Absolutely incredible footage of #LoyaltonFire#pyrovortex ("Fire Tornado") earlier today. Pretty sure this validates @NWSReno's Tornado Warning--which is, I believe, the first ever issued by @NWS specifically for a wildfire-generated pyroconvective event. #CAwx#CAfire#NVwx
To be clear: this is *not* first documented instance of a large-scale fire vortex. Devastating #CarrFire in 2018 near Redding, CA produced one of the strongest such events in recent memory, outside of a couple of previous events during Australian firestorms. (1/3) #CAwx#CAfire
Such events are not a new phenomenon--they have probably occurred during particularly intense wildfires under the right atmospheric conditions since...well, time immemorial. But I suspect these recent events have been more noticeable for two key reasons: (2/3) #CAfire
1) We're formally documenting more large-scale fire vortices in smartphone camera era simply because there are more eyewitnesses, & 2) wildfire burning conditions across West have been particularly intense in recent years, increasing likelihood of extreme/exotic fire behavior.
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A strong, prolonged, very moist, and relatively warm #AtmosphericRiver event, in conjunction with rapidly-strengthening #BombCyclone (yes, that's the term!), will bring major rain (and, locally, wind) impacts to OR/NorCal this week. Flooding is likely. #CAwx #ORwx #CAwater [1/6]
First, a low pressure system west of OR and WA will undergo explosive deepening (rapid strengthening, known as "bombogenesis") over the next 2 days. It may become one of the strongest low pressure systems on record in this region. (~940mb) #CAwx #ORwx #CAwater [2/6]
This very strong low will generate hurricane-force sustained winds well offshore (& 50-60ft+ waves!). The strongest winds will remain well offshore, but damaging 70-90 mph gusts will still be possible in coastal OR & perhaps along far North Coast of CA. #CAwx #ORwx #CAwater [3/6]
Signs of some "big time" weather for TBD portions of U.S. West coast over next 10 days. A major #AtmosphericRiver, & perhaps a short sequence of very wet ARs, will affect some section of coast between NorCal & WA--perhaps bringing very heavy rain accumulations. #CAwx #ORwx [1/6]
First, it's important to consider the broader context. This autumn to date has been very (anomalously) dry across most of CA (except for far northern parts of state), but much less so in PacNW. It has also been broadly warmer than average across the West. #CAwx #ORwx [2/6]
In around 5 days, upstream Rossby wave breaking over the central North Pacific will set up a favorable pattern for cyclogenesis (storm development) in a position that will likely allow a strong #AtmosphericRiver to develop, likely tapping subtropical moisture. #CAwx #ORwx [3/6]
We are witnessing a genuinely extraordinary, and regionally quite deadly and destructive, period for extreme #weather in the United States. And, quite frankly, the fingerprints of #ClimateChange are all over what has transpired in recent weeks and may yet occur in coming days.
An incredible, ongoing, & increasingly record-shattering heatwave has plagued much of Southwestern U.S. for *weeks* now. Phoenix has now seen *2 consecutive weeks* with record temperatures *every day.* Many other locations have set new Oct and/or "heat streak" records.#CAwx #AZwx
Hurricane #Helene, which intensified very rapidly before making landfall in Florida's Big Bend, bringing record 15+ foot storm surge, then brought an even greater disaster in form of widespread, catastrophic flooding in Southern Appalachians. Hundreds are dead. #NCwx #TNwx #SCwx
The images and stories just beginning to emerge from eastern TN and western NC in the aftermath of widespread catastrophic flooding wrought by #Helene are genuinely horrifying, and the full scale of the disaster is likely as yet untold. #TNwx #NCwx [Thread: 1/n]
20-30 inches--and perhaps locally 40+ inches--of rain fell along highest ridges of the Southern Appalachians due to 1-2 punch consisting of extreme "predecessor rain event" (PRE) that was historic in its own right followed by further extreme rain directly from #Helene. [2/n]
This was, by far, the most extreme rain event in observed record across much/most of the region, where reliable records date back over 100 yrs. Unsurprisingly, the flooding which resulted has also been widespread, historic, and generally catastrophic across a broad region. [3/n]
For the first time since June in many parts of California and the broader Southwest, *cooler* than average temperatures can be expected for the next week, thanks in part to arrival of a *second* anomalously deep August low pressure system over NorCal Thu/Fri. #CAwx [1/4]
Another round of widespread rain & possible t-storms will occur in western WA & OR. In far NorCal, esp. northern mtns (Shasta region), some decent showers & t-storms are possible. Few showers/isolated thunder may reach farther south than last event--locally to I-80 corridor. #ORwx #WAwx #CAwx [2/4]
All of this will be fortuitous for fire season in western Washington and Oregon--mainly west of Cascades. While active fires will continue to east of Cascades, this may be season-ending precip (or close to it) for western WA and NW OR. #ORwx #WAwx [3/4]
For folks in Colorado wondering what the heck is going on with #Xcel's large-scale pre-emptive power line de-energization to avoid wildfire ignitions during high wind events, I wanted to share a some thoughts as a scientist who studies climate/weather/wildfire. #COwx [1/n]
The first utility-scale "Public Safety Power Shut-offs" (#PSPS) in response to fire risk of which I'm aware began in 2010s in California in response to catastrophic wildfire events in urban interface sparked by power infrastructure during extreme fire weather/wind events. [2/n]
Such fires occur when energized lines fall to ground or trees fall onto live wires (igniting vegetation). They tend to be preferentially dangerous precisely because they occur under "worst case" conditions, when weather favors rapid spread & fire suppression is ineffective. [3/n]