From the Cliff Mass Weather Blog
Cliff Mass
The atmospheric river currently over the Gulf of Alaska may be the strongest on record in that area.
The latest model runs show extreme values of the key measure of atmospheric river strength, vertically integrated moisture transport (IVT), which describes how much water vapor is being moved over a period of time.
Below is the map of IVT for this morning, with values exceeding 1900. I have personally never seen anything like it.
An estimate of the strongest atmospheric river over observed for 1990-2019 by Dr. Lexi Henny of NASA/Goddard suggested this is the strongest atmospheric river during that period of record. Impressive.
The plume of moisture was very apparent in water vapor satellite imagery this afternoon (below). Do you see the southwest-northeast directed plume aimed at SE Alaska and BC? Some of the associated clouds have moved into Washington.
This atmospheric river is predicted to hit land as an AR-5, the strongest level observed. We can be thankful that the center of the river will make landfall north of Washington State, where only AR-2 levels should occur on the northern Olympic Coast.
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By Tuesday, as much as a foot of rain will fall over the coastal terrain of BC
Strong atmospheric rivers are not infrequent over SE Alaska and BC this time of year, with the path of the moisture plumes reaching Washington State in November.
The fact we are in a neutral to La Nina year means that there is a higher probability of more rain than last year (an El Nino year)…something shown for the western Washington lowlands below.
My advice. Make sure you have a decent umbrella.
Yea, I was watching that here. Impressive
https://tropic.ssec.wisc.edu/real-time/mtpw2/product.php?color_type=tpw_nrl_colors&prod=epac×pan=48hrs&anim=html5
It’s hard to fathom how much it pours in MacLeod Harbor sometimes. An average October has 36″ of rain.
What year did anyone I trust start measuring atmospheric river over the Gulf of Alaska?
Oh, yeah.
In the simplest possible language how can an Atmospheric River be explained to someone who has never heard of it?
We all know that wind and rain are highly variable. Just listen to farmer talk. Now and then a new record will be set. The big question in the present social mood is – did the new record have any help from the Hand of Man?
That is a very difficult question. Sadly, it attracts diverse commenters from scientists with experience to snake oil salesmen. Discerning which is which is also a difficult question, which WUWT helps to clarify.
Geoff S
I think the weakening Earth’s magnetic field has a lot to do with it. We can expect more “intense” low pressure systems and stronger jet streams as the weakening continues, especially during Solar outbursts. It’s going to be an interesting ride over the next decade or two and no one is sure how it will end.
If it’s any consolation, these precipitation transports usually don’t bring very cold air with them.
It is quite a sudden summer-to-full-on-autumn effect though.
Australia is copping its over-generous share of rain atm too.
What surprises this old world keeps presenting us with.
AR’s are one of many things that climate models don’t do well, if at all. Per NOAA, the average width of an atmospheric river is 250-375 miles. Per CMIP6, the nominal typical resolution is ~250 miles at the equator. (The ‘best’ are ~100 miles.) Atmospheric rivers can barely be ‘seen’ in CMIP6 model resolution. And they are sufficiently infrequent and varying in location that they cannot be reliably parameterized either.
Prince Rupert is going to wear it again.
Send some of that moisture to the central U.S. It’s getting a little dry around here.
We have a developing hurricane in the Gulf of Mexico and an Atmospheric River coming from the other direction and we are right in the middle, so we’ll probably get some rain out of this. Good!
“AR-5”, huh?
Next thing you know, they will be naming the damn things!
Coming soon to a theater near you: “Hunga-Tonga Eruption Gives Birth to Monster Atmospheric River Attacking Alaska”
Oh, the chills! Oh, the horrors!! You’ll be on the edge of your seat!!!
/sarc
Somewhat OT… maybe a story tip ??
But does anyone know what has happened to the Arctic sea ice data
NSIDC and OSI both have a several day gap from about 12th to 17th Sept, but after that NSIDC stays about level, but OSI climbs rather quickly.
MASIE doesn’t have the gap in the data, but seems to show a decrease over the last few days.
Something rather odd going on.
> The term atmospheric river can be traced to the Massachusetts Institute of Technology climate scientists whose research was responsible for the first descriptions of the phenomenon in the early 1990s.
I’m not willing to say “largest on record” when the phrase is so new.
In the meteorological profession “on this side of the Atlantic at least”, the process described is called a “warm conveyor” ….
”A warm conveyor belt (WCB) is a coherent warm and moist airstream, which originates in the boundary layer of an extratropical cyclone’s warm sector. Air within the WCB ascends in a day or two to the upper troposphere while moving poleward.”
The source of this analysis of the process involved suggests that it used to be the case on that side as well:
https://www.weather.gov/media/lmk/soo/Conveyor_Belts.pdf
Just because none of us have seen something before it doesn’t mean it has never happened before. For example higher sea levels.
How long has the term “atmospheric river” been used? Never heard of it until a few years ago.
Is it possible that this moisture is causing the slight warming of the ocean in that area?
There was a atmospheric river event in that area back in November of 2021 that
caused a large amount of flood damage during covid –>
https://en.wikipedia.org/wiki/2021_Pacific_Northwest_floods
How do I post a Pacific Ocean sea surface temperature map?
I have the source code, but only the code posts in my comment – no map.
Thanks for any helpful guidance on this.
Must tell my son not to get his gyprock delivered next week as planned. We are in the AR3 region.
Check the weather in Haida Gwaii, once the Queen Charlotte Islands, which are in the middle of that atmospheric river satelitte view. Oops, scattered cloud, low POP, seems like weather forecasting is an inexact science….
https://www.wunderground.com/forecast/ca/haida-gwaii
Would welcome some precip over NE Washington State… it has been a long, HOT, VERY dry Late Spring & Summer!