Tropical weather analysis - June 12, 2012
An area of low pressure located in the far eastern Pacific about 500 miles south-southeast of the Guatemala/El Salvador border ("94E") is showing signs of organization. Last light visible satellite imagery and Dvorak enhancement imagery from RAMMB suggests the low-level center is located on the northeastern edge of the convection. This was also confirmed by an earlier ASCAT pass, showing the strongest winds west of a sharp cyclonic wind shift assumed to be the trough axis.
Figure 1. Latest infrared satellite image of Invest 94E. Image credit: RAMMB imagery Colorado State University (CSU).
Atmospheric and oceanic parameters appear favorable for continued development over the next few days, and this low has the potential to become a tropical depression during the next day or so. I think the most likely timeframe for this to occur is around 0z Thursday. It is possible that this system could become a hurricane before moving inland.
As just mentioned, the synoptic pattern favors a gradual turn into southeast Mexico. Model guidance suggests this, and their theory is supported by the current large-scale pattern over the United States; water vapor imagery shows the ridge over the central US shifting eastward as a weak upper-level trough develops over the Rockies. Cyclonic flow is forecast to linger in this area for the next several days, which in combination with the ridge should induce a west-northwest motion, followed by a turn to the northwest toward the coast. This system is forecast to move inland late Friday or early Saturday.
Interests along the coast of southeast Mexico should monitor the progress of this disturbance.
Probability of genesis within the next 48 hours: 60%
A secondary of low pressure lies several hundred miles west of 94E. This low is not nearly as well organized, and any development here should be slow. This low is expected to move generally westward over the next few days. It poses no threat to land areas.
Probability of genesis within the next 48 hours: 20%
Atlantic development possible late this week and into next
The global models continue to portray two areas of interest across the Atlantic basin over the next 7 - 10 days: the first is off the waters of the western Atlantic, where they are unanimous in developing a weak surface low off the coast of North Carolina from the large trough moving across the eastern seaboard. Unlike with Alberto and Beryl, the synoptic pattern does not favor US peril, as a large trough is forecast to amplify over the western Atlantic, which favors a slow turn out to sea through the break in the subtropical ridge. I am not particularly confident on development, as northwesterly shear and dry air are present.
Demanding more immediacy is the potential for some sort of tropical development in the northwestern Caribbean or Gulf of Mexico next week. The models have been hinting at this for awhile, albeit with minimal consistency on the specifics -- i.e., whether we get a tropical cyclone. Without going into explicit detail, the large-scale pattern forecast over the United States and western Atlantic does favor development in this region, especially considering the MJO is forecast to move back into our basin soon. We are already seeing overt signs of this in the eastern Pacific. It is important not to let your guard down in regards to the potential for some sort of tropical cyclone forming in this region, the lack of consistency amongst the global models notwithstanding. This current upward pulse is fairly strong. As such, the models will probably have a little bit of difficulty in resolving it.
At the very least, a large surge of moisture will probably manifest over the waters of the western Caribbean, Gulf of Mexico, and portions of the western Atlantic over the next 7 - 10 days. Height anomalies over the US favor the development region over the Gulf of Mexico or northwest Caribbean. It is uncertain where such a system would go, but based on the large-scale pattern in the models, I feel like a north to northwest track into the Gulf of Mexico would be possible. The system's exact point of origin cannot yet be known, so there is enough uncertainty that the entire Gulf Coast could see something. It is also possible, as per the GFS, that the system could originate farther east, closer to Jamaica, get caught up in a trough, and move off to the northeast.