Eastern Pacific Basin Tropical Cyclones

Hurricane Blas Forecast Discussion

WTPZ42 KNHC 151457

Hurricane Blas Discussion Number   6
NWS National Hurricane Center Miami FL       EP022022
1000 AM CDT Wed Jun 15 2022

Since the prior advisory, the structure of Blas has continued to 
improve on both conventional and microwave satellite imagery. In 
fact, several SSMIS microwave passes indicate that Blas is 
developing an inner core, with at least a banding mid-level eye 
feature showing up on the 89-GHz channel. The latest 1200 UTC 
subjective Dvorak estimates were T3.5/55 kt from TAFB and T4.0/65 kt 
from SAB. In addition, the most recent objective Dvorak estimates 
from UW-CIMSS have been quickly increasing with the latest estimate 
at T4.3/72 kt. A blend of the aforementioned data yields 65 kt for 
the advisory initial intensity, making Blas a hurricane.

The center of Blas may have relocated a bit further south into the 
large overnight convective burst, but its mean motion this morning 
has continued a pronounced left turn, estimated at 290/4 kt. A 
continued west-northwest motion with some acceleration is 
anticipated over the next several days as the mid-level ridge 
poleward of the storm continues to build in and extend westward 
ahead of Blas. Towards the end of the forecast, Blas is expected to 
become a shallow system, resulting in a slowing westward motion as 
the low-level flow exerts greater influence. The latest forecast 
track has been adjusted a bit south in the short-term based on the 
adjusted initial position , but ends up just north of the previous 
forecast by the end of the period, close to the center of the track 
guidance envelope.

The most recent microwave images suggest that Blas is developing an 
inner core, which would likely support further intensification today 
as the system remains over warm (28-29 C) sea surface temperatures 
(SSTs) embedded in sufficently high mid-level moisture. A possible 
complicating factor is that both the GFS- and ECMWF-based SHIPS 
guidance indicates easterly shear increasing to 20-25 kt over 
the next 24-36 h. Assuming this does not play a major inhibiting 
factor, the latest NHC forecast indicates continued intensification 
and peaks Blas as category 2 hurricane in 24 h. After 36 h, Blas 
will be crossing a sharp SST gradient, moving over sub 26 C waters 
by 60 h. For this reason, weakening is anticipated to begin by 
Friday. At the end of the forecast period, Blas is likely to lose 
its deep-convective activity and become a shallow low-level vortex.

While Blas is expected to remain off the coast of Mexico, its
associated swells are expected to affect portions of the coast of
southwestern Mexico beginning today and continuing through the end
of the week.


INIT  15/1500Z 14.9N 102.8W   65 KT  75 MPH
 12H  16/0000Z 15.3N 103.5W   75 KT  85 MPH
 24H  16/1200Z 15.8N 104.8W   85 KT 100 MPH
 36H  17/0000Z 16.5N 106.6W   80 KT  90 MPH
 48H  17/1200Z 17.1N 108.3W   75 KT  85 MPH
 60H  18/0000Z 17.7N 110.0W   65 KT  75 MPH
 72H  18/1200Z 18.2N 111.6W   55 KT  65 MPH
 96H  19/1200Z 18.8N 114.1W   40 KT  45 MPH
120H  20/1200Z 19.0N 116.5W   30 KT  35 MPH

Forecaster Papin

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