Cyclone IDAI and Cyclone Kenneth -> Mozambique
You said that « the ECMWF model appears to be over-estimating its wind category ». But do you compare ECMWF gusts forecast with sustained winds /1min?
RMSC La Réunion forecast 70 to 80kt /10min. which is in line with the max 70kt Wind predicted by ECMWF.
By which I mean the category indicated within the second image down in this earlier link.
It shows Kenneth as already a Cat-3 range (according to ecmwf) while a Dvorak (observation) analysis indicates 65 to 70 kt winds or low to mid-level Cat-1 at that time, and currently.
Your second image is based on Wind accumulation, and Wind accumulation shows the maximum gusts forecast on the map during the week. So that’s gusts, while Dvorak analysis gives sustained winds /1 min. forecast...if I’m right.
Yes, but it's not referring to some other Cat-3 cyclone later this week. The passage just occurred (over a few hours, not over a week) and ECMWF has put the max gust range inside the Cat-3 range, but from a low-end Cat-1 storm. That's presuming the Dvorak wind number is reasonably accurate, and frankly the clouds are not particularly well defined within those early images, with lots of cirrus smudging out detail needed to do the classification. So the (early) ECMWF cyclonic-range gust forecast looks rather optimistic to me.
But looking at the early satellite images (visually and subjectively that is) it's clearly just a fairly disorganized Cat-1 trying to get established, and not a system with Cat-3 level gusts (yet).
Cyclone Kenneth, 981 hPa and 75 knot winds. It's beginning to get its act together with a well-established outflow developing during the past few hours.
It's clearly beginning to flare up convection within this last IR image. According the the forecast it should build a core very rapidly soon after it passes by the Island to its immediate WSW. Clearly edging towards Cat-2, and an outer rain band is already impacting the coastline
The cyclone has just developed deep-convection around a defined eye on IR within the past hour as it begins to pass-by the island to the SW.
22 hours to eye landfall
3 hourly track
The coastal impact area appears to have a fairly sparse population of small towns.
Very rapid development of deep convection during the past hour is transforming cyclone Kenneth into a much larger system. It's also developed a much larger eye with more distinct core banding.
This much uplift indicates rapid intensification. It should become a Cat-3 within hours.
Cyclone Kenneth is currently category-3.
The Dvorak classification a few hours ago was 100kts @ 948 hPa. It is expected to reach about 110kt winds with 135 kt gusts, before weakening some as it approaches land.. The core will come ashore as a major cyclone but the predicted track is slipping further south down the coast towards some more populated areas. It's a very wet system (as shown via the vapor sat image) and a major flood is going to occur within north eastern Mozambique. Note also that the Dvorak wind speed and pressure analysis is currently giving a central-pressure that's about 20 hPa lower than the ECMWF model predicted.
Vapor image confirms Kenneth will be a very wet cyclone
3 hr locations for the first 24 hours, then 12 hr position locations thereafter. The rain-laden storm remnant spends around 4 days over Mozambique before clearing northwards, delivering a double-hit of rainfall as it loops around and picks up more in-flowing moisture from the ocean.
There's an unusual amount of heavy thunderstorm activity predicted to be associated with this cyclone's landfall, especially around its periphery. These sustained lines of thunderstorms are going to quickly drive up local rainfall totals and produce flash flooding as the storm moves overland. Very wet cyclones tend to deliver stronger gusts, as the faster winds from higher above are dragged to the ground by heavy rainfall inducing strong down-drafts of air. The heavier the rainfall the stronger and more turbulent the gusts tend to be. Thus an otherwise rain-laden Cat-3 can contain Cat-4 level gusts within it.
This will be another serious event which takes days to unfold and for communications and recon to be established. Road and rail infrastructure will again be demolished by the widespread hinterland flooding.
The heaviest rainfalls should occur over a broad strip that's about 100 nm wide (west to east), and about 350 nm long (south to north).
The eye will be fully on land within 24 hours.
12 hours until destructive core begins to impact land.
Cyclone Kenneth has just reached Category-4
Recent Dvorak classification shows 115kt (213 km/h) winds with a central pressure of 937 hPa (~135 kt gusts).
The pressure has fallen to 30 hPa below what ECMWF had predicted. Even on the IR it's showing strong regional cirrus outflows indicating Kenneth is still undergoing an explosive intensification period.
The radial cirrus outflow from immediately around the central-dense-overcast core area is more pronounced again within this latest water vapor image. This is indicating the core of Cyclone Kenneth continues to rapidly intensify toward a mid-level Cat-4 (125 kt winds and 150 kt gusts - stronger than Cyclone IDAI at its' landfall).
This rapid intensification of convective uplift has been occurring for about 12 hours, during which time the Dvorak pressure plunged from about 985 hPa down to 937 hPa, or a 48 hPa drop in 12 hours.
This newest IR image also shows that the peripheral radial cirrus outflow has just intensified further indicating that more air is now flowing out of the top of the core region due to the still intensifying convection uplift that's rapidly dropping the central pressure further. Visually it now looks much more like Cyclone IDAI did just before it made landfall, except the pressure is now even lower, and the eye is smaller and becoming more intense. Plus Kenneth is strengthening quickly while IDAI was slowly weakening down to Cat-3 during its landfall.
This cyclone is exceeding the ecmwf forecast.
People in the projected path should expect cyclone Kenneth to come ashore with similar wind and rainfall intensities as Cyclone IDAI, and for its effects to last about as long.
Category-4 Cyclone Kenneth
Sunrise will occur soon so there should be some impressive low-angle visual images during the next few hours. Heavy outer storm bands are currently affecting the coast and moving inland around 60 km.
This IR image (taken 23 minutes later) is beginning to show signs that the rapid intensification phase may be topping-out and coming to an end.
The eye will be onshore in about 14 hours.
The outer core of Kenneth is about 6 hours from the coast at present.
Kenneth's Cat-4 outer core is beginning to impact the coast
It appears to be maintaining low-end Cat-4 strength but apparently not intensifying further.
It continues to move generally West and has not yet begun to turn more WSW.
First visible dawn images
The worst of the wind and waves should mostly occur during daylight hours.
Cyclone Kenneth's convection and outflow features appear to be going off the boil compared to about three hours ago.
Excerpt of warning details
Bulletin du 25 avril à 10H19 locales Réunion:
CYCLONE TROPICAL INTENSE KENNETH.
Vents maximaux (moyennés sur 10 minutes) estimés sur mer: 215 km/h.
Rafales maximales estimées sur mer: 305 km/h.
Pression estimée au centre: 934 hPa.
Déplacement: OUEST-SUD-OUEST, à 15 km/h.
Thus a low-end Cat-4 with a 934 hPa central pressure
Dvorak analysis now says CYCLONE KENNETH has 125 kt winds and 937hPa pressure. Reunion’s current warning estimates the central pressure is at 934 hPa.
Latest visible wavelength image:
The outflow features are still looking impressive within these latest comparison-pair images which were taken 30 mins apart. Although the cloud tops are mostly about 10 degrees warmer than they were 4 to 6 hours ago. The eye has been becoming more defined during the past few hours.
Overall it's not weakening (as yet) and appears to be slowly strengthening.
Cyclone Kenneth gains strength, threatening Tanzania and Mozambique
Africa / 25 April 2019, 08:52am
Tavares Cebola and Peter Nyanje
Augusta Maita, director of Mozambique's National Institute of Disaster Management (INGC), told a media briefing that evacuation orders were in force in the country's northern Cabo Delgado Province, just across the border from Tanzania. File photo: Bongani Mbatha/African News Agency (ANA)
Maputo/Dar es Salaam - A strengthening tropical cyclone north-west of Madagascar is headed for the coasts of Mozambique and Tanzania, weather authorities and the UN warned on Wednesday. The Tanzanian Meteorological Agency (TMA) said that Cyclone Kenneth would make landfall overnight packing winds of about 80 kilometres per hour [maybe in Tanzania, but more like 230 km/h winds with higher gusts to the south], which were "capable of causing extensive damage." Tanzania's southern regions of Mtwara and Lindi, near the border with Mozambique, were likely to be most affected by the cyclone after it makes landfall, the agency said.
People living up to 500 kilometres from the coast should take precautions, the TMA said. Authorities in Mtwara told dpa that all schools have been ordered to stay closed on Thursday, and that public servants were asked to stay home and prepare for cyclone-related developments.
Earlier in Mozambique, Augusta Maita, director of the National Institute of Disaster Management (INGC), told a media briefing that evacuation orders were in force in the country's northern Cabo Delgado Province, just across the border from Tanzania. The government had declared an alert and that "all measures will be implemented to save lives," she said. "We will make sure that people are evacuated today, even if it means forced evacuation," she said.
Evacuation helicopters and boats being used in Beira further south - as part of relief efforts after a previous cyclone hit in March - will be relocated to Cabo Delgado, she said.
Malawi could also experience increased rainfall when Kenneth hits.
The cyclone is expected to impact the Comoros islands on Wednesday and make landfall on the African mainland on Thursday, the UN's Office for the Coordination of Humanitarian Affairs (OCHA) said. More than 700,000 people - mainly in Cabo Delgado - are living in the cyclone's path, OCHA said.
In March, Cyclone Idai caused massive flooding, killed hundreds of people and displaced thousands in Mozambique.
Aid agencies warned of the cumulative impact the two storms could have. "We are especially concerned about [Cyclone Kenneth's] possible impact in Mozambique where communities are still recovering from the devastation of Cyclone Idai," said Fatoumata Nafo-Traore, regional director for Africa for the International Federation of Red Cross and Red Crescent Societies.
Mozambique braces for cyclone Kenneth
Published: 17:03 AEST, 25 April 2019 | Updated: 17:03 AEST, 25 April 2019
Mozambique was bracing for a powerful cyclone to make landfall on Thursday, just one month after another cyclone devastated the country and neighbouring Zimbabwe leaving more than 1,000 dead. The UN warned that the latest storm could trigger flash flooding and landslides in Mozambique's far north and the government closed dozens of schools likely to be in the storm's path.
National airline LAM has suspended flights between the capital Maputo and Pemba on the northeast coast because of Cyclone Kenneth, it said in a statement. The Red Cross warned it was "especially concerned about its possible impact in Mozambique where communities are still recovering from the devastation of Cyclone Idai". Idai was the most powerful storm to hit the region in decades and cut a path of destruction through Mozambique, Malawi and Zimbabwe on the night of March 14-15, causing damage of around $2 billion.
Comoros and Tanzania would also be impacted, added the statement issued by the International Federation of Red Cross and Red Crescent Societies' Africa director, Fatoumata Nafo-Traore. Cyclone Kenneth passed the Indian Ocean archipelago nation Comoros on Thursday but its effects, including high winds and heavy rains, were still being felt, the country's Meteorological Office wrote on Facebook. "We must stay alert, avoid touching fallen power cables, wait for permission before driving and keep children at home," it wrote.
An AFP team in the Comoran capital Moroni saw shacks destroyed by the rain and wind, and high seas as a result of the cyclone. "I have three children, one is small just one month and ten days. We were here until 11 p.m. last night when things deteriorated," a local resident told AFP. "It was our neighbours who evacuated us."
The UN World Food Programme (WFP) said it was "watching the approaching tropical storm in northeastern Mozambique closely". "This storm will hit the north and we are expecting that heavy rain will provoke flash floods and landslides impacting the northeastern provinces of Cabo Delgado and Nampula," it said in a statement. "WFP is working under government coordination and with other humanitarians on an emergency preparedness plan."
Latest ecmwf model run details.
Rain-Thunder overlay (3fps)
3 hr locations for the first 24 hrs, then 12 hr locations thereafter
Severe to record flooding levels are assured.
Latest visible and IR imagery
The core is touching the coast at this time.
Note that the eye has jogged SW within this latest image, and the outflow is looking more impressive than before. It's not weakening, it's actually beginning to look even stronger than it did earlier.
Winds are still given as 125 kt and 937 hPa via Dvorak (while ECMWF predicts 971 hPa), i.e stronger than Cyclone IDAI at landfall.
Kenneth appears to be further intensifying just prior to landfall.
And so it begins ... landfall!
It's moving fairly quickly toward land now and almost due west with 125kt winds and about 150 kt to 160 kt gusts (>275 km/hr gusts). It's a genuine category-4 at landfall.
The ecmwf model predicted the worst weather to be in the northern semi-circle, but the satellite images indicate the heavy weather has migrated to the southern semi-circle. Plus the CDO has built out rapidly to the west and narrowed in the north east. It also looks like the inner eye-wall was beginning to destabilize in the NE, so was probably about to initiate an eye-wall replacement cycle.
There's so much moist outflow that it's obscuring the storm at visible wavelengths (on top of poor resolution).
The outer core has made landfall right on low tide, but the eye will cross the coast nearer to high tide, so a large storm surge is possible soon after sundown, as the eye's passage drags the water on to the land.
Kenneth's inner-core bands are beginning to cross the coast.
120 kts 942 hPa
Fortunately cyclone Kenneth has struck the least populated and wilder part of Cabo Delgado Province. Nevertheless there are still a few hundred thousand people in the area.
"Quissanga District is a district of Cabo Delgado Province in northern Mozambique. It covers 2,150 square kilometres (830 sq mi) with 40,486 inhabitants (2015)."
"Population (2007 census) • Total 76 ,139"