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Tropical Storm BLANCA

Tropical Storm Blanca Discussion Number  12
NWS National Hurricane Center Miami FL       EP022021
900 AM MDT Wed Jun 02 2021

Similar to yesterday, deep convective activity has waned with Blanca 
this morning as the cyclone continues to be impacted by dry-air 
entrainment imported by high west-southwesterly vertical wind shear. 
The low-level center is once again becoming exposed to the west of 
the convective cloud mass. While there has not been any helpful 
overnight scatterometer passes, an earlier 0844 UTC AMSR-2 microwave 
pass suggested that the low-level circulation is gradually becoming 
more diffuse, with several possible low level swirls embedded 
within. The latest subjective Dvorak estimates are T2.0/35 kt from 
SAB and T3.0/45 kt from TAFB, while the most recent UW-CIMSS 
Advanced Dvorak Technique (ADT) estimate was 34 kt. The current 
intensity estimate was held at 40 kt for this advisory.

Even though current sea surface temperatures remain sufficently warm 
underneath the cyclone (27-28 C), low-level, cold-air stratocumulus 
clouds can be seen on first-light visible imagery being entrained 
into the low-level circulation of Blanca. Strong vertical wind shear 
will continue over the next few days as sea surface temperatures 
decrease and the environment aloft becomes drier and more stable. 
While diurnal convective bursts are still likely to occur during 
this time, they will become less organized and more intermittent as 
the cyclone succumbs to the increasingly stable environment. The 
official NHC intensity forecast still calls for Blanca to become a 
tropical depression by Thursday and a remnant low by this weekend, 
which is in close agreement with the intensity guidance.

After a minor northward position adjustment, Blanca appears to still 
be on a west-northwestward heading, albeit somewhat slower than 
earlier, at 300/4 kt. A westward turn is expected over the next 24 
hours as Blanca becomes a shallow cyclone and is mainly steered by 
the low-level easterly trade wind flow. The latest NHC track 
forecast is somewhat further north than the previous forecast early 
on, but by the end of the forecast period is very close to the 
previous forecast track, and lies close to the HCCA consensus aid.
INIT  02/1500Z 15.5N 112.2W   40 KT  45 MPH
 12H  03/0000Z 15.6N 112.8W   35 KT  40 MPH
 24H  03/1200Z 15.6N 113.5W   30 KT  35 MPH
 36H  04/0000Z 15.4N 114.8W   30 KT  35 MPH
 48H  04/1200Z 15.3N 116.0W   25 KT  30 MPH
 60H  05/0000Z 15.3N 117.4W   25 KT  30 MPH
 72H  05/1200Z 15.3N 118.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  06/1200Z 15.3N 120.7W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  07/1200Z...DISSIPATED
Forecaster Papin/Stewart