Slow translation speed causes rapid collapse of northeast Pacific Hurricane Kenneth over cold core eddy

Category 4 Hurricane Kenneth (HK) experienced unpredicted rapid weakening when it stalled over a cold core eddy (CCE) on 19-20 September 2005, 2800 km SE of Hawaii. Maximum sea surface temperature (SST) cooling of 8-9 degrees C and a minimum aerially averaged SST of 18.3 degrees C (over 8750 km(2)) characterized its cool wake. A 3-D mixed-layer model enabled estimation of enthalpy fluxes (latent and sensible heat), as well as the relative importance of slow translation speed (U-h) compared with the preexisting CCE. As U-h dropped below 1.5 ms(-1), enthalpy fluxes became negative, cutting off direct ocean energy flux to HK. Although HK's weakening was attributed to wind shear, our results indicate that slow U-h and consequent intense SST cooling were the main causes. The tropical cyclone-intensified CCE experienced rapid growth in magnitude (-6 to -40 cm), increased diameter (60 to 350 km), elevated chlorophyll a for 4 months, and 12 month longevity.