My 2023 Atlantic Hurricane Outlook Part Two

 

Here is part two of this year’s hurricane outlook. Part two will go more into the developing El Nino, other major weather outlet forecast, the cone of uncertainty, and other changes being implemented by the National Hurricane Center.  

 Refer to part one for definitions and acronyms.

Part One

My analogue seasons…

 1957,1965,1972,1982,2002,2009,1997, 2015

1957

 

1965

 

1972

 

1982

 

1997

 

2002

 

2009

 

2015

 

 

Typically, the analogues saw generally 6-10 named storms with very low seasonal ACE points.  This is something I will come back to.  

 

Sea Surface Temperatures (SST)…

ENSO

Over the last few weeks, upper ocean heat content has warmed rapidly.

SSTs are above average in the eastern equatorial Pacific, with SSTs in the central equatorial Pacific are near average.

Here is a look at Nino 1+2, Nino 3, Nino 3.4, and Nino 4 SST anomalies

 

The latest weekly

SST departures are:

Nino 4 0.2ºC

Nino 3.4 0.1ºC

Nino 3 0.4ºC

Nino 1+2 2.7ºC

 

The subsurface water temperatures in the equatorial Pacific Ocean are now dominated by positive temperature anomalies.

The Climate prediction Center /NCEP has issued an El Nino Watch

In part one I said the coming El Nino should be moderate to strong. Looking at the current SSTs in the Equatorial Pacific, we can see conflicting signals. Spring is a difficult time to forecast the ENSO, for this reason it is labeled the Spring Predictability barrier  

 

Pacific Decadal Oscillation (PDO)

We do have a warm blob in the western North Pacific.

With SST just off the West Coast of North America are cooler than average.

 

Currently our developing El Nino and the PDO are at odds with each other. When we look at the Ocean Current chart, we can see how the current off the Western North American Coast travel south where they mingle with the current in the Equatorial Pacific. As a result, as the two current compete, we have El Nino conditions in Nino 1+2, with neutral ENSO conditions in Nino 3.4. 

When we look at the Southern Oscillation Index (SOI) index numbers. Negative numbers tilt toward El Nino which creates weaker trade winds over the Pacific. When the numbers are positive, they tilt toward La Nina which creates stronger trade winds over the Pacific.

Trade wind anomalies over the next month over the Nino 3.4 region. The blues and greens indicate strong trade winds. The yellows and oranges indicate weaker trade winds. The chart shows trade winds will be generally average, with a burst of stronger winds. We need weaker trade winds if we want to see those warm subsurface waters to make their way to the surface in a big way.

So, we’re likely to experience El Nino this Summer. But the question still remains on how strong the El Nino will be. The strength of the La Nina will determine how much sinking air we see over the Atlantic Basin this hurricane season.

Here is a graphic that shows the typical areas of rising and sinking air during El Nino. Sinking air is very hostile when it comes to tropical cyclone formation. 

 

Some of the models, like the Euro do show a Super El Nino developing. But most show moderately strong to strong.

Atlantic Basin

SSTs are well above average in the eastern tropical and subtropical Atlantic. SST are also well above average off the East Coast in the Western Atlantic and the Gulf of Mexico. The SST are 10 degrees above average in parts of the Gulf of Mexico and near average in the Caribbean. With the MJO rotating through the favorable phases 8 and 1 along with those very warm SST in the Gulf. I wouldn't be surprised if something tropical spins up in the Gulf before the official start of the hurricane season.   

 Five of the analogue years were strong El Nino’s with two of the analogues being fairly strong moderate seasons. But all of those years typically saw cooler SST in the tropical and subtropical Atlantic.  But when we look back at the SST chart, we can see this year the SST in the tropical and subtropical Atlantic are abnormally warm. This is another conflicting signal for the number of possible named storms in the Atlantic this hurricane season.    

 Other Outlets hurricane outlook forecast...

 Colorado State University (CSU) is predicting that the 2023 Atlantic hurricane season will be slightly below average with 13 named storms, 6 of them becoming hurricanes, with 2 of those becoming major hurricanes. CSU is also calling for an ACE of 100.

Accuweather’s outlook shows that the 2023 season will be near the historical average with 11 to 15 named storms. Four to eight of those named storms are expected to reach hurricane strength, with one to three of those hurricanes achieving major hurricane status.

WeatherBELL Analytics outlook is showing 10-14 named storms, with 5-7 hurricanes, 2-3 major hurricanes, with a seasonal ACE of 70-110.

 

The Cone of Uncertainty…

The cone of uncertainty is the projected track of the center and intensity of a tropical storm or hurricane. The cone is issued by the National Hurricane Center. The cone, is a series of imaginary circles placed along the future forecast track at 12,24,36 hours, etc. The size of each circle is set so that two thirds of the official forecast track errors over the previous five years falls within the circles.

The size of each circle grows larger with every 12- or 24-hour forecast interval because forecast errors in the position of a tropical cyclone’s center increase with time. This is why the cone of uncertainty, made up of those invisible circles, grows wider as the forecast goes farther into the future.

Before 2003 the cone of uncertainty only went out three days. But in 2003 the cone was extended out to five days. Forecast error has generally decreased for the last 10 years, due to improved model performance and better satellite data.  Over the last several years the cone of uncertainty has been two and five days. But with the increased confidence in the models and satellite data; starting this year the cone of uncertainty will now be two days and seven days. Due to the added length of time, the area showing where the storm may form on the map could show up larger than in the past.

This brings me to an important point. Many people get confused when they look at the cone of uncertainty; they focus on the cones center line, instead of the entire breadth of the cone. We saw this with disastrous and deadly consequences with Hurricane Ian last year. I really would like to see the NHC not show the skinny line at the center on any of their maps; I think it would make people pay more attention. We have to remember that tropical cyclones stray outside the cone roughly one third of the time

What the cone doesn't communicate are critical factors such as storm size, intensity, hazards or potential impact..

    

Other big changes the NHC is making in 2023…

The NHC will be adding Invest Numbers to this season’s outlooks. If you followed my tropical post, you have seen me, use Invest (I) 90 to 99, followed by a suffix letter "L". The L signifies the Atlantic Basin. Invest is used to indicate an area of interest that could develop into a tropical cyclone.  I think including the Invest numbers will make it easier for the general public to understand tropical forecast.

For the last two years, the NHC has used experimental peak storm surge graphics. Starting this season, the NHC will make the peak storm surge graphic operational. Since storm surge is the number on killer when it comes to landfalling hurricanes. This will hopefully make the danger more identifiable and reduce the number of fatalities caused by storm surge.

The NHC will also remove land based tropical cyclone watches and warnings from the tropical cyclone forecast advisory. But they will continue to issue the watches and warnings in the public advisory.

 

Summary…  

 

During El Nino there is a tendency for tropical cyclones not forming in Caribbean due to high shear in that part of the Atlantic Basin. If we look back at the analogue season graphics, we see most of these years saw no tropical cyclone activity in the Caribbean, with 2002 being the only outlier with two tropical cyclones that track through the Caribbean. So based on those analogues this year should see well below average activity in the Caribbean.  

  

Also, typically we see weaker than average wind shear over the Gulf of Mexico and off the East Coast in the Western Atlantic, for this reason tropical cyclone tracks could stay north of the Caribbean and form in the southern Gulf. The setup hints that there could be a lot of activity off the East Coast. We also should see above average activity out in the middle with the fishes.

We do look to see a fairly strong moderate to strong El Nino develop by the heart of the hurricane season So this will likely tamper down the number of tropical cyclones in the Atlantic Basin. This is what the Analogues do indicate. But due to the fact that the SST anomalies in parts of the Atlantic Basin are generally warmer than they typically are during an El Nino; is the reason I’m calling for slightly higher numbers of Tropical Cyclones to develop this season.

Pre season tropical activity is very likely in May in the Gulf of Mexico.

For now, I’m staying with my thought that this will be slightly below average to average season, with 10 to 14 named storms 4-7 hurricanes and 1 -2 major hurricanes.  The Seasonal ACE looks to be 60-90.

I released part one before the other outlets released their preliminary 2023 hurricane outlooks. So, seeing that they look similar to my numbers is making me more comfortable with my ideas.

Link for part 3