Official Discussion issued by the National Hurricane Center

Franklin (AL082023) DATA RELEASED: 8/27/2023 3:00:00 AM UTC

Copy of official data

Hurricane Franklin Discussion Number  26
NWS National Hurricane Center Miami FL       AL082023
1100 PM AST Sat Aug 26 2023

The eye of Franklin has been obscured in conventional satellite 
imagery by deep convective bursts within its southern eyewall during 
the past several hours. At times, there has been some disruption of 
the inner core convection by drier air wrapping around the eastern 
and northern portions of the circulation. Both the Air Force and 
NOAA Hurricane Hunters investigated Franklin tonight and provided 
useful data to analyze the storm. Tail Doppler radar data from the 
NOAA aircraft reveal better vertical alignment of Franklin's vortex, 
although there is still a bit of tilt with height. Peak SFMR wind 
retrievals from both aircraft support an initial intensity of 75 kt, 
and the latest dropsonde data indicate the surface pressure has 
fallen to 975 mb. 

Conditions appear favorable for some significant strengthening of 
Franklin during the next couple of days. The deep-layer shear is 
forecast to continue decreasing over the cyclone while it traverses 
very warm SSTs greater than 29 deg C. The hurricane could be prone 
to more rapid fluctuations in intensity given its small inner core, 
and some of the rapid intensification (RI) guidance, particularly 
DTOPS, suggests there are well above average chances that Franklin 
could undergo RI during the next 48 h. Thus, the updated intensity 
forecast is raised in the near term, bringing Franklin to major 
hurricane strength in 24 h with a peak intensity of 115 kt on 
Monday. This lies near HCCA and IVCN, but below some of the regional 
hurricane models (HAFS and COAMPS-TC). Weakening is forecast at 
days 4 and 5 as Franklin encounters increased shear over cooler 
SSTs, but its wind field is expected to grow as it moves deeper into 
the mid-latitudes.

The aircraft fixes indicate Franklin has continued to deviate left 
of the forecast track, and its initial motion is northwestward at 7 
kt. The near-term track forecast has been adjusted west of the 
previous one based on Franklin's continued northwestward motion. A 
broad high pressure ridge to the east of Franklin should steer the 
hurricane more north-northwestward and northward during the next 
couple of days. Later in the period, a deep-layer trough is expected 
to move off the U.S. east coast, and most global models (except the 
ECMWF) show Franklin becoming captured within the southwesterly flow 
ahead of the trough and accelerating northeastward. The NHC forecast 
track still shows the core of Franklin passing west and north of 
Bermuda, but interests there should continue to monitor the latest 
NHC forecast updates. By day 5, interaction with the upper trough 
could bring about the start of extratropical transition.  


INIT  27/0300Z 23.9N  68.2W   75 KT  85 MPH
12H  27/1200Z 24.9N  68.9W   85 KT 100 MPH
24H  28/0000Z 26.2N  69.8W  100 KT 115 MPH
36H  28/1200Z 27.6N  70.4W  110 KT 125 MPH
48H  29/0000Z 29.2N  70.4W  115 KT 130 MPH
60H  29/1200Z 30.8N  69.9W  115 KT 130 MPH
72H  30/0000Z 32.5N  68.9W  105 KT 120 MPH
96H  31/0000Z 35.8N  63.7W   90 KT 105 MPH
120H  01/0000Z 41.0N  52.5W   75 KT  85 MPH

Forecaster Reinhart