Atlantic Basin Tropical Cyclones

Tropical Storm Julia Forecast Discussion

WTNT43 KNHC 072031

Tropical Storm Julia Discussion Number   6
NWS National Hurricane Center Miami FL       AL132022
500 PM EDT Fri Oct 07 2022

Julia's low-level center has been exposed for much of the day, 
after the burst of deep convection from this morning was stripped 
away by northerly shear.  Convective cells have been regenerating 
in the proximity of the center, but much of the activity still 
lacks organization due to the shear.  This morning's Air Force 
Reserve reconnaissance mission measured a peak 925-mb flight-level 
wind of 50 kt, which reduces to an intensity between 35 and 40 kt.  
Given that the pressure did not drop, and the convection has not 
increased in organization, the initial intensity remains 35 kt.

Julia has gained some latitude today, but overall it's moving 
quickly toward the west, or 280/16 kt, to the south of strong 
mid-level ridging.  The storm has been moving a little faster than 
was forecast during the past day or so, and global model guidance 
suggests that the current speeds should be maintained for the next 
12-24 hours.  Some deceleration is expected as Julia approaches the 
coast of Nicaragua, but because the storm has been moving faster 
than expected, it's now forecast to reach the coast of Nicaragua 
early Sunday morning.  The updated NHC prediction lies very near or 
along this morning's forecast, but it's just a little faster to 
account for recent models trends.

Shear guidance from SHIPS and the GFS insists that the 
north-northwesterly shear affecting Julia should abate soon, or at 
least take on a more easterly component during the next day or so, 
which should favor more intensification.  Ocean waters will also be 
plenty warm, and upper-level divergence over the system may 
increase as well.  The NHC intensity forecast most closely follows 
a blend of the SHIPS guidance and the HCCA consensus aid, showing 
Julia reaching hurricane strength by 36 hours, about the time it 
passes the Colombian islands offshore of Nicaragua.  Even though 65 
kt is the peak intensity shown in the forecast, additional 
strengthening beyond that value is possible before Julia reaches 
the coast of Nicaragua.

Julia is now expected to dissipate over Central America by Monday 
(72 hours).  Various model solutions depict Julia's leftover 
vorticity moving over the eastern Pacific waters, over the Bay of 
Campeche, or both after that time, but it is 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.


INIT  07/2100Z 13.0N  74.7W   35 KT  40 MPH
 12H  08/0600Z 13.1N  77.3W   45 KT  50 MPH
 24H  08/1800Z 13.0N  80.1W   55 KT  65 MPH
 36H  09/0600Z 13.0N  82.5W   65 KT  75 MPH
 48H  09/1800Z 13.2N  85.0W   50 KT  60 MPH...INLAND
 60H  10/0600Z 13.5N  87.5W   30 KT  35 MPH...INLAND
 72H  10/1800Z 14.3N  89.8W   25 KT  30 MPH...POST-TROP/INLAND
 96H  11/1800Z...DISSIPATED

Forecaster Berg

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