[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 040838
TCDAT5

Hurricane Danielle Discussion Number  13
NWS National Hurricane Center Miami FL       AL052022
500 AM AST Sun Sep 04 2022

There has been little overall change in the satellite presentation
of Danielle overnight. Curved convective bands wrap around the
center, with a large ragged banded eye-like feature evident at
times.  There is a large range in the satellite intensity estimates
this morning with objective estimates much lower than the
subjective Dvorak T-numbers from TAFB and SAB.  Although the SAB
Dvorak estimate increased to T4.5 (77 kt) at 06Z, given the general
steady state of the system's organization since the previous
advisory, the initial intensity remains 65 kt, which is a blend of
the various estimates and is in agreement with the latest TAFB
Dvorak satellite classification.

Danielle is forecast to remain over SSTs of around 27C and in a low
shear environment during the next 24 to 36 hours.  As a result,
most of the intensity guidance calls for some intensification
during that time, and the NHC forecast follows suit.  After that
time, gradually decreasing sea surface temperatures along the
forecast track should cause slow weakening.  By days 4 and 5,
increasing shear and the system's transition into a post-tropical
cyclone are likely to cause additional weakening.  The NHC
intensity forecast is a blend of the IVCN and HFIP corrected
consensus models.

The hurricane has been meandering overnight but a slow northward
motion should begin this morning.  Danielle is forecast to
gradually accelerate to the northeast beginning on Monday as
deep-layer trough moves over eastern Canada.  By 72 hours, the
storm should turn east-northeastward within the mid-latitude
westerly flow.  The latest dynamical model guidance predicts a
slightly faster motion over much of the forecast period, and the
NHC forecast has been adjusted accordingly.  The new forecast is not
as fast as the TCVA consensus model, therefore future modifications
regarding the forward speed of the cyclone may be required.

FORECAST POSITIONS AND MAX WINDS

INIT  04/0900Z 38.1N  45.2W   65 KT  75 MPH
 12H  04/1800Z 38.5N  45.1W   70 KT  80 MPH
 24H  05/0600Z 39.2N  44.6W   75 KT  85 MPH
 36H  05/1800Z 40.3N  43.7W   80 KT  90 MPH
 48H  06/0600Z 41.2N  42.4W   75 KT  85 MPH
 60H  06/1800Z 42.1N  40.6W   75 KT  85 MPH
 72H  07/0600Z 43.1N  38.1W   70 KT  80 MPH
 96H  08/0600Z 45.3N  32.0W   60 KT  70 MPH
120H  09/0600Z 47.1N  23.7W   50 KT  60 MPH...POST-TROP/EXTRATROP

$$
Forecaster Brown
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