WTPA44 PHFO 062055 TCDCP4 Tropical Storm Pena Discussion Number 1 NWS Central Pacific Hurricane Center Honolulu HI CP042026 Issued by NWS National Hurricane Center Miami FL 1100 AM HST Fri Nov 06 2026 Satellite imagery indicates that an area of low pressure (Invest CP95) that we have been monitoring for several days has developed a well-defined circulation, showing banded convection around its center. While the most recent constrained subject Dvorak analysis from HFO was CI number was 2.0/30 kt, the Data T was 3.0/45 kt, which probably better reflects the system's organization. A 1546 UTC SMOS microwave pass supports that assessment, showing winds above tropical-storm-force east of the center. Based on this, advisories have been initiated on Tropical Storm Pena, with an intensity of 40 kt. The initial motion is estimated to be westward, or 280/10 kt, and the storm is expected to continue this motion for the next several days due to a high pressure ridge centered over the Central Pacific. Model guidance remains in good agreement through 72 h on Pena's track, then cross-track spread increases among the model solutions, resulting in lower-than-normal confidence. Additionally, the storm's initial representation in much of the guidance is too weak, which adds another layer of uncertainty. The NHC track forecast has been set to follow the GDMI and HCCA aids. The intensity forecast is tricky because the overall environment generally seems conducive to strengthening for at least the next day or so. While there is an increase in shear in much of the models this weekend, this shear could abate early next week, with no obvious dry air or instability issues seen in the large-scale guidance. It is a little puzzling why many of the models show little change or even a weakening so quickly in seemingly conducive conditions, though perhaps it is linked to the unrealistically weak initial vortex representation of Pena. The first forecast is on the higher side of the guidance and reflects a blend of some aids that get close to hurricane-strength, while others weaken to a depression. It probably goes without saying that this too is an uncertain prediction, similar to the track forecast. FORECAST POSITIONS AND MAX WINDS INIT 06/2100Z 11.3N 150.1W 40 KT 45 MPH 12H 07/0600Z 11.5N 151.8W 45 KT 50 MPH 24H 07/1800Z 11.4N 153.9W 50 KT 60 MPH 36H 08/0600Z 11.3N 155.8W 50 KT 60 MPH 48H 08/1800Z 11.3N 157.8W 50 KT 60 MPH 60H 09/0600Z 11.2N 159.7W 50 KT 60 MPH 72H 09/1800Z 11.0N 161.8W 50 KT 60 MPH 96H 10/1800Z 11.3N 165.9W 50 KT 60 MPH 120H 11/1800Z 11.9N 171.4W 50 KT 60 MPH $$ Forecaster Pierce/Blake