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Tropical Weather Discussion
Issued: Thursday, August 28, 2008 730 am EDT
Well folks we have two classified systems
out there this morning, so let's get right into it:
Gustav: Gustav continues to pull surprises this morning.
An Air Force Reconnaissance Plane has found maximum winds of 70 mph and
it appears that Gustav will once again become a hurricane sometime today.
The Air Force Reconnaissance flight also found that Gustav has either
reformed to the south or been moving more to the south-southwest
overnight. So, I expect Gustav to strengthen today to a hurricane
and strengthen a little more tonight, however, interaction with
Jamaica may limit the overall intensification of this system through
tonight. After tonight, the global models are
forecasting a ridge of high pressure to be near the center of
Gustav, which would be quite favorable for strengthening. I
expect Gustav to reach hurricane strength on Friday and then to
ramp up rather quickly thereafter, reaching at least Category 3
strength as it tracks through the Yucatan Channel and into the
southern Gulf of Mexico Saturday night into Sunday morning.
Gustav is currently expected to maintain at least Category 3
strength through the Gulf of Mexico right up to the time of
landfall.
Gustav is currently tracking southwest at
a forward speed of 8 mph. Gustav is now forecast to track near
the south coast of Jamaica this afternoon and tonight. The
northeast-southwest oriented ridge of high pressure centered over
the Florida Peninsula that has been causing this southwestward
motion is expected to weaken over the next few days. This should
allow Gustav to turn more to the west and then northwest around
the time it enters the Gulf of Mexico. Another high pressure
system is forecast to be located over the Ohio Valley around
Tuesday and this high pressure system may allow Gustav to remain
on a northwesterly course through landfall rather than a more
northward motion like the GFDL model suggests. It should be noted that the European model still forecasts Gustav to make landfall near New
Orleans on Monday night. The model consensus guidance has shifted westward and now aims Gustav at the
upper Texas coast and southwest Louisiana. With the initial
position of Gustav now more southwest than what it was yesterday,
the consensus model guidance seems quite reasonable.
Ok, here is my thinking for the future
track and intensity of Gustav through Sunday morning: I expect
Gustav to either track just south of Jamaica or perhaps track
right over the southern part of the island this afternoon and
tonight. As I mentioned earlier in this discussion, I expect
Gustav to stengthen to hurricane strength today and then perhaps
only strengthen slightly tonight as it tracks near Jamaica. Gustav is then forecast to track into the
northwestern Caribbean on Friday and Saturday where it is
expected to intensify by quite a bit and I expect Gustav to be at
least Category 3 strength as it tracks through the Yucatan
Channel and into the southern Gulf of Mexico on Saturday night
and Sunday morning.
Looking beyond Sunday morning and into
next week, here is my thinking on the possible track and
intensity of Gustav once it is in the Gulf of Mexico:
Based on Gustav's more southwest initial
position this morning, I like the ideas set forth by the model
consensus guidance. Therefore, I think Gustav will eventually
make landfall somewhere over the central or southwestern
Louisiana coast or the upper Texas coast, basically somewhere
between Houma, Louisiana and Houston, Texas. Areas further east,
including New Orleans and the Alabama and Mississippi coastlines
and areas further west, including Port O' Connor and Victoria,
Texas are still at a significant risk as any shifts in the
forecast track will put these areas at a significant risk from a
significant hurricane.
As for timing, it looks like Gustav will
come ashore sometime during the day on Tuesday.
Now for strength, all indications continue
to point towards the idea that Gustav will be a major hurricane
in the Gulf of Mexico and it should be assumed that it will make
landfall as a major hurricane of at least Category 3 strength.
All interests on the Louisiana and upper
Texas coast should pay very, very close attention to the forecast
of Gustav.
For the latest maps, graphics, advisories
and any watches and warnings related to Gustav, please refer to
our Gustav Page.
I will be monitoring this situation very
closely and keep you all updated.
Tropical Depression #8:
An area of low pressure located about 350 miles east-northeast of
the northern Leeward Islands has developed enough of a surface
circulation and deep organized convection to be classified as a
tropical depression. The model guidance is
forecasting that a ridge of high pressure will prevail around
this system, resulting in a light shear environment. This
tropical depression is expected to become Tropical Storm Hanna at
some point today and may reach hurricane strength by about
Sunday.
Tropical Depression #8 is currently
tracking to the northwest at a forward speed of 6 mph. A large
trough of low pressure currently located over the western
Atlantic is forecast to be replaced by a large ridge of high
pressure over this coming weekend. This pattern should force this
system to turn more west-northwest and perhaps even due west by
this weekend. This forecast track is well modeled in the track model guidance and especially in the consensus model guidance. It should be noted that many of the global models
are bringing this storm dangerously close to Florida and the US
Southeast Coast in about one week. This building model consensus
includes the UKMET model, NOGAPS model and particularly the European model, which forecasts this system to impact south
Florida next Friday.
One last thing to note about Tropical
Depression 8 and the overall weather pattern this system will be
in is that the upper level pattern for the early to mid part of
next week as progged by the GFS and European model are similar to
the upper-level pattern that accompanied Hurricane Betsy in 1965. It should be noted that Betsy tracked
northwestward on September 3rd and 4th and then slowed down
considerably and looped by September 5th, resulting in a
southwest track by September 6th and a due west track after that.
The GFS and European models initially have
a more north to south oriented ridge of high pressure, but
eventually shift the ridge to a more east to west orientation,
which would favor a westward movement. It should also be noted
that the GFS, Canadian and NOGAPS model have trended to the
European model in showing a stronger ridge of high pressure by
the early to mid-part of next week.
Therefore, this storm poses an eventual
threat to Florida and the rest of the US Southeast Coast late
next week. Folks in Florida and the US Southeast Coast should pay
very close attention to the track of TD #8/Hanna. I will be
keeping a very close watch on the progress of this system and
will keep you all updated.
The next tropical weather discussion will
be issued by 7 am EDT Friday morning. No updates will be issued
this evening due to prior commitments.
Prepared by Rob Lightbown, Crown Weather Services
Disclaimer: All forecasts herein are made to the
best ability of the forecaster. However, due to standard
forecasting error, these forecasts cannot be guaranteed. Any
action or inaction taken by users of this forecast is the sole
responsibility of that user.
