Tropical Storm Nolo

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WTPA42 PHFO 240843
TCDCP2
 
Tropical Storm Nolo Discussion Number  15
NWS Central Pacific Hurricane Center Honolulu HI   EP152026
Issued by NWS National Hurricane Center Miami FL
1100 PM HST Wed Sep 23 2026
 
Nolo's convective organization has gradually improved during the 
past several hours, with a curved band of persistent deep convection 
tightening around the circulation center. The latest subjective 
Dvorak intensity estimates from JTWC and HFO are both T2.5/35 kt, 
while objective intensity estimates range from 35 to 55 kt. Given 
the improved convective organization and the higher objective 
estimates, the initial intensity is raised to 45 kt.
 
Nolo has slowed considerably and appears to be making its 
anticipated northward turn, with an initial motion of 360/2 kt. A 
weakening subtropical ridge northeast of Hawaii should allow Nolo to 
continue moving slowly northward into Thursday, followed by a 
north-northeastward motion as an upper-level trough deepens 
northwest of the Hawaiian Islands. As the trough shifts westward and 
the subtropical ridge rebuilds north of the cyclone, Nolo is 
forecast to make a sharp westward turn Friday night into Saturday. 
The latest GDMI and HCCA guidance has shifted slightly northward, 
bringing the system closer to the Big Island. Given the run-to-run 
inconsistencies in the guidance, the NHC track forecast is 
essentially an update of the previous advisory and shows Nolo 
passing south of the Big Island on Saturday before continuing 
westward south of the smaller Hawaiian Islands through the latter 
portion of the weekend. However, considerable uncertainty remains 
regarding the influence of the deepening upper-level trough on 
Nolo's track, as well as the timing and strength of the subtropical 
ridge rebuilding north of the cyclone. Even relatively small 
differences in the evolution of these steering features could 
significantly alter the timing and location of Nolo's sharp westward 
turn and, ultimately, how close its center passes to the Big Island. 
A track closer to the Big Island could also result in interactions 
with the island's terrain that could further influence the cyclone's 
subsequent motion. Given these uncertainties, confidence in the 
track forecast remains lower than normal.
 
Environmental conditions remain favorable for strengthening, with
very warm sea surface temperatures and plenty of mid-level moisture
along the forecast track. However, around 10 kt of easterly vertical
wind shear may temper the rate of intensification during the next 24
h or so. As the shear relaxes and Nolo continues to develop an inner
core, a faster rate of intensification is forecast while the cyclone
moves northward to north-northeastward during the next couple of
days. These conditions could support a period of rapid
intensification, and Nolo is forecast to become a hurricane by
Thursday night and reach major hurricane strength on Saturday as it
passes south of the Big Island. The latest NHC intensity forecast
hovers near the upper end of the guidance envelope throughout the
forecast period. A track closer to the Big Island could
substantially increase the threat of damaging winds, particularly
over higher terrain, along exposed ridges, and in areas downwind of
the ridges. 
 
Key Messages:
 
1. Tropical Storm Nolo is expected to strengthen into a hurricane by 
Thursday night as it moves northward to north-northeastward, 
potentially making its closest approach to the Big Island of Hawaii 
as a major hurricane on Saturday. A Hurricane Watch remains in 
effect for the Big Island, and residents there should follow advice 
given by local officials, including evacuating if told to do so.

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. Large and damaging waves are possible along portions of the
Big Island's coastline into the weekend.

4. Interests elsewhere in Hawaii should closely monitor the latest
forecast updates and ensure that they have their preparedness plans
in place.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/0900Z 14.9N 156.0W   45 KT  50 MPH
 12H  24/1800Z 15.1N 156.0W   55 KT  65 MPH
 24H  25/0600Z 15.8N 155.7W   65 KT  75 MPH
 36H  25/1800Z 16.7N 155.4W   75 KT  85 MPH
 48H  26/0600Z 17.3N 155.3W   85 KT 100 MPH
 60H  26/1800Z 17.6N 155.8W   95 KT 110 MPH
 72H  27/0600Z 17.6N 157.1W  105 KT 120 MPH
 96H  28/0600Z 18.1N 160.8W  105 KT 120 MPH
120H  29/0600Z 20.3N 163.7W   95 KT 110 MPH
 
$$
Forecaster Gibbs