Hurricane Fiona made landfall in the southwest corner of Puerto Rico at 3:20 p.m. EDT Sunday as a Category 1 storm with winds of 85 mph. Although Fiona arrived as “only” a Cat 1, the impacts from Fiona’s rains have been catastrophic – characteristic of a major hurricane – with widespread amounts of 1-2 feet of rain causing devastating flooding.
Challenging a 24 hour rainfall record
Multiple locations in Puerto Rico recorded more than 8 inches of rain in the 24 hours ending midnight Sunday. According to the National Weather Service, Puerto Rico’s record for 24-hour rainfall is 23.75 inches, set in the Toro Negro Forest on October 7, 1985, during the passage of a tropical wave that later became Tropical Storm Isabel. National Weather Service reported that Fiona brought 22.00 inches during the calendar day Sunday at a COOP (Adjuntas) location. Rain gauges near Ponce reported 21.09 inches and near Caguas reported 20.62 inches, respectively.
The rain gauge in Caguas recorded an astounding 27.14 inches of rain in the 24 hours ending at 10:15 a.m. Monday, which if confirmed would set a new 24-hour rainfall record for Puerto Rico.
As of 11 a.m. EDT Monday, the National Weather Service reported that three rivers in Puerto Rico were in major flood stage, and at least 10 rivers have been in major flood since Sunday, with some exceeding flood levels. their all-time records set in 2017 during Hurricane Maria.
While rain has been the main story with Fiona, the hurricane also brought strong winds that caused significant damage to trees and power lines. Winds were gusting up to 103 mph at the Ponce Yacht and Fishing Club just before 2 p.m. EDT Sunday, and up to 113 mph inland at higher elevations at Yauco in southwestern Puerto Rico.
Coming on top of ongoing problems with Puerto Rico’s power grid, Fiona’s winds and flooding are likely responsible for an island-wide power outage that began around 1 p.m. EDT Sunday. As of 10 a.m. EDT Monday, poweroutage.us was reporting that 90% of the island was still without power. Since wind damage will be less with Fiona than with Maria, power in larger cities may be restored more quickly this time, but extended outages are still quite possible, especially in remote areas where flooding will difficult to access. Approximately 25% of the island’s population was as well without wateras of 8 a.m. EDT Monday.
Severe flooding in the Dominican Republic
Overnight, Fiona raced west through the Mona Passage between Puerto Rico and the Dominican Republic, strengthening into a 90 mph hurricane before making landfall at 3:30 a.m. EDT Monday about 20 miles south- southwest of Punta Cana in the Dominican Republic. Torrential rains from Fiona began affecting the eastern Dominican Republic on Sunday night and continued into Monday afternoon, causing damaging flooding (see Tweet below from the city of Higüey).
As of 11 a.m. EDT Monday, Fiona was moving back offshore along the northeast coast of the Dominican Republic. The hurricane’s strength decreased only slightly during its landward journey, as sustained winds were still at 85 mph. More worryingly, Fiona’s widespread circulation continued to pull bands of heavy rain northward into Puerto Rico midday Monday. Rainfall totals of 8 to 16 inches Sunday through Monday morning are spread across the island, according to reports from CoCoRaHS and other sources.
Fiona is expected to become the first major Atlantic hurricane in 2022
As Fiona leaves the Caribbean and embarks on a classic repeat route, she will enter a very supportive environment for strengthening. Moderate wind shear of 15-20 knots will largely match Fiona’s movement, and the well-organized storm structure and very warm and moist low-level air should allow her to thrive despite an atmosphere of deep around that is only moderately humid (average relative humidity level of about 60 percent). Fiona will also benefit from very warm sea surface temperatures (SST) of 29-30 degrees Celsius (84-86 °F), or about 1.5 degrees Celsius (2.7 °F), warmer than average. Moreover, these warm waters lie at unusual depths with high heat content.
Two operational intensity models, HWRF and HMON, agree with statistical guidance in calling for Fiona to rapidly intensify from Monday into Tuesday. The SHIPS DTOPS tool by Monday 12Z shows a 63% chance that Fiona will gain 35 mph sustained winds by Tuesday 12Z, which would bring it to solid Category 3 (120 mph) status. HWRF and HMON also have Fiona become a major Category 3 storm by midday Tuesday, and the National Hurricane Center (NHC) forecasts Fiona to be a major storm by Wednesday 0Z.
As of midday Monday, the NHC does not explicitly forecast Fiona to reach Category 4 strength, and the storm could begin eyewall replacement cycles around midweek that prevent it from intensifying further, but both HWRF and HMON suggest that periods of Category 4 power are quite possible. . The new HAFS model agrees.
There is high confidence in Fiona’s general track, keeping the hurricane east of North America but keeping it near Bermuda late Thursday or early Friday. Despite the overall high confidence, it is still too early to know for sure whether Fiona may pass to the west, east or over Bermuda.
The latest guidance is headed for a path west of Bermuda, but potentially close enough to bring damaging winds from the hurricane’s strongest right side to the island. That said, a direct hit is still not out of the question. Given the unusually warm waters ahead of Fiona, this hurricane has the potential to produce the largest impacts on Bermuda since the west wall of Hurricane Nicole passed directly over the island in 2016 as Nicole was a Category 3 storm.
On Friday night or Saturday morning, Fiona is expected to reach Newfoundland, possibly as a storm, but more likely as a powerful, fast-moving post-tropical cyclone. Either way, Fiona will likely be near hurricane strength.
New threat approaches the Caribbean
A tropical wave about 700 miles west of the Windward Islands on Monday afternoon was moving west-west-northwest at about 10-15 mph and was producing a disorganized area of severe thunderstorms. The wave is expected to pass through the Windwards and enter the Caribbean on Thursday. This wave, with support for development from the operational GFS model and a number of members of the GFS and European model ensemble forecasts, will need to be monitored for development later this week. In its 2 p.m. EDT tropical weather forecast, the NHC gave this system a 20% chance of development, mostly between Wednesday and Saturday.
Well to the north, in the central North Atlantic, another system could briefly take on tropical characteristics in the next couple of days, but would pose no threat to land. This system has 2- and 5-day development chances of 30%, meaning the odds are low beyond Wednesday.
The next name on the Atlantic storm list is Gaston.
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