000
WTNT44 KNHC 202038
TCDAT4

HURRICANE DANNY DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL042015
500 PM AST THU AUG 20 2015

The overall cloud pattern of Danny has continued to improve with the
development of a tiny eye within a small central dense overcast,
as well as some outer convective banding features. The
initial intensity of 70 kt is based on a blend of consensus Dvorak
satellite intensity estimates of T4.0/65 kt from TAFB and SAB and
an NHC objective Dvorak classification of T4.5/77 kt using the
pinhole eye scene type.  Satellite data continue to indicate that
Danny is an unusually small tropical cyclone.

The initial motion is 295/09 kt. NHC model guidance continues to be
in good agreement on Danny moving west-northwestward for the next 48
hours or so, followed by a turn toward the west thereafter
as a weakness in the subtropical ridge along 60W fills in. As the
ridge builds westward to the north of Danny, the cyclone is expected
to accelerate and move a little faster during the 72-120 hour
period. The official forecast track is essentially just an update of
the previous advisory and lies close to the consensus model TVCN.

Danny's compact size makes it subject to significant fluctuations in
strength, both up and down, and such fluctuations are difficult, at
best, to forecast.  Low-shear conditions and SSTs near 28 deg C are
expected to continue along the forecast track for the next 24 hours
or so, which should allow for some further strengthening during that
time. Although Danny continues to be surrounded by dry mid-level
air, the recent development of outer banding features noted in
satellite images suggests that entrainment of this dry air might not
be as much of an inhibiting factor as it has been during the past
couple of days. However, by 36 hours and beyond, the 850-200 mb
vertical wind shear is expected to increase from a southerly to
southwesterly direction, which should induce weakening, especially
as Danny approaches or moves through the Leeward Island. The NHC
intensity forecast is similar to the previous advisory and lies
close to the IVCN consensus model.

Both NOAA and Air Force Reserve Unit reconnaissance aircraft will be
investigating Danny Friday afternoon, and that data will provide a
better estimate of the hurricane's structure and strength.

FORECAST POSITIONS AND MAX WINDS

INIT  20/2100Z 13.0N  45.7W   70 KT  80 MPH
 12H  21/0600Z 13.6N  46.9W   75 KT  85 MPH
 24H  21/1800Z 14.4N  48.6W   75 KT  85 MPH
 36H  22/0600Z 15.0N  50.6W   70 KT  80 MPH
 48H  22/1800Z 15.5N  52.8W   65 KT  75 MPH
 72H  23/1800Z 16.2N  57.8W   60 KT  70 MPH
 96H  24/1800Z 17.2N  62.9W   55 KT  65 MPH
120H  25/1800Z 18.0N  67.5W   50 KT  60 MPH

$$
Forecaster Stewart