11am adv warnings are now up

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Tropical Depression One Advisory Number 4


Statement as of 11:00 am EDT on August 01, 2004



...Depression a little stronger...Tropical Storm Warning issued...
At 11 am EDT...1500z...a Tropical Storm Warning has been issued from
Cape Fear to Cape Hatteras North Carolina...including the Pamlico
Sound. A Tropical Storm Warning means that tropical storm
conditions are expected within the warning area within the next 24
hours.

A tropical storm watch remains in effect from Edisto Beach South
Carolina to Cape Fear North Carolina.

At 11 am EDT...1500z...the poorly-defined center of Tropical
Depression One was re-located near latitude 31.9 north...longitude
79.2 west or about 80 miles...125 km...southeast of Charleston
South Carolina.

The center of the depression has been meandering over the past
several hours. A slow northward motion is expected later today
with a turn to the north-northeast tomorrow. On this track...the
center of the depression is expected to be very near the South
Carolina coastline later today.

Maximum sustained winds are near 35 mph... 55 km/hr...with higher
gusts...in squalls to the south and east of the center. The
depression has the potential to become a tropical storm during the
next 24 hours.

The minimum central pressure reported by reconnaissance aircraft is
1011 mb...29.85 inches.

Rainfall accumulations of 1-2 inches...with isolated higher
amounts...can be expected in association with the depression.
Repeating the 11 am EDT position...31.9 N... 79.2 W. Movement
...Stationary. Maximum sustained
winds... 35 mph. Minimum central pressure...1011 mb.

For storm information specific to your area...please monitor
products issued by your local weather office.

An intermediate advisory will be issued by the National
Hurricane Center at 2 PM EDT followed by the next
complete advisory at 5 PM EDT.

Forecaster Franklin
Tropical Depression One Discussion Number 4


Statement as of 11:00 am EDT on August 01, 2004



the depression continues to have an ill-defined and elongated center
with multiple swirls. The Air Force reserve unit reconnaissance
aircraft did fix a center south of the previous advisory and closer
to the deep convection. This could indicate that the depression
may be starting to organize a bit...or they could have fixed a
transient feature. The official center position is relocated a
little south of the previous track but based on the overall
satellite appearance I am not going all the way down to the fix
location. The aircraft did report flight-level winds of 33 and 36
kt...with a visual surface estimate of 30 kt...and these
observations are the basis of raising the initial intensity to 30
kt. There is currently very little wind to the north or west of
the center.
Water vapor imagery indicates strong upper-level northeasterly flow
and subsidence over the northern part of the depression's
circulation...which should hinder significant strengthening of the
tropical cyclone. However...upper-level southwesterlies are headed
toward the cyclone...and as the flow transitions the depression may
find a briefly more favorable upper pattern in 24 hours or so. The
SHIPS guidance brings the depression to near 50 kt in 36
hours...while the GFDL shows little change. The official forecast
roughly splits the difference and has the system as a tropical
storm very close to the coast in 24 hours. As a result...a Tropical
Storm Warning is required at this time. Later in the forecast
period...global model guidance shows the cyclone merging with a
larger extratropical low pressure system.

Given the ragged nature of the circulation...the initial motion is
hard to determine...but appears to be essentially stationary. The
depression is approaching a break in the subtropical ridge...so
steering currents are weak and the cyclone is forecast to move
rather slowly and remain near the south and North Carolina coasts
through 36-48 hours. Thereafter...a gradually amplifying mid-level
trough is likely to carry the tropical cyclone northeastward with
an increase in forward speed. The official track forecast is fairly
similar to the previous advisory. If the depression is in fact
reorganizing farther south...then the current forecast is likely to
be too fast.

Forecaster Franklin

forecast positions and Max winds

initial 01/1500z 31.9n 79.2w 30 kt
12hr VT 02/0000z 33.0n 78.8w 30 kt
24hr VT 02/1200z 34.1n 77.8w 35 kt
36hr VT 03/0000z 35.1n 76.2w 40 kt
48hr VT 03/1200z 36.5n 74.0w 40 kt
72hr VT 04/1200z 41.0n 66.0w 40 kt
96hr VT 05/1200z 46.0n 56.0w 40 kt...extratropical
120hr VT 06/1200z...absorbed by extratropical low


$$

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