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WTPZ43 KNHC 252052
Tropical Storm Boris Discussion Number 6
NWS National Hurricane Center Miami FL EP032020
1100 AM HST Thu Jun 25 2020
Convection has increased further in association with the tropical
cyclone, with the center now under a poorly-organized band or dense
overcast. A just-received ASCAT-A overpass indicates that 35-kt
winds are occurring over an area about 40 n mi from the center in
the southeastern semicircle and based on this, the depression is
upgraded to Tropical Storm Boris.
While conditions appear to be favorable for some additional
strengthening for the next 12 h or so, none of the intensity
guidance forecasts significant intensification during that time.
Thus, the intensity forecast holds the intensity at 35 kt through 12
h. After that time, increasing vertical wind shear and dry air
entrainment should cause Boris to weaken, leading to the system
degenerating to a remnant low by 60 h and dissipating completely
after 72 h. The new intensity forecast has been adjusted downward,
but it still is a little above the intensity consensus.
The initial motion is now west-northwestward or 285/8. This motion
should continue for the next 24 h or so as Boris moves along the
south side of a low- to mid-level ridge. After that, a turn toward
the west and west-southwest is forecast as the cyclone weakens and
the low-level trade winds become the dominant steering mechanism.
The new forecast track has only minor changes from the previous
forecast, and it again lies the near consensus models.
FORECAST POSITIONS AND MAX WINDS
INIT 25/2100Z 11.2N 137.1W 35 KT 40 MPH
12H 26/0600Z 11.5N 138.0W 35 KT 40 MPH
24H 26/1800Z 11.9N 139.1W 30 KT 35 MPH
36H 27/0600Z 12.2N 140.3W 30 KT 35 MPH
48H 27/1800Z 12.3N 141.6W 25 KT 30 MPH
60H 28/0600Z 12.2N 143.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 28/1800Z 12.0N 145.5W 20 KT 25 MPH...POST-TROP/REMNT LOW