Eta’s zig-zag track continues (H. Michael Mogil, CCM, CBM, NWA-DS*)
The other day, I used the word “serpentine” to describe Eta’s past and expected movements. Eta has not disappointed.
First, the storm moved westward, then headed northward along the Central American coast; and then northeastward toward the Central part of Cuba (where it resided earlier this Sunday morning). The storm exited Cuba around midday and then entered the Florida Straits (Fig. 1).
The forecast track (Fig. 2) takes the storm northward briefly, then has it making a sharp turn to the west (and west-southwest) into the eastern Gulf of Mexico. Longer-range forecasts have the storm moving northeastward again, this time, toward Tampa.
These movements are closely linked with changes in upper-level steering winds (five to 10 miles above ground) near and over the storm. Since the storm is separated from the stronger westerly winds over much of the United States, movements are much more convoluted.
Similarly, wind strengths have shown an up-down-up pattern based on storm evolution over warm ocean waters and the effects of movement over and near mountainous terrain. With a protracted stay over warm Gulf of Mexico waters, Eta is now expected to become at least a minimal (CAT 1) hurricane by Monday.
By tonight and Monday, tropical storm-force winds are anticipated across southwest Florida, including Collier County. Additional rainfall of some four to six inches (with locally higher amounts) is likely. As the storm passes to the south of Collier County on tonight and Monday, southerly winds on the east side of the storm will likely push water onshore, leading to a “storm surge” of two to four feet. Note that winds around a tropical storm/hurricane in the Northern Hemisphere spin counterclockwise.
With the storm only moving away slowly from Collier County, gusty southerly and southeasterly winds will become established on Tuesday. For Wednesday through Friday, winds will still be in the 15 to 20 mph range. Rainfall will become more scattered in nature, but there could still be locally heavy downpours.
While winds across southwest Florida and nearby coastal waters will be from the south and southeast, further offshore, Eta will be producing persistent southwesterly winds to the south and east of the storm’s center. This will be much like what is expected tonight on south-facing coasts. This ongoing push of water toward the southwest Florida coast will result in higher than average water levels along the coast for the next three to four days. It will also produce a greater than average wave action pattern (which could lead to some beach erosion). Given the slow movement of the storm and its expected low-level hurricane or strong tropical storm status, a major surge of water toward the coast is not anticipated.
This scenario, where higher water levels and tides arrive as the storm is moving away from the coast is not usual. However, along the west coast of Florida, with a west-facing coastline, such events are more likely.
The biggest threat from the storm for most of Collier County will be winds (45 to 55 mph) with higher gusts from tonight into Monday and locally heavy downpours (possibly leading to roadway ponding and flooding in normally flood-prone areas). Yes, there will also likely be some scattered power outages. However, this is not expected to be a major hurricane event (in part because the storm should remain offshore).
Still, please keep abreast of the latest forecasts and warnings and take necessary safety actions, as appropriate.
© 2020 H. Michael Mogil
Originally posted 11/8/20
* The National Weather Association Digital Seal (NWA-DS) is awarded to individuals who pass stringent meteorological testing and evaluation of written weather content. H. Michael Mogil was awarded the second such seal and is a strong advocate for its use by weather bloggers.