Tropical weather analysis - June 13, 2012
An organized and potentially dangerous tropical disturbance ("94E") located about 360 miles south of the Mexico/Guatemala border appears likely to become a tropical depression. The center appears to be closed and within the convection, and the system appears to be on the verge of becoming a tropical depression.
Figure 1. Latest infrared satellite image of Invest 94E. Image credit: NOAA
Upper tropospheric shear over the system isn't strong, although the large scale flow pattern does not yet resemble an anticyclone. Interestingly, water vapor imagery shows a small upper low over southeast Mexico. Since this low appears to be moving westward away from 94E, it is unlikely to alter its chance at becoming a tropical cyclone. Luckily the global models recognized this vortex, otherwise I would be concerned about a busted intensity forecast due to unexpected shear. They quickly elongate and weaken this low over the next 12-24 hours. It should be noted that the HWRF makes the system a major hurricane prior to moving inland. While experience has taught me to be cautious, forecasting hurricanes is hardly an art, and once an inner core becomes established, there is definitely the potential for rapid strengthening.
The model consensus is in surprising agreement on the track for a system that hasn't even developed yet, although they differ a bit on the timing of landfall. The GFS is about 12-18 hours ahead of the other models, apparently seeing more pull from the trough. Since the large scale pattern over the United States looks rather zonal at the moment, I tend to side with the other models, comprised of the generally reliable ECMWF. Amusingly, but perhaps unsurprising, the 12z NOGAPS initialization was terrible, spinning the system around, and eventually weakening it because of, an adjacent vortex to the west. Since the latter system is quite weak, this solution was ignored. I am to the left of the GFS, in best agreement with the ECMWF. This should pull the system inland over central Mexico by late Saturday afternoon.
Interests along the Mexican coast from Acapulco to Puerto Angel should closely monitor the progress of this potentially dangerous system. Tropical storm warnings or hurricane watches could be required rather quickly tonight for a portion of the coast. I would also like to note that the potential for abrupt weakening or dissipation before landfall in a fashion mimicking Bud last month does not seem feasible this time around. Bud was in an area of cooling sea surface temperatures, and was also ingesting the very dry marine layer airmass that is typically found over the eastern Pacific west of 110W. That is not the case with this system. This system will probably become a strong tropical storm, and even that is probably conservative. A much more dangerous system is certainly possible.
Probability of development within the next 48 hours: Near 100%
Another area of low pressure, the one the NOGAPS initialized as the stronger of the two, is located several hundred miles west of 94E. This system is embedded in a large cyclonic circulation within the ITCZ, and is undergoing easterly shear, which is not forecast to abate. Development is not anticipated with this system, and I probably won't mention it again.
Probability of development within the next 48 hours: Near 0%
Atlantic development still possible
While I have ceased monitoring the Carolinas system, there is still the potential for some development in the northwest Caribbean or southern Gulf of Mexico beginning in about 5 days. It appears that the mechanism by which this development will arise is the mid-level remnants of 94E/Carlotta, which could combine with a tropical wave to enhance cloudiness and showers over this area. Although the incipient wave is already approaching 85W, with 94E forecast to become a deep system, the typical easterly flow found in this region of the basin may temporarily become halted due to large scale cyclonic flow surrounding 94E. This could slow the forward progression of the tropical wave some, and allow it to stick around until 94E moves inland, and into the Caribbean.