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Mangled
Jet Stream to Collide with Tropical System over Southeastern US for
Major Rain Event?
14
August, 2013
(Image
source: NOAA)
In
the southeast this year, rain follows rain follows rain. Now a
tropical system may be preparing to add its own moisture to the
already very wet mix.
The
river of upper level airflow called the Jet Stream begins an almost
due south movement at the Arctic Circle near the Northwest Territory
and Canadian Arctic Archipelago. The atmospheric river dives down
over Central Canada and into the Great Lakes region. Continuing ever
southward, it finally encounters a wall of warmer air setting up near
the south Tennessee border where it speeds up and turns eastward,
joining another Jet Stream flow coming in over the Rockies.
Riding
along these convergent Arctic and Pacific Jet Stream flows are a
number of wet and stormy impulses. Because this deep north to south
dip has been in place over the Eastern and Central US for much of the
summer, storm after storm has continued to impact a large region from
Missouri to New Jersey southward through the Carolinas and then again
southwestward along through Georgia and the Gulf Coast states. This
persistent stormy pattern, a result of a slow, wavy, stuck Jet
Stream, which is, in turn, caused by sea ice and snowfall loss in the
Arctic, has pushed rainfall totals 20 inches or more above the yearly
normal in some locations. It has delivered extraordinarily moist
storms that dump inches of rainfall in just a few hours. And
it resulted in some regions of Missouri receiving four months worth
of rainfall in just one week.
In
the above water vapor image, provided by NOAA, you can see the storms
riding along the south frontal boundary of this Jet Stream trough
through the Dakotas, Montana, Nebraska and Colorado then down into
Texas, turning eastward through the Gulf Coast States and then
surging north along the US East Coast.
Yesterday,
this pattern delivered a powerful storm complex to Pennsylvania and
New Jersey — flooding roads, knocking out power and dumping as much
as six inches of rain. Now, the Jet Stream has driven further south,
pushing the frontal boundary over the Gulf Coast and US Southeast.
(Image
source: California
Regional Weather Server)
But
as if the convergent flows of the Jet Stream delivering very powerful
storms, as if the stuck weather pattern keeping this storm-delivering
trough over the Eastern US for months, and as if the human-added
atmospheric heat amping up the hydrological cycle and spurring more
intense rain events were all not enough, we now have a large, moist
tropical weather system moving in and threatening to become entangled
in an already very wet pattern.
As
of this morning, the National Hurricane Center had issued an advisory
for a tropical system in the western Caribbean predicting a 60%
likelihood of tropical storm formation over the next several days.
The system is a large, sprawling and disorganized mass of
thunderstorms and moisture moving toward the north-west at 10 to 15
mph. A circulation appears to be trying to form in a region near the
densest thunderstorms. The system is predicted to move toward the
northwest until it is eventually captured by the frontal boundary at
the leading edge of our deeply sagging Jet Stream. Should this mix-up
occur, a tropical weather system and potential tropical cyclone will
have again combined with an Arctic originating air-mass over the
Eastern US, setting the stage for a rather intense and widespread
rainfall event.
If
there are some reading this analysis and thinking that it rhymes
somewhat with set up for Superstorm Sandy, they wouldn’t be
entirely off the mark. Until recently, it was less likely that
tropical systems would combine with polar originating air masses over
the US. The troughs originated and faded rapidly, only infrequently
coming into dramatic collisions. But now, with the Jet Stream
increasingly settling into a stuck pattern (spurred by human caused
warming and sea ice loss) and seeming to favor trough development
over the continental US and not over the ocean, such collisions are
far more likely.
With
the current system, unlike Sandy, rain appears to be the primary
concern for now — not storm hybridization, expansion, and
superstorm development. These are not on the radar. But we are still
very early in storm development and we don’t yet know how powerful
the slowly organizing tropical system will become. What we have right
now is a large, and potentially strengthening package of tropical
moisture setting its sights on an already soaked US southeast.
So
the risks at the moment are for a potential major flooding event on
the five to seven day horizon as the tropical system continues to
track northwestward until it is pulled into the stormy flow of the
Jet Stream trough. At that point, it is predicted to dump a heavy
load of moisture and rain over the US southeast.
Current
predictions from NOAA reflect uncertainty in storm development and
track and, at the moment, call for 3-5 inches of rainfall from the
Gulf Coast States through Georgia and the Carolinas over the next 5-7
days. Local amounts, however, could be much higher, on the order of 8
inches or more. Such an event would intensify an already severe flood
problem over this large area, likely resulting in major and
widespread flooding.
Any
significant wind field of 40 mph or more would also likely result in
a mass of fallen trees. The ground in this region is saturated with
moisture, making it harder for tree root systems to grip the soil. So
it takes much less wind to blow them down. Widespread power outages
due to trees falling over power lines is, therefore, also a potential
threat for this system.
Given
the current position of the Jet Stream and uncertainty over potential
storm strength and track, this situation could rapidly develop into a
dangerous event for the southeastern US or we could end up with a
storm system making landfall closer to Texas and Mexico. So we’ll
be closely watching storm strength and path over the coming week.
UPDATE:
Tropical
weather system 92 L is starting to exhibit some cyclonic turning:
Links:
Why
Do I Call it a Mangled Jet Stream? Learn More Here.
A
Song of Flood and Fire: One Million Square Kilometers of Burning
Siberia Doused by Immense Deluge
14
August, 2013
About
a week and a half ago, I reported on a
great burning event in which a massive region of Russian Siberia
erupted in hundreds of wildfires blanketing it in a sea of smoke
clearly visible in the NASA Aqua Satellite record.
Today, reports from Interfax/Radio Russia describe an immense flood
emergency in which over 1 million square kilometers of Russia’s
Yakutia region have been submerged by a catastrophic rain event.
“It
is a unique situation in the sense that it has spread over more than
2,000 kilometers if one looks from west to east, while its depth or
width is more than 500 kilometers,” Vladimir Stepanov, head of the
National Crisis Management Center of the Emergency Ministry, told a
news conference in Moscow.
According
to the report, hundreds of villages in this, thankfully, sparsely
populated region have been inundated by water putting hundreds of
thousands of people in amongst a swirling flood. According to reports
from Russian government, the region is now the site of a massive and
major rescue operation. As of August 11, the operation composed an
army of 20,000 personnel — a force that is likely to have greatly
swelled as this major climate disaster expanded through today.
A
Song of Flood and Fire
As
of late July, heavy rainfall had emerged in a dense band along
eastern Russia and bordering north China. This band of dense and
heavy moisture rose north over an ocean
heat dome that was setting off very dangerous high temperatures over
the region of Southeast China even as it was baking a large region of
ocean,
heating a vast expanse of the surface waters to above 30 degrees
Celsius. The added moisture and heat content provided fuel for low
pressure systems skirting the high.
By
early August, major flooding had begun to occur in this eastern
region as very heavy storms sprang up over this large area.
We
can see the development of this massive storm system starting on
August 4th in the image below:
Russia
August 4 — Heavy Rains to the East, Massive Fires to the West
In
the above image, we are looking down on the Earth from a shot taken
above the North Pole. The region we are looking at is Siberian Russia
and Yakutia which dominates the central section of the image. Toward
the lower left are the Laptev and East Siberian sections of the
Arctic Ocean. Toward the central and upper left is Eastern Russia
(Kamchatka), Mongolia, and extreme north China. In the upper right
corner is central Asia.
Note
the very dense region of clouds and rain pulsing up from the Pacific
Ocean and overlaying Kamchatka and southern Yakutia. The storm at
this point is vast and its cloud coverage immense. But it is just
getting started.
Russia
August 7 — Low Pressure Emerges From Central Asia
By
August 7, the storms had sagged toward the south, drifting slowly
eastward along the monsoonal flow. Occasional pulses of moisture rose
northward from the Pacific to refresh and intensify this storm and
cloud flux. This action brought the Pacific and monsoonal storms in
direct contact with a hungry low pressure system rising up out of
Central Asia and moving from the southwest toward the northeast. By
August 7 we can begin to see this storm system entraining the massive
volume of moisture associated with the Pacific storm pulse and
monsoonal flows.
The
storm was emerging over a region of Yakutia that had experienced a
massive and terrifying explosion of very energetic wildfires. The air
was heavily laden with particles of dense smoke from a great burning
that had intensified since late July. There the moisture erupted into
a powerful deluge that by August 11th had broken flood records set as
far back as 1896. By that time, more than 20,000 personnel had been
mobilized to help deal with the floods as hundreds of homes and
scores of roadways were inundated.
Russia
August 11 — Deluge Fully Formed Over Yakutia
As
of August 11, we see a massive and fully formed storm complex
directly over Yakutia. The storm has now fully entrained the dense
smoke cover belched out by the hundreds of fires, some of which were
still burning throughout the region. It was also still drawing in
moisture from the Pacific storms and monsoonal flow over south
Russia, Mongolia and northern China. A second arm of the storm
stretched northward linking the storm with the Arctic. With a strong
south and north linkage, the storm had accessed energy to maintain
strength and intensity for an extended period.
The
large storm system continued to churn through Yakutia and by today,
August 14th, a massive region covering 1 million square kilometers
was inundated by floodwater. What we see in the satellite shot for
today are not one, not two, not three, but four rivers of moisture
linking the major storm system that has inundated Yakutia
Russia
August 14 — Rivers of Moisture Collide
The
first river of moisture is a continuation of the Pacific flow rising
up along the southeast Russian coast, the second is the monsoonal
flow moving from west to east to combine with this Pacific flow. A
third flow feeds into the storm from Europe as it rides along
parallel and to the north of the more southerly monsoonal flow. A
final river of moisture rides up the from the storm, linking it to
the Arctic and likely sharing energy and instability with that cold
and dynamic region.
With
a second low developing to the west of the first and moving along in
its shadow and with moisture continuing to feed into these storm
systems from the monsoonal flow to the south, it appears that rainy
conditions will persist for the already inundated Yakutia region over
the next few days at least. And if this pattern continues as
predicted, it may well come to rival the great Pakistani floods of
2010.
Fires
Still Burn Near the Flooded Lands
One,
rather odd, feature of this major flood and fire event is that large
areas of wildfires are shown to still be burning throughout Russia.
Though the onrushing deluge clearly put out some of the major fires
burning in north and central Yakutia, still other major fire
complexes continue to burn — some of which remain very near to
flooded regions.
In
the below MODIS shot a major fire complex is still visible in a
region of Russia to the west and south of areas most heavily affected
by flooding:
Fires
Burn in One Part of Russia as Another Part Floods.
These
fires are burning directly in the shadow of the second storm system
with their smoke trails feeding into the storm along its southerly
inflow.
Conditions
in Context
Earlier
this year, drought and heatwaves blanketed Siberia and Yakutia. But
late July, this region had begun to erupt in a series of
extraordinary wildfires that blanketed almost all of northern and
eastern Russia in very dense smoke. By early August what is perhaps
the worst rainstorm in the history of this area of Russia had begun
to form. As of the writing of this article, on August 14, major
storms and flooding continued with no immediate end in sight.
Major
heatwaves and droughts in extreme northerly regions of Siberia are an
anomalous event linked to human caused climate change. Rapid sea ice
and snow cover retreat combine with temperatures that are warming at
a rate of .5 degrees C each decade over this region to increase the
likelihood of such extreme events. Methane and organic carbon stores
in the thawing tundra steadily release under this heat forcing and
likely provide an amplifying feedback to summer heating events by
locally providing more greenhouse gas emission and also providing
another fuel store that is available to wildfires. In some of these
wildfires, there are reports coming in that fires burn as far as 3
feet into the ground, taking out root systems and stumps along with
the trees that burn above ground. Reports of burning ground have also
been trickling in (Hat
tip to Colorado Bob)
Such
burn events are anomalous enough. But for a flood that covers a 1
million square kilometer area to immediately follow in the wake of
such amazingly large and widespread fires is anything but normal.
Atmospheric patterns that link major weather systems and increase
their intensity can be attributed to the formation of powerful heat
dome high pressure systems along with weakened and meandering Jet
Stream waves. Rising atmospheric heat caused by human warming adds to
the density and strength of heat domes (identified as becoming more
intense by meteorologist Stu Ostro). Meanwhile erosion of the Jet
Stream caused by reduced snow and sea ice cover (identified by Dr.
Jennifer Francis) is implicated in a host of problems including more
intense and persistent droughts and storm events along with the
increased likelihood that weather systems will link up as north to
south weather patterns deepen, back up, slow down, and elongate.
A
massive ocean heat dome to the south over the Pacific adjacent to
China and sea ice and snow cover remaining near record lows must be
taken into account when looking at features that likely contributed
to the extreme swings from drought, heatwave and fire to massive
deluge and flood in Russia.
One
last point to consider as a likely contributor is the fact that for
each degree (Celsius) of human-caused temperature change, the
hydrological cycle amplifies by about 8 percent. This means that
rates of evaporation and rainfall are now about 6 percent more
intense than they would be in the world of the 1880s. When combined
with powerful new weather features like a mangled Jet Stream and
immense heat dome high pressure systems, an amped up hydrological
cycle further inflates an already extreme environmental condition.
Links
and Credits:
Hat
Tip to Commenter Steve
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