2021 Atlantic/Pacific Hurricane Season

Gaoth Laidir

Not Atlantic or Pacific, but Oman is getting landfall now from a minimal hurricane Shaheen-G, with heavy rain and winds currently 54 knots in Suwaiq along the northeastern coast. The capital Muscat has had 172 mm of rain (I presume storm total?), so the wadis will be in full flow as the system moves inland and southwestwards.

Live observations from the Oman Met

Directorate General of Meteorology

https://twitter.com/snWFDQaCai8KCoI/status/1444748577964806148

It briefly peaked at 70 knots earlier today.

Gaoth Laidir

The Arabian Peninsula, and in particular (obviously) Oman, gets these storms more frequently than I thought. There were very good records going back to the 19th century, with landfalls reported every few years, on average.

List of Arabian Peninsula tropical cyclones - Wikipedia

Pre-1900[edit]

• June 2, 1881 – A storm crossed Masirah Island and dissipated over southeastern Oman.[38]
• June 1, 1885 – A cyclone moving westward through the Gulf of Aden passed just north of the Yemeni island of Socotra with rough seas and high winds. The storm later affected a ship just off the city of Aden, Yemen, which reported winds of Force 12 on the Beaufort scale, along with heavy rainfall and lightning.[19]
• June 1889 – Curving westward away from India, a storm crossed the northern Arabian Sea and hit near the eastern tip of Oman.[39] A computer simulation in 2009 estimated that the storm would have produced waves of 10 m (33 ft) along the northeast Omani coast.[7]
• June 5, 1890 – After entering the Gulf of Oman, a cyclone struck Sohar in northeastern Oman after passing just northeast of Muscat, where it washed ships ashore. There, the storm dropped 286 mm (11.3 in) of rainfall over 24 hours, the highest daily precipitation total in the nation's history. High winds wrecked many houses, and about 50 people died in Muscat and nearby Muttrah. Inland flooding downed thousands of date palm trees and inundated valleys. Nationally, the storm killed at least 757 people.[19]
• June 2, 1898 – A strong storm moved through eastern Oman, dissipating in the Gulf of Oman.[40]

1900–1949[edit]

• May 2, 1901 – Curving northward, a storm passed just east of Oman before turning to the northeast and hitting Pakistan, producing high waves along the coast.[7][41]
• November 2, 1906 – A tropical storm brushed the southern coast of Socotra.[42]
• May 26, 1911 – A severe cyclonic storm struck Oman south of Duqm.[13]
• January 15, 1912 - A "heavy storm" destroyed more than 30 boats, with some casualties.[43]
• May 27, 1916 – The Dhofar region of Oman was hit by a cyclonic storm.[13]
• June 2, 1916 – Northeastern Dhofar was again struck by a cyclonic storm.[13]
• October 13, 1921 – A long-tracked storm moving across India eventually moved ashore over southwestern Oman.[13][44]
• December 6, 1922 – Originating near Sri Lanka, a long-tracked cyclone brushed the north coast of Socotra with the equivalence of hurricane-force winds, reaching at least 120 km/h (75 mph). It was the last storm of that intensity to strike the island until 2015.[45]
• June 6, 1927 – A dissipating storm struck Oman south of Duqm.[46]
• September 30, 1929 – Southeastern Oman was struck by a cyclone that quickly dissipated inland.[47]
• October 25, 1948 – A storm moved through much of the eastern Arabian Peninsula, crossing from Salalah, Oman, and dissipating in the Persian Gulf near the United Arab Emirates.[48] The storm dropped 156 mm (6.1 in) of rainfall in Salalah, which later contributed to a locust outbreak.[6]

Gaoth Laidir

Now 78 knots wind at Suwaiq!

Directorate General of Meteorology

Gaoth Laidir

Latest windfield

Gaoth Laidir

Al Suwaiq received 294 mm in the past 24 hours, which is not far off 3 times its annual rainfall total. Widespread flooding reported.

https://twitter.com/Hashtagelyoum/status/1444707413899157505

hatrickpatrick

Very strange situation in the Atlantic right now - despite La Nina and very warm SSTs, an upper trough (TUTT or Tropical Upper Tropospheric Trough) has been sitting over the Western Atlantic for the last several weeks, thus choking what was predicted to be a very active second half of October. Nobody seems to be quite sure why this feature has become established where it has, considering the conditions in place which would usually prevent that from happening.

Anyone here have any insight into this?

Gaoth Laidir

https://www.boards.ie/discussion/comment/118048862#Comment_118048862

Philip Klotzbach and Michael Bell's 2-week forecasts are a good source of information during the season. Their most recent forecast (14th October) did call for a quiet first week, but possibly an uptick in the second week as the MJO moved into Phases 8/1. The developing La Nina seems to be causing some uncertainty, however.

CSU Hurricane Seasonal Forecasting (colostate.edu)

3) Global Model Analysis The ECMWF ensemble is pretty anemic at Atlantic TC development during the next two weeks, while the GFS ensemble is highlighting potential TC development in the Caribbean in 10-14 days.

4) Madden-Julian Oscillation The MJO, as measured by the Wheeler-Hendon index, is currently in phase 6 over the western Pacific. This phase is generally not conducive for Atlantic TC development, but there is fairly good agreement that the MJO should propagate fairly rapidly into phases 8- 1 over the next two weeks (Figure 4). These phases tend to be more conducive for Atlantic TC formation, as they typically have anomalously weak levels of vertical wind shear. While the ECMWF model is forecasting the MJO to move into phases 8-1 in the next two weeks, there is considerable spread amongst the ensemble members, likely due to the current La Niña development and potential interference between subseasonal variability and the La Niña-like background state (Figure 4). Table 2 summarizes the typical MJO impacts on Atlantic TC activity. The upper-level velocity potential field generally favors suppressed vertical motion over the tropical Atlantic in week one, but the large-scale pattern looks to be more conducive for Atlantic hurricane activity in week two, with suppressed vertical motion over the central and eastern tropical Pacific and enhanced vertical motion over the Caribbean and tropical Atlantic (Figure 5). The Climate Forecast System (CFS) model is generally predicting below-normal shear across the Caribbean during week two, which could favor Atlantic TC development in the Caribbean during that time (Figure 6).

Gaoth Laidir

https://twitter.com/philklotzbach/status/1462590310031114240

Gaoth Laidir

The 2021 Atlantic hurricane season has come and gone, officially ending on November 30th. Here are the stats, with the ranking out of the 170-year record from 1851.

• Named storms: 21 (rank 3rd)
• Named storm days: 78 (rank 30th)
• Hurricanes: 7 (rank joint 32nd)
• Hurricane Days: 27.5 (rank 45th)
• Major hurricanes: 4 (rank joint 18th)
• Major hurricane days: 13.75 (rank joint 12th)
• ACE: 145.1 (rank 28th)

Of the 21 named storms, 12 had max winds of 50 knots or lower. Of these, four lasted 1 day or less. Four storms reached above 75 knots.

The most powerful storm by far was Sam (135 kts | 929 hPa | 7.75 Major Hurricane Days | ACE 53.8).

September was the most active month, with nine storms forming, while the least active months were November (0 storms formed) and July and October (1 storm formed in each).

EDIT: The date in the graphs below should read 02/12/2021, not 02/10/2021. This stupid site won't allow me to correct the images.

Despite the relatively active Atlantic, overall the Northern hemisphere has been relatively inactive, especially in the northwest Pacific.