Some mixed news on CA weather front over next couple of weeks. First, by Monday, another "inside slider" system will bring another burst of cooler & winder conditions statewide. Once again, some Sierra snow showers are possible, but most places stay dry. #CAwx#CAwater
Midweek, however, an even colder airmass and associated low pressure center will slide down the coast slightly farther to the west. This system, although still quite dry, stands a better chance of bringing convective activity (scattered showers/isolated thunder) statewide. #CAWx
The biggest impact from this mid-week system, outside of some additional modest Sierra snow accumulations and a few pockets of accumulating small hail showers at lower elevations (like last week in SoCal), will be a dramatic shift toward much colder temperatures. #CAwx
In fact, I would expect significant agricultural impacts in Central Valley where several consecutive nights of sub-freezing temperatures are possible. This may be especially disruptive following weeks of record warmth, which allowed some tree crops to bud unusually early. #CAwx
Despite this fairly active/unsettled pattern, I still don't foresee widespread hydrologically meaningful precipitation over the next 10+ days. But heading into early March, the pattern gets a bit murkier... #CAwx
It is possible that a cool & modestly unsettled pattern will bring slightly more widespread rain and mountain snow by early March. There are currently still *no signs* of big storms, but this would still represent a departure from unrelentingly dry Jan/Feb 2022. Stay tuned! #CAwx
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A classic winter-like "tule fog" pattern will persist for at least a few more days in CA's Central Valley (w/spillover into SF Bay), but warm, dry, and mostly sunny conditions persist above and south of the fog layer! But how about some deeper tule fog context? [Thread] #CAwx
Folks are remarking on how this persistent Central Valley fog is "unprecedented." But that is *very* far from reality! While Nov is fairly early season for this pattern, dense & frigid "tule fogs" actually used to be *more* common, lasting days or even weeks in decades past. #CAwx
In fact, despite the damp chill in recent days, this isn't even an especially cold tule fog by historical standards! When I lived in Yolo County for a few years (almost 20 years ago! 👀), there were multiple occasions when temps never made it out of the 30s under the fog layer!
A high-amplitude flow pattern, characterized by near-record strength ridging and troughing (respectively) over the western and eastern U.S. and a very wavy jet stream, will bring a progression of notable weather to North America in the coming days.
Over the next few days, balmily warm temperatures will occur across western North America, including California (where temperatures into the 90s are likely in SoCal). Some record warm daytime temperatures are possible, & notably warm overnight temperatures will continue as well.
As the ridge-trough sequence reached maximum amplitude on Tue, very warm temperatures will continue in the West but anomalously cold temperatures will develop in the East. In fact, there may even be a day or two of record cold temps in parts of the Southeast.
I wanted to offer some thoughts on the Gates climate memo that has been circulating this week. While I can't directly speak for others, I can say that my own response is one of dismay & deep frustration (and that this view is shared by many climate/Earth scientists). [1/n]
I first want to emphasize that there are a few "kernels of truth" in this memo. More than kernels, even--there are whole sections/paragraphs with which I strongly agree! But there are multiple fatal flaws in its underlying premise, and thus in its conclusions. [2/n]
I strongly agree--both because I personally believe that it's the right thing to do and also because the evidence supports it--that rapidly addressing poverty, health inequity, and food/water insecurity should be a first-order priority. Full stop. No argument there. [3/n]
The discourse surrounding precipitation changes in a warming climate (both public discussion and even scientific one at times) is complicated by widespread conflation of changes in averages vs extremes (and also actual vs *potential* evaporation/evaporative demand). [Thread]
Increased temperatures rapidly raises "ceiling" on both precipitation & evaporation intensity--but same is *not* true for typical/average values of either! Regional mean precip can increase or decrease with warming, and actual evaporation is constrained by local H20 availability.
This is the basis for "Expanding Atmospheric Sponge" effect that we coined to help visualize practical implications stemming from more heavier downpours (i.e., flash floods) & also more extreme evaporative demand (e.g., faster-developing droughts, more intense wildfires).
And now: A thread regarding my thoughts on "1.5°C"--not only as a Paris Agreement target, but also re: relevance to recent #climate events & overlaps (or not) w/geophysical realities. (This was originally written as a response to a journalist, who used excerpts in their article.)
First and foremost, it's absolutely true that every tenth of a degree matters; each increment of global warming will bring a relatively larger increase in adverse societal and ecological impacts than the last.
This statement is not so much about rate of warming itself, but a reflection of growing recognition that Earth system (especially the biosphere and cryosphere) can respond non-linearly, and sometimes abruptly or even irreversibly on human timescales, to gradual shifts in climate.
There have been claims that NOAA/NWS did not foresee catastrophic TX floods--but that's simply not true. This was undoubtedly an extreme event, but messaging rapidly escalated beginning ~12 hrs prior. Flood Watch mid PM, "heads up" outlook late PM, flash flood warnings ~1am.
As always, this is not to blame the victims! Quite the opposite; this truly was a sudden & massive event and occurred at worst possible time (middle of the night). But problem, once again, was not a bad weather prediction: it was one of "last mile" forecast/warning dissemination.
I am not aware of the details surrounding staffing levels at the local NWS offices involved, nor how that might have played into timing/sequence of warnings involved. But I do know that locations that flooded catastrophically had at least 1-2+ hours of direct warning from NWS.