000
WTPA32 PHFO 231448
TCPCP2
BULLETIN
Tropical Depression Fifteen-E Advisory Number 12
NWS Central Pacific Hurricane Center Honolulu HI EP152026
Issued by NWS National Hurricane Center Miami FL
500 AM HST Wed Sep 23 2026
...INTERESTS IN THE HAWAIIAN ISLANDS SHOULD CLOSELY MONITOR THE
PROGRESS OF THIS SYSTEM...
SUMMARY OF 500 AM HST...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...14.5N 154.4W
ABOUT 320 MI...520 KM SSE OF SOUTH POINT HAWAII
ABOUT 525 MI...840 KM SSE OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES
WATCHES AND WARNINGS
--------------------
Interests in the Hawaiian Islands should closely monitor the
progress of this system. A Hurricane or Tropical Storm Watch will
likely be required for a portion of the state later today.
DISCUSSION AND OUTLOOK
----------------------
At 500 AM HST (1500 UTC), the center of Tropical Depression
Fifteen-E was located near latitude 14.5 North, longitude 154.4
West. The depression is moving toward the west-northwest near 6 mph
(9 km/h), and this motion is expected for the next day or so. A
sharp turn to the north and north-northeast is expected on
Thursday, with this motion continuing through the end of the week.
On the forecast track, the system is expected to approach the
Big Island of Hawaii on Friday and Saturday.
Maximum sustained winds remain near 35 mph (55 km/h) with higher
gusts. The system is expected to become a tropical storm later
today, with further strengthening to a hurricane likely on Thursday
and possibly a major hurricane by this weekend.
The estimated minimum central pressure is 1004 mb (29.65 inches).
HAZARDS AFFECTING LAND
----------------------
Key messages for Tropical Depression Fifteen-E can be found in the
can be found in the Tropical Cyclone Discussion under AWIPS header
HFOTCPCP2 and WMO header WTPA42 PHFO.
WIND: There is an increasing risk of wind impacts in the Hawaiian
Islands regardless of the exact track of this system.
RAINFALL: Tropical Depression Fifteen-E will produce rainfall totals
of 15 to 20 inches across the Big Island with maximum amounts of 35
inches. This rainfall may produce catastrophic life-threatening
flooding and mudslides, especially in areas of steep terrain.
Rainfall totals of 5 to 10 inches with maximum amounts of 20 inches
expected across Maui. Life-threatening flooding and mudslides
possible across Maui, especially in areas of high terrain, Across
the remainder of the Hawaiian Islands, rainfall totals of 1 to 3
inches with maximum amounts of 6 inches are expected with isolated
flooding possible.
For a complete depiction of forecast rainfall associated with
Tropical Depression Fifteen-E, please see the National Weather
Service Storm Total Rainfall Graphic available at
hurricanes.gov/graphics_ep15.shtml?rainqpf
SURF: Swells generated by Tropical Depression Fifteen-E are
expected to reach the east and south-facing shores of the Big Island
on Friday, spreading westward and building through the weekend.
These swells are likely to cause life-threatening surf and rip
current conditions. Please consult products from your local weather
office.
NEXT ADVISORY
-------------
Next complete advisory at 1100 AM HST.
$$
Forecaster Blake
000
WTPA42 PHFO 231449
TCDCP2
Tropical Depression Fifteen-E Discussion Number 12
NWS Central Pacific Hurricane Center Honolulu HI EP152026
Issued by NWS National Hurricane Center Miami FL
500 AM HST Wed Sep 23 2026
Satellite imagery shows that the depression is becoming better
organized. Banding features are becoming more defined on the
western and northern sides of the system, with expanding outflow
noted. However, the low-level circulation appears to be on the
southeastern edge of the deep convection and isn't well aligned
with the deep convective mass. Satellite intensity estimates have
a large spread this morning, from about 25-40 kt. Without
definitive evidence it has become a tropical storm, the initial wind
speed will stay 30 kt, which is also consistent with winds from a
recent OSCAT scatterometer pass.
The depression has slowed since the last advisory and seems to be
moving west-northwestward at about 5 kt. A ridge to the northeast
of Hawaii is forecast to weaken and slide eastward as a mid-
latitude trough drops over the northwestern Hawaiian islands.
This evolution is likely to the cause the cyclone to slow down
later today or tonight and then turn northward or north-
northeastward by tomorrow with some increase in forward speed. The
trough is forecast to move westward this weekend as the ridge
rebuilds north of Hawaii, which should force a sharp westward turn
while the cyclone is close to the Big Island. At this time frame,
it is impossible to know exactly when that turn will happen and,
unsurprisingly, there is a large north-south spread in the guidance.
Our best guidance is on the northern side of the track envelope,
and new NHC forecast remains essentially the same as the last
advisory. Interests in the Hawaiian Islands, especially on the Big
Island, should closely monitor the system, with life-threatening
catastrophic flooding possible over the steep terrain on this track.
The depression should intensify slowly at first, given the current
structure of the low-level center not co-located with the mid-level
circulation as seen on satellite. However, after the system
develops an inner core, the environment seems conducive for
significant strengthening, with low shear, high mid-level moisture
and SSTs from 28-29C. The rapid intensification probabilities are
increasing, and the best model guidance is showing this as a major
hurricane in a few days. Given the environment and the
best-performing aids (Google DeepMind and HCCA) again showing
major-hurricane strength, the NHC forecast is raised from the
previous one and shows the cyclone as a major hurricane when it
approaches the Big Island of Hawaii by the weekend.
Key Messages:
1. Tropical Depression Fifteen-E is expected to strengthen into a
tropical storm later today and a hurricane on Thursday as it turns
northward, potentially making its closest approach to the Big Island
of Hawaii on Saturday. There is an increasing risk of wind and wave
impacts in the Hawaiian Islands, and a Hurricane Watch may be
required for the Big Island later today.
2. The time to prepare for significant heavy rain and flooding
impacts on the Big Island is now, as heavy rain becomes more likely
by Thursday and Friday. Periods of heavy rain are likely to
continue across the Big Island and Maui through the weekend.
Life-threatening, catastrophic flooding and mudslides are possible,
especially in areas of steep terrain across the Big Island and Maui.
Across the remainder of Hawaii, lesser rainfall totals are expected,
with isolated flooding possible.
3. Interests in Hawaii should closely monitor the latest forecast
updates and ensure that they have their preparedness plan in place.
FORECAST POSITIONS AND MAX WINDS
INIT 23/1500Z 14.5N 154.4W 30 KT 35 MPH
12H 24/0000Z 14.7N 155.2W 40 KT 45 MPH
24H 24/1200Z 15.0N 155.5W 50 KT 60 MPH
36H 25/0000Z 15.7N 155.2W 65 KT 75 MPH
48H 25/1200Z 16.7N 154.8W 80 KT 90 MPH
60H 26/0000Z 17.6N 154.5W 90 KT 105 MPH
72H 26/1200Z 18.2N 154.7W 100 KT 115 MPH
96H 27/1200Z 18.1N 157.0W 100 KT 115 MPH
120H 28/1200Z 18.7N 160.2W 95 KT 110 MPH
$$
Forecaster Blake