Tropical Depression 14 formed in the Bay of Campeche in the southwestern Gulf of Mexico at 11 a.m. ET on Saturday and appeared to be on the verge of developing into Hurricane Milton, which will hit the west coast of Florida on Wednesday. This situation – involving an unusual storm track, and the potential for rapid intensification – is developing rapidly and should be taken very seriously by Floridians, especially along the West Coast.
TD 14 in the formative stage
At 11 a.m. EDT on Saturday, TD 14 was located 210 miles (340 kilometers) north-northeast of Veracruz, Mexico, moving north-northeast at 3 mph (6 km/h), with maximum sustained The wind speed was 35 mph (55 km/h) and the central pressure was 1007 mb. Satellite loops and radar in Brownsville, Texas, show that TD 14 has an area of moderately severe thunderstorms with frequent rotations that are steadily growing and becoming more organized near the Texas/Mexico border The coast brings heavy rain.
Trajectory prediction for TD 14
TD 14 will be in an area of weak steering flow through Sunday, then move east-northeast to the northeast at an increasing rate under the steering influence of a northwest trough. Along this path, TD 14 is expected to make landfall on Florida's west coast on Wednesday while moving at a forward speed of about 15 mph (25 kph). This is a very unusual path for tropical cyclones: Rarely does a system form in the western Gulf of Mexico, then move eastward and make landfall on the Florida Gulf Coast as a hurricane. One of the historical analogies for October is the Category 1 hurricane that hit Tampa on October 28, 1859 (see tweet below). Given that we are now in early October rather than late October, and given that climate change has increased sea surface temperatures since the mid-1800s, the waters that TD 14 passed through were likely much warmer than the 1859 hurricane.
The models are fairly uniform, taking TD 14 to the west coast of Florida along some of the most densely populated areas between Fort Myers and Tampa Bay. Importantly, TD 14 will approach the west-southwest of Florida at a near-vertical angle, rather than the more common southerly angle approaching the west coast of Florida. Vertical approaches tend to have smaller track errors because slight changes in track are not amplified by the fact that the track is roughly parallel to the coast. However, large urban areas are spread across Florida's west coast, meaning even small orbital differences can have important local effects.
There is more uncertainty surrounding the timing of the TD 14 than its track counterpart. The five high-resolution hurricane models forecasting 6Z on Saturday have landfall times of approximately 14 hours, between 1 p.m. ET Wednesday and 3 a.m. ET Thursday. The NHC expects landfall earlier than that, around 9 a.m. ET Wednesday, but notes: “Users are cautioned not to focus on accurate forecast tracks or times at longer distances, as the NHC's 4-day average track error is approximately 150 miles (240 kilometers)”. (This may be due to timing and trajectory errors.)
Strength Forecast for TD 14
As of Tuesday, conditions are very favorable for a TD 14 intensification. Ocean temperatures in the western Gulf of Mexico hit record highs, reaching 30-31 degrees Celsius (86-88°F), about 1-2 degrees Celsius above average. In addition, large amounts of warm water extend to great depths (i.e. the ocean has a high ocean heat content). Wind shear is expected to be light, with wind speeds less than 10 knots, and the atmosphere to be very humid, with a relative humidity of mid-range 70-80%. These conditions will allow TD 14 to become Tropical Storm Milton on Sunday and Hurricane Milton on Monday.
Intensity forecasts will become more complicated on Tuesday and Wednesday when TD 14 appears in the central and eastern Gulf of Mexico. There will be a lot of dry air to the north and the storm will begin to wrap toward its core, although for now it appears wind shear will remain low and this dry air will have difficulty penetrating into the storm's core. Ocean temperatures along TD 14 will drop about one degree Celsius, but will still be strong enough to support hurricanes, and the storm will pass through an area of warm water extending to great depths – the gyre. TD 14 will pass through the same waters that Hurricane Helene passed through in late September, but Helen's passage did not cool the waters of the East Bay much because it was moving at a high speed. As TD 14 approaches Florida, it will approach an area of strong upper winds to its northeast associated with the jet stream, which will provide a very favorable upper-level outflow channel (as well as increased wind shear).
The NHC's official forecast at 11 a.m. EDT on Saturday said TD 14 would peak Wednesday morning as a Category 2 hurricane just below major hurricane strength with winds of 110 mph (175 kph). However, as the NHC points out, this forecast may be conservative, with many intensity models predicting that TD 14 will become a Category 3 or 4 hurricane (Figure 2). The DTOPS model gives a 67% chance that TD 14 will intensify to at least 75 mph (120 km/h) winds in the 72 hours ending at 8 a.m. ET Tuesday, making it 110 mph (175 km/h). km/h) for high-end Cat 2.
Florida could experience dangerous and damaging storm surges
If TD 14 hits densely populated areas of Florida as a high-end Category 2 hurricane, as current NHC forecasts indicate, storm surge damage will be in the billions of dollars and could exceed $10 billion. TD 14 is expected to be a moderate hurricane when it makes landfall, with tropical storm force winds extending up to 150 miles (240 kilometers) from the center. But large and damaging storm surges are expected as the storm will push it over large swaths of shallow water off Florida's west coast. Assuming TD 14 hits at high tide and is Category 2 intensity, water levels could be 6 feet (1.8 m) above normal dry ground along the approximately 100 miles of shoreline near TD 14 and to the right. The 20 miles of coastline traversed by the right front eyewall may experience storm surges in excess of 9 feet (2.7 m). The NHC's Category 2 hurricane storm surge risk map (Figure 3) shows areas of highest risk.
Florida faces severe flooding, strong wind threat
Forecast models show that ahead of the arrival of TD 14, moist air over Florida will trigger precursor rain events (PRE) on both sides of the Florida peninsula on Sunday and Monday — from Tampa southward on the West Coast, and from Vero Beach southward. as far south as Miami on the East Coast. TD 14 arriving on Wednesday will bring additional heavy rainfall, with 5-day rainfall totals of 6-10 inches (150-250 mm) across much of Florida.
Wind damage will also be a major issue for TD 14, and may extend quite far inland, as the system is expected to move at a fast forward speed of about 15 mph.
The first hurricane search mission into TD 14 is scheduled for early Sunday morning.
Bob Henson contributed to this article. We may not publish a new post until Sunday evening or Monday at noon, but until then we will put updates in the current post.
