EPAC: BORIS - Remnants

[cycloneye]

Tropical Depression Boris Discussion Number 14
NWS Central Pacific Hurricane Center Honolulu HI EP032020
1100 AM HST Sat Jun 27 2020

A burst of deep convection in the northwest quadrant of Boris
flared earlier this morning and has collapsed in the past hour,
exposing the low-level circulation center. Dvorak Current Intensity
estimates range from 1.0 at SAB to 1.5 out of PHFO and ADT, while
JTWC has deemed the system unclassifiable. Given the recent burst of
deep convection, we will hold the initial intensity at 30 kt,
though this could be generous. The depression continues to move
toward the west (265 degrees) at 6 kt.

Boris is expected to slowly weaken over the next couple of days.
Southerly vertical wind shear will limit the depth of the
circulation and will likely only allow deep convection to
periodically flare and collapse near the center. The system will
also continue to ingest relatively dry low- to mid-level air. As a
result, the depression is expected to degenerate into a remnant low
tonight or Sunday and dissipate on Monday. The official intensity
forecast has changed little and remains in line with LGEM, SHIPS,
and ICON. Guidance remains in good agreement that a deep ridge to
the north is expected to push the increasingly shallow system
toward the west then west-southwest until dissipation.


FORECAST POSITIONS AND MAX WINDS

INIT 27/2100Z 12.3N 141.3W 30 KT 35 MPH
12H 28/0600Z 12.1N 142.4W 25 KT 30 MPH
24H 28/1800Z 11.6N 144.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 29/0600Z 11.0N 146.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 29/1800Z...DISSIPATED

$$
Forecaster Wroe

[cycloneye]

Next.

Post-Tropical Cyclone Boris Discussion Number 15
NWS Central Pacific Hurricane Center Honolulu HI EP032020
500 PM HST Sat Jun 27 2020

The low-level circulation center of Boris has been exposed through
most of the day. There have been only two, brief flare ups of deep
convection near the center during the past 24 hours with another
one starting now. The system is also surrounded by dry air aloft as
southeasterly vertical wind shear persists, and JTWC, PHFO, and SAB
all deemed the system too weak to classify this afternoon. Thus,
Boris will be designated as a post-tropical remnant low with an
intensity of 25 kt. Additional bursts of convection can be expected
as the system slowly spins down over the next couple of days, even
as vertical wind shear relaxes on Sunday.

The center of Boris is moving toward the west-southwest (255/07 kt)
under the influence of a deep ridge to the north. This general
motion, along with a slight increase in forward speed, is expected
to continue over the next couple of days until dissipation. The
track forecast is essentially an update from the last advisory and
remains within a tightly clustered guidance envelope.

This is the last advisory issued by the Central Pacific Hurricane
Center on Boris. Additional information on this system can be found
in the High Seas Forecasts issued by the National Weather Service
in Honolulu under AWIPS header HFOHSFNP and WMO header FZPN40 PHFO.


FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 12.1N 142.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
12H 28/1200Z 11.8N 143.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 29/0000Z 11.2N 145.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 29/1200Z 10.5N 147.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 30/0000Z...DISSIPATED

$$
Forecaster Wroe