5 AM TD#13 -- 35 MPH, W 11, 1005 MB...LISA POSSIBLE in 24 hr

[yoda]

**LOW CONFIDENCE FORECAST FROM NHC (see discussion)**

5 DAY --
http://www.wunderground.com/tropical/tr ... _5day.html



Tropical Depression Thirteen Advisory Number 3


Statement as of 5:00 am AST on September 20, 2004



...Depression continues westward on the heels of Karl...
At 5 am AST...0900z...the center of Tropical Depression Thirteen was
located near latitude 13.5 north...longitude 34.9 west or about 750
miles...1205 km...west-southwest of the Cape Verde Islands.

The depression is moving toward the west near 12 mph
...19 km/hr...and this motion is expected to continue for the next
24 hours.

Maximum sustained winds are near 35 mph... 55 km/hr...with higher
gusts. The depression could become a tropical storm during the next
24 hours.

Estimated minimum central pressure is 1005 mb...29.68 inches.

Repeating the 5 am AST position...13.5 N... 34.9 W. Movement
toward...west near 12 mph. Maximum sustained
winds... 35 mph. Minimum central pressure...1005 mb.

The next advisory will be issued by the National
Hurricane Center at 11 am AST.

Forecaster Franklin

[yoda]

Tropical Depression Thirteen Discussion Number 3


Statement as of 5:00 am EDT on September 20, 2004



Dvorak intensity estimates remain at 30 kt from all agencies and the
initial intensity is held at 30 kt. The depression is maintaining
a small Ball of convection near the presumed center but has no
discernable outflow pattern at this time. Indeed...the depression
is caught between Hurricane Karl about 650 nm to its west-northwest
and a large but disorganized area of disturbed weather to its
southeast. The GFS...NOGAPS...and UKMET all make the depression
the weakest of these three systems within a couple of days. While
both the SHIPS and GFDL guidance bring the depression to hurricane
strength...I am reluctant to do so given the competing systems in
its near environment...and it is quite fossible this depression
will be short-lived.
The initial motion estimate is 275/10. For the next day or so the
depression should move generally westward underneath a mid-level
ridge to the northwest of Karl. After that there is considerable
uncertainty with the track as the guidance models are giving a wide
variety of possible solutions. The GFS loses the depression in the
disturbance to the southeast...while the UKMET entrains it into
Karl. On the other hand...the GFDL keeps the depression and takes
it west and then west-southwest as heights build in after Karl
lifts out...while the BAM models have varying degrees of a Bend to
the right. Currently the depression is moving faster than
Karl...increasing the chance of it moving to the west-northwest or
northwest on Karl's eastern periphery. The official forecast has
been adjusted north of the previous forecast to reflect the
possibility of some interaction...but then bends the track back to
the west near the end of the forecast period under the Assumption
that Karl will leave the depression behind. Given the very
complicated environment...this is a rather low confidence forecast.
Forecaster Franklin

forecast positions and Max winds

initial 20/0900z 13.5n 34.9w 30 kt
12hr VT 20/1800z 13.6n 36.4w 35 kt
24hr VT 21/0600z 14.1n 38.2w 40 kt
36hr VT 21/1800z 14.5n 39.7w 45 kt
48hr VT 22/0600z 15.0n 41.5w 50 kt
72hr VT 23/0600z 17.0n 45.0w 55 kt
96hr VT 24/0600z 18.0n 48.0w 55 kt
120hr VT 25/0600z 18.5n 51.0w 55 kt

[Cookiely]

Thanks Yoda for all the advisories and discussions.