New work co-led by @xingyhuang and me on the rising risk of a California #megaflood due to #ClimateChange is out today in @ScienceAdvances! This paper also describes the new #ARkStorm2 scenarios in detail, & will be the basis for ongoing work. (Thread:1/n) science.org/doi/10.1126/sc… For context: the work and findings presented here represent the first phase of the broader #ARkStorm2 project, a multi-year, cross-institutional effort involving multiple @UofCalifornia campuses, @DRIScience, @USGS, @CA_DWR, & @NCAR_Science. (2/n) science.org/doi/10.1126/sc…

New research on dry lightning events in California, led by @wx_statman, and including co-authors @climate_guy, @NickyNaus, @Weather_West, @danielletouma, & @ClimateChirper, is out today in @IOPenvironment (open access!). #CAwx #CAfire (1/n) iopscience.iop.org/article/10.108… We assess regional-scale atmospheric conditions favorable for dry lightning in central & northern California (N&C CA), as well as seasonality. We find that nearly half of all lightning strikes in N&C CA are "dry" (accompanied by <0.10 in. of rain). (2/n) iopscience.iop.org/article/10.108…

Much of CA & NV has had a fairly mild start to summer--especially in the northern third of state, which even received some late-season precip and some locally below average temperatures over the past month or so. Well, that's all about to change across the interior... #CAwx A huge ridge of high pressure will expand westward from its current position near center of continent (where it has been bringing record heat to Texas). This will bring an extremely broad region of hotter than usual temperatures to the entire western 2/3 of the country. #CAwx

This was, by any quantitative measure, an extraordinary (and meteorologically extreme) lightning event across the southern half of California. But the societal impacts will be nowhere as severe as the dry lightning event in August 2020? Why? A brief thread: #CAwx #CAfire

https://twitter.com/COweatherman/status/1539970993250193409

First, & most importantly, the June 2022 thunderstorms were generally significantly wetter than the Aug 2020. Yesterday, most of these cells brought at least brief rains (and sometimes downpours). There were certainly dry strikes outside of rain cores, but most strikes were wet.

Although I almost always keep my Tweets focused on weather, climate change, and related Earth system events, this thread is going to be a little more personal. May is #EhlersDanlosAwarenessMonth...and I have Ehlers Danlos Syndrome (hypermobility type). #hEDS (1/41) Before continuing, I want to emphasize that I'm #NotThatKindofDoctor--I'm a physical scientist & science communicator, not a biomedical scientist nor a medical doctor. All the information and reflections in this thread are therefore either personal reflections... (2/41)

#ClimateChange is increasing risk of extreme precip events following extreme fire weather events in American West: new analysis out today in @ScienceAdvances by @danielletouma, @slgstevenson, @Weather_West, @ClimateChirper, @wx_statman,& @xingyhuang. (1/n) science.org/doi/10.1126/sc… We use climate model large ensembles (CESM-LENS and CanESM2) to quantify projected changes in 99.9th percentile rainfall days that follow 99.9th pctile fire weather days. We find strikingly large & widespread increases in every Western state.(2/n) science.org/doi/10.1126/sc…

Now that activity on the #NCARFire in Boulder, CO has calmed down significantly, a majority of the evacuation orders have been lifted, and the risk of property loss moving forward appears low, I wanted to share a few related thoughts. (All photos from yesterday, 3/26/22.) #COwx 1) NCAR Fire is an example of a relatively small fire posing disproportionately high risk to homes in wildland-urban interface. Should an ignition have occurred exactly the same place during one of Boulder's infamous downslope windstorms, it could have been a catastrophic event.

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

Very compelling and timely new analysis out in @Nature led by @DrBalch and featuring co-authors including @climate_guy, @_mikoontz, and @peedublya on how #climate warming is weakening the global barrier to nighttime fire. nature.com/articles/s4158… They find a strong trend toward increased nighttime fire activity across most regions globally, driven primarily by increases in overnight vapor pressure deficit (VPD). In western U.S., number of flammable nights have increased by 45% in past 4 decades! nature.com/articles/s4158…

Folks with self-described severe climate anxiety now reach out to me (& other climate scientists I know) essentially every week. It is often hard to know how to respond, since climate scientists are not trained clinical psychologists. (1/12)
nytimes.com/2022/02/06/hea… The nature and volume of these requests can become overwhelming for those not professionally equipped to help people in that way. This is especially frustrating since many of these folks have actually sought professional help, yet those practitioners have been dismissive...(2/12)

Our new study on co-occurring air pollution extremes (ozone & PM2.5), led by @wx_statman & w/co-authors including @ClimateChirper, @climate_guy, & @Weather_West, is out today in @ScienceAdvances. We find large increases in co-occurrences in U.S. West.(1/n) science.org/doi/full/10.11… Increasing air pollution co-occurrence trends are widespread across the U.S. West over the last ~20 years, and encompass almost all of the West's major population centers from the Rocky Mountain Front Range to the Pacific Coast. (2/n) science.org/doi/full/10.11…

Some photos, footage, and commentary from yesterday's devastating #MarshallFire in Boulder County. All photos and videos taken at various points along South Boulder Road (north side of the fire, looking south, on 12/30/21). Winds were gusting around 90mph at the time. #COwx (1/4) Fire behavior was as you'd expect in grass/brush amid extreme wind & drought conditions: rapid rates of spread, continuous spotting and periodic sheeting fire. Fire jumped 6-lane Hwy 36 like it was nothing, and there was a 2+ mile long active fireline. #MarshallFire #COwx (2/4)

Conditions along South Boulder Road right now. #marshallfire #COwx Unfortunately can confirm that numerous structures are now burning, many of them homes. This is an extreme/dangerous wildland-urban interface fire. Mainly Superior/Louisville. Gusts in excess of 80mph continue.

Serious wind driven brush fire in wildland-urban within/just south of Boulder, CO city limits. Along Marshall road. Estimating downslope wind gusts near 90 mph. #COwx @NWSBoulder @mitchellbyars #COwx

As a climate scientist, one aspect of #DontLookUp that resonates strongly is notion that an otherwise solvable planetary crisis will go away if we just ignore it--or that a silver bullet solution will magically present itself. Spoiler alert: it won't. @davidsirota @GhostPanther

https://twitter.com/ayanaeliza/status/1475257735184891909

Also highly relatable was the impassioned and exasperated rant by @LeoDiCaprio's character. There's a reason why much of the climate science community has responded to this film in a similar way--variations on a theme of "yep, that's all uncomfortably familiar."

Being a climate scientist sometimes feels like being an astrophysicist in one of those 90s asteroid impact disaster movies...
except instead of coming to together to save humanity, the people in power shrug & point out how sending rockets might increase inflation. #ClimateChange

https://twitter.com/LeoDiCaprio/status/1460636837798580230

I was once, coincidentally, seated on a flight next to a @NASAJPL scientist who described his job as "taming near-Earth asteroids" from a planetary protection perspective. This is a person who would actually be called to the White House in scenarios portrayed in Hollywood films.

California, on statewide basis, is now experiencing its worst drought in observational record going back to late 1800s--narrowly beating out peak of last drought in 2014-15 (as measured by PDSI, a metric that takes into account both precip & temperature). #CAwx #CAfire #CAwater There is a clear trend toward increasing aridity in California--and yet little trend in mean precipitation. How can this be? A very strong warming trend due to #ClimateChange means same the amount of water falling from sky just doesn't go as far as it used to. #CAwx #CAwater

1/New work aimed at resolving the "extreme precipitation-#flood paradox" in warming #climate, led by @ManuelaIBrunner (@UniFreiburg) & including co-authors @Weather_West (@UCLAIoES), @Climate_Done (@C3WE_NCAR), is now out in @CommsEarth (open access!). nature.com/articles/s4324… 2/The "extreme precipitation-flood paradox" arises from fact that despite abundant evidence for increasing rainfall extremes due to #ClimateChange, there is not (yet) a correspondingly clear & systematic increase in flood magnitude. nature.com/articles/s4324…

Dry lightning event of *some* magnitude is now looking increasingly likely across *some portions* of CA on Sun/Mon. Details to come. But first, some thoughts on potential wildfire risks posed if this comes to fruition. (Thread) #CAwx #CAfire Usually, fewer than 1 in 10 lightning strikes actually ignites a wildland fire. These numbers can be higher if lightning is not accompanied by precip, or if lightning occurs under unusually dry conditions in dense vegetation. But in general, lightning ignition *rate* is low-ish.

Posting as heads-up to weather modeling world (not as a realistic prediction of future conditions): the (new) GFS has occasionally been spitting out completely absurd surface temperatures for CA's Central Valley. 18z run today shows 128-130F. Anyone know what's up? An intense and very possibly record-breaking heatwave is indeed possible in that interval, but not "hottest temperature in modern history" hot. I'm assuming it's the surface scheme, but then again, the 850mb temps are absurdly high also (though maybe feedback from sfc?).

Correction to give more accurate context: vegetation dryness & flammability metrics (1000hr fuel moisture & ERC, respectively) are indeed exceeding record levels for *calendar* date over most of Sierra Nevada, but *not* records for *any date.* (Phew!) (1/4) #CAwx #CAfire For those interested, the confusion apparently arose due to a differing period of record for NorCal vs. SoCal data via the NorthOps/SouthOps GACCs. In SoCal, period of record is only ~10 years, so "any date" records less meaningful. So: data not wrong, but context is missing.