From the Cliff Mass Weather Blog
Cliff Mass
A significant atmospheric river event will occur tomorrow (Sunday) and Monday, with heavy precipitation in the mountains and South Sound.
The latest UW WRF model forecast predicts up to 10 inches in the Cascades, with the southern WA Cascades being hit the hardest (see below). In contrast, a profound rain shadow will extend from the NE Olympics to Bellingham.
It is now clear that there will be some serious flooding in some locations. For example, the NOAA/NWS River Forecast Center is forecasting major flooding on the Snoqualmie River near Carnation.
Want to see something spectacular? Go to Snoqualmie Falls on Monday. If you can get there.😁
Atmospheric rivers in our region are associated with plumes of warm, moist air from the south, southwest, and west.
NOAA weather satellites can sense the water vapor, which is very evident in the water vapor image from this morning (below). A massive plume of water vapor is moving our way.
Numerical weather prediction models, like the UW WRF model, can skillfully forecast such water vapor plumes, which release massive amounts of water as the air is forced to rise by our region’s substantial terrain.
Meteorologists favorite diagnostic for atmospheric rivers is integrated water vapor transport (IVT), which is the amount of water vapor times the wind speed, summed up in the vertical (that is where the integrated comes from). This quantity is more closely related to the potential for regional rainfall.
The prediction of IVT for Sunday morning is shown below, with the arrows showing both the direction and magnitude of the moisture transport Large values, but not record-breaking by any means.
Such moisture plumes are generally warm as well. In fact, to get large values they HAVE to be warm since the amount of moisture air can hold depends on temperature (warm air can potentially hold more water vapor than cold air).
Atmospheric rivers form in our region when strong southwesterly atmospheric wind currents occur, currents that move large values of water vapor out of the subtropics.
The atmospheric flow pattern that does this is usually characterized by a strong low-pressure area in the Gulf of Alaska and higher pressure west of southern California.
Not surprisingly, this is exactly the pattern forecast for Sunday morning at 10 AM for a level around 5000 ft (below). With high pressure to the south and low pressure to the northwest, a strong pressure/height change is created, which produces a strong southwesterly flow.
The interesting thing about atmospheric rivers is that they are like regular rivers in another way…not only does water come into the river at the beginning, but there is a convergence of water vapor from the sides along the way, not unlike the small streams that drain into a river over its entire path.
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I understand what they are, but not why they are so ‘narrow’. Storm fronts?
Why are jet streams narrow?
According to Google AI, zonal jet streams it is. TY. Learned something.
Here’s the current jet stream
https://earth.nullschool.net/#2025/02/24/1600Z/wind/isobaric/500hPa/orthographic=-119.28,32.69,422
It looks that way on the North Pacific color GEOS image, as there is dry, clear air along a sharp shear boundary to the north of the “River”, but it is more apparent on windy.com at this image (I hope it takes you there) of the North Pacific. Note there is a sharp temperature boundary with a strong wind gradient.
https://www.windy.com/-Temperature-temp?temp,40.844,-105.590,4,p:temp
Great explanation here by Cliff Mass. This is a good time to be reminded that dynamic energy transport from the tropics toward the poles and from the surface toward space is powered by water vapor. In this image the west coast is being presented with air containing 20-40 kg/m^2 of precipitable water. 25 kg/m^2 represents about 17,400 W-h/m^2 of latent energy. A one-inch-per-hour rate of rainfall thus represents a 17,600 W/m^2 conversion of latent to internal energy in the atmosphere. (1 inch per hour = 25.4 mm per hour or 25.4 kg/m^2 per hour)
(this image address will likely only be valid for Feb 23rd and then update to the next day.)
Powerful dynamic self-regulation, including energy conversion. Another reason why expecting the static radiative effect of incremental CO2 (say 4 W/m^2 for 2XCO2) to drive any trend of any metric of climate interest to a bad outcome has been unsound all along.
Thank you! Thank you! thank you! Finally talking about “Energy transport”. The “metrics of (local) climate interest” include daily and seasonal VARIATIONS (not averages) of temperature, humidity, precipitation, wind, cloudiness, etc., all of which are methods of energy transport, the most significant of which is the water cycle of evaporation, convection, condensation and precipitation. The Earth’s daily precipitation (~1.3*10^12 metric tonnes) is almost as much as the entire atmospheric CO2 content (~2*10^12 mt) and carries orders of magnitude more energy than CO2 can possibly absorb.
The Earth’s climate “magic molecule” is H2O, not CO2!
“Finally talking about “Energy transport”.”
Perhaps you are new here. 🙂
https://wattsupwiththat.com/2022/05/16/wuwt-contest-runner-up-professional-nasa-knew-better-nasa_knew/
“The Earth’s climate “magic molecule” is H2O, not CO2!”
True story.
Missed your 2022 post. Otherwise I would have given it many thumbs up. It’s sad to see NASA scientists continue to support the Climate Catastrophe Hoax even though, as you said, they know better.
https://andymaypetrophysicist.com/2025/02/01/energy-and-matter/
Good report, supporting the dominant role of water. Thank you!
In addition to convection as energy transport, and inherent to the general circulation, there is yet another angle to what is happening constantly throughout the depth of the troposphere. It is the concept of energy conversion: [internal energy + potential energy] <–> [kinetic energy]. This arises from the physics of compressible fluids, which also of course is the basis of the lapse rate. Energy conversion massively overwhelms any tendency for the computed IR absorbing power of incremental CO2 to be realized as sensible heat gain in the lower atmosphere, on land, or in the oceans. The ERA5 reanalysis model computes an hourly parameter – the vertical integral of energy conversion – from which I have plotted the daily min/median/max values for 2022 at 45N for each longitude gridpoint. This video is a time-lapse of those plots for emphasis. The Readme description gives a full explanation with references. Perhaps you have seen this before.
https://youtu.be/hDurP-4gVrY
It is also posted on X as one of my “highlights.”
https://x.com/DavidDibbell/status/1722012790368416058
Discerning atmospheric water from space above 75mm or so is very difficult. The error increases rapidly above 60mm because the satellites cannot view through the moisture laden air. So a reading above 60mm could be higher than that and above 70mm almost certainly higher.
You can guarantee the amount of water vapour in a cyclone is under reported by satellite observation and not many soundings inside cyclones to know what is really happening.
The are currently;y 6 tropical cyclones developing in the vicinity of Australia. The highest satellite moisture indication in any of them is 72mm but you can guarantee it will be much higher than that.
Do you take into consideration the jet stream and how it affects the weather?
We get the same thing in the Midwest, Ohio, Michigan, strong warm fronts that come up from Texas, they bring warmth and rain, and sometimes tornadoes.
There are small local rainfalls that can be dangerous to someone standing outside…the water is like a waterfall from a very high altitude…..not a fun experience.
Think of a marble-to-golfball sized hailstorm. Does a job on a solar farm, right?
AI Overview
The term “atmospheric river” was first used in 1994 in a geophysical research paper. It was coined by researchers Reginald Newell and Yong Zhu of the Massachusetts Institute of Technology.
Context
The term was used to describe the transport of water vapor across mid-latitudes.
It was used to describe the narrowness of the moisture plumes involved.
The term compares the phenomenon to a river because of the similarity in the flow of moisture from one place to another.
Current use
The term has become part of regular use in the western United States and in some other regions affected by atmospheric rivers.
It’s used by meteorologists to better warn a region about the potential impact of an incoming system
The term “atmospheric river” was first used in 1994
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There were no atmospheric rivers before 1994. Instead we had the pineapple express. Terminology change not climate change.
It seems that after Hansen they started looking for new names for things that happen all the time.