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Tropical Storm Hilda Discussion Number   1
NWS National Hurricane Center Miami FL       EP082021
300 PM MDT Fri Jul 30 2021
 
A pair of ASCAT passes from a few hours ago indicated that the area 
of low pressure located about 800 miles south-southwest of the 
southern tip of the Baja California peninsula has strengthened, and 
is producing 35-40 kt winds on its east side.  In addition, 
satellite images show a fairly persistent area of showers and 
thunderstorms on the south side of the circulation and the center 
appears to be fairly well defined in recent visible images.  Based 
on these data, advisories are now being initiated on Tropical Storm 
Hilda and the initial intensity is estimated to be 40 kt.
 
Hilda is moving westward at about 14 kt and is embedded in the flow
on the south side of a sprawling subtropical ridge that extends from
the south-central U.S. westward across the subtropical eastern
Pacific.  A general west-northwestward motion at about the same
forward speed is expected during the next day or two as the synoptic
pattern holds.  After that time, a decrease in forward speed is
predicted due to a combination of the subtropical ridge weakening
and the interactions with the areas of low pressure to the east and
west of Hilda.  The ECMWF is the slowest model at long range due to
it showing the most interaction with the low to Hilda’s east.  The
NHC track forecast lies generally near the model consensus and
roughly between the GFS and ECMWF models.
 
Hilda appears to be in generally conducive conditions for
strengthening with SSTs currently around 28 C, abundant mid-level
moisture, and fairly low wind shear. Given that these conditions are
expected to persist for another couple of days, steady strengthening
is forecast during that time period and Hilda is predicted to become
a hurricane in 24 to 36 hours.  Beyond a couple of days, however,
moderate easterly shear, progressively drier air, and decreasing
SSTs should end the strengthening trend and induce gradual weakening
of the cyclone.  The NHC intensity forecast lies near the middle of
the guidance envelope, closest to the intensity model consensus
IVCN.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  30/2100Z 12.1N 113.6W   40 KT  45 MPH
 12H  31/0600Z 12.6N 115.4W   50 KT  60 MPH
 24H  31/1800Z 13.2N 117.6W   60 KT  70 MPH
 36H  01/0600Z 13.8N 119.7W   70 KT  80 MPH
 48H  01/1800Z 14.3N 121.6W   75 KT  85 MPH
 60H  02/0600Z 14.9N 123.1W   75 KT  85 MPH
 72H  02/1800Z 15.3N 124.4W   70 KT  80 MPH
 96H  03/1800Z 16.6N 126.4W   65 KT  75 MPH
120H  04/1800Z 18.3N 129.5W   55 KT  65 MPH
 
$$
Forecaster Cangialosi
 
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