Tropical Cyclone Discussion
671 WTPA44 PHFO 072046 TCDCP4 Tropical Storm Pena Discussion Number 5 NWS Central Pacific Hurricane Center Honolulu HI CP042026 Issued by NWS National Hurricane Center Miami FL 1100 AM HST Sat Nov 07 2026 Visible and infrared satellite imagery show that Pena's convective structure has degraded slightly since the previous advisory. The previously well-defined center has become obscured by an expanding central dense overcast (CDO), with embedded cloud-top temperatures as cold as -80 degrees C. A 1938 UTC ASCAT-B scatterometer pass showed an asymmetric system with peak winds of around 40 kt located northeast of the center, which helped verify the initial wind radii. The latest subjective Dvorak classification from HFO was T3.0/45 kt, in good agreement with objective estimates from UW-CIMSS that range between 42 and 47 kt. Based on these data, the initial intensity is held at 45 kt. The initial motion is estimated to be west-northwestward, or 285/8 kt. Pena is expected to maintain a general westward motion over the next couple of days while steered by a broad low- to mid-level ridge anchored to its north. Track guidance remains tightly clustered on this westward heading through 72 h. Thereafter, an approaching upper-level shortwave trough should induce a gradual turn toward the northwest with a slight increase in forward speed. The updated NHC track forecast is largely unchanged from the previous package, nudged only fractionally northward in the short term, and lies close to the HCCA and GDMI aids. Pena's intensity forecast remains a bit of a conundrum. Statistical SHIPS guidance continues to insist on gradual intensification throughout the period, responding to warm SSTs, low vertical wind shear, and adequate mid-level moisture. However, there remains some indications that Pena is likely contending with mid-level dry air entrainment and marginal upper-level winds, which could suppress significant strengthening over the next 36 to 48 h. The dynamical and statistical guidance reflects this tension with larger-than-normal model spread, yielding lower-than-usual forecast confidence. Consequently, the new NHC intensity forecast remains very similar to the previous advisory, situated near the consensus aids while remaining slightly higher than HCCA and GDMI throughout the period. FORECAST POSITIONS AND MAX WINDS INIT 07/2100Z 11.5N 153.9W 45 KT 50 MPH 12H 08/0600Z 11.6N 155.1W 55 KT 65 MPH 24H 08/1800Z 11.6N 156.8W 55 KT 65 MPH 36H 09/0600Z 11.5N 158.7W 60 KT 70 MPH 48H 09/1800Z 11.5N 160.8W 60 KT 70 MPH 60H 10/0600Z 11.5N 162.9W 60 KT 70 MPH 72H 10/1800Z 11.8N 165.0W 60 KT 70 MPH 96H 11/1800Z 12.7N 170.5W 65 KT 75 MPH 120H 12/1800Z 14.5N 177.7W 65 KT 75 MPH