Tropical Cyclone Discussion
381 WTPA44 PHFO 101443 TCDCP4 Tropical Storm Pena Discussion Number 16 NWS Central Pacific Hurricane Center Honolulu HI CP042026 Issued by NWS National Hurricane Center Miami FL 500 AM HST Tue Nov 10 2026 Moderate southwesterly wind shear is affecting Pena this morning. A swirl of low clouds in evident on proxy-vis satellite imagery, although it is unclear whether this feature represents the low-level center emerging from beneath the core of the deep convection or is simply a transient feature. Earlier microwave imagery suggested that the center could be located farther north. Consequently, the initial location is more uncertain that usual, but has been adjusted southward. Deep convection persists, with cloud top temperatures colder than -80 C evident within the convective overcast. Recent objective and subjective intensity estimates range from 31-45 kt. Based on the recent satellite presentation, the initial intensity is maintained at 35 kt for this advisory. Pena is moving westward around 10 kt, steered by a low to mid-level ridge centered to the northwest of the cyclone, west of the International Date Line (IDL). This general motion is expected to continue over the next couple of days, followed by a slight increase in forward speed as a shortwave trough impinges on the ridge and progresses eastward. The official NHC forecast calls for Pena to cross the IDL late this week. Owing to the southward adjustment of the initial position, the track forecast has been shifted to the left of the previous forecast and is near the center of the track guidance. Despite moving over warm sea surface temperatures and within a moist mid-level environment, Pena has struggled to develop a deep, vertically aligned structure. Vertical wind shear could decrease over the next several days, potentially allowing for modest intensity fluctuations. However, only a few intensity models support any meaningful strengthening during this period. Later this week, an increasingly dry mid-level environment and a modest increase in wind shear are expected to promote weakening, and it is possible that Pena could degenerate into a remnant low or open into a trough before that time. The latest NHC forecast intensity remains unchanged through 72 h, and is near the middle of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 10/1500Z 11.1N 164.7W 35 KT 40 MPH 12H 11/0000Z 10.8N 166.2W 35 KT 40 MPH 24H 11/1200Z 10.6N 168.5W 35 KT 40 MPH 36H 12/0000Z 10.6N 171.3W 35 KT 40 MPH 48H 12/1200Z 11.0N 174.3W 35 KT 40 MPH 60H 13/0000Z 11.5N 177.3W 35 KT 40 MPH 72H 13/1200Z 11.8N 179.9E 35 KT 40 MPH 96H 14/1200Z 12.5N 174.8E 30 KT 35 MPH 120H 15/1200Z 12.9N 170.8E 30 KT 35 MPH