08/09/2022, 10:03 am EDT

Daily Tropical Feature: Tropical upper troposphere trough protects western North Atlantic basin from tropical activity.

Highlight: Tropical upper troposphere trough protects western North Atlantic basin from tropical activity. Feature likely to last into final third of August. Fig. 1: A tropical upper tropospheric trough is identified over the Caribbean Islands in the morning 250 MB (high-level) wind analysis. Discussion: Inhibiting tropical cyclone development across the western half of the North Atlantic basin in July and into August is evolution of a tropical upper tropospheric trough (TUTT). In the upper troposphere, on average, wind direction is out of the north across the Gulf of Mexico and becomes westerly in the Caribbean Sea and then northerly over Puerto Rico on the back side of an upper-level ridge pattern in the southeast North Atlantic (Fig. 1). So far in August, an upper trough is apparent at 250 MB centered over Southern Florida/Western Cuba also identifying presence of TUTT (Fig. 2). The TUTT pattern remains over the next 2 weeks. In 15 days, ECM ENS indicates TUTT is weaker but still present across the Caribbean Sea (Fig. 3). The TUTT pattern strongly inhibits tropical cyclone development through the middle third of August. The TUTT pattern is likely to ease later this month. Implications are that an active hurricane season ahead forecast is delayed and either less active than forecast or very active over a relatively short period of time. The last time TUTT was present during early August was in 2013. In 2013, 10 of 14 tropical cyclones occurred after mid-August and only 2 hurricanes formed. The season lasted into early December. Fig. 2: The early August 250 MB anomaly analysis identifies presence of a tropical upper tropospheric trough. Fig. 3: The ECM ENS 250 MB wind forecast in 15 days identifies presence of the TUTT remaining over the northern Caribbean Sea although weaker.
07/18/2022, 11:57 am EDT

Tropical Feature: Weekly North Atlantic SSTA Update

Highlight: North Atlantic SSTA unusually (mostly) cool. Fig. 1: North Atlantic basin SSTA analysis and regional commentary. Discussion: The North Atlantic basin is unusually cool for this time of year. Anomalous warmth is potent east of New England and south of the Canadian Maritimes. The warming in this zone is caused by the blocking of the Gulf Stream by the North Atlantic warm hole (NAWH) south and southeast of Greenland. However, waters off the remainder of the East Coast are marginally warm and the Gulf of Mexico warmth has eased back the past couple weeks. A strong “Bermuda High” centered east of Bermuda in the central North Atlantic basin has propelled above normal trade wind speeds to up-well cool water in the North Atlantic subtropics. In the deep tropics waters are marginally warm with a steady trend.
05/22/2022, 8:44 am EDT

Short Version – North Atlantic 2022 Hurricane Outlook

Highlight: La Nina continues – seasonal activity forecast increases. Executive summary: The Climate Impact Company 2022 North Atlantic seasonal activity forecast has increased slightly since the initial projection one month ago. The number of tropical storms, hurricanes and intense hurricanes each increases by a count of 1 to 20 storms, 10 hurricanes and 5 intense hurricanes. The ACE index increases from 135 to 149. The increase in activity is due to a more confident La Nina climate forecast. Less confident is the extent of upper ocean heat in the tropical/subtropical North Atlantic which is forecast near average in this outlook. If the upper ocean heat forecast is warmer in subsequent updates, the number of hurricanes for 2022 will likely increase. The projected tracks for 2022 are clearly most active in the subtropics including the Gulf of Mexico, the Bahamas and close to the Southeast U.S. Coast.   Tropical Storms Hurricanes Major Hurricanes ACE Index 5/3/22 FCST 20 10 5 147 4/7/22 FCST 19 9 4 135 15-YR NML 16.4 7.3 3.2 110.6 30-YR NML 14.8 7.3 3.2 120.5 50-YR NML 12.6 6.4 2.6 99.2 Last Year 21 7 4 146 2020 30 13 6 180 Table 1: The Climate Impact Company 2022 North Atlantic basin seasonal tropical cyclone activity forecast for May 3rd compared to the April outlook and various climatology and the past 2 seasons. Fig. 1: Based on the analog years the 600 MB relative humidity projection combined with climatology identifies the most likely primary tropical cyclone tracks for the 2022 season. Updated forecast tracks: Analog storms for the 2022 season include Hurricane Humberto (2001) which formed south of Bermuda in September and drifted northward across that small island. Another analog storm is Earl (2010) which was a major hurricane shifting out of the tropics and intensifying and just missing the U.S. East Coast. Another major hurricane in 2010 (Igor) moving north close to Bermuda is another analog storm. An early season hurricane such as Alex (2010) moving into northeast Mexico is an analog storm for 2022. Eastern Gulf of Mexico storms that turn into Western Florida are analog storms for 2022 similar to Hermine (2016). Unfortunately, Louisiana is targeted for a major hurricane in 2022 similar to the Ida track of last year. The tropical/subtropical North Atlantic 600 MB relative humidity forecast for AUG/SEP based on the analogs clearly identifies the Gulf of Mexico to Bahamas subtropics as the very active region for 2022 including the U.S. East Coast. An out-to-sea storm track across Bermuda and west of the Azores is also likely. The regime identified implies limited time to react for planning purposes. Not the dry RH pattern across and just east of the Caribbean Sea where tropical cyclone activity is suppressed. As previously stated, the prevailing RH pattern matches the anticipated -QBO pattern for the 2022 tropical cyclone season. Other forecasts: Most forecasts are in agreement that the 2022 tropical cyclone season across the North Atlantic is more active than normal. The Climate Impact Company forecast has ticked-up a notch since the early April original outlook primarily due to the influence of a lingering La Nina episode. Anticipated is a similar slight increased with June updates of the CSU and TSR forecast. The NOAA outlook will be issued in May and should also be more active than normal.   Tropical Storms Hurricanes Intense Hurricanes ACE Index CIC 5/3 20 10 5 149 CSU 4/6 19 9 4 160 TSR 4/6 18 8 4 138 NOAA N/A         30-Year NML 14.8 7.3 3.3 126.3 Table 2: Lead providers of seasonal tropical cyclone activity for the North Atlantic 2022 season.