Discover and read the best of Twitter Threads about #CAwx

Most recents (6)

New work led by @SciGibson @NASAJPL! We take a deep dive into northeastern Pacific high pressure ridging, including trends, implications for California drought, #AtmosphericRiver activity, and possible underlying physical mechanisms. (1/6) #CAwx #CAwater…
We find several distinct "flavors" of high pressure ridging that tend to recur historically. Each spatial configuration affects atmospheric river activity & western U.S. precipitation in a distinct manner. (2/6) #CAwx #CAwater #AZwx #ORwx #WAwx…
All three ridge types (north, west, and south-centered) are associated with drought in California and the Colorado River basin, but only "north-type" ridges are associated with drought in the Pacific Northwest. #CAwx #ORwx #WAwx #AZwx #UTwx #CAwater… (3/6)
Read 6 tweets
No sign of widespread/significant precipitation anywhere in California over the next 2+ weeks. Already large seasonal precip deficits will continue to grow, esp. across Norcal, as very strong and persistent northeastern Pacific ridge builds. #CAwx
In fact, much of the Northern Hemisphere mid-latitudes will experience anomalous ridging in the coming days. This hemispheric atmospheric mass displacement is a reflection of the presently record-strong positive phase of the Arctic Oscillation...
As @RobMayeda pointed out, this already prolonged dry spell is already leading to low soil moisture and dry vegetation at what is typically wettest time of year in California. #CAwx #CAfire
Read 4 tweets
Complex and honestly pretty bizarre weather pattern shaping up for California over next 10+ days. First, widespread record heat possible this weekend/early next week. Temperatures into 80s and even 90s in some spots. #CAwx #CAfire (1/3)
Then, a slow-moving cut-off low will likely bring some showers & thunderstorms to parts of SoCal, including coast, and *eastern* slopes of Sierra Nevada. Still some model disagreement, but precip could range from trivial (GFS) to significant (ECMWF) there. #CAwx #CAfire(2/3)
Meanwhile, northern 2/3 of CA will stay dry despite this system to the south. Strong pressure gradients on north side of the low could drive strong northerly winds, possibly leading to another round of extreme fire weather concerns given record-dry vegetation. #CAwx #CAfire (3/3)
Read 3 tweets
New research led by @k_r_gonz points to striking #AtmosphericRiver warming trend along U.S. West Coast in recent decades. We found that ARs have already warmed by > 2°C (3.6°F) in some months--faster than previous #climate projections had suggested. (1/8)…
#AtmosphericRiver warming signal is robust in all regions during at least some months, including coastal Washington, Oregon, & California. But warming has been greatest in central & southern CA, especially during January & March. #CAwx #ORwx #WAwx (2/8)…
This #AtmosphericRiver warming appears to be driven by both local and geographically remote warming, but appears to scale most closely with near-shore ocean and local background (non-AR) temperature trends. (3/8)…
Read 8 tweets
Thread inspired by yesterday's truly spectacular and widely discussed Great Plains-style supercell in California's Sacramento Valley. #CAwx #Redding #ShastaCounty (1/n)
Thunderstorms in general are much less common along the West Coast of North America than across nearly all other parts of the continent. Some parts of coastal California see one (or even fewer!) thunderstorms in a typical year. #CAwx (2/n)
Cumulonimbus clouds associated w/t-storms require strong upward vertical motion in order to form. Sometimes, this can be generated by boundary, like a cold front; other times, mere heating of humid lower atm can be sufficient for air to spontaneously rise, cool, &condense.(3/n)
Read 13 tweets
If Northern California had received anywhere near the typical amount of autumn precipitation this year (around 4-5 in. of rain near #CampFire point of origin), explosive fire behavior & stunning tragedy in #Paradise would almost certainly not have occurred. (1/n) #CAfire #CAwx
Rainy season has started late this year in California...again. While autumn precipitation isn't usually huge fraction of overall annual average, it's hugely important to ecosystems & in bringing "fire season-ending" moisture. This yr, autumn precip was <20-30% of avg. #CAwx (2/n)
Objective indicators of vegetation dryness and potential fire intensity were at record-high levels for the date this week in vicinity of #CampFire--and would have been very high even for peak summer levels--at a time of year when the rainy season is usually ramping up. (3/n)
Read 19 tweets

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