Tropical Storm Franklin A Potential Long-Range Threat Update Three

000

WTNT33 KNHC 250232

TCPAT3

BULLETIN

Tropical Storm Franklin Advisory Number  18

NWS National Hurricane Center Miami FL       AL082023

1100 PM AST Thu Aug 24 2023

...FRANKLIN FORECAST TO TURN NORTHWARD AND STRENGTHEN OVER THE

WESTERN ATLANTIC OVER THE WEEKEND...

SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION

-----------------------------------------------

LOCATION...22.6N 68.3W

ABOUT 195 MI...315 KM ENE OF GRAND TURK ISLAND

ABOUT 705 MI...1130 KM SSW OF BERMUDA

MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H

PRESENT MOVEMENT...ENE OR 70 DEGREES AT 8 MPH...13 KM/H

MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES

WATCHES AND WARNINGS

--------------------

There are no coastal watches or warnings in effect.

DISCUSSION AND OUTLOOK

----------------------

At 1100 PM AST (0300 UTC), the center of Tropical Storm Franklin was

located near latitude 22.6 North, longitude 68.3 West.  Franklin is

moving toward the east-northeast near 8 mph (13 km/h), and this 

general motion is expected to continue through late Friday.  A sharp 

turn toward the north is expected Friday night and Saturday, with a 

northward or north-northwestward motion over the western Atlantic 

continuing through early next week.

Data from an Air Force Reserve Hurricane Hunter aircraft indicate 

that maximum sustained winds remain near 60 mph (95 km/h) with 

higher gusts.  Gradual strengthening is forecast during the next 

couple of days, and Franklin is expected to become a hurricane on 

Sunday.

Tropical-storm-force winds extend outward up to 105 miles (165 km)

mainly to the east of the center.

The minimum central pressure based on dropsonde data is 1000 mb 

(29.53 inches).

HAZARDS AFFECTING LAND

----------------------

None.

NEXT ADVISORY

-------------

Next complete advisory at 500 AM AST.

$$

Forecaster Berg

000

WTNT43 KNHC 250234

TCDAT3

Tropical Storm Franklin Discussion Number  18

NWS National Hurricane Center Miami FL       AL082023

1100 PM AST Thu Aug 24 2023

Franklin is still a strongly sheared tropical storm, with deep 

convection displaced to the east and southeast of the surface 

center.  An Air Force Reserve Hurricane Hunter mission flying at 

700 mb this evening fixed a center within the strong thunderstorm 

activity, but because of the cyclone's tilted structure, the 

surface center is estimated to be a few tenths of a degree farther 

west.  SFMR and flight-level winds suggest that the maximum winds 

could be between 50-55 kt, but the central pressure has risen a few 

millibars since this morning's flight.  Therefore, the initial 

intensity is held at 50 kt.

Franklin is embedded in the base of a deep-layer trough located 

over the western Atlantic, which is steering the storm toward the 

east-northeast (70 degrees) at 7 kt.  The parent trough is forecast 

to lift northeastward and allow mid-level ridging to build over the 

central Atlantic during the next couple of days, and Franklin is 

expected to respond by making a sharp but slow northward turn by 36 

hours.  The ridge could even be strong enough to push Franklin 

toward the north-northwest for a time while the storm moves across 

the western Atlantic, and the HAFS regional models in particular 

favor that scenario, being the westernmost of the guidance suite.  

Those models have tugged the consensus aids a bit west too, and as 

a result the new NHC forecast track is nudged in that direction 

compared to the previous forecast.

Moderate to strong deep-layer shear is likely to continue over 

Franklin for the next 36-48 hours, until the storm makes its 

northward turn.  That said, warm ocean waters and a favorably 

diffluent upper-level pattern should still allow for gradual 

strengthening during the next couple of days, and Franklin is 

expected to become a hurricane by 48 hours, about the time the shear 

abates.  More significant strengthening is likely after 48 hours 

while Franklin moves over the western Atlantic, and the NHC 

intensity forecast remains close to the HCCA and IVCN consensus 

aids.  The HAFS regional models continue to show stronger solutions, 

so trends in the other models will have to be monitored for 

potential upward adjustments to the official forecast in the coming 

days.

FORECAST POSITIONS AND MAX WINDS

INIT  25/0300Z 22.6N  68.3W   50 KT  60 MPH

 12H  25/1200Z 22.9N  67.5W   50 KT  60 MPH

 24H  26/0000Z 23.2N  66.7W   55 KT  65 MPH

 36H  26/1200Z 23.7N  66.6W   60 KT  70 MPH

 48H  27/0000Z 24.8N  67.0W   65 KT  75 MPH

 60H  27/1200Z 26.1N  67.7W   75 KT  85 MPH

 72H  28/0000Z 27.8N  68.1W   90 KT 105 MPH

 96H  29/0000Z 31.9N  68.2W   95 KT 110 MPH

120H  30/0000Z 37.1N  65.6W   85 KT 100 MPH

$$

Forecaster Berg