[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 090851
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Hurricane Julia Discussion Number  12
NWS National Hurricane Center Miami FL       AL132022
500 AM EDT Sun Oct 09 2022

Julia is estimated to have made landfall as a 75-kt hurricane around
0715 UTC along the coast of Nicaragua near Pearl Lagoon. The
hurricane appeared to strengthen through landfall, with a more
well-defined inner core noted in passive microwave imagery and a
center that was embedded deep within the very cold central dense
overcast overnight. With the center now located just inland over
eastern Nicaragua, the initial intensity is held at 75 kt for this
advisory, which is supported by the last ADT estimate from UW-CIMSS
(75 kt) and the 06 UTC Dvorak estimate from SAB (77 kt).

Julia is moving westward at about 14 kt, and a strong ridge that
extends across the southern Gulf of Mexico will continue to steer
Julia quickly westward across Nicaragua today. The center of the
cyclone is forecast to emerge over the eastern Pacific waters this
evening or tonight and then move westward or west-northwestward near
the Pacific coast of El Salvador and Guatemala on Monday. There is
still above average uncertainty in this part of the forecast. While
some models (ECMWF, HWRF, HMON) have trended closer to the coast and
even show Julia moving inland, the UKMET lies on the southern edge
of the envelope and keeps Julia farther offshore. The GFS is
somewhere in the middle, generally showing the vortex skirting the
coast. The NHC track forecast has been adjusted to the north of the
previous one at 36-48 h, in line with the majority of the models.

Land interaction should result in considerable weakening of Julia
during the next 12 h or so. However, the fast forward motion is
forecast to keep the surface circulation intact, and various models
indicate the cyclone will maintain enough organization to remain a
tropical storm as it moves off the Pacific coast of Nicaragua later
today. The NHC forecast track keeps the center near the coast, where
the topography of Central America could further disrupt its
low-level structure. The models also indicate that deep-layer
easterly shear may increase over the cyclone during the next 24-36
h. Based on these factors, the official NHC forecast shows Julia
gradually weakening on Monday and then dissipating on Tuesday. If
the track deviates farther north as suggested by some of the models,
Julia could move inland and dissipate even sooner than forecast.

Regardless of Julia's track and future status as a tropical cyclone,
the evolving weather pattern 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. Hurricane-force winds and a dangerous storm surge are occurring
along portions of the coast of Nicaragua where the core of Julia
made landfall this morning.

2. Life-threatening flash flooding and mudslides are expected across
portions of Central America Sunday and Monday. Flash flooding is
anticipated across the Isthmus of Tehuantepec in Mexico early this
week.

3. Julia is forecast to remain as a tropical storm while it moves
across Central America to the adjacent Pacific waters, and tropical
storm warnings are in effect along the Pacific coasts of Nicaragua,
Honduras, and El Salvador to account for the possibility of
tropical-storm-force winds in those areas later today through
Monday.


FORECAST POSITIONS AND MAX WINDS

INIT  09/0900Z 12.4N  84.0W   75 KT  85 MPH...INLAND
 12H  09/1800Z 12.5N  86.2W   50 KT  60 MPH...INLAND
 24H  10/0600Z 12.7N  88.8W   45 KT  50 MPH...OVER WATER
 36H  10/1800Z 13.3N  91.4W   40 KT  45 MPH
 48H  11/0600Z 14.1N  93.3W   30 KT  35 MPH
 60H  11/1800Z...DISSIPATED

$$
Forecaster Reinhart
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