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Alex Headshot
Atlantic Hurricane Season Outlook 2020
By: Alex Avalos, Meteorologist

With the start of the Atlantic Hurricane Season less than one month away, many are likely wondering what is in store for this year?

As you may know, hurricane season officially begins in the Atlantic Basin on June 01st, peaking around September 10th, before ending on November 30th. On average, the Atlantic experiences 11 named tropical systems, 6 hurricanes, with 2 major hurricanes of Category 3 strength or higher.

For tropical development to occur, it is important to understand some of the atmospheric and oceanic parameters which must first come together:
  • Warm sea-surface temperatures of at least 26.5C (80F)

  • Light winds aloft

  • An atmosphere rich in moisture
The El Niño Southern Oscillation, also known as ENSO, is a primary driver of climate across our world's oceans, and especially ocean temperatures in the E'rn Pacific. ENSO also plays a significant role in tropical development across the Atlantic Basin. When ENSO yields a warming phase in E'rn Pacific sea-surface temperatures, El Niño develops, while a cooling phase will result in a developing La Niña. The effects of ENSO on the Atlantic Tropical Season are shown in the below table:

El Niño La Niña
Trade Winds
Stronger than average
Weaker than average
Sea Surface Temperatures
Cooler than average
Warmer than average
Squalls
Less frequent
More widespread
Tropical Cyclone Development Frequency
Below normal
Above normal

Looking ahead, we expect that ENSO will remain neutral into the Summer and Autumn months. A weak La Niña is more likely to develop closer to the peak of Hurricane Season. Sea surface temperatures are currently averaging between 1-2 degrees Celsius above average across the W'rn Tropical Atlantic through much of the Gulf of Mexico, coupled with weaker winds aloft. If a more notable La Niña develops, then expect an increase of tropical activity in the Atlantic basin.

For these reasons, WRI predicts an above average season in the Atlantic Basin, with 16-19 named tropical systems.

At WRI, we provide a number of ways to keep you informed of potential tropical development around the world. This includes our Dolphin website Tropical Tracker, and emailed tropical basin summaries and storm-specific alerts. We also create our own in-house tropical lows, often before official agencies, allowing for advanced notice of hazardous tropical concerns. You can also receive the most up to date information by consulting one of our Meteorologists who are available 24/7 for assistance.

Be sure to join us on 2 June for our Tropical Webinar discussing the 2020 Atlantic Hurricane Season and the various tools available on the Dolphin website. Additional details regarding this Webinar will be announced shortly.

Typical tropical setup and features during a La Niña year in the Atlantic Basin.


Amanda Headshot
Onset of the Southwesterly Summer Monsoon
By: Josh May, Meteorologist

As we continue through the month of May, SW'ly monsoonal winds across the N'rn Arabian Sea and Bay of Bengal will begin to develop. These SW'ly winds will freshen through the month of May and will continue strengthening through the month of June. Many are familiar with the increased precipitation which is brought on by the summer SW'ly monsoon across India, but few may understand exactly why. What causes this monsoonal pattern across the N'rn Indian Ocean, and how long does it normally last?

These SWly monsoonal winds are a result of the following factors:
  1. The sun moves N'ward across the Equator to N'rn Latitudes, increasing solar radiation across N'rn India.

  2. Warm Sea Surface Temperatures across N'rn Indian Ocean compared to cooler temperatures across the S'rn Indian Ocean during spring/summer months.
These factors result in the development of a thermal trough across N'rn India and the Tibetan Plateau which strengthens from the late spring into the early summer. This thermal trough usually extends W'ward across N'rn India to near 65E and continues ESE’ward across NE'rn India toward the N'rn Bay of Bengal. As the warm air across N'rn India and the Tibetan Plateau rises, a large-scale thermal atmospheric circulation develops, where S-SW winds develop across the Arabian Sea and Bay of Bengal.

Overall weather pattern during the Southwest Monsoon season.

The monsoon flow typically follows the below pattern:

May: The thermal low tends to fluctuate in intensity in a diurnal pattern, causing SW’ly winds to be at their strongest during the afternoon/early evening while the thermal low is at its strongest. Additionally, the strongest SW'ly winds are expected within 100-200nm of the coastline of India.

June: Diurnal fluctuations tend to diminish as the thermal low fully materializes and will be producing a massive inflow across mainland India. These persistent SW'ly winds will bring abundant amounts of rainfall across India and SW'rn Asia during June and July.

July: The SW'ly monsoon will be in full swing. SW'ly winds of Beaufort Force 6-8 will persist across the Arabian Sea and Bay of Bengal with swells building to 4.0-5.0 meters. These rough conditions will remain in place through the month of July and will fluctuate little in intensity as the thermal low across N'rn India is in its "mature" stage.

August: The thermal low across N'rn India gradually weakens as daytime heating is reduced. As this occurs, the persistent SW'ly monsoonal conditions will gradually ease across the Arabian Sea and Bay of Bengal by late in the month.

September: The thermal low continues to weaken, and the SW'ly winds gradually diminish. The end of the monsoon usually comes in "phases", with a temporary lull in conditions, often followed by a brief resurgence, before finally dissipating. This will open the opportunity for tropical cyclones to begin developing later into the Autumn (October/November), as vertical wind shear diminishes during the transition season.

Contact us today for assistance while navigating through these persistent SW'ly conditions over the next few months. Variations from the "standard" route are often required during the monsoon season to minimize heavy weather conditions. We will be standing by and are looking forward to hearing from you.



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