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Tropical Storm Julia Forecast Discussion


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WTNT43 KNHC 080240
TCDAT3

Tropical Storm Julia Discussion Number   7
NWS National Hurricane Center Miami FL       AL132022
1100 PM EDT Fri Oct 07 2022

Satellite imagery indicates Julia has become somewhat better 
organized during the past several hours, with the development of a 
central convective burst with cloud top temperatures colder than 
-80C and several outer bands appearing.  Reports from NOAA and Air 
Force Reserve Hurricane Hunter aircraft show this has resulted in 
some strengthening, with the maximum sustained winds near 40 kt and 
the minimum pressure near 999 mb.  However, the aircraft data show 
that Julia is still disorganized.  The 850-mb circulation is weak 
in the southwestern quadrant, and the 700-mb center is notably 
south of the 850-mb and surface centers.

The surface center is a little to the south of the previous advisory 
position, possibly due to reformation caused by the convective 
burst.  The initial motion is westward or 270/15 kt.  The guidance 
suggests that a quick westward motion should persist for the next 
24-36 h or so as the storm is steered by a strong low- to mid-level 
ridge to the north.  This motion should bring the center near San 
Andres and Providencia Islands in about 24 h and to the coast of 
Nicaragua in about 36 h.  A slower westward motion is expected after 
landfall, followed by a turn toward the west-northwest starting at 
about 48 h.  This motion should continue until the system 
dissipates.  The new official track forecast is a little to the 
south of the previous forecast based mainly on the current initial 
position, and it lies near the various consensus models.

The vertical wind shear over Julia is decreasing, and the 
environment is becoming favorable for steady to rapid 
intensification once the cyclone becomes organized enough to take 
advantage of it. Based on the trend of the intensity guidance and 
the SHIPS rapid intensification indices, the new intensity forecast 
calls for Julia to be near hurricane strength when it passes near 
San Andres and Providencia, and for it to reach a peak intensity of 
70 kt at landfall in Nicaragua.  After landfall, the cyclone is 
expected to rapidly weaken over the rugged terrain of Central 
America, with the surface center dissipating between 72-96 h.

Although Julia is expected to dissipate over Central America by 
Monday night, various model solutions depict Julia's leftover 
vorticity moving over the eastern Pacific waters, over the Bay of 
Campeche, or both after that time.  However, it is still unclear at 
this time if that will lead to genesis of a new tropical cyclone.  
We'll continue to monitor model trends and update the forecast as 
needed.  Regardless of new development, the set up is likely to lead 
to heavy rains over Central America for several days, which could 
cause life-threatening flash floods and mudslides, especially in 
areas of mountainous terrain.


Key Messages:

1. Julia is forecast to strengthen into a hurricane by Saturday
evening or Saturday night while it moves over the southwestern
Caribbean Sea, and a Hurricane Warning is in effect for portions of
the Nicaragua coast and the offshore Colombian islands.
Hurricane-force winds and a dangerous storm surge are expected in
areas where the core of the system crosses the islands and moves
onshore in Nicaragua.

2. Life-threatening flash flooding and mudslides are expected across
portions of Central America this weekend.


FORECAST POSITIONS AND MAX WINDS

INIT  08/0300Z 12.8N  76.1W   40 KT  45 MPH
 12H  08/1200Z 12.8N  78.7W   50 KT  60 MPH
 24H  09/0000Z 12.7N  81.5W   60 KT  70 MPH
 36H  09/1200Z 12.8N  83.7W   70 KT  80 MPH...INLAND
 48H  10/0000Z 13.1N  86.1W   45 KT  50 MPH...INLAND
 60H  10/1200Z 13.6N  88.5W   30 KT  35 MPH...INLAND
 72H  11/0000Z 14.4N  90.9W   25 KT  30 MPH...POST-TROP/INLAND
 96H  12/0000Z...DISSIPATED

$$
Forecaster Beven



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