A large monsoonal trough over the northern Caribbean is
drifting towards the Gulf of Mexico. Global models are all suggesting future
development, and the National Hurricane Center has flagged this area of
disturbed weather with a 10% chance of developing into a tropical cyclone
through Thursday evening.
Currently the trough is under a good amount of northeasterly
shear. This is expected to continue in the short term. However, a small upper
level anti-cyclone is located to the north of the system, which is aiding in
providing lift over the southern Gulf and northern Caribbean, which should
allow this trough to continue to fire some convection over the coming days as
it drifts towards the northeast.
As you can see by the dark colors over the northern and western
Gulf on the image above however, there is a good amount of dry air ahead of
this tropical wave. Given the severe drought over Texas and high pressure
expected to remain in place over the southern US, this may be an issue to
contend with down the road.
Currently, the tropical wave/trough is associated with a
weak area of vorticity, or spin in the atmosphere. This shows that there is
currently no attempt at a defined surface circulation forming, and this should
not occur in the near term as the system hangs around near the Yucatan Peninsula
As the system moves into the Gulf of Mexico however, it will
become better situated under the aforementioned upper level anti-cyclone. This
will promote continued convection as mentioned above and will allow convection
to become better organized and concentrated. This will allow the system to
attempt to organize over the western Gulf of Mexico late this week into the
Right now all of the global models (GFS, UKMET, NOGAPS, CMC,
ECM) attempt to develop some sort of a tropical cyclone out of this system over
the western Gulf as it drifts around. Given warm sea surface temperatures and
what appears to be at least a marginal if not decent environment for further
development once this tropical wave gets into the Gulf of Mexico by some point
Thursday, this seems reasonable and this might be the next tropical cyclone
threat close to home.
As an example, the 12z European model (ECMWF) develops a
large area of low pressure over the western Gulf this weekend and shows it
hanging around for a few days. The large, broad wind field is not atypical with
systems that try to spin up from large, broad troughs of low pressure such as
What is interesting is that most models develop at least a
sliver of ridging to the north, east, and west of this area of disturbed
weather once it moves into the western Gulf. This supports the weird drift to
the south or southwest over the western Gulf most models show at this time.
Given uncertainty about the future intensity of this system
and where it will exactly spin up given the large gere that would spawn any
future system, it is too early to say for sure where this will go. The upper
level environment and warm SSTs may support a moderately strong cyclone down
the road, but the system’s likely large size and proximity to land and dry air are
possible hindrances to an intense cyclone, so the intensity forecast at this
point would be highly uncertain. But a slow moving possibly tropical system
looks like a decent bet over the western Gulf by the weekend.
Based on heightened chances of a tropical cyclone near the
region, I have placed the Gulf coast from New Orleans south/west through
eastern mainland Mexico into “low risk” area for impacts from this system, the
second from bottom risk level on a scale that goes from minimal, to low, to
medium, to high, to extreme risks. A low risk on my personal, unofficial and
experimental Tropical Cyclone Risk Assessment Scale indicates that adverse
weather caused by a tropical cyclone is possible within the next 5 days.
Disclaimer: All tropical cyclone forecasts and discussions
found on this blog are the personal opinion of Jim Sullivan and Jim Sullivan
only. Jim Sullivan is not yet a degreed meteorologist and is not liable for
personal damages resulting from decisions made due to reading this blog. This
blog is for entertainment purposes and is meant to illustrate what goes behind
tropical cyclone forecasting and to foster discussion, and is NOT intended to
be used for life or death decisions. For official information/forecasts, visit
your local National Weather Service Office webpage or National Hurricane Center
webpage through weather.gov. Listen to all evacuations/advice that comes from
emergency management or local officials.