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Tropical Depression Fifteen-E Discussion Number  11
NWS Central Pacific Hurricane Center Honolulu HI   EP152026
Issued by NWS National Hurricane Center Miami FL
1100 PM HST Tue Sep 22 2026
 
Recent satellite imagery indicates that the low-level circulation 
associated with the remnants of former Tropical Depression Fifteen-E 
has once again become well-defined as the system crossed from the 
western East Pacific basin into the central Pacific basin. There has 
been persistent deep convection, mainly in a band to the north and 
west of the low-level center. Since the remnants have maintained 
trackable with continuity for over a week since losing its tropical 
cyclone status, advisories are being re-initiated and the system 
will retain its original designation as Tropical Depression 
Fifteen-E. The initial intensity is set at 30 kt and is based on the 
latest objective intensity estimates from UW-CIMSS. It is worth 
noting that if the cyclone becomes a tropical storm, it will receive 
the Central Pacific name Nolo.

The depression is moving west-northwestward at about 10 kt on the 
southwest side of a low- to mid-level ridge. This ridge is expected 
to shift eastward and weaken while a mid- to upper-level low dives 
southwestward near the northwestern Hawaiian Islands. This pattern 
change should cause the cyclone to slow down and then turn northward 
or north-northeastward later this week. That motion should take the 
cyclone near the Big Island of Hawaii late Friday or on Saturday.  
Around that time, the upper low is expected to weaken and move 
westward, allowing mid-level ridging to become re-established to the 
north of the system. In response, the cyclone should turn and then 
accelerate westward. The NHC track forecast is closest to the 
best-performing models of the year so far, HCCA and GDMI. Given the 
complex steering evolution and significant model spread, confidence 
in the details of the track forecast is low. Interests in the 
Hawaiian Islands, especially on the Big Island, should closely 
monitor the system. 

The environmental conditions are favorable for strengthening over 
the next few days with vertical wind shear expected to be around or 
less than 10 kt, high mid-level humidities, and SSTs of around 29 
C. The only limiting factor is the system's sprawling low-level 
structure. Considering these conditions, the NHC intensity forecast 
calls for slow strengthening to start, followed by more significant 
intensification when the system moves toward Hawaii. Most of the 
reliable intensity models are quite aggressive, and the NHC 
intensity forecast follows a combination of the HAFS guidance and 
HCCA and GDMI aids. This prediction shows the system becoming a 
hurricane in a couple of days and nearing major hurricane strength 
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 on Wednesday and a hurricane in a couple of days as
it turns northward. Although it is too soon to specify the exact
location and magnitude of impacts, interests in Hawaii should
closely monitor the latest forecast updates and ensure that they
have their preparedness plan in place.
 
2. Heavy rainfall associated with Tropical Depression Fifteen-E will 
begin to affect the eastern portions of Hawaii Wednesday. Periods of 
heavy rain are likely to continue across the Big Island and Maui 
through Saturday. Life-threatening, catastrophic flooding and 
mudslides are possible from rainfall totals in excess of a foot, 
especially in areas of steep terrain. Across the remainder of 
Hawaii, lesser rainfall totals are expected, with isolated flooding 
possible. 
 
3. There is an increasing risk of wind and wave impacts in the
Hawaiian Islands regardless of the exact track and intensity of the
system. Hurricane or Tropical Storm Watches may be required for
portions of the Hawaiian Islands on Wednesday.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  23/0900Z 14.0N 153.7W   30 KT  35 MPH
 12H  23/1800Z 14.4N 154.7W   35 KT  40 MPH
 24H  24/0600Z 14.6N 155.5W   45 KT  50 MPH
 36H  24/1800Z 15.0N 155.6W   55 KT  65 MPH
 48H  25/0600Z 15.9N 155.2W   70 KT  80 MPH
 60H  25/1800Z 17.0N 154.9W   85 KT 100 MPH
 72H  26/0600Z 17.9N 154.7W   95 KT 110 MPH
 96H  27/0600Z 18.3N 156.0W   95 KT 110 MPH
120H  28/0600Z 18.2N 159.0W   95 KT 110 MPH
 
$$
Forecaster Kelly/Cangialosi
 
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