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Tropical Storm Blanca Discussion Number   6
NWS National Hurricane Center Miami FL       EP022021
900 PM MDT Mon May 31 2021
 
The satellite presentation of Blanca has continued to improve this
evening. Bursts of deep convection have recently developed near the
estimated center, which has led to an increase in banding that can
be seen in the latest microwave imagery. Subjective Dvorak
classifications are T3.0 (45 kt) and T3.5 (55 kt) from TAFB and
SAB, respectively.  Based on these data and the continued
organization seen in recent satellite imagery, the initial
intensity has been set at 50 kt for this advisory.
 
Blanca is currently located within a favorable environment for
strengthening that consists of low vertical wind shear, warm sea
surface temperatures, and a moist atmosphere.  These conditions
favor additional strengthening during the next 12 hours or so, but
by Tuesday afternoon increasing southwesterly shear is likely to
put an end to Blanca's intensification phase.  After that time, an
additional increase in shear and gradually decreasing sea surface
temperatures are expected to cause slow weakening throughout the
remainder of the forecast period.  Blanca is now forecast to become
a remnant low by day 5, but it could occur a little sooner than 
that.  The NHC intensity forecast is in best agreement with the 
HCCA and ICON consensus aids.
 
The initial motion estimate is 300/8 kt, a little slower toward the
west-northwest than before.  A deepening mid- to upper-level trough 
near the central portion of the Baja peninsula is forecast to 
weaken the western extent of the ridge, which is expected to cause 
Blanca to slow its forward speed over the next couple of days.  As 
the tropical storm weakens in 2-3 days, it should turn more westward 
when it becomes a vertically shallow system and is steered by the 
low-level easterly trade wind flow.  Although there is an increase 
in the spread of the guidance after 72 hours, the latest NHC track 
forecast remains near the middle of the guidance envelope, and it 
is very similar to the previous official forecast.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  01/0300Z 13.9N 109.4W   50 KT  60 MPH
 12H  01/1200Z 14.4N 110.4W   55 KT  65 MPH
 24H  02/0000Z 15.1N 111.6W   50 KT  60 MPH
 36H  02/1200Z 15.6N 112.5W   45 KT  50 MPH
 48H  03/0000Z 15.9N 113.2W   40 KT  45 MPH
 60H  03/1200Z 16.0N 113.8W   35 KT  40 MPH
 72H  04/0000Z 16.1N 114.6W   35 KT  40 MPH
 96H  05/0000Z 16.1N 116.5W   30 KT  35 MPH
120H  06/0000Z 16.2N 118.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Brown
 
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