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Tropical Disturbance 98L: Why it matters to the Big Bend

Satellite image  "Tropical Depression Nine"  (11am 09/23/2022)
Posted at 2:04 PM, Sep 20, 2022
and last updated 2022-09-23 06:19:45-04

TALLAHASSEE, Fla. (WTXL) — UPDATE: 9/23 (5 AM)
Thunderstorm activity has increased with Invest 98-L with more organization and strengthening signs showing up early Friday morning.

The increase in strength also comes with an increase in strength which now means Invest 98-L has been upgraded to Tropical Depression Nine.

For the latest updates and tracks please visit the new ongoing article that includes tracks, speeds, and latest updates with this storm.

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First to Know: Tropical disturbance "98L" outlook (09/22/2022)

A lot of attention is being paid to an unnamed, disorganized tropical disturbance currently dubbed "Invest 98L" that's been straddling the northern shores of South America and just less than 2,000 miles from the Big Bend region. And rightfully so:

  • We're still in an active phase of the hurricane season, based on historical record.
  • Water temperatures in the Caribbean and Gulf are well into the middle 80s, thanks to a lack of systems moving over those waters in recent weeks.
  • The National Hurricane Center highlights the disturbance having a high chance to become a tropical depression in five days or less.
  • Forecast indicators are strongly suggesting the development of a tropical storm, which has room and conditions for it to eventually become a hurricane.
  • Caribbean tropical cyclones have an overall higher chance to affect the Gulf region compared to Atlantic-based systems like Hurricane Fiona.
Disturbance 98L strengthening factors (09/22/2022)
Disturbance 98L strengthening factors (09/22/2022)

Water temperatures in the central and western Caribbean, as well as the eastern Gulf, are among the highest in the entire Atlantic basin. Warm water provides the fuel that supports the growth and strength of tropical storms and hurricanes. Additionally, the upper-level wind pattern is light and weak, meaning the structure of the storm/hurricane can be strong enough to sustain a rapid strengthening trend.

Despite long-range forecast model evidence suggesting a hurricane in the Gulf next week, there are still no foregone conclusions to be made at this time about where a possible hurricane will go. But, the local pattern next week can give us some rough insight into factors that might play into a tropical scenario for the Gulf states and the Big Bend.

98L steering factors map (09/22/2022)
98L steering factors map (09/22/2022)

The First to Know Weather Team will be watching very keenly a series of troughs, or upper-level low pressure areas, that are being shown to bring a couple of cold fronts into the state line area. One of these fronts is poised to affect our area Friday, and another one around next Monday or Tuesday. These fronts (troughs) will break the high-pressure systems that will steer the disturbance and create a weakness in the atmosphere in which the theoretical tropical system may turn toward.

Tropical cyclones go toward a path of least resistance. High-pressure zones force tropical lows to move around the edge of the high, and toward areas of general lower pressure. Fronts can create this zone of lower pressure.

If the cold fronts over the weekend and early next week are strong enough to push through the Big Bend region, with a high-pressure system coming in behind it over Georgia, this setup can cause the tropical low to curve more to the north or northeast sooner, which can bring yet-unspecified effects for Cuba and/or the Florida peninsula. A very strong high could even keep the tropical system on a more westerly course, but based on forecast trends over the last few days, this would be a less-likely (but not impossible) situation to unfold.

If the state line cold front systems are weaker or don't clearly pass through early next week, this can cause the weakness created by the front to linger across the northern Gulf coast and cause a delayed turn to the north of the potential tropical system, stretching its time over the very warm Gulf waters.

Disturbance 98L path factors (09/22/2022)
Disturbance 98L path factors (09/22/2022)

When the disturbance becomes better formed, the location of the center of the eventual tropical depression will also play a role in its future path. A central low situated farther south (or closer to South America) can cause a delay in that anticipated northerly turn.

Again, we can't say at this time precisely which situation will play out. There are several other factors to consider, and the time frame of any potential storm impacts (middle to end of next week) is still beyond the reliable time frame to make a definitive call on an outcome. But the ultimate position strength of the early-week cold front will be a key factor in where the likely hurricane can go.

The prudent course of action for folks in the Big Bend/southern Georgia region, as well as all of the Gulf coast states and Florida, is to assess readiness for the remainder of the hurricane season, and stay updated with reliable and credible sources of forecast information.

The First to Know Weather team will help you stay in the know with all the important updates and forecasts regarding this disturbance and implications on the local weather situation in the days ahead.