Take a ride on the wavetrain...

Take a ride on the wavetrain...

Africa and the tropical Atlantic have become crowded with easterly
waves, greatly increasing the odds that at least one will develop.  As
many as 5 waves can be found from the Lesser Antilles eastward to
central Africa, some of which are looking quite interesting.

The westmost is the one we've been watching for a few days now,
presently at about 15N 65W and tracking W at 15kts.  It has had a
drastic increase in deep convection and some band-like features appear
to be forming.

Watching a large area of convection and a broad circulation at about 10N
40W (halfway between Lesser Antilles and Africa) that's tracking W at
15kts.  Also, a similar system to the previous is at about 10N 20W
(south of the Cape Verde Islands) and tracking W at 15kts.

Africa still has a couple fairly impressive MCCs (mesoscale convective
complexes) trekking westward across it and should be watched for
development over the next week as they enter the eastern Atlantic.

The majority of the computer models do not favor any of the systems
currently in the Atlantic, but do develop one that's over
western/central Africa now.

The next numbers/names on deck are 9/Fabian and 10/Grace.

I will be gone through 1 Sep for vacation, so that would be the next
update, assuming something's happening then.

Please visit my tropical Atlantic headquarters.

Two easterly waves worth watching in the central Atlantic...

The wave and embedded Low I mentioned yesterday just east of the Lesser
Antilles is a bit less organized today, and in fact, appears to no
longer have an embedded Low.  It is at about 14N 55W and moving W at
15kts.

And the wave that exited the African coast yesterday is now passing west
of the Cape Verde Islands and tracking W at 10kts.  The axis of the wave
is at about 35W.

Of these two waves, the models favor the eastern one for development,
but not very significant.  However, a short wavelength wavetrain is
trekking across Africa and will eject a new easterly wave into the
tropical Atlantic about every two days.

Please visit my tropical Atlantic headquarters.

Erika made landfall, tropical wave still traversing the central Atlantic...

TS Erika ended up being a well-forecast storm, particularly in terms of
the track.  The intensity was persistently overforecast, and she never
reached hurricane status.  Although the MSLP dropped to 987mb and there
was a beautiful eye as seen from radar, maximum reported winds were
60kts.  Landfall occured on Saturday (August 16) at 11Z near Laguna
Madre, Mexico.  She ten continued westward acorss Mexico and if I'm not
mistaken, has entered the East Pacific just south of the tip of the Baja
Peninsula.

Elsewhere, the tropical wave I mentioned in Friday's update is still
intact and slowly organizing.  Presently at about 14N 48W, it's tracking
WNW at 12kts and has a 1014mb Low embedded in the wave.  It is just
crossing the 28C isotherm and SSTs will continue to be favorable; also,
vertical shear is favorable for development.  Lastly, a wave still over
Africa seems favored by many models to develop, so we'll keep an eye on
the deep tropics this week for perhaps a couple storms.

Please visit my tropical Atlantic headquarters.

Erika forms in the central Gulf...

At 21Z on Thursday, the disturbance I had mentioned off the coast of
Florida developed into Tropical Storm Erika, the fifth named storm of
the season.  It organized quickly upon entering the Gulf, and continues
to do so, threatening areas along the western Gulf coast.

As of 15Z today, TS Erika was located at 26.1N 91.4W and tracking W at
20kts.  This forward speed is racing it toward the coast, and the
question that remains is how fast will she intensify before making
landfall.  Current intensity is 45kts and 1008mb (surprisingly high
pressure considering the appearance).  The satellite presentation is
beautiful, with a cold CDO, obvious banding features, and symmetric
outflow aloft.  Cloud tops at the center are nearly -80C, with a large
dome of -70C or colder.  SSTs under the forecast track are in the 29-30C
range, supplying enormous amounts of energy to the storm.  And although
that warm water doesn't extend very deep, Erika is moving fast enough
that upwelling will not be a concern. (I'm a bit lost for words as to
why she hasn't developed faster... conditions seem optimal, yet she's
still a TS)

A Tropical Storm Warning is in effect for parts of the Texas coast
between Baffin Bay and Port O'Connor.  A Hurricane Warning is in effect
from Baffin Bay, TX southward to La Pesca, Mexico.

The forecast is for continued strengthening, and a westward track,
making landfall near Brownsville as a hurricane during the early morning
hours on Saturday.  With nearly 24 hours remaining until landfall from
the time of this writing, a lot can happen with a storm, and coastal
residents need to be prepared for the possibility of a rapid
intensification (NHC is typically and appropriately conservative with
their forecasts).

Elsewhere, a tropical wave that exited the African coast yesterday is
now at about 13N 25W (very near the Cape Verde Islands) and moving W at
10kts.  There is an embedded 1010mb Low with this wave, and conditions
in advance of it appear favorable for gradual development during the
weekend.  The next number/name on deck are TD9/Fabian.

I want to direct you
specifically to a great visible shot from 1445Z today, available at
http://www.nrlmry.navy.mil/archdat/atlantic/tropics/vis/20030815.1445.goes12.vis.x.trop.x.jpg. 
You can clearly see Erika in the central Gulf, and the disturbance over
the Cape Verde Islands.

Please visit my tropical Atlantic headquarters.

Development in the Gulf...

A feature I've been watching for several days (seemingly spawned by an
upper-level Low closer to Bermuda), approached the U.S. mainland
yesterday and just crossed the central Florida peninsula.  It has
gradually been getting better organized and deep convection has been
persistent.  It's now near 27N 83W, MSLP of 1013mb, and showing signs of
banding as it enters the Gulf of Mexico west of Fort Meyers, FL.

Aircraft recon into the system was unable to locate a closed surface
circulation, but the mid-level circulation is very well defined as
evident on satellite imagery.  You can also see the mid-level
circulation on Tampa's NEXRAD radar
(http://www.srh.noaa.gov/radar/latest/DS.p20-r/si.ktbw.shtml).

It seems likely that this will develop into TD8 sometime today, and
perhaps a named storm within 24 hours (Erika is the next name). Some
model stuff: ETA and GFS are hesitant to intensify the system very much,
but they both track it due west into northern Mexico (Tampico-ish) on
Saturday morning.  NOGAPS keeps the same timing, but a bit further
north, around Brownsville.

Please visit my tropical Atlantic headquarters.

Disturbance slow to get going...

Same system I've been talking about for the past couple days, but it's
in moderate easterly shear, and more importantly [it seems] is that it's
in a stable, dry air mass.  This has choked off convection and inhibited
new convection from firing.  However the circulation is still intact and
awaiting more favorable conditions, which should be just a day away.

Presently at about 11N 42W and tracking W at 15kts, the MSLP is stil
1010mb.  The computer models paint a grim future for this system... very
hard to find a solution that intensifies the storm.

Please visit my tropical Atlantic headquarters.