Tropical Depression Five Discussion Number 1
Statement as of 4:00 PM CDT on August 03, 2008
satellite imagery during the day has shown that the low pressure
area in the Gulf of Mexico has a low-level circulation center
exposed just to the northwest of a cluster of somewhat disorganized
convection. Recent reports of an Air Force Reserve hurricane
hunter aircraft indicate that the circulation is well-defined
enough for the low to be designated a tropical depression. The
aircraft has reported maximum flight level winds of 36 kt and a
minimum central pressure of 1007 mb. Based on this...the initial
intensity is set to 30 kt.
The initial motion is a somewhat uncertain 265/5. The depression is
on the southwest side of a strong mid-level ridge over the Southern
Plains...with the large-scale models forecasting the ridge to build
eastward during the next 24-48 hr. This should steer the cyclone
generally westward or west-northwestward toward the Upper Texas and
western Louisiana coasts. The track model guidance is in good
agreement in calling for landfall in this area...with the GFS and
UKMET aiming at western Louisiana and the rest of the dynamical
guidance aiming at Texas. The official forecast track follows the
model consensus and call for landfall on the Upper Texas coast in
36-48 hr. The forecast track is in best agreement with the ECMWF.
The depression is currently encountering northerly vertical wind
shear and dry air entrainment...which has given the system a ragged
appearance. The large-scale models forecast the shear to diminish
and the upper-level winds to become more favorable for
intensification during the next 48 hr. The intensity forecast
calls for the system to make landfall with 50-55 kt winds in
agreement with the SHIPS model. It should be noted that the latest
GFDL calls for the cyclone to reach hurricane strength before
landfall... which is a sharp contrast to previous runs. Due to
this lack of consistency...the intensity forecast will not yet
reflect this possibility.
Tropical storm warnings and watches are required for portions of the
Louisiana and Texas coast on this advisory.
Forecast positions and Max winds
initial 03/2100z 28.2n 88.1w 30 kt
12hr VT 04/0600z 28.2n 89.4w 35 kt
24hr VT 04/1800z 28.4n 91.5w 40 kt
36hr VT 05/0600z 28.9n 93.8w 50 kt
48hr VT 05/1800z 29.5n 96.2w 40 kt...inland
72hr VT 06/1800z 30.5n 100.5w 20 kt...inland remnant low
96hr VT 07/1800z...dissipated
$$
Tropical Storm Public Advisory
Statement as of 4:00 PM CDT on August 03, 2008
...Tropical Depression Five forms in the northern Gulf of
Mexico...warnings and watches issued...
at 4 PM CDT...2100 UTC...a Tropical Storm Warning is in effect for
the Louisiana coast from the mouth of the Mississippi River
westward to Intracoastal City. A Tropical Storm Warning means that
tropical storm conditions are expected within the warning area
within the next 24 hours.
At 4 PM CDT...2100 UTC...a tropical storm watch is in effect west of
Intracoastal City to Port Oconnor Texas. A tropical storm watch
means that tropical storm conditions are possible within the watch
area...generally within 36 hours.
For storm information specific to your area...including possible
inland watches and warnings...please monitor products issued
by your local weather office.
At 400 PM CDT...2100z...the center of Tropical Depression Five was
located near latitude 28.2 north...longitude 88.1 west or about 85
miles...140 km...southeast of the mouth of the Mississippi River and
about 415 miles...665 km...east of Galveston Texas.
The depression is moving toward the west near 6 mph...10 km/hr...and
a general motion toward the west or west-northwest is forecast
during the next couple of days. On the forecast track...the center
of the cyclone will move parallel to the Louisiana coast tonight
and Monday...and approach the Upper Texas coast on Tuesday.
Maximum sustained winds are near 35 mph...55 km/hr...with higher
gusts. Slow strengthening is forecast during the next 24
hours...and the depression is expected to become a tropical storm
later tonight or on Monday.
The latest minimum central pressure reported by an Air Force Reserve
hurricane hunter aircraft is 1007 mb...29.74 inches.
Tides of 2 to 4 ft above normal tide levels can be expected in the
warning area in areas of onshore flow.
The tropical depression is expected to produce total rain
accumulations of 1 to 2 inches along the the Louisiana coast with
possible isolated maximum amounts of 3 inches. Once the system
moves to the Upper Texas coast...total rain accumulations of 2 to 4
inches with isolated maximum amounts of 6 inches are possible over
southeast Texas.
Repeating the 400 PM CDT position...28.2 N...88.1 W. Movement
toward...west near 6 mph. Maximum sustained winds...35 mph.
Minimum central pressure...1007 mb.
An intermediate advisory will be issued by the National Hurricane
Center at 700 PM CDT followed by the next complete advisory at 1000
PM CDT.
$$
Forecaster Beven