First Data Suggests 12-15 Named Storms. But It’s Early. Very Early.
BY: STAFF REPORT | BocaNewsNow.com
BOCA RATON, FL (BocaNewsNow.com) (Copyright © 2021 MetroDesk Media, LLC) (News App readers click here for full report) — Colorado State University is set to release its first outlook for the 2021 Atlantic Hurricane Season on April 8th.
The CSU forecast is considered the gold standard of early hurricane season predictions. The now available early pre-forecast advisory suggests 2021 will be a busy, but not off-the-charts season. We stress it is extremely early. This is official language from the Department of Atmospheric Science at University of Colorado as of early March:
University of Colorado Report
We are providing a qualitative discussion of features likely to impact the 2021 Atlantic basin hurricane season rather than a specific number forecast. This outlook for 2021 will give our assessment of the probability of five potential scenarios for Accumulated Cyclone Energy (ACE).
The current way that we assess the following year’s activity in the December outlook is in terms of two primary physical parameters:
- the strength of the Atlantic Multi-Decadal Oscillation (AMO)
- the phase of ENSO
The Atlantic had three quiet hurricane seasons from 2013-2015, followed by a slightly above-average season in 2016, near record-breaking levels of activity in 2017 slightly above-average seasons in 2018 and 2019 and an extremely active season in 2020. Five above-average seasons lends high confidence that the AMO remains in a positive phase, although the far North Atlantic has generally been characterized by below-average sea surface temperatures (SSTs), especially during the winter. Another big question for 2021 is how El Niño-Southern Oscillation (ENSO) will trend over the next few months. As is typically the case at this time of year, there is considerable model disagreement as to what the phase of ENSO will look like for the summer and fall of 2021.
For the 2021 hurricane season, we anticipate five possible scenarios:
1. AMO becomes very strong in 2021 and no El Niño occurs (resulting in a seasonal average Accumulated Cyclone Energy (ACE) activity of ~ 170) – 25% chance.
2. AMO is above average and no El Niño occurs (ACE ~ 130) – 35% chance.
3. AMO is above average and El Niño develops (ACE ~ 80) – 20% chance.
4. AMO is below average and no El Niño occurs (ACE ~ 80) – 10% chance.
5. AMO is below average and El Niño develops (ACE ~ 50) – 10% chance.
Typically, seasons with the above-listed ACE values have TC activity as follows:
170 ACE – 14-17 named storms, 9-11 hurricanes, 4-5 major hurricanes
130 ACE – 12-15 named storms, 6-8 hurricanes, 2-3 major hurricanes
80 ACE – 8-11 named storms, 3-5 hurricanes, 1-2 major hurricanes
50 ACE – 5-7 named storms, 2-3 hurricanes, 0-1 major hurricane
The official CSU forecast will be unveiled on April 8th. The Atlantic Hurricane Season starts on June 1st.
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