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Scott Duncan Profile picture
@ScottDuncanWX
Nov 13, 2021 • 9 tweets • 5 min read • Read on X
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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

Scott Duncan Profile picture
Sep 15, 2024
Flooding disaster unfolding right now in Central Europe.

Why is it so bad?

This thread takes a quick look at some of the key ingredients of this record-breaking storm.
Image
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Let’s start with the background. It has been an exceptional Summer for the Mediterranean Sea. Heat records have been broken.

Warmer sea surface temperatures allow more moisture to evaporate, like fuel for a storm. The warmer the water, the greater the evaporation…
We then had a historic cold wave (for this early in September) plunge south out of the Arctic and through Europe.

We now have an unprecedented combination of hot and cold (ideal for strong thermal boundaries/weather fronts).
Read 12 tweets
Scott Duncan Profile picture
Sep 14, 2024
Insane full-winter scenes emerging from Austria right now. The historic September storm in Central Europe is delivering record cold, record early deep snow and heavy flooding rains.

This is Obertauern (resort elevation range 1600-2500 m).

For those who may not believe this report, the live webcams reveal all. Blizzard conditions with drifting deep snow. This camera is 1700 m elevation.

obertauern.com/en/service-inf…
Image
The storm came as no surprise. Weather models were in good agreement that exceptional cold, snow, rain and wind would impact Central Europe several days in advance. Austria is in the bullseye.

Read 6 tweets
Scott Duncan Profile picture
Sep 12, 2024
Shock to the system 🥶

Unusually strong cold is pouring south out of the Arctic into Europe right now. This is an ideal setup for deep fresh snow accumulations in the Alps and flooding in Central Europe.

This is about as cold as it gets this early in September.
Incredible contrast in temperatures.

This map shows how much cooler (🔵) or warmer (🔴) it is compared to average at this time of year. Image
This is one weather model estimation for fresh snow totals in the coming days. Well over 1 metre of fresh snow for the upper Austrian Alps expected with some places probbaly exceeding 2 metres.

Outstanding for this early in September.
Read 6 tweets
Scott Duncan Profile picture
Sep 5, 2024
Very impressive weather pattern in Europe right now.

Strong easterly winds and hot in Central/Northern Europe meanwhile heavy rain plagues the west with much cooler conditions. The heat is breaking records (for this time of year).

THREAD
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Many monthly heat records set in Germany 🇩🇪 yesterday... Beating some records which have stood for a long time (1895). Great summary here by @EKMeteo which links to comments by official @DWD_presse

@EKMeteo @DWD_presse It appears Norway has broken September national heat record, final numbers to be confirmed.

Impressive foehn effect to the west of high ground. The dry easterly winds in southern Norway is ideal setup for incredible temperatures in unusual places.

Read 5 tweets
Scott Duncan Profile picture
Mar 3, 2024
Truly outlandish.

Some places in Europe didn't just record their warmest February on record.... They went on to beat their warmest MARCH temperature levels.

[THREAD] Image
Effectively everywhere in the dark red shading smashed warmest February record - most by large margin. Austria 🇦🇹 has over 250 years of temperature record and nothing compares to this. Not even close.

Source: zamg.ac.at/cms/de/klima/n…
Image
Wiener Neustadt in the east of Austria was so warm that temperature of February 2024 exceeded the warmest MARCH record (data here since 1949).

uwz.at/de/a/waermer-a…
Read 11 tweets
Scott Duncan Profile picture
Aug 27, 2023
Heatwave going out with a bang in Europe.

Watch how the jet stream digs aggressively into Southern Europe. The atmosphere is primed for severe weather - unfolding right now...
This animation captures the transition from extreme heat (unprecedented for this late in August) to relatively cool conditions.

The variable shown here is the temperature at 850 hPa (usually around 1.5km above sea level). This can help show where our airmass is coming from.
The Mediterranean is also acting like an extra source of fuel for the storms. The sea surface temperatures are at record hot levels.

The Gulf of Lion (just south of France) is especially hot. The sea surfaces will likely cool dramatically during this breakdown.

You can access the satellite derived sea surface temperature data here:

The graph can be found here:
Read 7 tweets

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