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Tropical Depression Three Discussion Number   3
NWS National Hurricane Center Miami FL       AL032020
400 AM CDT Tue Jun 02 2020
 
Satellite data, Mexican radar data from Sabancuy, and nearby surface 
observations indicate that the depression has become a little better 
organized and has strengthened slightly since the previous advisory. 
 Radar data indicate a mass of convection has developed north of and 
over the low-level center, and a broken curved band has also formed 
in the eastern semicircle. The initial intensity has been increased 
to 30 kt based on a 0201 UTC ASCAT-A overpass that showed a couple 
of 27-kt vectors located in the northeastern quadrant outside of the 
most active convection. An Air Force Reserve reconnaissance 
aircraft is scheduled to investigate the depression later this 
morning.
 
The initial motion is westward or 270/02 kt. The latest 00Z model 
guidance continues to show the depression remaining embedded within 
the larger Central American gyre for the next few days, with the 
gyre gradually contracting around the depression, with the two 
entities merging into one system by 72 hours.  Similar to last 
night, tonight's model runs have again abandoned the development of 
a secondary low east of the depression and moving it northward 
toward the U. S Gulf coast. This may be due in part to the lack of 
Mexican and Central American upper-air data at 0000 UTC, except for 
the Belize sounding. But the global and regional models are in 
overall in good agreement on the cyclone remaining trapped in a 
break in the subtropical ridge to the east and west of the 
depression.  By 72-96 hours, a weak shortwave trough is forecast to 
drop southward out of the southern plains and into into the ridge 
weakness and act as a catalyst to nudge the depression slowly 
northward on days 4 and 5.  Until that time, the cyclone is 
expected to meander over the the Bay of Campeche for the next 2-3 
days, possibly making landfall along the coast of extreme 
southeastern Mexico and the west coast of Yucatan.  The new NHC 
forecast track is similar to the previous advisory track, and 
brings the center close to the coast of Mexico on days 2 and 3.  It 
should be noted, though, that in 5 days there could be a cyclone 
near the forecast point that is not actually TD-3 due to land 
interaction and the possible formation of a secondary cyclone.
 
Although the vertical wind shear is forecast to remain low while the 
cyclone remains trapped in the Bay of Campeche during the next few 
days, only slow strengthening is expected due to possible land 
interaction and intrusions of dry air caused by southwesterly 
downslope flow coming off of the mountains in the state of Chiapas, 
which already appears to be underway based on satellite and radar 
imagery.  After the cyclone starts moving northward, increasing 
southerly shear is expected to inhibit any significant or rapid 
strengthening. An alternative intensity forecast scenario is that 
the cyclone moves far enough inland over Mexico to dissipate 
completely in less than 5 days as forecast by the GFS and HWRF 
models.

Given the complexity of the situation, both the track and intensity 
forecasts are currently low confidence.  However, either of the 
current scenarios will result in widespread heavy rains over
portions of southern Mexico and Central America.
 
 
Key Messages:
 
1. Deadly flooding has already been occurring in portions of 
Guatemala and El  Salvador.  The depression is expected to bring 
heavy rainfall to portions of southern Mexico, Guatemala, Honduras 
and El Salvador, which could cause life-threatening flash flooding 
and mudslides. Refer to products from your local weather office for 
more information.
 
2. Tropical storm conditions are expected along the coast of Mexico
where a tropical storm warning is in effect.
 
3. The system is forecast to begin moving northward across the Gulf
of Mexico later this week.  However, it is too soon to specify the
location and timing of any potential impacts along the U.S. Gulf
Coast.  Interests in these areas should monitor the progress of this
system through the week and ensure they have their hurricane plan in
place as we begin the season.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  02/0900Z 19.6N  92.1W   30 KT  35 MPH
 12H  02/1800Z 19.5N  92.4W   35 KT  40 MPH
 24H  03/0600Z 19.1N  92.7W   40 KT  45 MPH
 36H  03/1800Z 18.8N  92.7W   40 KT  45 MPH
 48H  04/0600Z 18.7N  92.5W   45 KT  50 MPH
 60H  04/1800Z 19.0N  92.3W   45 KT  50 MPH
 72H  05/0600Z 19.3N  92.1W   45 KT  50 MPH
 96H  06/0600Z 20.7N  91.7W   50 KT  60 MPH
120H  07/0600Z 23.5N  91.2W   55 KT  65 MPH
 
$$
Forecaster Stewart
 
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