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New Extreme Climate to Hurl More Rain Bombs at Texas, Light off Another Record West Coast Heatwave
30
June, 2016
They
call them rain bombs. A new breed of severe storm fueled by a record
hot atmosphere. One capable of dumping 2-4 inches of rainfall an hour
and generating voracious flash floods that can devour homes and cars
in just minutes. And in southeast Texas, the
rain bombs have been going off like gangbusters.
In
this week’s most recent iteration of flaring, climate change
induced, storms, a region north of Houston and south of Dallas saw
flood after flood after flood. Now, hundreds of people have been
forced to abandon inundated homes, thousands of cars have been
submerged, and
seven people are dead.
Rainfall totals for the region over the past seven days have averaged
between 7 and 10 inches. But local amounts in the most intense
bombification zones have
come in at 16, 19, and even as high as 30 inches in Washington
County.
All time record rainfall totals that might be associated with a
powerful hurricane. Floods that would typically happen only once
every 500 years. But in the new moisture-laden atmosphere of a record
warm world, a garden variety thunderstorm now has enough atmospheric
oomph to frequently set off what were once multi-century floods.
(Rain
bombs again explode over Texas in a huge complex of storms on Tuesday
afternoon in this GOES enhanced satellite shot. It’s all part of
the same stormy weather pattern — associated with a trough and an
upper level low — that over the past five days produced another
round of record flooding over Texas. And it’s expected to remain in
place through the end of this week. With more severe storms firing
and 4-8 inches of additional rainfall on the way for some sections of
soggy Texas, it appears that still more extreme flooding is likely.
Image source: NOAA.)
It’s
under these new, freakish, conditions that the
Brazos River is today expected to crest at 53.5 feet —
its highest level ever recorded. And this crest is predicted to
push a flood of 8-9 feet into neighboring communities.
Extreme flooding that local officials say Texans are not at all
prepared for. In total, more than 40,000 people have been urged to
evacuate. But with the worst flooding still on the way, the situation
is still very fluid.
In
isolation, the current Texas floods would be an extreme record
disaster worthy of the weather history books. But it is just one of
three such severe rainfall events to strike southeastern Texas since
April. And, unfortunately, more storms are on the way as a strong
ridge of high pressure out west is expected to generate another deep
Central US trough and related rain bomb inducing storm pattern over
the next five days.
West
Coast Turns up the Heat
As
parts of Texas face never-before-seen flooding, the US West Coast is
staring down the gullet of an extraordinary surge of heat. A gigantic
blob of hot ocean water off that region of the world is feeding the
growth of a powerful atmospheric wave. And once the ridge of this
wave really starts to swell northward on Friday, Saturday, and
Sunday, record hot temperatures are bound to explode all over the US
West Coast and on up into Canada.
(Sea
surface temperature anomalies on May 31, 2016. Extremely hot sea
surface temperatures over a vast area stretching from the Equator to
Alaska and all along the US West Coast enhance the development of
strong ridges in the Jet Stream that have tended to spur extreme
heatwaves over the past few years. Ocean temperatures over this zone
now range between 1 and 6 C above normal late 20th Century values.
Image source: Earth
Nullschool.)
In
Fresno, the
mercury is expected to rocket to 108 degrees Fahrenheit by Saturday —
or about 18 degrees above normal for early June. Sacramento is
expected to see 106 F readings at the same time — which is around
20 degrees above average for that Central California location.
Further north, temperatures are also expected to skyrocket with
Portland predicted to strike near 98 F on Sunday and Spokane calling
for 96 F. In fire-ravaged Fort McMurray, the mercury is expected to
top out at 85 F on the same day.
This
expansive bulge of heat is expected to cover pretty much all of
Western North American. Rising from the Desert Southwest, it is
predicted to run through Oregon and Washington, rise up through
Canada, and touch even the shores of the rapidly thawing Arctic
Ocean.
Conditions
in the Context of Human Caused Climate Change
The
broader conditions fueling both record rain and potential record high
temperatures over the North American West are the same. A record hot
global atmosphere is one that is burdened with more heat and moisture
than ever before. One that will inevitably produce more extreme
rainfall and heatwaves than we are used to.
Locally,
additional features related to a fossil fuel based warming of the
world further contribute to the problem. Over the Northwestern
Pacific, sea surface temperatures ranging from 1-6 degrees Celsius
above average (2 to 10 F) generate a tendency for heatwaves and
strong high pressure formation. These systems have often taken in all
of the US West even as they’ve extended on up into Canada and
Alaska. Adding to the problem is sea ice loss over the Arctic Ocean —
which as of today is seeing the lowest ice extent ever recorded for
this time of year. This sea ice loss tends to aid in Arctic warming
which weakens the Jet Stream, which in turn tends to meander —
creating these exaggerated trough and ridge patterns that have been
associated with so much extreme weather recently.
(Earth
Nullschool map of Jet Stream wind pattern predicted for early June 5,
2016. A powerful ridge expected to form over the US West Coast is
predicted to drive record heatwave conditions there by this weekend
even as a facing trough will again spike the risk for extreme
rainfall events over Southeastern Texas. This Jet Stream feature and
related severe weather conditions — ranging from severe heat to
floods — is now influenced by numerous effects currently emerging
as human-forced climate change worsens. Image source: Earth
Nullschool.)
Large,
hot ridges forming in one region tend to generate deep, stormy
troughs in another. And the ridge over the US West has resulted in
the formation of a related trough and unsettled weather pattern over
the South-Central US centering on Southeast Texas. This trough has
pulled cold, unstable air into the upper levels of the atmosphere
over Texas even as it fed upon an uncanny volume of moisture
streaming in off the abnormally hot waters of the Gulf of Mexico and
Pacific Ocean.
The
results? Well, we’ve already experienced them in the form of record
floods for Texas, periods of record heat for the Western US, and a
never-before-seen May wildfire outbreak in Alberta, Canada. This
week, the overall pattern is again expected to ramp into high gear —
which is likely to produce possibly never-before seen June heat out
west and more extreme flooding for Texas.
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