Incessant heavy rain will pile into the Pacific Northwest, USA 🇺🇸 & British Columbia, Canada 🇨🇦 in the next 72 hours due to a significant atmospheric river event.

Flooding & landslides are highly likely. The atmospheric warmth & moisture can be traced all the way to the tropics.
A strong meander in the jet stream allows Alaska to cool under Arctic air but also helps lift Tropical warmth & moisture into British Columbia & the Pacific Northwest.
Notice how the atmospheric moisture aligns and focuses on the same area. This is like nature's firehose. Extreme rain and locally very high freezing levels expected. Meteorologists call this an atmospheric river.

Some refer to this atmospheric river as 'the Pineapple Express'.
A warmer atmosphere can hold more moisture. As the tropical air crashes into the terrain of North America, air is forced upwards and enhances rainfall amounts further.

This is called orographic lift.
Speaking of temperature...

The thermal contrast between Alaska and California is extremely impressive for November.

More about that in this previous thread...

Public weather alerts & warnings for British Columbia can be tracked here: weather.gc.ca/warnings/index…

Pacific Northwest of the USA public warnings can be accessed here: weather.gov

#bcstorm #wawx #orwx
This thread and all the animations summarised on Instagram in a single post ⬇️

instagram.com/p/CWOgFHfsBFh/…
A month's worth of rain in 48 hours is possible. Not surprising in this setup to be honest, the source of air is very rich in moisture.

Certainly a significant atmospheric river (AR).

The freezing levels will also shoot to very high levels for a time (melting snow and adding to flood threat).

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More from @ScottDuncanWX

13 Nov
Extreme temperature contrast across North America right now.

Alaska shivering with brutal early winter cold Meanwhile California sets daily heat records.
We often see extreme anomalies at this time of year...

The long nights in the Arctic are starting to build the cold while summer heat lingers in the south.

However, this is exceptional.

🔵= colder than average for time of year
🔴 = warmer than average for time of year
Some more info on the daily heat records in California

Read 4 tweets
26 Oct
Hottest October day in history for Buenos Aires, Argentina 🇦🇷 Ferocious Spring heatwave.

Records go back to 1906 and beats the record of 35.6°C from 2014.
Much of the southern half of South America are in a strong spring heat episode right now.
Thanks to @s_d_roberts for the heads up and very useful link regarding previous records in Bueno Aires: www3.smn.gob.ar/serviciosclima…
Read 5 tweets
26 Oct
Life-threatening flash flooding in Catania, Sicily 🇮🇹

Enormous rainfall totals have fallen under slow moving thunderstorms.

🎥 via @3BMeteo

You can see the thunderstorms piling into the east coast of Sicily all day, wrapped around a broader circulation from a developing cyclone to the south.

Catania (home to over 500,000 people) was in the bullseye for near constant thunderstorms today.

Sat via @metdesk/@eumetsat
Truly horrific scenes emerging from Catania, Sicily 🇮🇹

Continuous thunderstorms today have turned the streets into raging rivers.

Via 🎥 @myrtamerlino

Read 5 tweets
25 Oct
Record-breaking low pressure off the coast of the Pacific Northwest.

The storm also delivered record-breaking rainfall to parts of California after record-breaking dry streak.

Record-breaking number of times I have written record-breaking in a tweet.
More on the rainfall/lack of rainfall records

The storm was well forecast.

This thread summarised some of the big-picture in the lead up to the storm

Read 5 tweets
23 Oct
Explosive cyclogenesis under a rip-roaring jet stream in the Pacific is about to bring extreme weather down the west coast of North America.

Nerd bit: I have contoured mean sea level pressure under the jet to show the text book interactions of the left-exit. Poetry in motion.
This is how the wind gusts look as the low pressure rapidly develops. The storm is likely to reach hurricane force out at sea with waves of 30-50 feet.

Nasty.
Large rainfall totals incoming as tropical moisture blasts along atmospheric river like a firehose.

Some relief for the extreme drought covering much of western USA.
Read 5 tweets
3 Oct
We have just observed the hottest (or joint hottest) October days in recorded history for 4 countries.

🇮🇷 Iran 46.0°C (new record)
🇲🇦 Morocco 43.5°C (new record)
🇨🇳 China 38.9°C (tied record)
🇰🇷 South Korea 32.3°C (new record)
More about the South Korean 🇰🇷 record here

More about the record from Iran. This record was tied the day before too

Read 5 tweets

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