Tropical Update 11 AM EDT Thursday, September 6, 2018 Tropical Depression Gordon, Hurricane Florence, Invest 92L (90%) & African Tropical Wave (50%)

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1 Tropical Update 11 AM EDT Thursday, September 6, 2018 Tropical Depression Gordon, Hurricane Florence, Invest 92L (90%) & African Tropical Wave (50%) This update is intended for government and emergency response officials, and is provided for informational and situational awareness purposes only. Forecast conditions are subject to change based on a variety of environmental factors. For additional information, or for any life safety concerns with an active weather event please contact your County Emergency Management or Public Safety Office, local National Weather Service forecast office or visit the National Hurricane Center website at

2 Atlantic Basin Satellite Image

3 The National Hurricane Center is issuing advisories on Hurricane Florence, located over the central subtropical Atlantic. The Weather Prediction Center is issuing advisories on Tropical Depression Gordon, located near the Mississippi-Arkansas border. A broad and elongated area of low pressure is centered several hundred miles west-southwest of the Cabo Verde Islands. Environmental conditions are conducive for development, and a tropical depression is expected to form within the next few days while the system moves slowly westward or west-northwestward across the tropical Atlantic Ocean. Formation chance through 48 hours: high (70%) Formation chance through 5 days: high (90%) A tropical wave is forecast to move off the west coast of Africa on Friday. Some development of this system is anticipated after that time, and a tropical depression could form over the weekend or early next week while the wave moves westward or west-northwestward over the far eastern tropical Atlantic Ocean. Formation chance through 48 hours: low (10%) Formation chance through 5 days: medium (50%)

4 Hurricane Florence Satellite Image Florence was a powerful Category 4 Hurricane yesterday, but strong southwesterly shear has taken its toll. Florence is now much less organized and weaker.

5 Florence will weaken further, turn toward the westnorthwest, and slow over down the next over 5 days. the next couple Little to no change is strength is forecast days. Restrengthening is expected later this weekend and early next week.

6 Track Models (Florence) Florence will move generally west-northwest this week, but computer models are still highly divergent on the eventual track beyond 3-5 days. A weaker Florence would generally move more westward, but a stronger Florence would favor a recurve.

7 Weakening is forecast through the next 2 days, but Florence should regain some strength again later this weekend into early next week.

8 Invest 92L Satellite Image 92L has not become better organized since yesterday, and the system still lacks a well-defined center.

9 92L is forecast to move west-northwestward for the next 5-7 days. Any track forecasts beyond this point may be unreliable and subject to changes.

10 92L could reach tropical storm strength in 2-3 days if it becomes organized sooner rather than later.

11 Tropical Wave Satellite Image A tropical wave near the west coast of Africa is currently disorganized, but it could develop once it emerges into the eastern tropical Atlantic. The Cabo Verde Islands could see impacts this weekend.

12 Tropical Wave Ensemble Models Once the tropical wave moves off the coast of Africa, it could develop into a tropical depression or tropical storm. The National Hurricane Center gives this system a 50% chance of formation over the next 5 days. Impacts to the Cabo Verde Island are possible this weekend. The general track will be to the west-northwest over the next 5 days.

13 TD Gordon Satellite Image Gordon is a much weaker tropical depression slowly meandering near the Mississippi- Alabama border.

14 Gordon (or its remnants) will slowly move across Arkansas over the next couple days before being swept to the northeast by a front.

15 Some Panhandle rivers rose as a result of Gordon s rainfall. The Styx River in southwest Alabama rose to major flood stage. However, the only Panhandle river that rose to minor flood stage is the Perdido River near Barrineau Park. Several other West Central Florida rivers remain in minor flood stage.

16 Rip Current Forecast Today

17 Summary Tropical Depression Gordon is centered over southeastern Arkansas with maximum sustained winds of 25 mph. Gordon will continue moving west-northwest across Arkansas today before turning north and northeast over the weekend while weakening and getting absorbed by a frontal system. At 11 AM EDT Thursday, Hurricane Florence was located in the central Atlantic Ocean about 1,015 miles northeast of the Windward Islands, or approximately 1,975 miles east of Miami, Florida. Maximum sustained winds have decreased to near 105 mph, making Florence a Category 2 on the Saffir-Simpson Hurricane Wind Scale. Some additional weakening is possible through the weekend due to wind shear influences, but Florence will remain a hurricane through the next 5 days and may regain major hurricane status early next week. Florence is currently moving northwest near 10 mph, but a westward motion is forecast for the next 2-3 days, followed by a turn back to the west-northwest or northwest next week. Beyond 4-5 days, there is large disagreement in the computer models on the eventual track of Florence, and is dependent on the strength of Florence as well as forecast steering currents. Invest 92L is located in the eastern Atlantic Ocean about 400 hundred miles southwest of the Cabo Verde Islands. There is not yet a defined center of circulation, but environmental conditions are favorable for development. The National Hurricane Center, as well as many computer models, are giving 92L a 70% (high) chance of becoming a tropical depression within the next 48 hours, and a 90% (high) chance of becoming a tropical depression or storm in 3-5 days. Some models even predict 92L could become a hurricane within 3-5 days. 92L is forecast to continue moving slowly west or west-northwest across the eastern and central tropical Atlantic through the next 5-7 days. Farther east, a tropical wave is expected to move off the west coast of Africa tomorrow. Some development of this wave is possible over the weekend, with a better chance of development next week as it moves west to westnorthwest over the far eastern Atlantic. The National Hurricane Center is currently giving this system a 10% (low) chance of formation within the next 2 days, but a 50% (medium) chance of becoming a depression or tropical storm in 3-5 days. The next names on the 2018 storm list are Helene and Isaac.

18 Florida Outlook: In the wake of Gordon, river rises are occurring along many western Panhandle rivers. Only the Perdido River is experiencing minor flooding and no significant impacts are anticipated. Rivers should crest between today and Saturday and recede next week. Residual ocean swells over the Gulf will result in a moderate to high risk of rip currents for all Panhandle beaches for the next few days. Given the large uncertainty in Florence s track beyond 5 days, it is too soon to speculate what, if any, direct impacts Florence may have on the Florida or U.S. East Coast next week. Regardless of Florence's eventual track, large swells emanating from the hurricane will reach portions of the U.S. East Coast (including Florida) this weekend, resulting in life-threatening rip currents. It is also too early to tell if the systems near Africa will have any impact on Florida. Another briefing packet will be issued late Friday morning. For the latest information on the tropics, please visit the National Hurricane Center website at

19 Tropical Update Created by: Amy Godsey, Chief State Meteorologist Cameron Young, Assistant State Meteorologist State Meteorological Support Unit Florida Division of Emergency Management Users wishing to subscribe (approval pending) to this distribution list, register at _Tropics. Other reports available for subscription are available at