Sandra is nu een categorie 3.
Even though it’s late November, conditions are unusually supportive for Sandra to continue intensifying into a major hurricane. A small eye has become evident on satellite imagery over the last few hours, with a compact zone of intense convection around it. Sea surface temperatures are at record highs for the time of year (29-30°C, or 84-86°F), and there is plenty of oceanic heat content below the surface (see Figure 2). Although Sandra is gradually moving into a region of higher vertical wind shear, the current values of 10 - 20 knots should allow continued strengthening. Things will change quickly by Thursday, however, as Sandra’s northwestward motion takes it into much stronger flow ahead of a powerful upper-level trough moving into the Southwest U.S. Cooler SSTs and higher shear will take its toll, weakening Sandra dramatically. There remains some spread in computer model guidance on Sandra’s intensity and track as it approaches the Mexican coastline, although a stronger, more intact Sandra would tend to recurve more quickly and further south due to greater influence of the upper-level steering flow. The 00Z ECMWF model brings Sandra into the Baja Peninsula as a very weak cyclone, while the 06Z runs of the HWRF, GFDL, and GFS models bring Sandra to the coast near or north of Mazatlan early Saturday as a stronger system, possibly a Category 1 hurricane. Hurricane or tropical storm watches or warnings may be issued as soon as Wednesday evening for parts of the Mexican coastline, and the Hurricane Hunters are on call to investigate Sandra on Friday afternoon. According to WU contributor Phil Klotzbach (Colorado State University), Sandra is on track to become the latest landfalling tropical cyclone on record for Mexico, beating out Tara (Nov. 12, 1961).
http://www.wunderground.c(...)t.html?entrynum=3193