Tropical storm warnings have been issued for the northern Leeward Islands – including Saba and St. Thursday afternoon or evening. Existing watches will likely be upgraded to warnings as the 50 mph storm churns west at 14 mph. How a Pacific hurricane could help fight California wildfires Winds up to tropical storms will likely reach there starting Friday night and will bring heavy rainfall of 3 to 6 inches. After passing near or over Puerto Rico, Fiona appears to curve northward, so a puzzle of uncertain atmospheric components will play a West vs. East tug-of-war to determine where it will eventually go. Fiona is the sixth named storm of what has so far been a relatively quiet Atlantic hurricane season. The Atlantic basin is running at about 47.4 percent of the average for ACE, or accumulated cyclone energy — a measure of overall storm activity. According to hurricane researcher Philip Klotzbach, it’s the slowest start to a season since 2014, defying experts’ predictions for a particularly active 2022 season. By comparison, the hyperactive 2021 season had already spawned 20 named storms and was on the verge of immerse yourself in the Greek alphabet. From 11 am eastern time Thursday, Fiona’s center was about 495 miles east of the Leeward Islands and moving west at a typical rate. This westward movement is expected to continue through Friday, when Fiona will affect the islands and Puerto Rico. Maximum sustained winds were estimated at 50 mph, and the National Hurricane Center expects slight strengthening to a 55 mph storm. A plateau in intensity is then expected as it continues west. The agency asked ships within 300 miles of the storm’s location to record and submit weather observations every three hours, which will help with forecasting and modeling efforts. An Air Force Hurricane Hunter plane will be dispatched to survey the storm later Thursday. In infrared satellite imagery, Fiona is filled with deep convection or shower and thunderstorm activity. This is evidenced by the darker reds and whites, indicative of high, cold cloud tops. But the bulk of the storm is shifting to the east of the low-level circulation – notice the low-level plume spiraling in the center in white, which is hidden by higher clouds to the east. This lack of vertical alignment of the system is the result of wind shear from west to northwest, or a change in wind speed and/or direction with altitude. She hits the standby system and until she can stack better vertically, Fiona will struggle to step up. No strengthening is expected in the near term as the shear does not appear to be easing any time soon. Ultimately, the low-level center may stretch if a storm and associated updraft pass over the vortex in question, but it remains to be seen if this will happen before arrival in Puerto Rico. Fiona is expected to affect the northern Leeward Islands beginning late Friday, and its core should cross the archipelago sometime early Saturday. A total of 3 to 6 inches of rain is expected, with locally higher amounts possible. Showers with winds approaching 50 to 60 mph are also possible, along with dangerous coastal currents. From there, the US model (GFS) hints that Fiona could track north of Puerto Rico while still skirting the northeastern margin of the US territory. In contrast, the European model simulates a track south of Puerto Rico and eventually into Hispaniola. This could reduce the circulation of the storm before it emerges over the waters of the southeastern Bahamas. The storm’s torrential rains over the Dominican Republic and Haiti could well lead to flooding and mudslides, especially in mountainous areas where double-digit rainfall totals are possible. The Hurricane Center’s forecast for Fiona’s track splits the difference between US and European models, calling for a track over Puerto Rico before Fiona navigates Mona Passage west of the island and east of Hispaniola as it begins a northward curve. The absolute wild card, and therefore the different track scenarios, is when this right turn to the north will take place, which depends on the strength and location of the high pressure in the northeast. This tall one acts as a guard rail. Eventually, Fiona will head north, where, if it avoids land and its inner core remains intact, it could begin to intensify over the next five to seven days. Some computer model simulations predict it will pass ominously close to the Eastern Seaboard, move west of the Bermuda High and drift further inshore approaching low pressure in an attempt to capture it. Other models allow him to escape into the sea, which would pose a greater risk to Bermuda. All in all, it’s just too early to tell — but this is something you’ll want to keep a close eye on.
