Please finish your preparations as soon as possible for those under-affected regions, and evacuate now if you are in low-lying areas or near mountains!

Watch Here: https://www.youtube.com/watch?v=6sc5eAbCgdA

The post Hurricane Agatha Bearing Towards Mexico, Live Coverage Starting at 19z appeared first on Force Thirteen.

Force Thirteen will be going live in an hour, at 14:00UTC (19:30IST) to provide extensive discussion on the system. Please stay safe and the prevention procedures should be ongoing, especially with a closer track now expected.

Link: https://www.youtube.com/watch?v=b3bx19M5VNg

The post Asani shifted westward, now bearing to Andhra-Pradesh – Live update 19:30IST appeared first on Force Thirteen.

Current Storm Information

As of 20:00 SAST (18:00UTC), according to the latest advisory of MFR, Issa is located at 31.1S 31.1E, with estimated maximum 10-minute winds of 95km/h, with gusts reaching hurricane-force (130km/h), and a pressure of 994hPa.
Issa is moving southeast at 13km/h.

At the same time, estimates from ATCF suggest Issa is weaker, with maximum 1-minute winds of 75km/h, but a slightly deeper pressure of 993hPa.

Issa’s Formation Process

An upper-level trough persisted over Southern Africa since last week and has been slowly moving eastward. It brought prolonged unstable weather over the eastern part of South Africa and the Kingdom of Lesotho, while bringing clear weather behind (west of) the low. The induced convergence at the lower level led to a formation of a surface non-tropical low on April 11th off the coast near the South Africa-Mozambique border, bringing even more serious rainstorms to the eastern coast of South Africa, This low was the precursor of Issa (Pre-Issa).

As it became traceable on the 11th, models such as ECMWF and GFS started to indicate signs of formation. GFS shows it to become a barotropic system in the later 12th to early 13th. The forecast is reflected as relatively accurate as the pre-Issa skirted along the coast and continues to develop under a decent 25-26C sea-surface temperature. Wind shear continues to decline as the upper-level low approaches it, favouring its formation. ASCAT passes showed it was gale-force, with a defined low-level centre.
As it develops, it continued to obtain tropical characteristics. At 14:00 SAST, Meteo-France upgraded this low into a gale-force subtropical depression with 10-min winds of 45mph and a pressure of 997hPa. ATCF followed suit and designated it as subtropical storm 92S.

Right after it formed, development and appearance became more pronounced, with convection wrapping rapidly and eliminating extratropical characteristics. An eye-like feature formed after sunset in various satellite imagery. GFS vertical cross-section shows the warm core extending up to mid-level (300mb), with high level (above 300mb up to tropopause) remaining dominant by the upper-level low as potential vorticity is still positive, supporting that Issa is a subtropical storm. Given the recent improvement, MFR estimated that it intensified into a storm-force subtropical depression, from 75km/h to 95km/h.

Forecast Track

It is expected to be a short-lived system. Under the steering of the subtropical high, it is expected to continue moving southward in general, and weakens substantially, before accelerating southeastward and turning extratropical on the 14th as an extratropical low moving eastward creates a fracture in the subtropical high and picks it up.

Torrential rainfall over the eastern part of South Africa.

Due to the impact of the upper-level low and Issa, it brought rainstorms to the Kingdom of Lesotho and the southeastern part of South Africa, particularly in Kwazulu Natal. Based on surface observations, at least 600mm of rainfall has been recorded in areas near Port Edward and Durban over the past 5 days, with over 310mm dumped solely on the 12th, The outer rainbands of Issa are also bringing strong winds (41-62km/h) near the mentioned areas, with a gust of 59km/h recorded in Port Edward at 20:00 SAST.

This rainstorm that started last Friday has caused severe flooding and mudslides. Structures are flooded. Walls and roads collapse due to excess intrusion of rainwater.  At least 59 died, with 45 in Durban. More are still missing. The rainstorm also paralyzed road traffic, water and electric supplies, causing struggles in rescuing operations because only one helicopter is available to lift people out of danger, as local media reported. Hence, the KZN government has called for deploying the South African National Defence Force (SANDF) to facilitate the rescue.

The mayor of EThekwini, Thomas Mxolisi Kaunda, said the disaster management teams are trying their best to rescue communities and save lives and are making effort to resume water and electric supplies as well. He also apologized to those who failed to get through the emergency call centre to the centre “overwhelmed” by the number of calls.

Locals have been posting the aftermath scenes on social media:

More aftermath scenes on Twitter can be found with the hashtag #KZNFloods.

The content on external sites does not represent Force Thirteen’s stance.

Please stay safe for those under the impact of the rainstorm as unstable weather is expected to continue for the next day or two.

The post Subtropical Storm Issa Develops off of South Africa, Associated Flooding Causes Devastation appeared first on Force Thirteen.

CURRENT CONDITIONS

Typhoon In-fa maintained its strength as it barrels towards the Ryukyu Islands. It was last located at 23.4°N 125.7°E or 125 km south of Miyakojima, 155 km southeast of Ishigaki, 430 km east-southeast of Taipei, or 920 km southeast of Shanghai. After the eyewall replacement cycle, In-fa remained to be a Category 2-equivalent typhoon. Force Thirteen analysis has put it at winds of 10-minute winds of 150 kph (1-minute winds of 100 mph) and a minimum central pressure of 950 millibars. Gradual intensification into a Major Hurricane-equivalent Typhoon is still expected. Its movement is stationary.

CURRENT WARNINGS

Japan
Storm (Typhoon) Warning – Miyakojima, Yaeyama excluding Yonaguni
Gale Advisory – rest of Ryukyu islands including Yonaguni.
Daito islands, Kagoshima, Saga, and Nagasaki

Taiwan
Sea Typhoon Warning
Heavy Rain Warnings- Keelung City, Taipei City, New Taipei City, Taoyuan City, Hsinchu City, Hsinchu County, Miaoli County, Taichung City, and Yilan County

China
Blue Typhoon Warning
Coastal Fujian from Fuzhou County northward to coastal Zhejiang south of Hangzhou Bay

Philippines
Tropical Cyclone Wind Signal #1
Batanes, Babuyan Islands
Officials warn the typhoon may bring winds strong enough to knock down houses. Evacuation orders have been issued in the cities of Miyakojima and Ishigaki as well as the town of Taketomi. Officials are advising people in the region to evacuate to strong buildings.

Officials are advising people in the region to evacuate to strong buildings. Other parts of China, including Shanghai, Zhejiang, and Fujian, are braced for the typhoon’s arrival and have warned of days of heavy rain and strong winds, but the particular circumstances that caused the intense rainfall in Zhengzhou are not expected to occur elsewhere.

Typhoon In-fa as well as Tropical Depression Cempaka that’s still inland are pulling the Southwest Monsoon bringing heavy rains toward Eastern Luzon.

FORECAST

Weather models are still expecting large amounts of rain to be dumped by In-fa on the Okinawa Islands, Taiwan, and China with some local areas expected to receive as much as 750 mm of rain (~30 inches.) Winds remain a major threat with gale winds extending for hundreds of kilometers away from the eye.

Latest Force Thirteen forecast cone expect In-fa to regain Major Hurricane-equivalent Typhoon with the second peak reaching 10-minute winds of 180 kph (1-minute winds of 120 mph) as it moves northwest for the next 60 hours. Then it’s expected to move northeast towards South Korea and Japan, still as a typhoon. The forecast cone remained highly uncertain due to the uncertainty on the Subtropical Ridge that’s determining the storm’s movement.

Force Thirteen advises people in East Asia to remain vigilant on the storm’s movement and do measures to mitigate any damage.

The post Typhoon In-fa remains a major threat in East Asia appeared first on Force Thirteen.

Current Storm Information

As of the latest Force Thirteen Analysis (12:00 UTC July 17), Felicia is located at 14.5N 124.3W, with maximum sustain winds of 165mph (265km/h) and a minimum central pressure of 932mb. Felicia is moving WSW at 9mph (15km/h).

Meanwhile, as of the latest NHC update statement at 13:30UTC, Felicia is located at 14.5N 124.3W, with maximum sustain winds of 145mph (230km/h) and a minimum central pressure of 947mb.

Felicia has been going all out in the last few hours. Due to the southwestward movement, it has reached a lower latitude where the sea surface temperature increases from 27C to 28C. Although it’s just 1C, it is a world of difference in terms of energy supply. Given other environmental conditions remain favorable, after maintaining its intensity during sunset, it developed as an annular hurricane with overshooting tops and surface gravity waves, along with a very warm (20C) and dry eye, which such characteristics in cloud tops can only be seen in extreme intensity. In short, that is the reason Force Thirteen has given it a 165mph rating.
Yet it will weaken soon due to decreasing sea surface temperature and the latest microwave imagery shows an eyewall replacement cycle is imminent.

Full forecast discussion from Force Thirteen Cyclone Analysts.

Eye

Felicia is simply enough expressing all the hallmarks of an extremely intense tropical cyclone. The storm has maintained a structure that is actually analogous to past 145kt tropical cyclones, like Hurricane Isabel of 2003, for several hours, along with various other 145kt+ cyclones that would help aid in concluding this storm’s current intensity of 145kts. Further analysis of this storm’s structure finds an eye that is currently perfectly symmetrical, and hovering at around 7-8C below the current sea surface temperature, at 19-20C, which is a deficit only in more intense tropical cyclones because they normally have the lift modes and such to cause such subsidence to clear and maintain it. This system has maintained such an eye for 12+ hours and counting. Little storms have done this with such success.

Central Dense Overcast (CDO) structure

The storm is currently maintaining and improving a full-fledged gravity wave-type CDO structure with several clustered overshooting tops, which can assist the vertical transport of momentum within the atmosphere, and gravity waves can also mean that there is more localized latent heat release in the storms, which more latent heat release signified by these gravity waves would lead to a thermal expansion of the atmospheric column, and deepening of the storm, therefore having a better structure for both rapid deepening and mixing. The storm also had many overshooting tops in the north quadrant during peak, which is another good thing for mixing of stronger winds, signifies a greater depth of stratospheric cooling being achieved through adiabatic lofting and increases the intensity of turbulent mixing across the troposphere, which would assist mass transport across the area of the cloud tops. This also easily implies higher cloud tops, which would signify greater lapse rates and a more intense updraft to help the storm while rapidly intensifying. Such a CDO is really only seen in 145-150kt+ cyclones, and this pattern is fairly analogous to the likes of even Hurricane Irma of 2017. The symmetry and the lack of variability of cloud tops in the -74-75C CDO also highlights the presence of neutral buoyancy which shows an extremely stable and healthy storm. Microwave imagery also showed a full red ring, which along with the fully initiated CDO provides great support for a higher intensity than 140kts, as many systems with 150-155kt+ strength enter an axisymmetric quasi-isentropic mode, which is when lift symmetrizes due to the theta e surface between the eye and eyewall. That would help keep the cloud tops of similar temperatures, with more uniformity, once again due to the theta e difference between the lower theta e eye, and higher theta e eyewall. This all allows idealized isentropic lift which is something many 150kt-155kt+ cyclones exhibit due to their maturity.

Microwave and Water Vapour Analysis

This also relates to MW symmetry because of even stronger updrafts throughout the entire eyewall, which would scatter ice to around the same temperatures. The storm is also currently exhibiting an azimuthal arch in its northwest quadrant, which as of lately, hasn’t been seen in any cyclones at all below 150kt intensity, which helps boost the intensity. Water vapor imagery has also revealed likely extreme intensification with a rapidly drying eye, drying to around -15C, which is also only seen in more intense tropical cyclones. Although the intensity correlation spread is somewhat large, once again -15C and below hasn’t been seen in storms below 145kts. The storm is also expanding its CDO actually, which isn’t in the form of an eyewall replacement cycle due to microwave imagery confirming a singular eyewall. Many structural regimes of 150kt+ cyclones show great similarities to Felicia, and the intensity is adjusted as such. Taking into account the satellite presentation and the fact that many 145-150kt+ systems have exhibited structural similarities to Felicia, leading to the fix of 145kts at this time.

To summarize, the sheer impressiveness of this structure, signs showing that it’s not near finished yet, analogs and correlations contribute to the storm’s 145kt strength.

The reasoning behind the official estimates

The NHC, as an official meteorological agency, has to follow protocol. Without direct observations from reconnaissance plane, surface, or radar observations, the  Subjective and Objective Dvorak Technique are their only tools for intensity estimates. The latest Dvorak estimate from the Satellite Analysis Branch (SAB) and Tropical Analysis and Forecast Branch (TAFB) has estimated a Final-T number of 6.0 (WMG eye surrounded by B embedded by LG) and 6.5 (WMG eye embedded by B), respectively. Though they also notice the annular structure and an eye with significant stadium effect, which both factors may lead to a higher intensity.

The ineffectiveness of the Dvorak Technique in this specific case

Dvorak Technique, invented in 1984, is considered to be one of the most effective estimation methods by infrared enhanced satellite imagery. It has been extensively using in all meteorological agencies. But why it is considered to be less effective in this case?
The first reason is the overall size. Felicia is a very tiny storm with a CDO of only around 90km in radius. However, step 2C in the Dvorak Technique has stated that the ring of B and W spectrum (representing -63 to -69, -69 to -75C cloud tops respectively)  to be at least 0.5 degrees wide (around 55km) to be classified as the eye number. Given that, such a small system is hard to generate such a cold ring that matches the threshold thickness to be considered as the eye number, only the warmer ring, light gray (-53-63C cloud tops) can be counted, which resulted in a lower estimate from Dvorak by SAB and TAFB.
The second reason is the low tropopause height and annular characteristics which resulted in generally warmer cloud tops but a higher intensity in actuality. The coldest temperature in the tropopause is estimated to be around -73C, which means -73C is more or less the limit of the cloud tops and falls under just the W category in Dvorak. So, it is hard for Felicia to generate thick enough overshooting tops and maintain it as a T7.0, which resulted in the underestimation from Dvorak. What is more, Felicia has exhibited annular characteristics, which in most past cases like Felicia’s structure, even with warmer cloud tops overall and surface gravity waves, recon found significantly higher winds than what Dvorak Technique estimated, which Felicia probably is not an exception. Hence from the above two reasons, it’s highly likely that Felicia is being underestimated by the Dvorak Technique which is the main tool that the NHC uses.

The post Felicia a Category 5 by Force Thirteen Analysis – Is it being underestimated? appeared first on Force Thirteen.

Current Storm Information

As of the latest Force Thirteen Analysis (09:00UTC), Felicia is located at 15.1N 120.9W, with maximum sustained winds of 115mph and a pressure of 965mb, and is moving west at 9mph.

Similar to the National Hurricane Center (NHC) advisory 9, Felicia is located at 15.1N 121.0W, with winds of 115mph and a pressure of 968mb, moving west a 9mph.

Felicia has produced a well-established CDO with a complete -70C ring and is clearing its eye. Instant Dvorak Technique estimates yielded a Data-T number of 6.0 (off-white eye surrounded by white embedded by black cloud ring). Conditions remain moderately favourable with ~28C sea surface temperatures and low vertical wind shear, but mid-level relative humidity is not as favourable and is also declining over time. Also, Felicia is a small-sized storm, wherein a small tropical cyclone is vulnerable to slight atmospheric environmental changes. It is expected to peak within the next few hours before weakening occurs as the environment becomes too dry and stable for Felicia to maintain intensity.

Developmental Process

It started as a tropical wave on 12/7 as invest 96E and developed substantially, becoming a tropical cyclone in just two days. Under a rather moist environment in the inter-tropical convergence zone (ITCZ), along with a rare but favourable upper-level environmental and moderate easterly wind shear setup, it significantly intensified with excellent upshear convection. A cold comma was observed at midnight, which indicated a rapid development. The whole rapid intensification process didn’t go very smoothly, however, with occasional dry air intrusion at the western quadrant. According to the NHC, Felicia underwent an eyewall replacement cycle yesterday, though such a view is not really supported firmly by satellite appearance. The only microwave imagery at 15:12UTC 15/7 from METOP-B showed no concentric eyewall, but only a developing eyewall with a fracture at the western side due to the aforementioned dry air intrusion. A later pass at 20:55UTC from AMSR2 showed a healthy, tiny but solid, symmetric eyewall. The tininess of eyewall doesn’t support NHC’s claim as well as an eyewall replacement cycle means an expansion in size. Visible imagery also didn’t show a moat (a gap between concentric eyewalls) as well. 

Microwave showed that Felicia is tiny, but the structure remains mature and symmetric, which is especially reflected by AMSR2 microwave imagery. Throughout the day, it has been trying its best, wrapping convection from the eastern and southern quadrant to solidify its core gradually as an infrared eye popped out yesterday.

Track Forecast

There is a good consensus in terms of track forecast. Felicia is expected to move westward under the influence of the gigantic subtropical Pacific high-pressure area, while the peak is expected to occur after ~6 hours as a hurricane with winds of 125mph. After that, as it approaches a pool of dry air north of the ITCZ, along with declining sea surface temperatures. These factors are expected to cause it to weaken gradually, down to a tropical storm after day 4. From the forecast track, it will remain over the open Eastern Pacific, so no land areas are expected to get any impact from Felicia.

Elsewhere in the tropics, there’re also 97E, 99L, 09W (FabianPH), and 99W. Invest 97E follows behind Felicia with a high chance of formation. Invest 99L is dying off in the subtropical Atlantic. Invest 09W has been designated and is expected to become a significant typhoon that strikes the Japanese Islands and China. Last but not least, invest 99W in the South China Sea is expected to have slight development with a low chance of formation.

The post Felicia Significantly Intensifies and Becomes a Major Hurricane Over the Open Ocean. appeared first on Force Thirteen.

Click the link below to join our livestream with the latest information, surface reports, and storm analysis provided!

Elsa has been steadily developing despite moderate wind shear with some dry air. The partial eyewall is attempting to wrap with downshear convection. From the AF302 reconnaissance plane, at the strongest northeastern quadrant, it has found flight level (850mb) winds of 73kts with Stepped Frequency Microwave Radiometer (SFMR) of 61kts, which blended them yields a max sustained winds of 60kts, with a minimum central pressure of 998mb by a center dropsonde at 18:23 UTC with the pressure of 1000mb and 28kts winds at the surface.
Moreover, it should also note that dropsonde indicated a continuous intensification trend with a Y-shape temperature and dew point temperature pattern as it drops, so as a 5C temperature spike at the center, which reflected that further intensification is possible. The National Hurricane Center agrees that development will continue up to Florida landfall with an expected peak of 75mph, which is a low-end category 1 hurricane.

Please stay indoors and away from the coast. Evacuate to shelters at higher elevation immediately if needed. The strongest winds and rain from Elsa are expected to arrive within 12 hours. Stay safe.

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Current Storm Information

As of 02:00 am PHT June 4th, 2021, by F13 latest fix, Choi-Wan is located at 19.3°N 118.5°E, with 1-minute sustain winds of 40mph (65kph) and a minimum central pressure of 999mb.

At the same time, according to the latest ATCF, Choi-Wan is located at 19.5°N 118.5°E, with 1-minute sustain winds of 40mph (65kph) and a minimum central pressure of 997mb.

After leaving the Philippines, the convection reorganized and the center was partially covered by convection again as Choi-Wan is free from land interaction. ASCAT at around 21:00PHT found 40kts winds in the main central convection at the southwest.
In recent imagery, the size of the convection near the center has shrunk significantly although it still successfully generated some central convection as the time approached diurnal maximum (DMAX). The increasing wind shear is because the South Asian high-pressure area, centered at around 25N 110E, is providing at least 25kts of wind shear. In addition, its northward movement is pointing opposite to the northerly shear direction which further increases the effective wind shear. Moreover, due to high wind shear, the convection weakened even though the time approaches the DMAX.

Current Warnings

The Philippines: all warnings have been lifted.
Although all warnings have been canceled, sometimes strong gust and swells may still affect northern Luzon. Please stay away from the coast and avoid water activities as the sea is still rather turbulent. Potential threats after flash flooding still exist, so please stay alert outside as well.

Taiwan: Sea and Land Typhoon Warnings are in effect.
Sea warning areas: Bashi Channel, Pratas, Southeast Taiwan offshore, and Southern Taiwan Strait.
Land warning areas: Hengchun Peninsula, Pingtung County, and Taitung County.
Due to the outer bands of Choi-Wan, there will be stronger winds and waves in Southern Taiwan Strait, Eastern Taiwan offshore, and Bashi Channel today (June 4th).
There will also be stronger winds and swells in coastal areas such as the Hengchun Peninsula, the Southern part of Taiwan (including Lanyu, Green Island), Kinmen, and Matsu Islands. Please stay away from the coast and stop all water activities due to the turbulent sea.
Because of the subsidence current outside Choi-Wan, Taitung and Hualien may suffer from very hot weather (36°C) during daytime today.

Developmental Process Before Leaving the Philippines

The precursor of Choi-Wan, 99W first formed on May 26 and rapidly organized itself in the next three days. It quickly developed into tropical storm 04W on the 29th under a very favorable, low wind shear environment. By our analysis, it peaked at 50mph on the 30th as the wind shear magnitude was still on its side.

Nevertheless, the favorable environment ended on the 31st as wind shear skyrocketed due to the formation of the tropical upper tropospheric trough (TUTT) at the north. Hence the convection was heavily lopsided to the southwest, with the center partially exposed. Choi-Wan approached the Philippines as it had moved west-northwest generally since its formation until landfall. The table below listed the landfalls Choi-Wan has made in the Philippines. Due to land interaction, it kept moving westward and recurved northward in the South China Sea, making the track forecast of HWRF accurate.

Impact on the Philippines

Because of the very intense convection at the southwest quadrant, Choi-Wan brought a significant impact on the Philippines. Mudflow and extensive flash flooding are reported. Over 200mm of rainfall was recorded on the Visayas and Mindoro. 8 people died and 15 are missing during the storm, with over 45,000 people being affected and 3,000 people being displaced, in which 600 of them moved to evacuation centers. The Philippines coast guard is still conducting rescue missions in the Eastern Visayas and Mindanao to search for the missing. All three named storms so far (Dujuan, Surigae, Choi-Wan) have affected the Philippines and all have left considerable impacts on the Philippines to cleanup.

Forecast Track

Choi-Wan is going to meet its end soon as the conditions are deteriorating overall. Models agree that the shear will have a temporary drop as it makes its closest approaches towards the South Asian high-pressure area and the main convection of the Meiyu front in Guangdong. Yet afterward, the sea surface temperature will slide down rapidly, and wind shear will skyrocket as Choi-Wan moves to higher latitude and meet the subtropical jet after moving past Southern Taiwan. Local meteorological agencies in the West Pacific also have a consensus that Choi-Wan will degenerate to below tropical depression status after two days as it merges with the Meiyu front and the subtropical jet.

Elsewhere in the tropics, all three systems suffer from high wind shear. Tropical storm Blanca in the East Pacific has weakened into a tropical depression as the low-level center becomes exposed. Invest 90W east of the Philippines and 93S east of Cocos Islands are near its dissipation.

Please stay tuned to the latest Force Thirteen storm updates on our social media platforms. Stay safe.

Sources:
https://twitter.com/earthshakerph/status/1400424056264871939?s=20

https://www.washingtonpost.com/world/storm-leaves-3-dead-displaces-hundreds-in-philippines/2021/06/02/06953578-c37e-11eb-89a4-b7ae22aa193e_story.html

http://www.xinhuanet.com/english/asiapacific/2021-06/03/c_139987247.htm

https://www.cwb.gov.tw/V8/C/P/Typhoon/TY_WARN.html

http://floodlist.com/asia/philippines-storm-choi-wan-dante-june-2021

The post Choi-Wan Remains as a Tropical Storm, approaching Taiwan while leaving the Philippines. appeared first on Force Thirteen.

Current Storm Information

As of 18:00UTC (23:30IST), Force Thirteen has located Yaas at 20.3°N 87.7°E, with 1-minute sustained winds of 85mph (140km/h) and a pressure of 962mb, moving NW at 10mph (16km/h).

At the same time, the latest ATCF has Yaas as a category 1 cyclone in the SSHS. ATCF located it at 20.3°N 87.8°E, with winds of 75mph (120kph), and a pressure of 974mb.

While at 15:00UTC (20:30IST), according to the latest estimates from Indian Meteorological Department (IMD), they have Yaas located at 19.5°N 88.0°E, with 3-minute sustained winds of 120km/h (Very Severe Cyclonic Storm) and pressure of 974mb, and is moving NNW at 15km/h.

Developmental Process

Yaas started as a large monsoon low that lacked organization, yet as models expected, tropical cyclogenesis underwent quickly and a well-defined circulation developed. However, as Yaas contracted and lost monsoonal characteristics as it developed under 31°C of the sea surface temperature, it became more prone to wind shear, thus the convection has been lopsided to the southwest, with the southern quadrant being the strongest. Though the infrared appearance has been quite poor due to 25kts of wind shear, observations by especially microwave imagery and Kolkata Buoy (17.9°N 89.2°E) have revealed that Yaas, instead of holding intensity, has been improving constantly still. From 36GHz-H AMSR2 Microwave imagery at 07:12UTC, it showed a rather solid lower-level core. In addition, with the aid of Kolkata Buoy pressure data, it showed that the central pressure of Yaas has been decreasing at a rate of roughly a millibar per hour, as it recorded a minimum pressure of 976mb at 05:30IST.

In recent hours, as Yaas has entered the range of Paradip radar, a rapidly developing eyewall is also observed with a Doppler radial velocity of at least 38m/s at 350m elevation. Radar also reflects that Yaas is attempting to repair the eastern side that suffered from high wind shear earlier. What is more, a very strong hot tower firing upshear with cloud tops temperature near -90°C signifies more intensification as it approaches closer to an upper-level anticyclone (ULAC) where shear weakens. The latest (17:30IST) Subjective Dvorak estimate by IMD also concluded a final T number of 4.0 (65kts) with an increasing trend, as well as a likeliness of some underestimation as surface pressure observation from Kolkata Buoy and microwave may indicate higher winds than what Dvorak Technique suggests. The isobar map of Hong Kong Observatory indicated a radius of closed isobar of at least 900km, not to mention the average gale wind radius of around 300km derived by ASCAT, which showed the huge influence of Yaas due to its monsoonal nature. The increasing intensification trend is triggered by two factors. The first one is because of weakening wind shear to 20kts, as well as improving the upper-level divergence, and the second one is because the frictional convergence starts to induce more convection as it is off the coast of Odisha, such that more convection favors intensification near land.

Current surface reports

Many sources have reported a turbulent sea with waves over 1m brushing the coastline. The wave height will increase exponentially as Yaas continues approaching. In West Bengal least 40 houses were damaged in Halisahar and Chuchura respectively, with 5 people injured. Two unfortunately died due to lightning strikes in Chinsurah that come from a rare damaging tornado there.

Current Warnings, Preparations Done.

To start with, the Chief Minister of Odisha, Naveen Patnaik urged the residents of coastal regions to cooperate with local administration and shift to cyclone shelters, as well as maintain the COVID-19 protocols and wear masks. So far at least 300,000 residents in Odisha have been deployed, as well as fishermen and ships have also been taken to shelters due to strong waves and the water level rise due to torrential rain, storm surge, and tidal waves.

India’s navy and air force are also on standby to effectuate the relief and rescue work, along with 149 teams deployed by the National Disaster Response Force (NDRF) in 5 states, mostly to West Bengal and Odisha, with a total of 99 teams on the ground. Apart from institutional teams posited under high alert of Yaas, Municipal Corporation in Calcutta and Bidhannagar has deployed teams comprising personnel from civic bodies, police, and the power utility to utilize the efficiency of the preparation and the relief work such as restoring power, removing fallen trees.

Here are the summarized reminders when a storm approaches:
1. Please stay in a reasonably protected place indoors. Evacuate from the coast as urged. STOP all water and fishing activities due to the turbulent sea.
2. Do NOT stand beside trees, power lines, and exposed windows as they will easily fall and break which imposes life-threatening danger. Stay in the interior of the room. Beware of flying debris.
3. Storm surge up to 4m and heavy rainfall will cause serious flooding in low-lying areas especially near the delta region. Evacuate to higher indoor places.
4. If the eye directly passes above you, the winds and rain will be calm for some time. However, do NOT be caught off guard, as the strongest winds and rain from the backside of the vortex will suddenly blow from another direction.
5. After the passage of the storm, the possibility of danger will continue. Please remain alert for your safety.

Forecast Track

As a consequence of continuously improving environments such as weakening shear, better divergence, and frictional convergence, it is forecast to keep strengthening all the way until landfall after 6 to 12 hours. Therefore, Force Thirteen has forecast a 90mph peak and make landfall at peak. To reiterate, the projected landfall location is between Bhadrak and Contai, Odisha region, with a high consensus of model support. The landfalling regions are expected to suffer winds up to 180km/h and at least 400mm of rainfall, along with a storm surge of around 4 meters, while the area within a 300km radius from its center will also suffer from at least 100mm of rainfall and destructive gale or storm force winds.
After Yaas make landfall, land interaction will cause significant weakening and the system is expected to dissipate over the next two days. Nevertheless, rainfall threat from the remnants of Yaas is expected to persist until the end of May.

Please finish your preparations now as the storm is arriving within 12 hours. Stay tuned to official warnings and advisories, as well as Force Thirteen videos, and graphical and live updates on our Twitter. Stay safe.

Sources:

https://mausam.imd.gov.in/imd_latest/contents/cyclone.php#.

https://www.hindustantimes.com/cities/kolkata-news/two-electrocuted-40-houses-partly-damaged-in-tornado-ahead-of-yaas-mamata-101621951493381.html

https://www.telegraphindia.com/west-bengal/calcutta/how-calcutta-is-preparing-for-cyclone-yaas/cid/1816654

https://opinionexpress.in/odisha-cm-urges-people-on-coasts-to-shift-to-cyclone-shelters

https://timesofindia.indiatimes.com/city/kolkata/cyclone-yaas-live-updates-yaas-intensifies-into-cyclonic-storm/liveblog/82873733.cms

https://www.financialexpress.com/lifestyle/science/yaas-cyclone-yaas-live-updates-cyclone-yaas-live-may-25-odisha-paradip-balasore-puru-bhubaneswar-west-bengal-kolkata-sagar-island-imd-cyclone-weather-live/2257981/

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Current Storm Information

As of 12:00UTC (16:00 MUT) March 10th, according to the estimates by Meteo France La Reunion (MFR), Habana locates at 17.4S 76.2E, with maximum 10-minute sustain winds of 205 km/h and gusts up to 285 km/h, as well as a minimum central pressure of 940mb, moving west at 11 km/h.

In unison, the latest Joint Typhoon Warning Center analysis has put Habana to a category 4 status, with 1-minute sustained winds of 155 mph (250 km/h) and a pressure of 928mb. Habana locates at 17.5S 76.1E, moving west at 7mph (11kph).

At 15:00UTC (19:00 MUT) Force Thirteen analysis thinks it is a high-end category 4 with a 1-minute sustain of 155 mph (250 km/h) and a pressure of 926mb. Habana locates at 17.4S 75.8E and currently moving west at 7mph (11 km/h). Analysis fixes 3 hours before made by Force Thirteen thinks Habana peaked as a category 5 cyclone with winds of 160mph (255 km/h) and a pressure of 924mb.

When Habana was making a U-turn from east to west in the last 1-3 days, Habana struggled with dry air intrusion such that it gradually weakened from category 4 to a category 1 cyclone in 2 days, then bottomed at 75mph. Yesterday, with mid-level relative humidity increased to more than 50% again, Habana bottomed out and rapidly intensified for the second time from a minimal category 1 cyclone to a 155-160mph borderline category 5 storm in a day. At peak intensity, it showed a near-perfect central dense overcast (CDO) that is axisymmetric and smooth, with -75 to -80C cloud tops surrounded the eye that has near +20C, completely, which showed its impressiveness of the structure. Despite a marvellous appearance in the infrared imagery, microwave imagery data from polar satellites reflected that something is hindering Habana to go further. A pass from AMSR2 at 08:19UTC (March 10th) indicated signs of an eyewall replacement cycle, as at the low-level, concentric eyewalls are observed. Another scan from SSMIS F-16 at 11:38UTC also suggested it. Soon after the peak, its CDO started to wobble, showing some fractures in it, indicating an eyewall replacement cycle has begun and intensity starts to go downward. What’s more, in the process, it’s likely that Habana is developing annular characteristics based on current satellite appearance.

Forecast Track

It is expected to weaken a bit as the eyewall replacement cycle is currently in progress. After that, its intensity will climb up again, and make another peak for its intensity curve, with a recovered core. Note that in an eyewall replacement cycle, the uncertainty of where Habana will bottom is high. In general, storms undergoing an eyewall replacement cycle weaken by at least 1 category. While it is making a gradual southward turn in the next few days as remnants of Iman created a fracture between two subtropical high ridges southeast of the southern part of Africa and northwest of Australia, Habana is prognosticated to weaken after peaking in the next 2 days due to increasing wind shear and decreasing ocean heat content. Later on, as the fracture closed, models forecast that Habana will move west again, before another extratropical cyclone creating another fracture to the subtropical high ridge, bringing Habana to the mid-latitudes and ending its journey.

Elsewhere in the tropics, invest 92W is at the south of the Philippines with a low chance of formation. An area of interest northeast of Madagascar might develop in the future.

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The post Habana Explodes Yet Again with a Higher Intensity, Expected to Remain Intense. appeared first on Force Thirteen.