000 WTPA41 PHFO 012036 TCDCP1 Tropical Storm Iona Discussion Number 23 NWS Central Pacific Hurricane Center Honolulu HI CP012025 Issued by NWS National Hurricane Center Miami FL 1100 AM HST Fri Aug 01 2025 Convection associated with Iona remains disorganized, with clusters of convection now occurring only in the southern semicircle. While satellite imagery shows that the circulation is becoming elongated, it is still uncertain whether it is actually closed. An upcoming scatterometer overpass should help provide more information on whether the circulation still exists and on the maximum winds. For the time being, the initial intensity is held at 35 kt as a blend of the objective and subjective satellite intensity estimates. The initial motion is now at 285/16 kt. Iona is expected to move west-northwestward during the next couple of days with a gradual decrease in forward speed along the southern periphery of the subtropical ridge to the north. A turn toward the northwest is forecast after 36-48 h as the system approaches a developing break in the ridge west of 165E. The track guidance has shifted a little to the west on this cycle, and the new forecast track is slightly to the west of the previous track. The intensity forecast scenario is unchanged from earlier. Iona continues to be affected by westerly shear, which should persist for the next 12-18 h. After that, the system is forecast to interact with an upper-level trough, and it will likely enter an area of upper-level convergence by 60-72 h. Based on this scenario and the dynamical guidance, the intensity forecast calls for Iona remain a tropical storm for 12 h or so, followed by weakening to a depression by 24 h and degenerating into a remnant low by 72 h. Given the current state of organization and the generally unfavorable environment, there remains the possibility the system could weaken to a trough at any time during the next 60-72 h. FORECAST POSITIONS AND MAX WINDS INIT 01/2100Z 15.0N 177.6W 35 KT 40 MPH 12H 02/0600Z 15.8N 179.6W 35 KT 40 MPH 24H 02/1800Z 17.0N 177.8E 30 KT 35 MPH 36H 03/0600Z 18.2N 175.5E 30 KT 35 MPH 48H 03/1800Z 19.4N 173.4E 30 KT 35 MPH 60H 04/0600Z 21.1N 171.3E 30 KT 35 MPH 72H 04/1800Z 22.7N 169.5E 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 05/1800Z...DISSIPATED $$ Forecaster Beven
Source link