268
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
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