Hurricane Nolo Advisory Number 21

Public advisory

Central Pacific Hurricane Center · issued Sep 25, 8:55 PM UTC · source


000
WTPA32 PHFO 252055
TCPCP2
 
BULLETIN
Hurricane Nolo Advisory Number  21
NWS Central Pacific Hurricane Center Honolulu HI   EP152026
Issued by NWS National Hurricane Center Miami FL
1100 AM HST Fri Sep 25 2026
 
...LIFE-THREATENING FLASH FLOODING POSSIBLE AND DAMAGING WAVES 
LIKELY ON THE BIG ISLAND OF HAWAII OVER THE WEEKEND FROM NOLO...
 
 
SUMMARY OF 1100 AM HST...2100 UTC...INFORMATION
-----------------------------------------------
LOCATION...16.5N 155.4W
ABOUT 175 MI...280 KM S OF SOUTH POINT HAWAII
ABOUT 370 MI...595 KM SSE OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS...105 MPH...165 KM/H
PRESENT MOVEMENT...NNE OR 15 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...978 MB...28.88 INCHES
 
 
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
 
None.
 
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
 
A Hurricane Watch is in effect for...
* Hawaii County
 
A Tropical Storm Warning is in effect for...
* Hawaii County
 
A Tropical Storm Watch is in effect for...
* Maui County
 
A Hurricane Watch means that hurricane conditions are possible
within the watch area, in this case within 24-36 hours.
 
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 24-36 hours.
 
A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, in this case within 36-48 hours.
 
Interests elsewhere in the Hawaiian Islands should closely monitor
the progress of this system.
 
For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.
 
 
DISCUSSION AND OUTLOOK
----------------------
At 1100 AM HST (2100 UTC), the eye of Hurricane Nolo was located by 
an Air Force Reserve Hurricane Hunter aircraft near latitude 16.5 
North, longitude 155.4 West.  Nolo is moving toward the north- 
northeast near 5 mph (7 km/h), and this general motion with a 
decrease in forward speed is expected through tonight.  A turn 
towards the west with an increase in forward speed is forecast 
Saturday and Sunday. On the forecast track, the center of Nolo will 
remain well south of the main Hawaiian Islands.
 
Maximum sustained winds are near 105 mph (165 km/h) with higher
gusts.  Nolo is forecast to strengthen into a major hurricane this 
weekend, and could further intensify early next week.
 
Hurricane-force winds extend outward up to 45 miles (75 km) from the
center and tropical-storm-force winds extend outward up to 140 miles
(220 km).
 
The estimated minimum central pressure is 978 mb (28.88 inches).
 
 
HAZARDS AFFECTING LAND
----------------------
Key messages for Nolo can be found in the Tropical Cyclone
Discussion under AWIPS header HFOTCDCP2 and WMO header WTPA42 PHFO.
 
WIND: Tropical storm conditions are expected to begin by tonight in
the warning area, with hurricane conditions possible by early
Saturday, particularly in areas of steep terrain.
 
Tropical storm conditions are possible in the tropical storm watch
area beginning on Saturday.
 
RAINFALL: For the eastern and southern portions of the Big Island,
Nolo will produce rainfall totals of 10 to 15 inches with maximum
amounts of 25 inches.  This rainfall could produce catastrophic
life-threatening flooding and mudslides, especially in areas of
steep terrain.
 
For the western portions of the Big Island, rainfall totals of 2 to
4 inches with maximum amounts of 8 inches are expected. For Maui,
rainfall totals of 4 to 6 inches with maximum amounts of 10 inches
are expected. Life-threatening flooding and mudslides are possible,
especially in areas of high terrain.
 
Across the remainder of the Hawaiian Islands, rainfall totals of 1
to 3 inches with isolated maximum amounts of 5 inches are expected
with isolated flooding possible.
 
For a complete depiction of forecast rainfall associated with
Hurricane Nolo, please see the National Weather Service Storm Total
Rainfall Graphic available at
hurricanes.gov/graphics_cp2.shtml?rainqpf
 
STORM SURGE: The combination of a dangerous storm surge and the tide
will cause normally dry areas near the coast to be flooded by rising
waters moving inland from the shoreline. The water could reach the
following heights above ground somewhere in the indicated areas if
the peak surge occurs at the time of high tide...
 
Hawaii County...1 to 3 ft
 
The deepest water will occur along the immediate coast and will be
accompanied by large and dangerous waves. Surge-related flooding
depends on the relative timing of the surge and the tidal cycle,
and can vary greatly over short distances. For information
specific to your area, please see products issued by your local
National Weather Service forecast office.
 
For a complete depiction of areas at risk of storm surge inundation,
please see the National Weather Service Peak Storm Surge Graphic,
available at hurricanes.gov/graphics_cp2.shtml?peakSurge.
 
SURF: Swells generated by Nolo are expected to reach exposed east-
and south-facing shores of the Big Island today, 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 intermediate advisory at 200 PM HST.
Next complete advisory at 500 PM HST.
 
$$
Forecaster Blake
 

Forecast discussion

Central Pacific Hurricane Center · issued Sep 25, 8:56 PM UTC · source


000
WTPA42 PHFO 252056
TCDCP2
 
Hurricane Nolo Discussion Number  21
NWS Central Pacific Hurricane Center Honolulu HI   EP152026
Issued by NWS National Hurricane Center Miami FL
1100 AM HST Fri Sep 25 2026

The eye of Nolo is becoming better defined on South Point Hawaii 
radar as well as on the latest satellite imagery, though is still a 
bit ragged.  The Air Force Reserve Hurricane Hunters have found 
peak 700-mb flight-level winds of 106 kt, which generally 
correspond to surface winds of about 95 kt using standard reduction 
factors.  However, the radius-of-maximum winds is pretty large, 
some dropsonde data suggests it isn't quite mixing down at a normal 
rate, and the central pressure is fairly high around 978 mb.  These 
factors point to a somewhat lower current wind speed, so the 
initial intensity is set to 90 kt.  

Nolo is gradually bending leftward, with the current motion 
estimated at 015/4 kt.  Nolo should slow down by late tonight and 
start to drift westward on Saturday as the steering flow changes 
from an upper-level trough over the far northwestern Hawaiian 
Islands to a building ridge north of the main Hawaiian Islands.  
This ridge is forecast to push Nolo faster to the west by Sunday 
before eventually the cyclone is likely to turn more to the 
north-northwest early next week due to another encounter with that 
upper trough.  The new model guidance is fairly close to the last 
cycle, and no significant changes were made to the last NHC 
forecast.  

Some increase in shear, along with nearby dry air, could briefly 
arrest Nolo's strengthening trend for the next day or so.  After 
that time, most of the guidance is showing Nolo becoming a very 
strong hurricane with decreasing shear and increasing ocean heat 
content.  The new forecast is leveled off tonight, but then is 
raised from the last one early next week, and I wouldn't be 
surprised if Nolo ended up stronger in 2-3 days given the upper- 
level wind pattern.  Weakening is still expected by days 4 and 5 due 
to forecast strong southwesterly shear east of the trough.
 
Key Messages:
 
1. Nolo is expected to remain south of the Big Island of Hawaii
through Saturday before turning westward and moving away from the
island. Tropical storm conditions are expected to begin on the Big
Island tonight with hurricane conditions possible on Saturday,
particularly in areas of steep terrain. Residents should follow
advice given by local officials, including evacuating if told to do
so.
 
2. The time to finish preparations for significant heavy rain and
flooding impacts on the Big Island is now as heavy rain increases in
both coverage and intensity late today. Periods of heavy rain are
expected 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 eastern
and southern portions of 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 likely along portions of the
Big Island's coastline into the weekend.
 
4. A Tropical Storm Watch is in effect for Maui County where
tropical storm conditions are possible beginning on Saturday.
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  25/2100Z 16.5N 155.4W   90 KT 105 MPH
 12H  26/0600Z 16.9N 155.3W   95 KT 110 MPH
 24H  26/1800Z 17.1N 155.7W   95 KT 110 MPH
 36H  27/0600Z 17.0N 157.0W  100 KT 115 MPH
 48H  27/1800Z 16.8N 158.8W  110 KT 125 MPH
 60H  28/0600Z 17.2N 160.8W  125 KT 145 MPH
 72H  28/1800Z 18.4N 162.6W  120 KT 140 MPH
 96H  29/1800Z 21.5N 164.4W   95 KT 110 MPH
120H  30/1800Z 23.5N 165.0W   70 KT  80 MPH
 
$$
Forecaster Blake