[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 061431
TCDAT5

Hurricane Danielle Discussion Number  22
NWS National Hurricane Center Miami FL       AL052022
300 PM GMT Tue Sep 06 2022

Danielle's overall appearance has changed little this morning. The
system remains characterized by fragmented deep convection within a
symmetrical and vertically stacked circulation. In addition, an eye
feature has remained generally identifiable in visible satellite
imagery. The latest Dvorak CI values of 4.0 from TAFB and SAB also
suggest little change in intensity, and thus the system will be kept
as a 65-kt hurricane for this advisory.

The hurricane has slowed its forward motion, and over the past 12-h
the system has been moving east-northeastward at around 5 kt.
Danielle is expected to accelerate east-northeastward tonight in the
increasing flow ahead of a digging upper-trough. This trough is
forecast to spawn a baroclinic system west of Danielle by late this
week, forcing it to make a cyclonic loop while the two systems merge
into a larger extratropical low. The merged system is then forecast
to move east-southeastward to southeastward over the weekend. There
was little change to the NHC track forecast compared to the previous
advisory.

Danielle is forecast to continue over SSTs of about 25 degrees C
over the next 12-24 h, so little change in strength is indicated
during that time. However, on Wednesday the cyclone should cross a
tight SST gradient and begin traversing over waters of 20 degrees C
or less for the remainder of the forecast period. The combination of
these cooler waters and the interaction with the baroclinic system
should cause extratropical transition to complete by Thursday. The
latest NHC intensity forecast is unchanged from the previous one,
and is close to the various multi-model consensus and SHIPS values.

Danielle is producing a large area of very rough seas over the
central-north Atlantic. Complete information on the High Seas
Forecasts can be found at the Ocean Prediction Center under AWIPS
header NFDHSFAT1, WMO header FZNT01 KWBC, and online at
ocean.weather.gov/shtml/NFDHSFAT1.php.


FORECAST POSITIONS AND MAX WINDS

INIT  06/1500Z 42.2N  41.2W   65 KT  75 MPH
 12H  07/0000Z 42.6N  39.8W   65 KT  75 MPH
 24H  07/1200Z 43.7N  37.2W   65 KT  75 MPH
 36H  08/0000Z 45.4N  34.5W   60 KT  70 MPH
 48H  08/1200Z 47.5N  32.3W   60 KT  70 MPH...POST-TROP/EXTRATROP
 60H  09/0000Z 49.5N  32.0W   55 KT  65 MPH...POST-TROP/EXTRATROP
 72H  09/1200Z 50.1N  32.8W   50 KT  60 MPH...POST-TROP/EXTRATROP
 96H  10/1200Z 48.2N  30.7W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  11/1200Z 45.5N  24.2W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$
Forecaster Latto
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