Satellite images and tracking maps of Tropical Storm Marty 2021, August 21 - 25. Max wind speed 45mph.
There has been no significant deep convection within 100 nautical miles of Marty's center for more than 12 hours. As a result, Marty has degenerated into a remnant low. The initial intensity has been maintained at 35 mph (30 knots) based on ASCAT-B/-A passes between 1700-18:00 UTC that still showed a significant fetch of 25-knot winds over much of the northern quadrant, including a few embedded 28-knot vectors. Since Marty is forecast to remain over sub-26°C sea-surface temperatures and within a large field of cold-air stratocumulus clouds, gradual spin down of the vortex and weakening of the cyclone's peak winds are expected until dissipation occurs in about 72 hours. The new NHC intensity forecast is similar to the previous advisory, and closely follows a blend of the IVCN and NOAA-HCCA intensity consensus models.
The initial motion estimate remains westward, or 270/10 knots. For the next 36 hours or so, the remnant low is forecast to move westward along the southern periphery of a sprawling deep-layer ridge located northwest through northeast of Marty. Thereafter, a motion toward the west-southwest is expected until the cyclone dissipates. The new NHC forecast track is essentially just an extension of the previous advisory track, and lies down the middle of the tightly packed consensus models, which have shifted a little to the south on this forecast cycle.
This is the last advisory being issued on Marty. For additional information on the remnant low, please see High Seas Forecasts issued by the National Weather Service under AWIPS header NFDHSFEPI and WMO header FZPN02 KWBC.
Forecaster Stewart. Information provided by the National Hurricane Center (NHC).