Round 2 – two new waves that have Tropical Cyclone potential (next 6 days)

While I was focused primarily on yesterday’s storm, the 1200 UTC forecast also showed that two potential storms would emerge this week.

Potential TC #1

The first is a wave that could move quickly across the Atlantic and impact the Caribbean next week. The global models have all picked up on this feature and the hurricane center gives is an 80% chance of TC formation over next 5 days.

NHC Tropical Weather Outlook for Tuesday September 8
850 hPa Vorticity based on September 7 (yesterday) 1200 UTC forecast.

The WRF model shows the system off the coast of West Africa Thursday at 0000 UTC. The sea level press is expected to decrease over time as the storm organizes itself on September 12. It is a fast mover that is for sure. We will follow it with tomorrow’s forecast.

WRF Sea Level pressure forecast based on Sept 7 1200 UTC

Potential TC #2

The second system is less discernable in the early part of the week and will initiate from a low amplitude AEW in low latitudes. It will gain latitude and finally is off the coast of Senegal on September 12 before passing onward into Cabo Verde. This is not that different from the system that produced Tropical Storm Rene and needs close watching. The potential to bring additional heavy rain to Senegal has me worried about the upcoming weekend.

WRF 7 day rain forecasts

Once again, the African Easterly Jet is expected to provide energy and spin to the system that may form off the coast on Friday. Let’s see what tomorrow’s forecasts say.

WRF forecast 700 AEJ based on 07 September 1200 UTC forecast

The potential for active and potentially dangerous disturbance for coastal West Africa and Cabo Verde remains high. Stay vigilant!!

Cabo Verde to begin feeling impacts of Tropical Depression 18 in next few hours

In the next few hours, Cabo Verde will begin to experience the effects of Tropical Depression 18. This is earlier than expected based on earlier forecasts. The Islands of Boa Vista and Sal should expect heavy rains and winds that may reach tropical storm force values. It is likely that the entire country will see heavy rain from this storm and that the northern islands could be impacted the worst at this time.

0600 UTC Early Track Guidance

The Early Track guidance suggests that the center of the storm will come closest to Boa Vista this afternoon and then tonight will move very close to Sao Nicolau, Sao Vicente, and Santo Antao. TD-18 will continue to strengthen as it cuts through the country and is likely to be a tropical storm when it reaches Boa Vista, Sal, Sao Nicolau, Sao Vicente and Santo Antao.

WRF 0000 SEPT 7 Output Analyses

The WRF simulation from last night provides some insight of what is possible over the next 18 hours

Initial Rains

The model suggest that the first rains will reach Sal and Boa Vista around 2000 UTC tonight. Satellite observations show that the first bands may arrive in the next few hours. I expect that when the main center arrives that the rain will be pretty heavy and extend southward to Santiago.

WRF Sea Level and simulated Maximum Reflectivity based on 0000 UTC forecast

Sea Level Pressure

WRF Sea Level Pressure forecasts based on 0000 UTC initialization

Based on the WRF forecast, the low will pass close to Boa Vista and Sal with tropical storm winds likely based on the latest NHC projection. During the night the low may pass over Sao Nicolau and then Sao Vicente and San Antao before continuing out to sea tomorrow afternoon. Because there are some high mountains, winds speeds and rains in these areas are likely to be enhanced.

Surface Wind Speeds.

WRF Surface winds speed based on 0000 UTC WRF run

Surface Winds speeds are likely to increase during the day as the storm deepens. Tropical Storm force winds can be expected over most of the Northern Islands, however these winds could be reached when rain bands pass by any part of the country.

WRF Rainfall Totals

Rainfall will be heaviest over the Eastern part of Cabo Verde tonight and then shift to Western Cabo Verde overnight. The 48 hour totals could reach 100-200 mm and could be higher in elevated regions. The rain will be intense when it does occur.

WRF rainfall totals for Monday September 7
WRF Rainfall Totals for Tuesday 8 September
WRF 48 Hour rainfall based on 0000 UTC September 7

Key Takeaways

  1. Make Final preparation for the storm now!! Charge your phones, fill your cars with gas and finish food shopping now. Touch based with loved ones before nightfall to make sure they are in good shape. Expect first rains in Sal, Boa Vista next few hours and poor conditions in about 5 hours.
  2. Heavy rains could produce flash flooding, so be ready to move quickly if required to safety. Mountainous regions of Santiago, San Nicolau, Sao Vicente and Santo Antao are vulnerable to flash flooding tonight and tomorrow morning.
  3. If you live near coastal zones, you will likely get some coastal flooding even for Islands to the south as a south fetch may produce heavy rains.
  4. Some storm surge is expected Sao Nicolau, Sao Vicente and Santo Antao, if the storm passes the the south of these islands and even in the eastern parts of the islands based on the wind direction.
  5. Please tune in to your local station to determine what is being done to protect people on your island and also know if there are local shelters.
  6. Please pay attention to fallen trees and down electric power lines and wait until daylight tomorrow to assess the situation. Do not go out into the storm please.
  7. Keep a cool head and prepare!!

Below are images from National Hurricane Center (1500 UTC)

NHC time of arrival for TD-18
Key Message in Spanish… Close to Portuguese but not exactly…..

OMG! the Tropical Disturbance is organizing, flooding possibility in Senegal today..Cabo Verde you up next!

When I woke up this morning, I did not expect to see an organized tropical disturbance, with clear cyclonic flow and banding. The last time that I saw this type of organization for such a large system was 2006, when TD-8 formed off the coast of Senegal during the NASA African Monsoon Multidisciplinary Analysis (NAMMA) campaign. However, that system was further south and many hundreds of miles more out to sea.

The global models are still not developing this system into a tropical cyclone near the coast, but I would say that the satellite observations should be enough to see the potential development. Ocean temperatures are above the threshold needed for tropical development (26 C) to occur and warm temperatures extend westward across the Atlantic to the United States.

Sea Surface Temperatures for the last week.

The latest Sea Surface Temperature anomalies show that waters off the coast of Senegal are 1 Degree C- 1.8 F) above normal which may provide additional energy for the storm to develop.

NOAA Sea Surface Temperature anomalies as of September 4

Key Takeaways

  • The tropical disturbance is organizing and is larger than suggested in model simulations. Over the next few hours, I feel that this will be an Invest and additional high-resolution hurricane models will focus on the system. For real-time images you can go to CIMSS http://tropic.ssec.wisc.edu/# as they are now following the system, just click on the invest (I).
  • Senegal
    • expect additional bands of heavy rain, today until the system moves away. Please careful for flash flooding and standing water on the roads.
    • A strong fetch from the south will occur over the next day and coastal flooding may become a real-possibility to many fishing communities and Dakar.
    • Pay attention to the national meteorological services, local TV, and Radio broadcast on weather conditions. If possible report your conditions via social media. Check-in with Raid on facebook at: La Météo Dakaroise de Riad
  • Cabo Verde– You should prepare for:
    • several days of rain and wind, with the possibility of tropical-storm-force winds on some of the islands.
    • The seas will be rough and coastal flooding is also possible. Fishermen should be careful.
    • In areas that are flood-prone or have steep hills also prepare for possible flash flooding especially tomorrow and Tuesday. This includes the city of Praia where the houses tend to sit on steep hills.
Homes in Praia Cabo Verde

Until later… Stay safe and will update this evening……

Flooding across Senegal tonight, possible tropical development increasing for Cabo Verde

An infrared satellite view from EUMETSAT at 0200 UTC (10 PM) shows deep convection indicating that heavy rain is falling across Senegal, likely creating life-threatening flooding in some regions. Rainfall estimates from UIUC show that a 100 mm or (4 inches of rain) have fallen in some parts of Senegal.

CHRS Irain product September 5, 2020

The heavy rain is tied to a tropical disturbance that is expected to develop over the next few days and move across Cabo Verde.

Global Forecast models have had a time determining the strength of a possible disturbance, however they all agree that some type of disturbance is going to pass across Cabo Verde.

I have been using the Weather and Research Forecast model in research mode to determine the potential strength and path of the disturbance. Thus far, the model has been consistently developing a tropical storm that passes across Cabo Verde.

Sep 5 1200 UTC forecasts

Intensity and path of the forecasted storm

In the last model forecast from this afternoon, a tropical depression/storm develops but the path is further south and more likely to impact the island Santiago where the capital is located. The system continues to deepen as travels across Cabo Verde as it moves into Westward. For those of you who remember, Hurricane Florence which struck North Carolina took a similar path (not saying that is is likely as the storm has thousands of miles to travel to reach the US)

WRF forecasted Sea level pressure through September 11 at 1200 UTC

The forecast also suggests that much of Cabo Verde will receive winds that could be tropical depression to tropical storm force values especially on September 8. The wind field expands as it moves through Cabo Verde on September 8, with western islands likely to see the strongest winds as the storm deepens.

Heavy rain a major threat to Senegal and Cabo Verde.

Today’s 1200 UTC forecast shows that a large rain field will develop as the storm moves westward.

WRF Sept 5, 1200 UTC simulated maximum radar reflectivity

The heaviest rainfall would first impact Senegal on 5 and 6 September and then Cabo Verde on during the evening of 7 September. The predicted rain amounts would cause significant and widespread flooding if it occurred. The rainfall amounts were very high near Dakar on Saturday 05 September

WRF Forecast September 5 total rainfall (1200 UTC – 2359 UTC)
WRF Forecast Rainfall for September 5
WRF 72 and 96 hour Forecast of Rain amounts in mm

The forecasts suggest that heavy rain will persist in Western Senegal on Sunday September 6 and as the storm moves westward will also produce high rainfall over Cabo Verde. The amounts foreasted in the model are beyond 10 inches for 4 days across Senegal and southern portions of Cabo Verde

Key Take Way Messages

  1. If you live in Senegal, please protect yourself from heavy flooding and seek shelter if your life is threatened. Please be careful driving and do not drive across flooded roads.
  2. Heavy rain is possible in Senegal until the storm pulls away from the coast on Sunday.
  3. While we do not know the degree of the potential storm and its impacts on Cabo Verde, all models indicate that some type of disturbance will make its way across the islands from late Monday through midnight Tuesday and potentially early Wednesday. Better to be prepared.
  4. A developing system that strengthens will pose some level of threat for coastal zones in Cabo Verde but it is still to early to tell the path of the storm or the strength of the winds which might produce surge and strong beach erosion. Fishermen and women will need to pay close attention to the news and the flag systems at local ports.
  5. Low lying and flood prone areas should be identified over the next 36 hours in Cabo Verde.
  6. Stay tuned to your local stations as the forecasts should get better as we get closer to the event.
  7. If a strong storm does come, make sure that you are prepared to deal with potential power outages.
  8. Until next time

Tropical cyclone may impact Cabo Verde ..Flooding possible in Senegal

A serious weather scenario is evolving in Senegal today and potentially over Cabo Verde at the beginning of next week. Unlike the powerful African Easterly Waves (AEWs) that typically pass at this time of year, these waves have been complex over the last week. The AEW that gave Cabo Verde good rain, is now moving towards the west and likely to become a named tropical cyclone in the next few days.

A new way is projected to develop today and will bring potentially heavy rains to Senegal and Guinea Bissau. It will then slowly move out over the Atlantic and deepen on Sunday and parts of Monday before impacting Cabo Verde. The WRF model runs, which are initialized by the US GFS model have been consistently developing what would be a tropical storm to impact Cabo Verde. It also suggest a second tropical cyclone will form later next week.

WRF Sea level pressure and winds based on Friday 1200 UTC forecast

The forecast winds from yesterday’s model run are tropical storm force with the heaviest winds impacting the northern parts of Cabo Verde.

WRF surface winds in Knots based on 1200 UTC Friday Forecast

Heavy Rainfall in Senegal

Since Thursday, the WRF model has been projecting heavy rain over Senegal beginning today through Sunday as the storm develops in the next 24 hours, with the western parts of Senegal receiving significant rains, including Dakar. The rain in Western Senegal is picking up this afternoon.

WRF 72 hour forecast between September 4-7 1200 UTC.

The simulated DBZ values suggest that rainfall amounts could be high through tomorrow noon in Senegal and the Gambia in coastal zone.

WRF Simulated maximum reflectivity values based on 1200 UTC Sep 4 forecast.

Is this Normal??

Typically this is the time of year when ocean temperatures are warmest and develop is possible. However, I feel that the northward position of the African Easterly Jet and its above normal strength is feeding energy (zonal kinetic) to disturbances off the coast of Senegal which would normally only amount to a minor disturbance. This has to be watched over the next 4-6 weeks

African Easterly Jet (blue and purple) based on 1200 UTC Sept 4 at 700 hPa

Key Takeaway:

  1. If you live in Senegal, be prepared for heavy rain tonight and tomorrow
  2. If you live in Cabo Verde…please pay attention to the news.
  3. Stay Tuned… for the next forecast later today.

The calm before possible Heavy Rainfall over Coastal West Africa

For the past day or so, a relatively stagnant pattern has developed near coastal West Africa with a traffic jam of disturbances (they are not moving westward as normal). As of today, weather disturbance over the ocean is expected to merge with the disturbance that just emerged off the coast of West Africa.

WRF Forecasted 850 Vorticity initialized 1 September

The weather system is then to pass over the country of Cabo Verde providing much-needed rain for farmers. However, the air is very unstable and likely to bring heavy rain to Senegal and Guinea Bissau tonight and tomorrow (Last night Senegal saw heavy rain from a Squall-line). This will be followed by another weather system that has the possibility of bringing more heavy rain to coastal West Africa. Some models have suggested that this second system will develop and maybe a tropical depression. At this point, it is still too early to tell but yesterday’s WRF model run forecasts heavy rain in Senegal and Guinea Bissau

3 day WRF forecasted rainfall totals from Sep 1-4, 2020
5 day WRF forecasted rainfall totals from Sep 1-6, 2020
7 day WRF forecasted rainfall totals from Sep 1-8, 2020

The rain is particularly heavy along the coasts on 7,8 September because the surface low exits Senegals and then moves north, missing Cabo Verde. However, today, September 2nd Global forecasts are suggesting that the storm may pass over Cabo Verde. The high-resolution model simulations are still running as of this post. Here is the sea level pressure animation from yesterday.

Main take away point:

  1. Heavy rain over Senegal, Guinea Bissau over the next 5 days
  2. Possible disturbances to impact Cabo Verde tomorrow and Friday and potentially next Monday
  3. Stay tuned

African Easterly Waves are active; potential activity for Cabo Verde over the next 10 days

This morning, when I saw rainfall over Northern Mali, I thought that this is certainly a strange wet season. Southern Mali, yes but northern Mali is the Sahara Desert.

As I mentioned in an earlier blog, the African Easterly Jet is very far north, and based on WRF analysis is generating new disturbances at 10000 feet off the coast of Africa in addition to the normal 3 to 5-day waves the move across all of West Africa. All of this adds up to a busy next few weeks with these disturbances leading to potential tropical cyclone activities

NHC 2 PM Tropical weather Outlook (image: NOAA)

All of this is adding onto the already active Tropical Atlantic. A long-range 14-day WRF forecast (initiated on Saturday Aug 29) shows westward-moving waves at 10000 feet (700 hPa) with 5-6 waves over the 2-week period.

WRF August 29-Sept 12 time-Longitude meridional winds across West Africa

Interesting Forecast for Cabo Verde

As the National Hurricane Center has noted, there is the possibility of an AEW developing once it leaves the coast of Africa in the next few days. The WRF model depicts the system impacting Cabo Verde at the end of the week but it does not look like a very strong storm. We will see.

WRF depicted Sea Level pressure and Max reflectivity (August 29-Sep 3).

The main disturbance that the NHC mentions is likely to combine with a disturbance that is forecast to be off the Coast of Guinea-Bissau tomorrow as depicted by the 850 hPa.

WRF August 29-Sep 12 850 hPa vorticity with cyclonic disturbance being depicted in red.

The model also suggests that the relatively weak disturbance off the coast of Africa gains vorticity (Spin) from the African Easterly Jet (AEJ) to its north. The AEJ remains strong throughout the next 14 days with disturbances being generated to the south of the Jet. There is also strong flow from the Atlantic to feed the waves.

WRF 29 August-12 Sept 700 millbar African Easterly Jet depicted in blue and purple.

An even strong Disturbance in one week exiting Africa (Sep 5-6)

As you may have noticed in the videos, a very strong disturbance at 5000 and 10000 feet develops at the end of the WRF forecast. While this is a long-range projection we need to watch it. The Canadian and ECMWF models are picking up this disturbance in today’s forecast (http://moe.met.fsu.edu/tcgengifs/).

The WRF depicts a tropical cyclone impacting Cabo Verde around the 7th of September. Either way, this next week is going to be active in the Caribbean and Atlantic. Stay prepared.

WRF 29 August-12 September Sea Level Pressure

Climate Change and Racism

A few weeks after the brutal killing of George Floyd, a reporter from the Washington Post contacted me as she was putting together a story on Climate change and Racism. She took a few of the lines that I sent her by email. Here is the full text that was sent. ON JUNE 7, 2020.

“Hi Sarah.  Yes, the situation is very exhausting but I have been very happy to see young people in particular protest to the injustice.  These same young people and their children are going to face a warmer climate, more extremes and disruptions to their daily lives from climate change. “

I teach a Freshman Seminar course called Climate Change, Climate Justice and Frontline communities.  In this course, I discuss how we got here, the role of past injustices and why frontline communities continue to grow. A couple of quick points


1.) Racism is inexorably climate change. This began more than four centuries ago when black people were forcibly removed from the continent to work and die as slaves. Much of the revenue from this free labor went to elevate Europe and the United States and provided the recourses for the industrial revolution.  Even after Slavery was abolished, the removal of resources from Africa, provided the raw materials for the Industrial revolution. For example, rubber, peanut oil and palm oil was needed for the machinery in the 1800s in France, Britain, and other location. Slavery led to chaos in Africa, which human capacity and materials extracted and, ultimately it is the poverty that we see today. The extraction of fossil fuels and other mineral resources in Africa promotes environmental devastation for the people who live near these sites, and often the benefits are not realized by the average person. Ultimately, the extractive process puts more CO2 into the atmosphere.

2.) Communities of color do not have the capacity to offset climate change. The inequity that has been created is realized when we discuss environmental justice, where dumpsites, power plants, highways, and other pollution sources are created without concern or input from communities of color. This situation has worsened under the Trump administration.

3. Globally the future is dim around climate change. When natural disasters such as floods or tropical cyclones strike communities of color, the impacts are longer-lasting, and resilience is questionable because of inequity.  Unless inequity is addressed now, future impacts from climate change will disable many communities of color.

4. The education system has failed people of color. In the geosciences, typically less than 5 % of the field is African American. This inequity is not related to the fact that black students are not interested in geoscience or climate sciences, but there are severe issues of access to higher education. The racism associated with migration in the north or limited funding to public education in the south has destabilized education. Black students from certain locations, such as my neighborhood in Philadelphia, may have limited access to science and math courses needed for college and are unlikely to have role models who can offset these differences. These students need space to develop their ideas and to be inspired. Even if these students making it the university, they are not likely to find black faculty members to support thoughts, goals, and aspirations. Consequently, the pipeline narrows more and more due to racism.

5. Universities in the US and around the world do not provide the necessary knowledge or services needed to support communities that will be impacted by climate change. Critical and important knowledge from university researchers is directed toward journals that may not be able to warn or apply critical knowledge to communities of color in a reasonable time or at a level where impacts can be easily understood.  Furthermore, the current review system of journals and funding makes it more likely that the work of people of color could be rejected or not funded, potentially removing important knowledge from the discipline.

6. There are no historically black colleges or universities (HBCUs) in the united states that have a climate science program.  HBCUs provide a nurturing environment for young scholars to thrive without dealing with the inherent racism in many pubic institutions.  HBCUs have the possibility of understanding how black communities will be impacted because of vested interest. The research undertaken by these departments or programs, if they existed, would likely have a different focus on climate sciences. They would need to focus on the physical and human dimensions of climate change. If this trend continues to exist, the efforts will be left to individual scientists or pubic institutions that may not have a vested interest in the community outside of publications and funding opportunities.  

7. Globally, there are large disparities in the observations of the environment. My work focuses on West Africa, and at present, we do not have enough ground observations to determine trends linked to climate change, coastlines are not monitored to understand rising sea levels, air pollution levels are not known, impacts from flooding or heat waves are known. Ultimately, we cannot protect vulnerable populations in Africa or its diaspora from the hazards of today or tomorrow.  

All Black Lives Matter.  

Police Justice, Climate Justice, and Hurricane Laura – The perfect storm

It feels like the movie called “The Perfect Storm” because many things are happening at once: Hurricane Laura,  COVID-19, the opening of universities, the RNC after the DNC, and finally the vicious shooting of Jacob Blake.  I don’t know how any sane person can stay focused on anything like work or even writing a blog.  I just pray that God and the ancestors will not allow this situation to persist and will protect the innocent because the police don’t seem to be able to deal with that responsibility.

Hurricane Laura, Wednesday Evening, August 26, 2020.

Since Hurricane Mitch and Georges back in the day, every time I see an eye like the one associated with Hurricane Laura  I feel fear for the people on the ground.  This fear has only increased since Katrina but new named Storms come to the surface of my mind, like Matthew, Michael, Dorian, Maria, Harvey, and Irma.  While I know that we can’t control a hurricane, but we may be influencing it through the burning of fossil fuels leading to warmer ocean temperatures –the fuel of hurricanes.  For people of color, this is another series of threats that many have faced their entire lifetime from systemic racism, harassment, job security, educational access, and police violence.  

This storm is different, because of COVID-19.  Many have mentally and emotionally struggled over the last 6 months, but with this impending storm, a new struggle emerges.  Shelters must take in fewer people because of COVID-19 while power, transportation, and communication will be impacted and the money required to recover will be hard to come by for many because so many people are not working.  Will the government help and not play politics?  Nature through the Coronavirus, a warming Climate and now Hurricane Laura is trying to get our attention.  

Uncertainty about the impacts of climate change, Hurricane Laura, COVID-19, and the police violence toward black people make for “the Perfect Storm”  on August 26, 2020– what I fear is that a new  “Perfect Storm” sits on tomorrow’s horizon for us, our children, grandchildren, and great-grandchildren.