Discover and read the best of Twitter Threads about #extremeweather

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#LaNina #ENSO & drought expectations in Africa - a deep dive into latest satellite imagery and model atmospheric precipitable water data.


[image: There is remarkably complex water transport activiy underway over North Africa and the Middle East.]
First some background. ENSO, La Nina and El Nino is an oscillation related to sea surface temperatures in the Eastern Pacific. It is an important indicator of drought activity, especially in the US, but also as far away as Africa and NZ. La Nina typically mean less rain.
The image above shows equatorial tropical atmospheric water flows, and helps with understanding of why the Eastern Pacific sea surface temperature is important. Less convective storms in the Eastern Pacific leads to less atmospheric water everywhere.
Read 27 tweets
What was Invest #99p is now Cyclone #23p and ought to really have a name by now.

As you can see here the track model spaghetti it’s remnant are likely to being #extremeweather to NZ

THREAD on this system attached. There is more to this than just a late season cyclone.
Read 4 tweets
With development underway of another potential cyclone near New Caledonia, NZ may get yet another #ExtremeWeather tropical driven weather event this cyclone season.

This animation shows a 10 day rain forecast with the impact of the potential storm arriving at the end on 13/4.
Here's a 24 satellite loop of the storm in question (currently Invest #99p) which has been meandering north of New Caledonia, and becoming increasingly organised.
Another view of the storm this time of IR satellite imagery which shows convective bands developing around the rotation.
Read 8 tweets
#Equinox is also the moment when the incoming energy balance shifts from the Southern to the Northern Hemisphere, and it was marked this year with some extraordinary temperature anomalies in the Arctic and Antarctic. Both caused by atmospheric rivers.

#ClimateChangeNow thread... ImageImage
And this year the northern hemisphere #extremeweather season has a Herald, a designated tropical disturbance which the JTWC had thought might become a cyclone. Whilst early this morning a cyclone formation warning was cancelled, the storm appears to not be giving up so easily.
This @zoom_earth animation shows the last six hours of explosive convection which picked up quickly after the storm moved back over the sea in the Bay of Bengal.
Read 37 tweets
The IPCC Climate Change 2022: Impacts, Adaptation and Vulnerability was released today. I'm going to go through the executive summary and post some "highlights". #IPCC #IPCCReport…
Risk can arise from the dynamic interactions among climate-related hazards,exposure & vulnerability of affected human & ecological systems. Risk that can be introduced by human responses to #climatechange is a new consideration in the risk concept. There are 127 key risks. Image
Observed Impacts from Climate Change:

" The rise in weather and climate extremes has led to some irreversible impacts as natural and human systems are pushed beyond their ability to adapt"
Read 25 tweets
#ExtremeWeather #Emnati #TCEmnati Update:

Recent @NOAA GFS simulation model runs for #Emnati are continuing to show the storm turning towards the south as it is north of Reunion island which would mitigate the worst threats to #Madagscar.

Impact comment from RMSC/@MeteoFrance
The model guidance though is unclear (image below shows latest @ECMWF model landfall solution). The numerical model guidance is discussed from the same @MeteoFrance advisory issued at midnight.

The official track still shows catastrophic landfall in #Batsirai affected areas.
@ECMWF @meteofrance Spaghetti ensemble runs below for GEFS (L) and EPS (R) (right).] These show the current trajectory disagreement clearly.

[HT to @WXNB_ : ]
As he says an improved impact outcome for Madagascar will likely mean a worse result for La Reunion.
Read 8 tweets
#ExtremeWeather #Warning #SouthEastAfrica

With formation of Tropical Storm #Emnati overnight and a high confidence forecast for the next five days. We need to also pay attention to potential impacts in Southern Africa, especially in the East.

Latest GFS 10 day rain sim below.
While Tropical Storm #Dumako has lost its JTWC designation the threat it poses to Mozambique is not over - we just won't have the same level of data to watch it as it crosses the Mozambique Channel.

The current spaghetti analysis from ECMWF suggests it won't strengthen.
However in the rainfall forecast we can see that heavy rain is forecast for Southern Mozambique and across the the continent over the next 10 days. This animation is from earlier today before #Dumako was taken off the monitoring list.
Read 12 tweets
#ExtremeWeather TS #Emnati Update:

After a night of explosive convection and organisation What was #96s #Invest96s or #TD5 is now #TSEmnati - and forecast to become - like #Batsirai an Intense Tropical Cyclone on Sunday packing Cat3 Hurricane intensity winds of 185kmh.
And the good news is that JTWC - [… website seems to be back online. They were missed. Here is the latest official track forecast issued by JTWC Pearl Harbour this morning at 3:00Z (UTC). This storm can now be considered to be a major threat to Madagascar.
The forecast track is almost identical to that of #Batsirai, which has left over 120 Malagasy dead, destroyed and damaged 10s of thousands of homes and buildings. Flooded areas have not even drained yet.
Read 14 tweets
#ExtremeWeather Update Thread: Madagascar #Invest96S

The JTWC is now saying there is a "High" probability of #Invest96S will become a TC within the next 24 hours.

The JTWC @USNavy @USNRL website [Here:] remains inaccessible.
@USNavy @USNRL While we do not have a JTWC track forecast yet, we do have a new forecast. the relevant part for #96s is in the 2nd image here and contains reasoning as to why:

Here's a current 24h animation of the storm, at the end you see the center of circulation is fully exposed. The storm is moving fairly fast and is being blown westwards by winds which are creating a lot of shear - which prevents development.
Read 19 tweets
This #ExtremeWeather thread on #Invest96s in the Indian Ocean is a weird one.

It began with apparent cancellation of the designation of two colliding tropical disturbances by the #JTWC (Joint Typhoon Warning Center) last night, followed by its re-designation this afternoon.
The re-designation wasn't by JTWC - which is having website outage issues - but rather by the RSMC, the local meteorological authorities in the Reunion & @meteofrance

If #Invest96s becomes a cyclone and intensifies, models indicate it will become the fourth cyclone to strike Madagascar in two months - possibly as the 2nd major cyclone.

It would follow #StormAna #Batsirai & #Dumako which made landfall in the north of Madagascar today.
Read 4 tweets
#ExtremeWeather Update:

The JTWC @USNavy run portal for Global surveillance/tracking of dangerous cyclones - seems to be out of action, inaccessible via the web, again.

Just as a third tropical storm is making landfall on Madagascar in the space of a month. @USNRL @WMO
The Joint Typhoon Warning Center website is here >>

It has been unreliable for several months normally it looks like the 2nd image here below (image src: - which aggregates cylone/storm data)
Tropical Depression 96S (see previous tweet) is the storm that is currently forecast by most models to develop into a dangerous cyclone threatening Madagascar and possibly SE Africa.

The storm was removed from the watch list yesterday morning - then reinstated this afternoon.
Read 29 tweets
Madagascar #ExtremeWeather Thread:

Yet another Indian Ocean Tropical Storm, #Dumako is forecast to make landfall in Madagascar in the next 24 hours.

And at around the same time models suggest a more dangerous Tropical Cyclone may form following closely behind.
#Dumako is a relatively minor storm and is forecast to weaken on its approach but as you can see here, simulations are pointing to a more dangerous storm following closely in Dumako's wake.

The new cyclone is modelled to form as #Invest93s & #Invest96s merge.
At this stage this formation event is just a possibility, but if it does take place landfall will follow fairly quickly afterwards, and at the moment its track over Madagascar looks very similar to that of #Batsirai which killed over 100 people and destroyed around 100,000 homes.
Read 12 tweets
NZ #ExtremeWeather Update Thread.

What was Tropical #CycloneDovi has fallen apart and is now more like a front. Overnight a lot of rain has fallen over central NZ Sth and Nth islands.

But the rain event will soon come to an end.

IMAGE: IR satellite image of remains of #Dovi.
Heavy rain over northern parts of NZ now looks unlikely. This animation shows model predictions (ECMWF model) of rain fall from 6pm last night NZ time through to Monday 6pm.
In this 24 hour @Metservice rain radar animation - from 4pm Saturday through to 4am this morning, a lot of this rain has already fallen. The forecast indicates it will continue to move northwards, but it appears to be weakening.
Read 6 tweets
#NZ #ExtremeWeather Update thread:

The latest JTWC update has Cyclone Dovi strengthening to 96 knots of sustained winds, putting it on the threshold of Category 3 Hurricane Strength.
While #CycloneDOVI is very unlikely to maintain anything close to this all the way to NZ, this is not good news for the Nth Island in rain/flooding terms.

[Image: 24 hour satellite animation of #Dovi featuring New Caledonian radar data showing an intense well formed eyewall.]
Outflow of moisture - an atmospheric river - generated by #CycloneDovi is already delivering intense rains in NZ in a band which is steadily moving northwards.

A strengthening #Dovi will increase the amount of moisture in this river.
Read 9 tweets
#ExtremeWeather Update 7: Madagascar

Whilst #CycloneBatsirai has now passed, Madagascar is not yet out of danger as the South Indian Ocean Cyclone Season remains very active.

Here is a satellite image of #Batsirai as it leaves Madagascar heading due south.
This morning a media briefing from @UNICEF @UNGeneva addressed humanitarian crises in East Africa, many of which are climate related. And included a briefing on Madagascar and its recent storms.…
Read 4 tweets
#KiwiDeluge Phase 2 begins.

#ExtremeWeather update thread

Cyclone 92p has now formed north east of New Caledonia and here you can see in the satellite imagery how an atmospheric river generated from its outflows is strengthening and heading towards NZ's West Coast.
Whilst the formation of a Cyclone in this position has been predicted in the models for a long time, its formation is uncertain until it happens, and a critical point in the unfolding story of this #KiwiDeluge.

In this animation you can see the circulation form and its size.
Towards the end of the animation you can also see that it has started to move south eastwards, also as predicted.

This animation shows the broader picture across the tropics, an area on the RHT here (roughly over Tonga) is also playing an important role in this.
Read 13 tweets
#Batsirai #ExtremeWeather Update Thread 6:

The center of Intense Cyclone Batsirai has nearly completed its crossing of Madagascar but the storm/wind field continues to impact the southern half of the island.
The most intense rainfall was concentrated near the Capital City Antisirabe, the 4th largest city moving slowly. Extreme flooding in this area appears likely. And there were two additional extreme rainfall events in the North and the West of the island, fueled by the storm.
We see in this image that the eye of the storm (with its most damaging winds) remained intact for several hours after landfall finally losing its structure in the early hours Sunday Morning.

The lightning display as seen in satellite imagery during this period is extraordinary.
Read 16 tweets
NZ's #ExtremeWeather event is not over.

Simulations of the area of tropical moisture that brought torrential rains to the South Island now show a storm system moving south into the Tasman Sea resulting in intense rainfall across Northern NZ through Feb 12th.
Forecasts for this system's exact impact remain highly uncertain but four major global forecasting models are in agreement that some form of extreme weather for NZ will be result.

These are the latest ensemble tropical storm "spaghetti" track graphics for storms north of NZ.
The event is expected to begin within 24 hours these are four different models showing the intense area of atmospheric moisture moving over Northern NZ this morning (Sunday) NZT.
Read 20 tweets
#Batsirai #ExtremeWeather Update Thread:

Cyclone Batsirai is weakening and accelerating on its final approach to Madagascar's East Coast. But while lower winds will be helpful - it's primary impact - widespread very heavy rain - is likely to be extreme.

The official forecast has not been updated, the eyewall landfall (diminished by the filling of the eye) is likely to take place a little later than forecast but wind and rain is already building over the island as is obvious in the satellite imagery.
As of 20 minutes ago the center of the cyclone had roughly 100kms to travel to the shoreline. It will a bring a significant tidal surge with it, especially on the southern side and likely cause significant coastal flooding over a large area of the coastline.
Read 14 tweets
#ExtremeWeather Split screen.

Two world's apart.

The US Eastern Seaboard and Madagascar.

The US experiencing yet another of what it calls "bomb cyclone". Madagascar about to experience a cyclone which will be much more like a bomb.
Both #Extrremeweather events caused by climate change, and 30+ years of failure to address known extreme damage to the biosphere caused by avoidable harms.

One nation responsible for the peril.

Another defenceless against it's catastrophic harms.
In one nation the harms will be felt mostly in travel delays.

In the other nation many will likely die, and 100s of thousands will have their lives scared and livelihoods threatened, and will likely be dependent on humanitarian aid for months if not years.
Read 4 tweets
#Batsirai #ExtremeWeather Update Thread.

As a poster child for the impact of climate change on developing nations this cyclone, is a truly terrifying phenomena. In the next 24 hours it will make landfall at most likely Cat 4 or Cat 5 Hurricane Strength.

The animation above is live and covers the last three hours. This animation shows the last 24 hours.

Madagascar is an impoverished nation of nearly 30 million people the majority of whom live in the path of this Cyclone's wind and forecast extreme rain.
Whilst at Cat 4 strength a day ago what was already Intense Cyclone #Batsirai underwent a eyewall replacement and slowed down, it is now accelerating and strengthening.
Read 10 tweets
All eyes on Westport (again). #ExtremeWeather #nz

An overnight satellite + weather radar overlap (12 hours) showing consistent moderate rain in the Buller River catchment.

The next 36 hours will be critical. With evacuation of the town expected today.
A live video cross to @radionz's @CheckpointRNZ from Westport, reporting on preparations in the town which was severely flooded last July by a similar #extremeweather event.…
Here's a broader view showing all of NZ and the cause of the rain converging atmospheric rivers coming together over the Tasman Sea and bringing a continuous stream of thunderstorms towards the Southern Alps.
Read 6 tweets
#NZ #ExtremeWeather Update Thread.

The quoted thread addresses the long term threat posed by current conditions - beyond five days - around which there is a lot of uncertainty.

Here's the latest ECMWF model PWAT forecast for the current event - next three days.
The longer term picture depends on a complex storm picture north of NZ with a potential 2nd #ExtremeWeather event beginning around 9th Feb.

The current atmospheric river generated event is expected to conclude in around 5 days. Here's the latest GFS 5 day rain accumulation sim.
Beyond five days as detailed in the quoted thread, the global weather simulations diverge. Here is the GFS's current simulation rainfall expectations Feb 8-13. In this scenario the bad weather continues for a further 6 days.
Read 7 tweets
Spaghetti model simulations of several tropical storms currently north west of NZ are not looking at all good.

The possibility of a cyclone coming into the Tasman and making landfall on NZ's West Coast is now non-zero.
The above map is the European ECMWF ensemble map for the area. This specific model map is for SPO9 a designated disturbance/low pressure system of concern.

Until very recently the models had suggested it would be pulled away to the East of NZ - which is what typically happens.
In this region we have four different models (GFS-US, ECMWF-Euro, AcessG-AU and CMC-Canada) each of which has a different solution on how this will play out.

But the trend is in the direction of a threat to NZ. Each of these plots show the water/energy modelling for around 12/2.
Read 7 tweets

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