Tropical Storm Pena Forecast Discussion
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000 WTPA44 PHFO 090839 TCDCP4 Tropical Storm Pena Discussion Number 11 NWS Central Pacific Hurricane Center Honolulu HI CP042026 Issued by NWS National Hurricane Center Miami FL 1100 PM HST Sun Nov 08 2026 Satellite imagery indicates that the convective structure associated with Pena has changed little over the past several hours. Deep convection has mostly remained confined to intermittent bursts near and north of the circulation, likely due to light to moderate southerly vertical wind shear affecting it. The latest subjective and objective intensities remain in the 35 to 45 kt range. Given these intensities and the steady satellite presentation, the initial intensity is held at 40 kt. The initial motion is westward, or 270/8 kt. This general motion is expected to continue during the next 48 to 60 h as a low- to mid-level ridge builds to the north. Thereafter, a gradual turn toward the west-northwest is forecast as a weakness develops in the ridge in response to a shortwave trough moving across the northwestern Pacific. An increase in forward speed is expected around day 3 and should continue into day 4. Track guidance remains in good agreement during the next couple of days, but the cross-track spread increases thereafter, with some of the regional hurricane models maintaining a more westward track. In contrast, the GFS, ECMWF, and consensus aids support a gradual turn toward the west-northwest. These differences could be partly related to how the models handle the cyclone's intensity, with weaker solutions becoming increasingly steered by the low-level flow. The NHC track forecast is essentially unchanged from the previous prediction and lies near the HFIP Corrected Consensus (HCCA). Light to moderate southerly vertical wind shear and potentially some drier mid-level air appear to be limiting Pena's ability to strengthen. Although guidance indicates that the shear should decrease during the next 12 to 24 h, only a few intensity models support modest strengthening over the next several days, possibly due to occasional intrusions of dry mid-level air. Toward the end of the forecast period, vertical wind shear is expected to increase out of the west-southwest, which, combined with increasingly dry mid-level air, should favor some weakening. The latest NHC intensity forecast is very similar to the previous prediction and lies near the middle to upper end of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 09/0900Z 11.3N 158.4W 40 KT 45 MPH 12H 09/1800Z 11.3N 160.4W 40 KT 45 MPH 24H 10/0600Z 11.2N 162.6W 40 KT 45 MPH 36H 10/1800Z 11.0N 164.6W 45 KT 50 MPH 48H 11/0600Z 11.0N 166.6W 45 KT 50 MPH 60H 11/1800Z 11.1N 169.3W 45 KT 50 MPH 72H 12/0600Z 11.4N 171.8W 45 KT 50 MPH 96H 13/0600Z 12.8N 178.4W 40 KT 45 MPH 120H 14/0600Z 14.3N 177.1E 40 KT 45 MPH $$ Forecaster Gibbs