Welcome to Meteorology Matters. We've been keeping
a close eye on tropical cyclone Errol out there
in the Indian Ocean near Australia. And it's
been quite something to watch. This storm really
intensified quickly. It really did. Yeah. Errol
got going Tuesday night. And by Wednesday morning,
Australian Western Time, it was already a category
two cyclone on their scale, sitting about 515
kilometers northwest of Broome. And it was heading
west at that point. And just to give folks a
sense of the power here, the Joint Typhoon Warning
Center, that's the collaboration between the
U .S. Navy and NOAA, the National Oceanic and
Atmospheric Administration, they reported early
Thursday, local time, that Errol hit sustained
winds of 144 miles per hour. Wow. Yeah, that's
significant. I mean, put that in Atlantic terms,
that's a category four hurricane on the Saffir
-Simpson scale. A major hurricane. So what exactly
was going on? What conditions allowed it to,
you know, ramp up like that? Well, a couple of
really key factors lined up perfectly. First
off, the ocean was incredibly warm there. Sea
surface temperatures were hovering around 30
degrees Celsius. 30 degrees? That's quite warm.
Oh, yeah. The minimum threshold you generally
need is about 26 .5 C, so it had... plenty of
fuel basically, like high octane fuel for the
storm's engine. Makes sense. Were there other
things happening in the atmosphere? Absolutely.
We also saw really good outflow aloft. So think
of it like a chimney. The storm could vent easily
up top, which helps it draw in more warm, moist
air near the surface. It just keeps that engine
running efficiently. OK. And I remember seeing
something about the storm's size. potentially
playing a role, is that right? That's an interesting
aspect, yeah. Sometimes these relatively smaller
tropical cyclones, when they hit those perfect
conditions, they can spin up remarkably fast.
It's almost like all that energy gets focused
into a tighter area, allowing for quicker intensification.
And looking at the satellite imagery, it seemed
like it got organized pretty quickly, too. It
did. By Wednesday morning, it looked very well
-defined. Seeing that clear symmetrical eye develop,
that's often a sign of a really strong storm.
that isn't facing much resistance like wind shear.
The Joint Typhoon Warning Center actually called
it an impressive look on the infrared satellite
pictures. They noted an eye about eight nautical
miles wide. And this is wild. They measured the
temperature inside the eye at positive 15 degrees
Celsius. That sounds really warm for the core
of a cyclone. What does that signify? It is quite
warm, and it's generally a sign of a very intense
system. That warmth comes from sinking air within
the eye, which compresses and heats up. So a
clear warm eye like that, surrounded by those
intense thunderstorms in the eye wall, that's
classic strong cyclone structure. And Errol,
I mean... It went through what was described
as an amazing period of extreme rapid intensification.
Amazing period, wow. Yeah, the winds increased
by 85 knots in just 24 hours. 85 knots. In a
day. In a day. And over 50 knots in just 12 hours,
those are just huge jumps in strength. That's
unbelievable. And some microwave satellite passes
suggested it might have undergone a quick eyewall
replacement cycle, too. Ah, explain that a bit.
What's an eyewall replacement cycle? So basically,
think of the original eye wall, that ring of
intense storms as the main engine. Sometimes
a new larger ring of thunderstorms starts to
form outside of it. Eventually, this outer ring
can strengthen, contract, and kind of choke off
the inner eye wall, replacing it. It can cause
a little dip in intensity sometimes, but often
the storm comes out stronger afterwards with
a larger eye. Right, like getting a bigger engine.
So at its absolute peak, what were the wind speeds
we were looking at? Well, the Joint Typhoon Warning
Center's initial assessment put the peak intensity
around 140 knots. That translates to roughly
161 miles per hour. Wow. And the Australian Bureau
of Meteorology, the BOM, they use a 10 -minute
average for sustained winds. They reported maximum
10 -minute winds of 100 knots, which is 185 kilometers
per hour. Okay. But they also noted three -second
gusts hitting 140 knots, or 260 kilometers per
hour, around 1800 UTC on April— 16th. So based
on their scale, that made Errol a severe travel
cyclone. Which is their equivalent of Cat 4.
Exactly. Equivalent to a category 4 on the Saffir
-Simpson scale we use for hurricanes. A very
potent storm. Okay, so you have this beast of
a storm. What was the thinking on where it was
going next? Was it just going to keep heading
west? Uh, no, actually. The forecast models are
pretty consistent in showing it making a distinct
left turn, sort of hooking back towards Western
Australia's Kimberley Coast. That turn was expected
around Thursday. And I guess making that turn
would change the environment around the storm.
Precisely. As it was forecast to make that turn,
the conditions ahead looked less... Well, less
ideal for it to stay that strong. Less favorable,
yeah. What kind of conditions? Mainly increasing
vertical wind shear. You know, winds blowing
at different speeds or directions, at different
heights in the atmosphere. Right, that can tear
a storm apart. It can disrupt the structure,
yeah. And also, an intrusion of drier air was
expected to get pulled into the circulation.
Storms like this need that moist air to survive,
so dry air is like poison to them. Okay, so the
forecast was for weakening as it got closer to
Australia. That was the consensus, yes. Most
forecasts had it weakening, potentially dropping
below tropical cyclone strength before it actually
made landfall. So coming ashore as a tropical
low sometime over the weekend. And the Joint
Typhoon Warning Center agreed with that weakening
friend. They did. They also pointed to the increasing
sheer and dry air, suggesting it could weaken
to tropical storm strength within about 48 hours
and then dissipate over land. How about the Australian
Bureau of Meteorology, the BOM? Similar outlook.
Very similar. They also expected it to weaken
as it neared the West Kimberley coast, likely
falling below cyclone intensity before crossing
the coast. Their specific forecast mentioned
landfall as a tropical low, maybe near Cape Lavec
or Kakatu Island on Saturday morning. Now, it's
important to remember, even if it weakens to
a tropical low, that doesn't mean the danger
is over. Absolutely not. That's a crucial point.
Even a weakening system, or its remnants, can
still bring really significant impacts, especially
heady rainfall. So what were the main concerns
for the Kimberley region? The remnants of Errol
were expected to deliver a pretty good burst
of heady rain across parts of the Kimberley,
starting Friday and going into the weekend. And
that rain could spread quite far inland, too.
And winds. Still concern. even below cyclone
strength. Yes. There was still a possibility
of gale force damaging winds, particularly for
the coastal stretch between Kakatu Island and
Beagle Bay from Friday into Saturday morning.
OK. And depending on the exact track it took
as it weakened, those stronger winds might have
extended south towards Broome as well. So heavy
rain. potential for damaging winds. Any specific
areas highlighted for the heaviest rain. Yeah,
they mentioned isolated heavy falls possible
between Curie Bay and Broome, especially overnight
Friday into Saturday morning. And it's always
worth stressing flash flooding is a major risk
with these systems, even while inland far from
the center. You don't need hurricane winds for
dangerous flooding rainfall. Good reminder. It's
interesting thinking about these southern hemisphere
cyclones compared to Atlantic hurricanes. Are
there big differences besides just the name and
location? That's a good question. Statistically,
they're less common. Only about a quarter of
the planet's tropical cyclones form in the southern
hemisphere. Oh, only a quarter. Yeah. But strength
-wise, once they reach sustained winds of 74
miles per hour or more, they're essentially the
same phenomenon as a hurricane, just called a
cyclone. So the potential impact is similar.
What about how they behave? The most obvious
difference is the spin direction. Because of
the Coriolis effect on a rotating Earth, cyclones
down there spin clockwise. Right. Opposite to
our counterclockwise hurricanes. Exactly. It's
a mirror image. And where do these cyclones typically
hit in the Southern Hemisphere? They can impact
Eastern Africa, Madagascar gets hit quite often,
and then of course the western, northern, and
eastern coasts of Australia, plus many of the
island nations nearby. And their season is different
too, right? Yep, opposite to ours. Their main
tropical cyclone season runs generally from late
October through to May. OK. With the peak activity
for the Australian region usually falling in
late February or early March. You mentioned Errol
was the 11th named storm in the Australian region
this season. Is that a lot? It actually is, yeah.
It makes this the most active season they've
had in six years. Wow, since 2019. That's right.
When forecasters are tracking these things, trying
to figure out intensity and path, where does
all the information come from? Seems like a massive
undertaking. It really is. The tracking data
comes from multiple centers, including NOAA,
the National Oceanic and Atmospheric Administration,
and the Joint Typhoon Warning Center we mentioned
earlier. Satellite imagery is absolutely crucial.
That comes from NOAA as well, and also the Japanese
Meteorological Agency, JMA. They have excellent
satellite coverage over that region. And rainfall
forecasts. Those also heavily rely on data and
models run by NOAA. It's a huge international
effort, really. Sounds like it. Yeah. You mentioned
the models earlier showed Errol turning. Was
there good agreement on where exactly it would
end up? You know, initially. On the westward
track in the turn, there was pretty good agreement
among the different computer models. But as the
forecast went further out in time, looking towards
landfall, there started to be a bit more spread,
a bit more divergence in the models about the
exact location and timing. Which just shows how
tricky forecasting these things can be, right?
Absolutely. It really highlights the complexity.
Predicting the precise path days in advance is
still one of the biggest challenges in meteorology.
So just to recap then, tropical cyclone Errol.
intensified incredibly rapidly in the Indian
Ocean, became a very powerful system equivalent
to a category four hurricane. Yep. Then it was
forecast to turn towards the Kimberley coast
of Western Australia, expected to weaken significantly
before hitting land likely as a tropical low.
That's the gist of it. But even as a weaker system,
it still pose a real threat of heavy rain and
potentially damaging winds to that region. Correct.
And the key message for anyone potentially affected
is always to stay tuned to the latest official
warnings and forecasts from the Australian Bureau
of Meteorology, the BOM. They'll have the most
current information. Definitely. You know, looking
at a storm like Errol, it just makes you appreciate
the sheer complexity involved in forecasting
these powerful weather events. So many factors
in the ocean and atmosphere, all interacting.
It's true. It underscores the constant effort
and the advancements being made in meteorology
to better understand and predict these phenomena.
Every storm teaches us something new. Absolutely.
Well, for listeners wanting more meteorological
insights and updates, definitely follow meteorologist
Rob Jones. You can find him on Instagram. His
handle is just Meteorologist. Easy to remember.
Yeah. And on TikTok, he's TV Meteorologist. Plus
check out his YouTube channel. Search for Rob
Jones Hurricane. That's also where you can find
the playlist for this podcast, Meteorology Matters.
Great resources to check out.