Tropical Storm JULIAN Advisory 8月30日

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Tropical Storm Julian Discussion Number   4
NWS National Hurricane Center Miami FL       AL112021
900 PM GMT Sun Aug 29 2021

The convective pattern and structure of Julian has remained
consistent throughout today, with the low-level center remaining
tucked under the southwestern edge of a deep convective mass and
good outflow in the northeastern semicircle. A late morning ASCAT-C
overpass sampled peak winds of 45 to 47 kt, and since the cyclone
has likely intensified slightly since that time, the initial
intensity has been increased to 50 kt.

Julian is now moving quickly to the northeast, or 050/21 kt in
southwesterly flow to the south of a deep-layer area of low pressure
located just east of Newfoundland. The storm is forecast to continue
to move northeastward at a similar forward speed through Monday, and
then begin to turn northward then northwestward Monday night through
Tuesday as the cyclone moves around the periphery of the larger low.
The model track guidance continues to be in excellent agreement on
this scenario, and the latest NHC track forecast is little changed
from the previous one.

A cold front associated with the low east of Newfoundland has
already begun to interact with the circulation of Julian, as noted
by dry air being pulled into the southern portion of the
circulation, and linear banding developing to the south of the
cyclone. Baroclinic forcing could allow for some slight additional
strengthening through tonight. However, Julian should cross the 26 C
isotherm this evening, and reach waters of 22 C by 24 h while
interacting with the cold front and associated mid- to upper level
trough to its north. These factors should cause the cyclone to go
through extratropical transition tonight through tomorrow morning,
with the transition complete by late tomorrow. The latest SHIPS
guidance as well as the FSU phase-space diagrams depict this
transition scenario. Once extratropical, the system should dissipate
within a couple of days over the north Atlantic. The latest NHC
intensity forecast was essentially an update of the previous one,
and is close to the HCCA and IVCN solutions.


FORECAST POSITIONS AND MAX WINDS

INIT  29/2100Z 36.7N  44.6W   50 KT  60 MPH
 12H  30/0600Z 38.8N  41.4W   55 KT  65 MPH
 24H  30/1800Z 42.2N  38.1W   55 KT  65 MPH...POST-TROP/EXTRATROP
 36H  31/0600Z 46.3N  36.8W   50 KT  60 MPH...POST-TROP/EXTRATROP
 48H  31/1800Z 51.0N  37.7W   45 KT  50 MPH...POST-TROP/EXTRATROP
 60H  01/0600Z 55.0N  39.6W   40 KT  45 MPH...POST-TROP/EXTRATROP
 72H  01/1800Z...DISSIPATED

$$
Forecaster Latto