[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 210844
TCDAT4

Tropical Depression Fourteen Discussion Number   4
NWS National Hurricane Center Miami FL       AL142020
500 AM EDT Fri Aug 21 2020

Recent METOP-A/B ASCAT overpasses and earlier aircraft
reconnaissance data indicate that the depression's circulation is
not well-defined.  In fact, the scatterometer data revealed multiple
swirls, particularly, one newly developed circulation near a recent
strong burst of deep convection near the coast of Honduras.  Highest
sustained winds from the scatterometer pass were 25-30 kt.  For this
advisory, the initial position is an uncertain centroid position of
the multiple surface centers and the intensity is held at 30 kt.  A
53rd Air Force Reserve reconnaissance flight is scheduled for this
morning and will hopefully paint a clearer picture on the
depression's location.

Deep convection has been increasing during the past few hours,
especially in the north portion of the depression, so gradual
strengthening is still expected before it makes landfall on the east
side of the Yucatan Peninsula in about 48 hours.  After that time,
some weakening is forecast while the cyclone traverses the
peninsula. The system is expected to enter the warm waters of the
southern Gulf of Mexico around the 60 hr period and restrengthen
through the remainder of the forecast.  Global models, however, are
indicating increasing south-southwesterly shear as the cyclone
enters the northwest portion of the gulf which could prevent it from
reaching hurricane strength prior to landfall.  For now, the
forecast will reflect a low-end hurricane making landfall, similar
to the HCCA intensity model.  The new intensity forecast is
basically an update of the previous advisory and is based on a
compromise of the various multi-model consensus aids.

The initial motion is estimated to be west-northwestward, or 290/10
kt.  The depression is forecast to be steered generally
northwestward during the next few days by a western extension of the
atlantic subtropical ridge that stretches westward across Florida
and into the eastern and central Gulf of Mexico.  This general
motion should result in landfall over the northeastern Yucatan
Peninsula on Saturday, with the system entering the northwestern
Gulf by the middle of next week.  I think it's worth noting that
both the UKMET and the DWD, Germany ICON global models are showing
some binary interaction between the depression and Tropical
Depression Thirteen around the 96-120 hr period while both systems
are situated in the Gulf of Mexico.  If this scenario actually
occurs, the interaction could delay or slow tropical depression
Fourteen's landfall over the northwestern Gulf coast.

The NHC forecast track is again adjusted a little to the right of
the  previous forecast and lies close to the TVCA and HCCA
consensus solutions.


Key Messages:

1. Tropical Depression Fourteen is expected to strengthen over the
northwestern Caribbean Sea through Saturday, and is likely to
produce tropical-storm-force winds and heavy rainfall over portions
of the coasts of Nicaragua and Honduras, including the Bay Islands,
through today.  The system is expected be near or at hurricane
strength when it reaches the Yucatan Peninsula of Mexico late
Saturday where a Hurricane Watch and a Tropical Storm Warning are in
effect.

2. The system is expected to move into the south-central Gulf of
Mexico as a tropical storm on Sunday.  Some strengthening is
anticipated while it moves northwestward over the western Gulf of
Mexico early next week, but it is too soon to know exactly how
strong it will get or the location and magnitude of impacts it will
produce along the central or northwestern Gulf Coast. Interests in
that area should continue monitoring the progress of this system
over the next few days.


FORECAST POSITIONS AND MAX WINDS

INIT  21/0900Z 15.4N  83.1W   30 KT  35 MPH
 12H  21/1800Z 16.3N  84.3W   40 KT  45 MPH
 24H  22/0600Z 17.7N  85.4W   50 KT  60 MPH
 36H  22/1800Z 19.2N  86.4W   60 KT  70 MPH
 48H  23/0600Z 20.7N  87.5W   50 KT  60 MPH...INLAND
 60H  23/1800Z 22.5N  88.8W   50 KT  60 MPH...OVER WATER
 72H  24/0600Z 24.5N  90.2W   65 KT  75 MPH
 96H  25/0600Z 28.1N  93.0W   65 KT  75 MPH
120H  26/0600Z 30.4N  94.6W   45 KT  50 MPH...INLAND

$$
Forecaster Roberts
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