000
WTNT44 KNHC 232048
TCDAT4

TROPICAL DEPRESSION FOUR DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL042014
500 PM AST SAT AUG 23 2014

The Air Force Reserve Hurricane Hunter aircraft investigating the
disturbance near the southeastern Bahamas found a well-defined
circulation this afternoon. Even though the convective presentation
is somewhat ragged, there is enough organization to classify the
system as a tropical cyclone. The intensity is set to 30 kt based
on flight level wind data from the aircraft and an earlier ASCAT
pass, and the central pressure of 1005 mb is based on a recent
surface observation from Providenciales in the Turks and Caicos. The
SHIPS model shows light to moderate shear over the cyclone for the
next couple of days, which should allow for intensification given
that the cyclone will be moving over waters of 29 to 30C. The NHC
forecast shows slow strengthening in the first 24 to 36 hours as
the cyclone organizes. Global models show more favorable upper-
level winds over the system in a couple of days, which should allow
for strengthening to a hurricane in by 3 days. The official forecast
is close to the IVCN intensity consensus through the period.

The initial motion estimate is a relatively uncertain 310/10 given
the recent formation of the center. The cyclone should continue
moving northwestward and north-northwestward into a developing break
in the subtropical ridge cause by a mid/upper-level trough off the
U.S. east coast. As the trough begins to lift out and steering
currents weaken, a slow motion is expected in 36 to 48 hours. Then
as a subtropical ridge rebuilds to the east of the cyclone later in
the period, the system is expected to turn northward and then
northeastward. However, there is significant disagreement in
the timing and sharpness of the turn in this and previous dynamical
model cycles. Currently the GFDL and GFS are along the western
edge of the guidance envelope showing a more westward track and
a slower motion at day 5. The ECMWF, GEFS mean, and HWRF show a
sharper turn and a more northeastward motion by day 5 on the east
side of the guidance envelope. The NHC forecast is near the TVCA
multi-model consensus through most of the period and a little to the
left of it at day 5. Given the spread in the guidance and the recent
formation of the system, confidence in the details of the track
forecast is lower than normal.

FORECAST POSITIONS AND MAX WINDS

INIT  23/2100Z 21.8N  72.3W   30 KT  35 MPH
 12H  24/0600Z 22.9N  73.6W   35 KT  40 MPH
 24H  24/1800Z 24.0N  74.4W   40 KT  45 MPH
 36H  25/0600Z 24.6N  74.8W   45 KT  50 MPH
 48H  25/1800Z 25.0N  75.0W   55 KT  65 MPH
 72H  26/1800Z 26.5N  76.0W   65 KT  75 MPH
 96H  27/1800Z 29.0N  77.5W   65 KT  75 MPH
120H  28/1800Z 32.0N  76.5W   70 KT  80 MPH

$$
Forecaster Brennan

BULLETIN
TROPICAL DEPRESSION FOUR INTERMEDIATE ADVISORY NUMBER   2A
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL042014
200 AM AST SUN AUG 24 2014

...DEPRESSION EXPECTED TO BECOME A TROPICAL STORM TODAY...


SUMMARY OF 200 AM AST...0600 UTC...INFORMATION
----------------------------------------------
LOCATION...22.6N 73.0W
ABOUT 15 MI...25 KM N OF MAYAGUANA ISLAND
ABOUT 325 MI...520 KM ESE OF NASSAU
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NW OR 325 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES