Long lasting Cyclone Freddy

[Jo Farrow]

Now Severe Tropical Storm Freddy is about to make landfall over Mozambique, an area already flooded and damaged from its rainy season, hampered by ruined infrastructure where cholera is on the rise and has areas of conflict. Cyclone Freddy hit Madagascar this week but wasn't as impactful as previous cyclones in this region but Freddy has travelled an awful long way and now has the highest ACE value for the southern ocean (records from 1980). 

https://www.netweather.tv/weather-forecasts/news/11841-long-lasting-cyclone-freddy-leaves-madagascar-for-mozambique

 

Latest humanitarian report from Mozambique by UN 

Mozambique: Severe Tropical Storm Freddy and Floods - Flash Update No.4 (as of 23 February 2023) - Mozambique | ReliefWeb

RELIEFWEB.INT

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Situation Report in English on Mozambique about Education, Health, Epidemic, Flood and more; published on 23 Feb 2023 by OCHA

 

[Jo Farrow]

A lot of data displayed here for Mozambique @WFPVAM 

ArcGIS Dashboards

UNWFP.MAPS.ARCGIS.COM

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ArcGIS Dashboards

 

[Jo Farrow]

Freddy is still going and WMO are monitoring it as it could be the longest lasting cyclone on record , if it peps up later this week before another landfall

https://public.wmo.int/en/media/news/tropical-cyclone-freddy-may-set-new-record

 

[Metwatch]

 

 

[Jo Farrow]

ACE Freddy 

 

[matty40s]

Freddy has now broken the record as the longest lasting tropical cyclone ever, breaking Hurricane John's 31 days in 1994.

 

[Eagle Eye]

If I take Geography for A-Level I have to do a paper based off my own research and I thought I'd get ahead and start by analysing convectively-couple Kelvin waves (CCKW's) in the formation of the cyclone so here's an extract from what I've done so far.

"

One forecasting and analysis tool for the formation and supposed life of a tropical cyclone is by using convectively coupled Kelvin waves (CCKW) which have higher wavenumbers than Rossby waves and are only equator-tropics waves characterised with typically smaller waves and weaker wave fluctuations than Rossby waves. Generally, for forecasting cyclogenesis you tend to get pre-CCKW easterlies followed by the convectively-active phase of the CCWK. They most frequently occur 2 days after the convectively-active phase passes through. CCKW’s affect the zonal wind structure along their passage as well as the convection in the inter-tropical area. They affect the general environment in terms of moisture shear and vorticity in the tropics.  

It is likely that the CCKW train (CCWKT) helped to increase the convection triggers with advection of moisture with the stream of warm unstable air off the Hamersley mountain range and great sandy desert area in western Australia. A wave off warm air was likely to have been lifted due to the kelvin waves passage through. With the convectively active phase and weakening of vertical shear that became a recipe for cyclogenesis. 

CCKW’s have been noted to interact with the feedback convective envelope of the MJO due to typically having stronger feedback in terms of convection. Enhancing the dynamical processes of inter-tropical forcing and it appears that this time these two worked together with Indian Ocean convection linked with the lag of phase 3 moving the convection envelope slightly further east and the timing was perfect for the exit of easterlies and the return of westerlies and weak shearing just north of Australia. Eventually, the inter-tropical forcing and convective action between Australian heat forcing and the eastwards moving convection. Eventually, these dynamics combined to become cyclone Freddy. 

If we look on the Hovmoller diagrams below we see the 850-hPa zonal wind anomalies and the 850-hPa velocity potential anomalies in the 20S-10S area. Looking at the zonal wind and we can see the pre-CCKW easterlies quite strong between 60E-150W around the 28th January and then the westerlies favourable for cyclogenesis around the 150E area in early February with the CCKWT moving west over time as the tropical cyclone also moves west. 

On the velocity potential diagram you will notice that the diagram base area is changed with 180 instead of 0 being on the left. We are looking at the 28th January onwards for CCKWT effects. Notice the dashed blue line just after the 28th; that is the convectively active phase of the MJO with the red outline being the convectively supressed phase of the MJO (the MJO-CCWK are coupled somewhat). Notice the divergence (negative) part of the kelvin wave between the 10th and 17th of February and that’s a sign of kelvin-wave enhanced convection along with MJO enhanced convection. As that made it’s way through the area that tropical cyclone was in, it became the first large intensification phase for the tropical cyclone by modifying the horizontal shear, moisture and low-level vorticity characteristics of the local area. There is a similar evolution in early March for the second major intensification of Freddy. 

At the time around formation and initial intensification of the disturbance, the eastwards moving MJO convection envelope (negatives show outflow from convection) and similarly moving Kelvin wave. Shearing tends to be strongest in the centre of the outflow but on the edge between the outflow-divergence and the supressed convection convergence is where cyclogenesis is most likely. You see the area between them on the Kelvin wave where cyclone Freddy NW of Australia. 

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[Rexychan]

With weather so wild around the world I am keen to join this forum so we can compare and see what is going on. Crazy cyclone Freddy has caused so much trouble.

[Jo Farrow]

Malawi and Mozambique continue to be hit by rains, flooding and mudslides from Freddy. 

 

[Rexychan]

Thank you for the update Jo. This cyclone storm is continuing to wreak havoc. Two hundred now killed in Malawi.

Storm Freddy: Malawi declares state of disaster as nearly 200 killed

WWW.BBC.COM

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More than 40 children are among the dead as rescue workers use shovels to find people buried in mud.

 

Edited March 14, 2023 by Rexychan

[Metwatch]

Very upsetting what is taking place in Malawi and Mozambique as a result of Freddy, I hope they recover after what looks to now be a once in a lifetime storm. 

Edited March 14, 2023 by Metwatch

[Kirkcaldy Weather]

Been mega busy with the UK snow but have been closely watching Freddys movement absolutely astonishing in many aspects. Prayers to everyone the storm has impacted

Lot of info within this thread 

 

[Jo Farrow]

Official from WMO -  " The World Meteorological Organization (WMO) has declared Tropical Cyclone Freddy to be the longest-lasting tropical cyclone on record, at 36 days. Freddy crossed the Indian Ocean basin, starting off the coast of Northwest Australia and reached southern Africa, in February and March 2023. It caused major human and economic losses in the worst-affected countries."

Tropical Cyclone Freddy is the longest tropical cyclone on record at 36 days: WMO

WMO.INT

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A WMO international committee of experts working under the auspices of the Weather and Climate Extremes Archive conducted a detailed analysis and verification of the distance and duration. The evaluation...