Next 10-day outlook. (4/26/2024)
2024 Atlantic hurricane season April P
No tropical activity over the next 10 days.
2024 Atlantic hurricane season April Prediction
Main Points:
- Active to very active season is expected
- Weak to Moderate La-Nina expected to develop by the end of Summer.
- Very warm Atlantic ocean
- Warmest heat anomalies concentrated in the tropical Atlantic and off the west coast of Africa/Europe.
- A -pmm & negative PDO
- This could be a high Ace type of season depending on steering patterns. Do we get stronger Bermuda/Azore high or not? Leaning to a mix.
- Atmospheric patterns over the Atlantic that would usually lead to a cool down are being short lived. Saharan dust out breaks so far have been weak
- Active ITCZ already but no tropical waves as of yet. But activity is ahead of schedule.
- Watching what the QBO does, its currently in the western phase but descending . ( a possible saving grace from the overly hyper-active seasons?)
- Watching how solar activity impacts the season. It has been hypothesised that increased solar activity = a more balanced atmosphere
General statement:
Hurricane season runs from June 1st to November 30th, over the past 5 years 4 of them look to be La-Nina with only one year of EL-Nino. This aligns with several recent studies showing that with our warming climate La-Nina is going to increase in occurrence not el-nino. This season looks very favorable for tropical activity over the Atlantic and unlike last year the western Caribbean looks open for business and unlike many of the previous seasons there is no warm pool off the NE United states/Canadian maritimes which has decreased stability effects over the MDR. This likely increases the threat to the eastern Caribbean from Cabo verde Hurricanes.
Seasonal Outlook.
Current SST and atmospheric conditions that are being watched
Current SSTs discussion. In the Pacific. We have the ENSO going from Postive ( El-Nino) to neutral. We have a – PDO and variable pmm moving towards negative all favorable for Atlantic activity. In the Indian ocean, the IOD is positive. In the Atlantic, the classic horseshoe shape for the SSTS currently exist with the highest heat anomalies concentrated in the MDR and cooler ssts being off the east coast of the USA in the Sub-tropical Atlantic. I am waiting to see how warm those anomalies get off of Canada. If these get warmer anomalies we could see a weaker ridge and more MDR activity going out to sea.
SSTS and what they look to do.
Pacific Ocean
- ENSO: In the 3.4 region that is generally used for identifying the ENSO state ( La Nina vs El-Nino). It has been dropping since the beginning of April. Many models are aggressive with the transition to La-Nina by June, some though are more conservative such as the ECMWF. Years such as 1933, 1995, 2005 and 2017 where all years with a cool neutral or weak La-Nina during peak season.
2. Pacific Decadal Oscillation also impacts the Atlantic hurricane season. If its in the same phase as the ENSO it can enhance the El-Nino if the PDO is positive or enhance La-Nina when its negative. If the PDO is opposite of the ENSO it can lower the influence of the ENSO depending on the strength. Usually the PDO aligns with the ENSO when the ENSO is strongly positive or negative. The negative PDO is linked to increased hurricane activity over the Atlantic and is also known to shift storms further west before they turn north increasing the threat to the eastern Caribbean and Bahamas. The PDO is negative and is expected to remain negative throughout the season.
3. The area between 10n and 20N called the Main development region or ( MDR) as this is where tropical waves tend to develop into systems. Some say this is from the west coast of Africa to the Lesser Antilles, the others classify the entire Caribbean basin is included in the MDR. I treat them separately. This area is currently well above normal. The Caribbean area is above normal. The areas east of the Lesser Antilles all models show above average sea surface temperatures for hurricane season with many keeping the warmest SST anomalies in this area possibly leading to long track storms this season.
The Atlantic Multi-decadal oscillation is positive with warmer anomalies in a horse shoe shape from south of Greenland to Europe to African coast and the MDR. The sub-tropics are cooling in the middle portion of the Atlantic.
5. The equatorial Atlantic . Models are split with how the equatorial Atlantic becomes. Some show it going negative while others keep it positive. Though warmer than average temperatures are currently there recently the eastern equatorial Atlantic is cooling
6. It is not just the sea surface we have to pay attention to, we also need to see how deep the heat goes down too. We have high levels of heat potential for tropical cyclones for this time of year and is about a month ahead of last year’s Especially for the eastern Caribbean and areas east of the Eastern Caribbean with the Usual bullseye of heat potential south of Cuba. Unlike last year in which EL-Nino kept a lid on Caribbean activity I believe we will see some of this heat utilized by tropical cyclones this year. Most activity stayed over sea. We will have to see how far east and north the TCHP goes but its likely to expand.
8. Quasi-biennial Oscillation (QBO) is currently positive or westerly, that favor hurricane activity in the Atlantic showing around a 50% increase in storm activity 200% increase in major hurricanes but it is going neutral and could be moving towards easterly phase as we go through the upcoming hurricane season. This phase is not as favorable for tropical activity.
(SOI) The Southern Oscillation Index of the Pacific went from 11.5 in January which = La- nina to now -2 which means the ENSO is in Neutral conditions going towards the warmer phase. When the SOI is between -/+ 7 the ENSO is usually in a neutral state. + equals La-Nina while negative is equal to El-Nino.This is currently going rapidly up showing that the ENSO is likely going to jump rather quickly over the next few months.
As many have heard there has been some of the strongest solar storms we have seen in 20 years giving a rather phenomenal light show across Canada and to millions across North America as far south as Georgia.
What are the models showing Below are the Precipitation anomaly maps. How far from average is the precipitation. The C3S and NMME are two suits of models put together to make an average. You have the C3S which combines many of the big met offices and the NMME which combines several models in North American countries. Both of these show an active main development region and Caribbean with a drier sub-tropics showing evidence of stronger ridging. The Cansips though is showing activity moving into the sub-tropics from the GOM and Caribbean curving out to sea. You see compare the ECWMF and Cansips and see that the placement of ridges are different between the models. This is the type of stuff that are very difficult to pinpoint this far out.
Below is Aprils SST forecast for this summer.
By the C3S and NMME which combines many models together, the Cs3 combines many models while the NMME combines North American based climate models
The precipitation anomalies : Both showing a similar pattern in precipitation. You see below average anomalies in the sub-tropics with the heaviest precipitations in the MDR and bending back into the Caribbean a possible sign of ridge steering.
Now taking two of the better individual climate models the Cansips and the ECMWF
Both in good general agreement with the SST configuration, One major differences is the equatorial Atlantic. the ECMWF is warm ( Altantic Nino) while the Cansips is cooler (Atlantic Nina) The other thing with both these the ENSO is cooler on the CANSIPS and warmer on the ECMWF both possibly showing their bias here and I am thinking something in between is more likely.
For the precipitation anomalies
ECMWF shows the concentration of precipitation in the MDR/Caribbean and a push off the east coast. The Canips shows an active look as well with MDR and the Caribbean.
What is the ECMWF showing for Numbers.
The ECMWF is showing a active season with
16 to 26 named storms, with the avg 21 named storms ( 7 storms above normal)
7 to 14 hurricanes with average being 11 hurricanes.
Ace is 1.7 of normal.
It is showing enhanced activity for the MDR, and east coast. Higher threat for NE Caribbean, Gulf of Mexico and east coast
Analog years:
Here are my analogs based off the ENSO, PDO and MDR/Subtropic SST configurations. These were all very active seasons. These years averaged 21 tropical storms, , 11 hurricanes and 5 Major Hurricanes. This matches well with the averages for the ECMWF numbers. It also matches well with the Ukmet, JMA & CMCC. These all are 22 to,25 named storms, 12, to 14 hurricanes and 6 to 7 major hurricanes. Averaging out 23 tropical storms, 13 hurricanes and 6 majors. Add the analogs to the climate models and its 23 tropical storms, 12 of them becoming hurricanes and 6 of them becoming major hurricanes.
1933 had the highest Accumulated cyclone energy output on record and thats prior to satellite era likely meaning that is a conservative number. Years such as 1933, 1995, 1998 and 2017 where high impact seasons for the eastern Caribbean. years such as 2005, 2010 and 2020 had very high numbers.
Looking at the 200vorticity prediction of the ECMWF created by Ben Noll @BenNollWeather we can see a sinking cell or stable air across most of the Pacific Ocean. Meanwhile you have Rising cells ( or unstable rising air) over the western Indian Ocean into the Atlantic. This is an extremely favorable look for tropical activity in the Atlantic. Storm development can be favorable just to the west of the rising cells.
The Atmosphere is extremely wet. A mix of Climate change, (warmer temperatures = more moisture) which can increase temperatures , normal climate patterns and the massive under water volcanic eruption Tonga-Hunga a few years ago that released massive amounts of moisture into the atmosphere are at play with this massive amount of moisture. This could have a large impact on the Atlantic hurricane season. Storms could have way more moisture to play with than normal. This can increase the ability for tropical waves to develop as they have a decrease in dry air to deal with and when the storms form, they have way more moisture within them dumping much higher rainfall amounts than it otherwise would.
Based off the analog seasons listed above, these are the general origin areas for storm development those years. The dark blue circle in the southwest Gulf of Mexico generally had weak sub tropical or tropical development which went into Mexico or Texas generally. The light blue in the southwest Caribbean had weaker systems that develop going into Central America or into the southwest Gulf of Mexico. The stronger systems that originated from here usually went closer to Cuba and threatened Florida then moving off the east coast and out to sea. The orange involve tropical waves that take their time in lower latitudes that develop as they move across the Caribbean. These analog years had the majority of these staying closer to Central America and the western Gulf of Mexico though a few went into the Greater Antilles. The red circle represents tropical waves that develop quicker than the orange. These are also highly influenced by the Azore Bermuda high to the north of the Main development region. Years such as 2010 and 2005 had most MDR activity either go out to sea or wait until they were in the Caribbean as the Azore-Bermuda high was weak allowing storms to turn well before the Caribbean. Meanwhile years like 1933, 2017 had stronger Azore-Bermuda high pressure that pushed major storms into the Northeast Caribbean and closer to the east coast. You also had years like 1995 and 1998 that were still high impact years for the northeast Caribbean but where a mix of the two other options.
Areas of greatest risk is the Eastern Caribbean, Bahamas, East coast of the United States and parts of central America. The map above and below are based off analog season but also climate models. This does not mean that areas that are not highlighted in Red are safer from a landfalling hurricane its just the areas that have an enhance number of storms that hit these areas during the analog years. Anyone in the Atlantic should be prepared for a very active season.
This is a season in which almost all signs point to a very active season and that is what I am going to be going with. Questions remain in steering patterns. Will it be active but a weaker Ridge? Is there internal seasonal parameters not able to be looked at this time. How warm does the sub-tropics get, do the temperature anomalies get closer to the MDR over the season? Do we get a warm pool up in the north Atlantic near the NE USA/Eastern Canada? Time will tell but we all need to be prepared
Now with all that said here are my forecast numbers for this upcoming season (April forecast)
My Forecast numbers
Tropical storm 20-24
Hurricanes 11-15
Major Hurricanes 5 to 8
Merrimack Valley Weather 