Today is May 15, the official start of the Eastern Pacific hurricane season. No tropical cyclones have developed yet in this basin in 2019; 2017 featured the pre-season Tropical Storm Adrian and 2018 featured the pre-season Tropical Depression One-E. The Eastern and Central Pacific is coming off a record-breaking 2018 season which featured 23 named storms, 13 hurricanes, 10 major hurricanes, 3 Category 5 hurricanes, and a record-high 318 Accumulated Cyclone Energy (ACE) units. With a weak El Nino event current in place that will likely persist for at least the next few months and a positive Pacific Meridional Mode (PMM), it appears likely that the Eastern Pacific will have yet another above-average season. Since 2014, every season in this basin with the exception of 2017 has had above-normal ACE, and all have featured an above-normal number of named storms.

Sea Surface Temperature Anomalies

Weak El Niño conditions currently prevail over the equatorial Pacific. The latest sea surface temperature anomaly value in the Niño 3.4 region was +0.5°C, which is right at the El Niño threshold. Although trade winds could stay fairly relaxed in the equatorial Pacific for the next several weeks, a strong westerly wind burst (WWB) recently occurred and was unable to significantly warm the equatorial Pacific subsurface.

Although it is a distinct possibility El Niño may dissipate by fall, it’s also a distinct possibility a weak event persists. El Niño events usually enhance hurricane activity in the eastern and central Pacific due to warmer sea surface temperatures, reduced wind shear, and increased instability. Since it is unlikely that ENSO goes into the negative phase, it is still likely the eastern and central Pacific will have above average activity even if the El Niño dissipates. This is largely due to the positive Pacific Meridionial Mode (PMM), which has resulted in much above normal sea surface temperature anomalies in the Central Pacific, near Hawaii. It is likely we will see some tropical cyclones threaten Hawaii this season, but it is unclear if the persistent wind shear near the Hawaiian islands will abate enough for a strong landfall.

The NMME (a multi-model climate forecast model) is predicting that much of the eastern and central Pacific basins, especially west of 120°W, will have above-normal precipitation rates. This means that the atmosphere will be more moist and more conducive for tropical cyclone development. It’s likely that we will see several hurricanes not reach peak intensity until around 120-140°W this season, similar to what we saw last year, because of the strong +PMM event which appears likely to persist through the peak of the hurricane season.

Cyclonic Fury’s 2019 Pacific hurricane season forecast (includes both the Eastern and Central Pacific basins):

• 16-22 named storms (average: 16)
• 9-13 hurricanes (average: 8)
• 5-8 major (category 3+) hurricanes (average: 4)
• Accumulated Cyclone Energy (ACE) 200 +/- 40 (average: ~130)

Cyclonic Fury also gives the probabilities of activity listed below:

• Above normal season (70%): Accumulated Cyclone Energy of at least 135 units, provided at least 2 of the following 3 parameters met or exceeded: 16 named storms, 9 hurricanes, or 4 major hurricanes.
• Near normal season (20%): Neither above-normal or below-normal activity.
• Below normal season (10%): Accumulated Cyclone Energy of 86 units or fewer.

It should be stressed that it only takes one tropical cyclone to cause problems. Residents in Hawaii, as well as the Pacific coast of Mexico, should be prepared for any tropical cyclone impact.

This is the only Cyclonic Fury forecast for the 2019 Pacific hurricane season. On May 21 at 10:00 a.m. EDT, the next Cyclonic Fury forecast for the 2019 Atlantic hurricane season will be released.