From NASA JPL, video animation follows.
Wet weather is again hitting drought-stricken California as the second and larger of two back-to-back storms makes its way ashore. The storms are part of an atmospheric river, a narrow channel of concentrated moisture in the atmosphere connecting tropical air with colder, drier regions around Earth’s middle latitudes.
The storm that arrived on Feb. 26, 2014, and the one about to hit, are contained within the “Pineapple Express,” an atmospheric river that extends from the Pacific Ocean near Hawaii to the Pacific coast of North America, where it often brings heavy precipitation. This next storm is expect to be the largest rain producer in Southern California in three years.
This animation, created with data acquired by the Atmospheric Infrared Sounder (AIRS) instrument on NASA’s Aqua satellite, shows the total amount of water vapor contained in the atmosphere for most of the month of February if it were all to fall as rain. Typically, the atmosphere over Southern California and most of the continental U.S. in winter holds only about 0.4 inch (10 millimeters) or less of water vapor. However, much wetter air lies tantalizingly close in regions to the south and west. The largest amounts of atmospheric moisture, up to 2.4 inches (60 millimeters), are associated with a persistent band of thunderstorms circling the tropics. These thunderstorms are the source of several atmospheric rivers apparent in this animation. One atmospheric river arises near Hawaii around Feb. 10 and comes ashore in Central California a few days later, bringing the largest Sierra Nevada snowfall of the season to date. Other atmospheric rivers can be see originating in the Gulf of Mexico and extending into the Atlantic on the right side of the movie; the northward movement of tropical water vapor is important in winter storms in the eastern U.S. and Europe. The animation concludes with the current Pineapple Express. Moisture from around Hawaii has surged northeast, and the persistent, dry air immediately west of Baja California has been replace by air with up to 1.6 inches (40 millimeters) of water vapor. The next storm will bring that moisture ashore, where it will be forced upward by coastal mountains to fall as heavy rain. Up to 8 inches (20.3 centimeters) of rain is predicted in some parts of the Los Angeles area by March 2, bringing possible flooding and landslides to recent wildfire burn areas.
The recent cold conditions in the eastern U.S. are also apparent in this movie as very dry regions. Because cold air can hold relatively little water (less than 0.4 inch or 10 millimeters), cold region are always dry. So, the eastern U.S. has some of the driest air in this animation. However, high pressure systems also dry the atmosphere by forcing down air from above.
That descending air expands and warms, but retains the low moisture amounts it had when it was higher and cold. So, cold Minnesota and warm Mexico have similar water vapor amounts in this movie.
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Ok people, nothing to see here. Its just another computer model crash. Get on with you lives people.
Mike Alger says:
February 28, 2014 at 10:38 pm
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Thanks for providing that most interesting link.
eyesonu says:
February 28, 2014 at 7:34 pm
I considered including both, but then I figured I’d have to hunt down air temperature maps and puzzle over dew point (and maybe wet bulb) temps too. While that northern water is cooler than the southern water, the dew point difference between water and air has a lot to do with how much water is evaporating from the surface. Given that the water vapor loop was showing lots of water over the northern region, I decided to leave out this layer of detail.
I suspect Bastardi will have lots to say about this in his Saturday talk. I’ll see if I can get a note to him.
Ric,
Thanks for your reply.
I don’t know if the set-up that has developed over the past couple of weeks is unusual but it sure is interesting to me. The more links that are offered here and many open tabs on my browser has my attention. This is all really neat.
Now after reviewing, and of course playing with, the archives going back a couple of weeks on the link provided by Mike Alger above, is there a similar site with data in the same format that would show actual observations that I could go back in time and walk forward? Anyone able to help?
Whether it’s the “Pineapple Express” or a more complicated weather pattern, I hope it continues. Here in the central Rockies we get the bulk of our snow in March and April. If the moisture doesn’t arrive during that time of the year, then forest fires become a huge problem during the summer, just as they have the past few years.
Today and tomorrow parts of the Rockies are supposed to get snow measured in feet. I say, “Let it snow, let it snow, let it snow.”
Thanks, A. Good article excellent movie.
We keep on watching ENSO.
Ric Werme says:
March 1, 2014 at 5:35 am
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Ric,
Is there a way that I can view Bastardi’s Saturday talk as you made reference to? I checked his weatherbell site but found no references.
I’ve been playing with http://earth.nullschool.net/#2014/03/01/1200Z/wind/surface/level/overlay=temp/orthographic=-136,30,672 and toggling between various data offered in the animations especially surface conditions (temp, RH, wind speed/direction, etc) and assuming the data/presentation is correct I’m having a problem with Bastardi’s “nonsense” statement (February 28, 2014 at 1:11 pm) in his earlier comment on this thread.
I’m trying to understand just what the real nonsense is.
eyesonu says:
March 1, 2014 at 7:29 am
> Is there a way that I can view Bastardi’s Saturday talk as you made reference to? I checked his weatherbell site but found no references.
It’s the little video window on the right side under “Joe Bastardi’s Saturday Summary (2/22)” That line is a link to the most recent video, currently http://www.weatherbell.com/saturday-summary-february-22-2014
That implies today’s will be http://www.weatherbell.com/saturday-summary-march-1-2014 .
Joe gets excited by weather of any sort (it’s the only weather we’ve got), you may want to be be on caffeine to keep up with him. 🙂
Kate Forney,
Read the words carefully – “descending air expands”
Insofar as “air” is made of molecules that neither expand nor contract, the text intends to say something else. The molecules have mass and gravity pulls them toward Earth and forces them into a smaller volume. The phrase in the text could be stated ‘That descending air increases in pressure and warms, . . .’
Also, in the last line above this paragraph there is “by forcing down air from above.” This to can be re-worded to better reflect what is actually happening. High pressure is the result, not the force. See:
http://newton.dep.anl.gov/askasci/phy00/phy00589.htm
Thanks Ric,
The link (per your assumption) is not yet available. If your assumption on its location/URL is correct it may not become available for a day or so (my assumption).
Maybe Bastardi will come on over to WUWT and straighten out any confusion I may have. Maybe even post a guest article. There’s probably a lot of lurkers here on this one. Anyway, what is the nonsense he referred to earlier? I would sincerely like to understand.
There still will be no water however for CA farmers. O needs the drought crisis. Brown is going to spend $700 M on drought relief also. The whole central valley could flood and they will not release water that is piling up in reservoirs.
All you see in Sacramento media is how Folsom won’t have enough water to cover the pumps (just last week), and nationally we keep seeing pictures from January of reservoirs that WERE empty. This will be a manufactured crisis almost as big as global warming itself.
What’s amazing is the people of CA buy it all.
I posted on weatherbell.com on this matter. This system came from well north of Hawaii, and precipitable waters near Hawaii are well below normal. Total water vapor does not show the relationship against the normals. The fact is the water is way above normal over the north Pacific and the very cold air that managed to come out over that resulted in uncommon deepening of this. The true pineapple connections so to speak usually occur in warm ensos and one can see high precipitable water being advected into the system from the south and southwest out of the subtropics, not lower than normal pws.
This whole tendency to label and blame one thing, be it agw, or polar vortex of the man in the moon is disturbing to me. I dont think the reasons for the occurrences in the weather are simple 5 second sound bites. I think it does a disservice to label a storm that came out of the northern branch over the very waters what we keyed on for this winter as something that had some kind of origin in the tropics and subtropics. The fact is as wavelengths start to shorten at this time of the year, troughs buckle into sharper systems and if there is enough baroclinicity will do this. Give this came from the west northwest, and I show this in no uncertain terms in the weatherbell post, its no more a pineapple connection storm than something in the northatlantic that deepens.
Next year, you will be able to see more of the true influence of the tropics and subtropics as the coming nino will indeed raise pws where they will have an origin traced to the tropics. Until then total water vapor is always going to be higher where this is shown but ITS THE DIFFERENCE FROM NORMAL, that is very important in such major systems. In my opinion and perhaps I am biased because its why D aleo and I jumped on this for the cold winter, The ignoring of the very warm water in the north pacific and the magnitude of the Deviation from normal was the reason for such a big bust in alot of winter forecasts this year, so perhaps its my stubborn idea that people have completely ignored this as a factor ( 1917-1918) that has lead me to once again bring up what has been going on, and why this deepened. As I said the post on weatherbell.com on this shows the PW and makes my case for me. The deepening is almost exclusively a northern branch situations
There is no one more acquainted with the connection out of the tropics with me. Paul Stokols of the medium range forecast center in the 1980s was one of the guys I learned from at PSU and was a nut about the Hawaiian connection and in the winters where he was a grad student at psu, he would show the cloud shots we could see of the subtropical jet firing up around Hawaii. You will see what I am saying next year because you will see higher PWS in there than this year, which has been paltry indeed and part of the overall cold PDO pattern of which we will have a bit of a break in with the enso, much like what we saw in 57-58 and other cold pdo warm enso situations.
Cheers
Joe, great comment!!!! I also thought the “pineapple express” was a bit odd in a conversation I was having with my wonderful boyfriend. Then I made the mistake of going to wiki and thought maybe it was. However, based on your comment, I am back to my original thought that this is not a Pineapple Express but could it be a Chinook Wind?
I have another example of misnamed weather pattern variations. Take a look at the Antarctic Circumpolar Wave overtake Australia. Wonder what sort of misnamed Australia droughts have occurred in the media when they should be calling it an Antarctic Wave Drought.
http://www-das.uwyo.edu/~geerts/cwx/notes/chap11/ant_wave.html
Kate Forney says:
March 1, 2014 at 6:49 am
Thank you all for your kind replies.
Mario Lento says:
February 28, 2014 at 5:28 pm
Kate you ask: “How can a parcel of air of a given mass get more dense while also expanding? I had always imaged density to be the ratio of mass to volume.”
+++++++++
There are two things going on – and both can exist.
If a parcel of air expands, it will be less dense.
If a parcel of air warms it will expand and be less dense, unless pressure increases.
The other issue has to due with relative humidity.
This is only based on temperature of the air.
So warmer air will hold more water than colder air, regardless of pressure
The summer of 1957 was hot up in No California. My father had taken me and my brother up to Trinity County to go steelhead fishing for the first time. Temps were triple digit almost the entire time, ranging up to 116 and possibly a bit higher than that. That was the year that the hills around Clearlake burned. As we drove up highway 101 early in the morning, the early morning skies to the east of us were red with flames for many miles. Highway 101 was still a mess from the flood the year 55/56 before, all the way to Eureka. I don’t remember any summer being that hot since that time.
I see that Joe Bastardi (March 1, 2014 at 8:39 am) is pointing out something worth noting about the origin (which is as plain as day on the illustrations to which I link below).
The blue fire-hose is crystal clear on nullschool’s global wind & precipitable water forecast maps for Monday:
500hPa 1200Z (3AM local) / Surface 2100Z (1PM local)
(Tip: The “earth” button toggles the menu off & on.)
The local forecast here (Vancouver, BC, Canada) trends upward by 8°C over the next few days showing a string of raining clouds & increasing POP, a familiar winter signal that locals will interpret as an oncoming Pineapple Express (despite whatever efforts Joe might make to help them interpret more subtly). (Bottom line from a local perspective: This week we won’t be sea-kayaking in snowfall like last week.)
By the way, here’s a wake-up call (based on a law-constrained aggregate proof; updated with ~2 years-worth of new data): http://imageshack.com/a/img203/3609/3vkq.png
That leaves 18% interannual. (CO2’s undetectable.)
“descending air expands” Really?
David Thomas says:
March 1, 2014 at 12:18 pm
“descending air expands” Really?
++++++++++
You should understand two different forces here. Air both contracts under pressure and expands under warming. They can and do both exist. PV=nRT. V=nRT/P you know this right?
@ur momisugly Mario — Ha! So THERE you are. #(:)) Good pressure point at 1:25pm.
Yes – Janice: David Thomas is a surgeon, I believe – so he should be educated on this subject –I only hope.
@ur momisugly Mario — lol. Good one.
PS – again: There are two things going on here. One is relative humidity – related to air being able to hold moisture which increases with temperature – and volume which is related to pressure and temperature. Things cannot be distilled into simple answers the way the questions are posed in this thread.
In CA, due to the relatively warm coastal water (~50 degree ocean) in winter, it’s relatively humid during winters, and relatively dry in summer when the relatively cold water (~55 degree) dries the warmer air. It’s nature’s air conditioning!!
Some people don’t get that when it’s drier, the air heats up faster due to the lack of moisture. In the humid tropics, the latent heat energy of evaporation reduces temperature – even the the air contains much more energy in the tropics. The air in the Arctic contains very little energy because there is almost no latent heat of H2O there. That is why Chico CA gets higher temperatures in summer than Hawii, even though Hawaii gets much more sun light energy.
So I submit that drought in summer causes higher temperatures… rather than higher temperatures causing drought…