just looking back in history we could see the Truckee River overflow into Reno and slides take out the Feather River Canyon route.  

I am including an image from the GFS forecast model showing precipitation for the 12 hours preceeding Friday afternoon (time is UTC).  

Todd Clark
Canyon Country, CA
Trainorders.com

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Interesting....  5-6 days out....its still a ways in metorological terms.  The  last forecast discussion from the LA office wasnt getting excited....altho its easy to get a deluge up in the Sierra without LA getting much.

Look at the 500mb chart and see where the max jet is...

Lol, atmosphereic river has to be the hot new weather term. 

Pineapple Express is what they were refereed to by friends and coworkers when I moved to CA. They have definitely been something this year.

Pacific5th Wrote:
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> Lol, atmosphereic river has to be the hot new
> weather term. 



Edited 1 time(s). Last edit at 03/05/23 20:25 by broken_link.

Remember January 1997?
Same situation, I hope the model is wrong.

Rob in Fremont

It's happened many times in recent knowledge, it's a well known mix for disaster. December 1964 was the one that made history with the SP on the NWP Eel river and also the Cascade Line in Oregon. In the 1980's there was a report of Propane tanks floating down the river in Truckee, getting jammed under the bridge with the high fast water. Many other occasions, the combination is really something to make preparations for.

Let's hope they are wrong, while I hate to wish against rain and ignoring the potential flood disaster we need that snow to stay on the ground for a while and not wash away. No pun intended but it's truly a snow bank for the coming summer.

If this happens look for Flooding in the Sacramento valley area.   Not a good thing at all.    

Here is the Reno, NV forecast office  long term discusson:
Thursday-Sunday:
For those dreaming of dry weather might be really let down by the
long-term forecast. Let`s just say we`re starting to get a more
consistent, converging solution among the ensembles in the weather
pattern. As of now, 70% of the ensembles favor a much wetter
solution (30% a day ago). This may setup an extended period of
heavy precipitation throughout the Sierra, northeast CA, and
western NV. Latest blended guidance has picked up on this signal,
with precipitation now looking likely (>60%) from late Thursday
through at least late Saturday. This is also possibly setting up
to be a warmer event too, with much higher snow levels, and lower
snowfall ratios (7-9" to 1). As we get closer to this event, more
details will emerge. But for now, stayed tuned and alert to the
forecast.


Sacramento Forecast office long term discussion:
.EXTENDED DISCUSSION (Thursday THROUGH Sunday)...
A flat ridge will be over the area on Thursday so for most
locations they should stay dry. Models are starting to come into
better agreement with the GFS and ensembles starting to look
closer to the European on bringing a storm into the region
Thursday night and Friday. Higher snow levels are expected with
this system. Snow levels will rise above the foothills and
probabilities for snow in the foothills drops into the single
digits. Snow levels do remain uncertain as to how high they will
rise at this time. Amount of precipitation is uncertain as well
but enough rain looks to get over the area to result in a decent
amount of snow melt below 3000 to 4000 feet. the storm looks like
it lasts at least into Saturday with a chance of some
precipitation continuing on Sunday

LA weather forecast office long term discussion
.LONG TERM (THU-SUN)...05/147 PM.
Looks like there should be at least one more dry day Thursday and
after that there is considerable uncertainty in the models, both
in terms of rain potential and the timing. Certainly the odds of
an AR hitting California have bounced back up after a couple days
where models had either shifted it much farther north or 
eliminated it all together. And in a shift from before the ECMWF 
appears to be leading the AR bandwagon at least in terms of the 
southern extent of it, while the GFS is focusing it farther north.
Timing is another huge question mark and likely another reason 
that 6 and 12 hour pops are so low. The GFS deterministic run does
show snow levels rising to over 10,000 feet Friday which is a 
classic AR signature and something that will need to watched 
closely as we get closer. Warming temperatures in areas with lots 
of snow on the ground in addition to heavy rain could pose a 
significant flooding threat, not just in those locations but also 
downstream as those waters flow down into the lower elevations.



Edited 1 time(s). Last edit at 03/05/23 21:54 by pdt.

Pacific5th Wrote:
-------------------------------------------------------
> Lol, atmosphereic river has to be the hot new
> weather term. 


It been around for a while at least the last 10 years or so that i have been following Weather... also check your PM's....

Posted from Android



Edited 2 time(s). Last edit at 03/06/23 04:47 by goduckies.

I drove around a lot of California a couple of years ago, and was shocked to how dry it was everywhere. I saw ponds, lakes, rivers and creeks, and reserviors dried up, or at extreme low levels. I saw a big reservior someplace where they just gave up and put in a big golf course, thinking the water will probably never come back up to that level. Not wishing anybody any bad luck, but I hope they get enough rain and run off to fill those up again.

Dang. Yeah today's news calling for up to 30" of additional snow between 3,500 - 4,500' in the Feather River watershed by Thursday morning, then possibly 5" of rain between Thursday and Sunday. Doesn't bode well for anybody by this late in the season, let alone the UP Canyon Sub. If it happens, Oroville will be releasing water for sure and it's already around 120% of average. That river gets awfully angry with rain on snow.

Posted from Android



Edited 1 time(s). Last edit at 03/06/23 15:09 by SPbird.

goduckies wrote of the term "atmospheric river ":

> It been around for a while at least the last 10 years or so that i have been following Weather...

Yes, the term has been around for awhile.  Here is what the Santa Barbara News-Press of Jan. 22, 2017 (pg. A2) wrote of "atmospheric river" :

"The term was coined in the early 1990s by MIT researchers Yong Zhu and Reginald Newell." 

California newspapers have commonly used the term since 2009.

 



Edited 1 time(s). Last edit at 03/06/23 15:34 by johnsweetser.

There was an upper level, advanced 'Weather people' Convention in Colorado a few weeks ago, they commented to the general Media to 'stop scaring people'.

https://en.wikipedia.org/wiki/Atmospheric_river

Past event of interest:
https://en.wikipedia.org/wiki/Great_Flood_of_1862

Future, bejebers version:
https://en.wikipedia.org/wiki/ARkStorm

One source of related info-- Cal Water stats - reservoirs, snowpack, precip, etc...and updates:  cww.water.ca.gov 
Updated daily. 

 

Daniel Swain has a very scientific perspective on this subject and I think you will find his recent article (7 March) a worthy read. 
https://weatherwest.com/archives/24693

cg