[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 062040
TCDAT5

Hurricane Danielle Discussion Number  23
NWS National Hurricane Center Miami FL       AL052022
900 PM GMT Tue Sep 06 2022

Danielle is holding its own over the north-central Atlantic. The
cyclone's structure has stabilized since early this morning and the
cloud tops have been cooling slightly over the past several hours,
suggesting that any weakening that had been occurring overnight has
temporarily ended. The initial intensity is being held at 65 kt for
this advisory, which is based on the latest subjective Dvorak
intensity estimate from SAB, and objective data from UW-CIMSS.

The hurricane continues to move slowly east-northeastward, or 070/6
kt. There is no change to the forecast track reasoning. Danielle is
expected to accelerate east-northeastward tonight in the increasing
flow ahead of a digging upper-level 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
were no significant changes to the NHC track forecast compared to
the previous advisory, as model guidance remains in good agreement.

Danielle is forecast to continue over SSTs of about 25 degrees C
over the next 18-24 h, so only minor fluctuations in strength is
indicated during that time. However, by late 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 closely follows the
latest multi-model consensus.

Danielle is producing a large area of very rough seas over the
central-north Atlantic. More information can be found in the
High Seas Forecasts issued by 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  06/2100Z 42.5N  40.3W   65 KT  75 MPH
 12H  07/0600Z 43.1N  38.6W   65 KT  75 MPH
 24H  07/1800Z 44.6N  35.9W   65 KT  75 MPH
 36H  08/0600Z 46.5N  33.2W   60 KT  70 MPH
 48H  08/1800Z 48.8N  31.9W   55 KT  65 MPH...POST-TROP/EXTRATROP
 60H  09/0600Z 50.3N  32.6W   50 KT  60 MPH...POST-TROP/EXTRATROP
 72H  09/1800Z 50.0N  33.6W   45 KT  50 MPH...POST-TROP/EXTRATROP
 96H  10/1800Z 47.1N  29.4W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  11/1800Z 44.1N  22.0W   35 KT  40 MPH...POST-TROP/EXTRATROP

$$
Forecaster Latto
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