Upgraded Monday morning to a tropical storm, conditions in the western Caribbean and southern Gulf of Mexico are favorable for intensification into a hurricane by mid-week, with rapid intensification likely. Thereafter, Delta will make a turn to the north and eventually northeast with landfall expectations by NHC most likely as a category-2 hurricane on the central Gulf Coast (somewhere from Louisiana to the western panhandle of Florida) on Friday October 9. Some shift in track and intensity can be expected over coming forecast cycles as the situation evolves.
- Record year continues: Tropical Storm Delta, the 25th named storm of 2020, formed a day after Gamma developed off the east coast of the Yucatan Peninsula, making landfall as a high-end tropical storm late Sunday. Gamma is not expected to have further significant impacts as attention turns to Delta. Delta will be the record setting 10th named storm landfall of the 2020 season, not recorded in data back to 1851.
- Favorable environment for intensification and then weakening: Delta will move over anomalously warm sea surface temperatures through the central Gulf of Mexico, also accompanied by very low levels of wind shear. Thereafter, waters in the far northern Gulf of Mexico are currently below average as Delta approaches the northern Gulf coast on Friday, after accelerating to the north and east. While the current NHC forecast calls for a peak intensity of category-2 strength in the central Gulf of Mexico, several high resolution models indicate that a major hurricane cannot be ruled out.
- Late season analogs: October landfalls in the central Gulf Coast are not uncommon. Including the state of Louisiana and 200 miles to the west and east, fifteen hurricanes have made an October landfall. Ten of the fifteen hurricanes were category 1 or 2, the most recent being Hurricane Nate (2017). Three category-3 hurricanes (Opal 1995, 1886 and 1894), one category-4 (1893) and one category-5 (Michael 2018) have been recorded.
- Landfall impacts: As seen with the other 2020 central Gulf Coast landfalls of Cristobal, Fay, Laura, Marco, and Sally, storm surge, damaging winds and heavy rainfall will all be of concern. Fortunately, Delta will be increasing in forward speed at landfall and thus compared to some slow moving prolific rainfall producers this season, there is relatively lower risk for excessive rainfall.
Tropical Storm Delta Track and Forecast. Source: NOAA/NHC.
Satellite animation of intensifying Tropical Storm Delta south of Jamaica. Source: Tropical Tidbits.
Tropical Storm Delta Model Track Guidance (06 UTC October 5). Source: Dr. Clark Evans University of Wisconsin Milwaukee.
Sea surface temperatures anomalies as of October 5, 2020. Note that sea-surface temperatures are running well above normal into the Gulf of Mexico along the forecasted path of Delta, favoring the potential for rapid intensification. Source: Tropical Tidbits.
Historical hurricanes to make landfall within 200 miles of Louisiana in the month of October. Source: NOAA / Guy Carpenter.Email alerts for Weather Sentinel and CAT-i reports are available on a subscription basis at the GC Preference Center here.
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U.S. National Hurricane Center
Official statements from the NHC and U.S. National Weather Service, and those of emergency management agencies supersede this update, and should be closely monitored concerning matters of personal safety.