WTPZ42 KNHC 021455
TCDEP2

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.


FORECAST POSITIONS AND MAX WINDS

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
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