[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 262044
TCDAT3

Hurricane Franklin Discussion Number  25
NWS National Hurricane Center Miami FL       AL082023
500 PM AST Sat Aug 26 2023


Visible and microwave satellite imagery show Franklin is becoming a
well organized hurricane. AMSR2 microwave data showed a closed
mid-level core that was vertically aligned with the low-level
center. The latest visible imagery shows a dimple where an eye may
be trying to develop. Deep convection has become more symmetrical,
wrapping around the center throughout the day. NOAA Hurricane
Hunters were in the system earlier this afternoon, with flight-level
winds and SFMR winds supporting an intensity of around 70 kt. The
UW-CIMSS ADT objective satellite estimates have been rising this
afternoon as well. Given the improved satellite structure combined
with the earlier data from the NOAA Hurricane Hunters, the initial
intensity is raised to 75 kt for this advisory. NOAA and Air Force
Hurricane Hunters will be in the system later this evening.

Franklin is moving north-northwestward at 7 kt.  A
north-northwestward to northward motion is forecast during the next
few days as the storm moves along the western periphery of a
mid-level ridge, taking it to the west of Bermuda on Tuesday.  By
the middle of next week, a faster northeast to east-northeast motion
is expected between the ridge and a mid- to upper-level trough over
eastern Canada and the northeastern United States. In the short
range, models once again have trended westward, and the official NHC
forecast has been nudged west as well. For the long term, models,
including the GFS and ECMWF, have made a fairly large shift to the
right. The NHC track was shifted in that direction in the long term,
but remains to the left of the consensus aids. The confidence of the
long-term forecast track is lower than usual.

Franklin has been steadily strengthening throughout the day. Further
strengthening is forecast during the next few days with lower
vertical wind shear and warm sea surface temperatures in the western
Atlantic. Franklin is forecast to become a major hurricane early
next week. The strengthening trend should end in about 3 to 4 days
with shear expected to increase over the system at that time. By day
5, the current forecast track takes the system over much cooler
SSTs. However, the intensity in the long range will be dependent on
the eventual forecast track of Franklin. The current intensity
forecast lies near the consensus aids, but still slightly lower than
the HCCA aid.


FORECAST POSITIONS AND MAX WINDS

INIT  26/2100Z 23.8N  67.5W   75 KT  85 MPH
 12H  27/0600Z 24.7N  68.1W   85 KT 100 MPH
 24H  27/1800Z 25.9N  68.9W   95 KT 110 MPH
 36H  28/0600Z 27.1N  69.6W  105 KT 120 MPH
 48H  28/1800Z 28.7N  69.9W  110 KT 125 MPH
 60H  29/0600Z 30.3N  69.9W  110 KT 125 MPH
 72H  29/1800Z 32.0N  69.4W  105 KT 120 MPH
 96H  30/1800Z 35.2N  65.6W   90 KT 105 MPH
120H  31/1800Z 39.1N  56.5W   75 KT  85 MPH

$$
Forecaster Kelly/Pasch
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