In this crazy unpredictable world we live in currently one thing that has become a norm as of late is active Atlantic hurricane seasons in terms of number of named systems.
Long range climate drivers are hinting at another active hurricane season.
ENSO (Area 1) is one of the most important aspects of seasonal forecasting.
Strong easterlies over the equatorial Pacific is maintaining the cold surface temperatures over the ENSO region keeping the warm SSTs over the western equatorial Pacific (Coral Triangle). Last month we were seeing warm anomalies propagations subsurface, and models were seeing this showing a weakening negative ENSO, instead though the stronger easterlies are creating strong upwelling in the east and is preventing warm water from the west being able to establish itself. I am not expecting it to stay this strong, but I am not expecting those warmer ENSO solutions models were showing in the January and February updates. The trend for these have been going cooler. We do have to monitor the current warm SSTS in the Nino 1+2 regions off of South America which are currently above normal, but this is shallow warmth and could quickly return to negative anomalies. the 1+2 Nino region is highly variable.
The Southern Oscillation Index of the Pacific is positive and continued to go positive this is helping to keep La-Nina in place though in past few weeks have come down a bit. When this is positive it favors La-Nina when its negative El-Nino.
The PDO is negative, which enhances La-Nina conditions and looks to stay negative to neutral through the summer.
The Indian Dipole is negative which has been linked to hurricane activity.
In the Atlantic, the Atlantic Nino region is above normal for now but there are signs that this area could go negative as we get into summer. This along with warm ocean temperatures over the higher latitudes in the Atlantic could lead to higher latitude storm systems this season. This also helps lead to decrease Saharan dust out breaks by increasing moisture over North Africa. We will have to also continue to monitor the AMO as we go through the spring. The GOM, Caribbean, and Western Atlantic will be more than warm enough to support activity come the start of Hurricane season but it might take until August for the eastern MDR to become warm enough.
Climate models are advertising an above normal Atlantic season.
- Many showing above average precipitation over the MDR, Caribbean ,Gulf of Mexico and portions of the east coast.
- They are showing 500mb patterns favorable for threatening tropical activity over the Northern and eastern Caribbean, Bahamas, portions of the Gulf of Mexico and east coast.
- Models are depicting below average wind shear over the western MDR and Caribbean. Mix signals of shear over the Gulf of Mexico and eastern MDR. This is in relation to the possible warm pool in Nino 1+2 regions depicted on some models to stay while others remove it. Wind shear could possibly help limit strengthening systems in the western Gulf of Mexico and Caribbean.
- Several models are depicting the 200 vorticity potential to be favorable in the MJO 1-4 regions.
Wind shear
Climate models are showing below average wind shear over the Caribbean through most of the season, with the wind shear increasing over the lower latitudes and eastern MDR by peak season. This could decrease the threat of those big long traveling hurricanes but could also increase the threat across the Caribbean as it could allow the weaker systems to travel further west again increasing the threat to the eastern and northern Caribbean Islands and Bahamas. Models are mixed in terms of the shear over the Gulf of Mexico.
The ECMWF has issued a very very aggressive first forecast for hurricane season . The ECMWF issues a forecast for accumulated cyclone energy (ACE), Hurricane and tropical storm frequency starting March of each year. The first forecast goes from April through September so it does not include all of hurricane season. An update will occur late this week.
Of particular note, since 2015 the number of hurricanes and tropical storms have been on the higher end of the ranges or well above the predictions.
This year’s March ACE forecast at 120% of the average is way higher than the previous two season’s. March Ace forecasts both of which were record breaking seasons in terms of number of storms but not in terms of ACE.
Another aspect of seasonal forecasting that many rely on are analog years.
This year based on SSTS and patterns these are the analog years I am going with. A note due to climate drivers and climate change I do not generally like to go past the 1990s
Years 1989, 2000, 2011, 2012, 2018, 2021
Numbers of each based on analog years
Analog Range Analog Average
Tropical depressions 15-21 18.3
Tropical storms 11-21 16.67
Hurricanes 7-10 7.8
Major hurricanes 2-4 2.8
Forecast for the 2022 Atlantic Hurricane season
Another active season is looking likely based on SSTS, other climate factors and analog years.
16-22 named storms with 6 to 10 being hurricanes with 3 major hurricanes with an ACE score or Accumulated Cyclone energy score of 130 to 150. An average season has 14 named storms, 7 hurricanes, 3 major hurricanes and ace score of 72 to 111.
A major storm track will likely involved a storm track starting in the western MDR to the east of the Lesser Antilles moving through these Islands or to the north of them into the Bahamas. There could be long track storms that accumulate the ACE earlier than usual this season due to increased moisture over North Africa and below average shear.
For this season like last year the weekly updates will start in May with the set up ;
Active storm information: No active tropical activity
0-5 day: No tropical activity
5-10 day. No Tropical activity
Long range. NA
Seasonal forecast: Above
Merrimack Valley Weather 