ZCZC MIATCDEP4 ALL
TTAA00 KNHC DDHHMM
 
Tropical Depression Fourteen-E Discussion Number   1
NWS National Hurricane Center Miami FL       EP142021
400 PM CDT Wed Aug 25 2021
 
Scatterometer data from a few hours ago revealed that a small but 
sufficiently well-defined circulation has formed on the western end 
of a broader circulation which lies a few hundred miles south of the 
southern coast of Mexico.  Although the system is still in its 
formative stages and banding features are not readily apparent, 
Dvorak estimates from TAFB and SAB have been a consensus T2.0/30 kt 
since this morning.  The system is therefore now designated as a 
30-kt tropical depression, although the scatterometer data 
suggested that its winds are already very near tropical storm force.

The depression's surface center apparently formed a little south 
of the vorticity maximum we have been tracking over the past day or 
so.  Therefore, the initial motion is very uncertain but is 
estimated to be westward, or 275/7 kt.  The evolution of the 
steering pattern is fairly consistent among the models.  A strong 
mid-tropospheric high over the U.S. Southern Plains is forecast to 
weaken over the next couple of days, causing the depression to turn 
from a westward motion now, to a west-northwest motion tonight, to a 
northwest and north-northwest motion by Friday and Saturday.  On 
this track, most of the models bring the center of the system near 
but still offshore the southwestern coast of Mexico.  The GFS has 
been a notable exception, bringing the system inland over 
southwestern Mexico in about 3 days.  However, that model shows a 
complex interaction with multiple low-level centers that 
consolidate farther east, and most of the GEFS ensemble members 
remain offshore with the other deterministic models.  As a result, 
this first NHC official forecast also shows a track remaining 
offshore and is a little to the left of the HCCA and TVCE consensus 
aids.

Moderate easterly to northeasterly shear is likely to continue over 
the depression for the next day or so, which would temper any fast 
strengthening in the short term.  Still, the system will be moving 
over warm waters of 28-29 degrees Celsius over the next few days, 
and lower shear in 2-3 days should allow it to strengthen to a 
hurricane by the weekend as it passes near the southwestern coast 
of Mexico and approaches the southern part of the Baja California 
peninsula.  The intensity guidance is in fairly good agreement 
during the first 2 days, but there is much more spread after that 
time, likely related to the degree of land interaction.  The NHC 
intensity forecast is near the consensus aids during the first 3 
days and then a little bit above them on days 4 and 5, lying 
between the HWRF and HMON models at those forecast times.


Key Messages:

1. The depression is forecast to strengthen to a tropical storm 
tonight and be near hurricane intensity by Saturday.  While the 
core of the storm is currently expected to remain offshore of the 
southwestern coast of Mexico, strong winds and heavy rainfall, 
possibly resulting in flash floods and mudslides, could affect 
portions of that area over the next several days.

2. The system is expected to pass near the southern portion of Baja 
California Sur as a hurricane Sunday and Monday, bringing a risk of 
wind and rain impacts to that area early next week.  Given the 
uncertainty in the forecast, it is too soon to determine the 
magnitude and location of these potential impacts, but interests in 
this area should monitor the progress of this system and updates to 
the forecast.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  25/2100Z 11.7N  99.4W   30 KT  35 MPH
 12H  26/0600Z 12.0N 100.4W   35 KT  40 MPH
 24H  26/1800Z 12.8N 102.1W   40 KT  45 MPH
 36H  27/0600Z 13.6N 103.7W   45 KT  50 MPH
 48H  27/1800Z 14.7N 105.0W   55 KT  65 MPH
 60H  28/0600Z 16.2N 106.0W   60 KT  70 MPH
 72H  28/1800Z 18.0N 106.9W   65 KT  75 MPH
 96H  29/1800Z 21.1N 109.6W   75 KT  85 MPH
120H  30/1800Z 22.7N 112.1W   65 KT  75 MPH
 
$$
Forecaster Berg
 
NNNN