ATL: DANNY - Advisories

[gatorcane]

000
WTNT34 KNHC 181447
TCPAT4

BULLETIN
TROPICAL DEPRESSION FOUR ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 AM AST TUE AUG 18 2015

...FOURTH TROPICAL DEPRESSION OF THE SEASON DEVELOPS OVER THE
EAST-CENTRAL TROPICAL ATLANTIC...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...10.6N 36.5W
ABOUT 1665 MI...2675 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...1009 MB...29.80 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
At 1100 AM AST (1500 UTC), the center of Tropical Depression Four
was located near latitude 10.6 North, longitude 36.5 West. The
depression is moving toward the west near 13 mph (20 km/h). A
motion toward the west is expected today, followed by a turn toward
the west-northwest later tonight or on Wednesday.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Gradual strengthening is forecast during the next 48 hours, and the
depression is expected to become a tropical storm later today.

The estimated minimum central pressure is 1009 mb (29.80 inches).


HAZARDS AFFECTING LAND
----------------------
None.


NEXT ADVISORY
-------------
Next complete advisory at 500 PM AST.

$$
Forecaster Stewart

[gatorcane]

000
WTNT44 KNHC 181448
TCDAT4

TROPICAL DEPRESSION FOUR DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 AM AST TUE AUG 18 2015

The low pressure system that has been moving westward across the
eastern tropical Atlantic the past few days has finally acquired
enough organized deep convection to be classified as a tropical
cyclone. A 1232 UTC ASCAT-B overpass indicated the system has a
well-defined circulation, and there was also a large field of 30-kt
and greater wind vectors in the eastern semicircle. Dvorak satellite
intensity estimates are a consensus T2.0/30 kt from TAFB and SAB, so
the initial intensity is set at 30 kt for this advisory. Upper-level
outflow is good to the south and fair to the north.

The initial motion estimate is 280/11 kt. The global and regional
models are in good agreement on the tropical cyclone moving
west-northwestward along the southern periphery of a deep-layer
subtropical ridge for the next 48-72 hours, accompanied by a
decrease in forward speed as the system approaches a weakness in
this ridge. After that time, the ridge is expected to build back in
as a trough to the north lifts out, forcing the cyclone to turn more
westward and accelerate through the remainder of the forecast
period. The official forecast track lies close to but a little
faster than the multi-model consensus TVCN due to the much slower
GFS model creating a slow bias in the consensus.

The overall atmospheric and oceanic environments surrounding the
cyclone appear conducive for slow but steady strengthening
throughout the forecast period. The only inhibiting factor will be
occasional brief intrusions of dry mid-level air associated with the
Saharan Air Layer that lies just to the north of the depression.
However, given the very low vertical wind shear of less than 5 kt,
the convective structure is expected to steadily increase in
organization, allowing the dry air intrusions to be mixed out. The
official intensity forecast closely follows the intensity consensus
model IVCN through 72 hours, and then leans closer to a blend of the
Decay-SHIPS and LGEM models at 96 and 120 hours.

FORECAST POSITIONS AND MAX WINDS

INIT 18/1500Z 10.6N 36.5W 30 KT 35 MPH
12H 19/0000Z 11.0N 37.9W 35 KT 40 MPH
24H 19/1200Z 11.3N 39.5W 40 KT 45 MPH
36H 20/0000Z 11.6N 40.9W 50 KT 60 MPH
48H 20/1200Z 12.1N 41.9W 60 KT 70 MPH
72H 21/1200Z 13.2N 44.2W 70 KT 80 MPH
96H 22/1200Z 13.7N 47.8W 80 KT 90 MPH
120H 23/1200Z 14.0N 52.4W 85 KT 100 MPH

$$
Forecaster Stewart

[gatorcane]

ZCZC MIATCPAT4 ALL
TTAA00 KNHC DDHHMM

BULLETIN
TROPICAL STORM DANNY ADVISORY NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 PM AST TUE AUG 18 2015

...DANNY STRENGTHENING OVER THE TROPICAL ATLANTIC...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...11.2N 38.8W
ABOUT 1505 MI...2420 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
At 1100 PM AST (0300 UTC), the center of Tropical Storm Danny was
located near latitude 11.2 North, longitude 38.8 West. Danny is
moving toward the west-northwest near 14 mph (22 km/h) and this
general motion is expected to continue for the next couple of days.

Maximum sustained winds have increased to near 50 mph (85 km/h) with
higher gusts. Some additional strengthening is forecast during the
next 48 hours, and Danny is expected to become a hurricane by
Thursday.

Tropical storm force winds extend outward up to 60 miles (95 km)
from the center. A few hours ago, PIRATA buoy 41026 reported
sustained winds of 48 mph (78 km/h) as the center of Danny passed
just to the south.

The estimated minimum central pressure is 1000 mb (29.53 inches).


HAZARDS AFFECTING LAND
----------------------
None.


NEXT ADVISORY
-------------
Next complete advisory at 500 AM AST.

$$
Forecaster Beven

NNNN

[gatorcane]

000
WTNT44 KNHC 190245
TCDAT4

TROPICAL STORM DANNY DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 PM AST TUE AUG 18 2015

Danny has become a little better organized since the last advisory,
with a central convective feature and some outer banding in the
southeastern semicircle. At 2200 UTC, PIRATA buoy 41026 reported
42-kt sustained winds just north of the center, and an ASCAT-B
overpass near 2330 UTC showed many 40-45 kt vectors. Based on
these data, the initial intensity is increased to 45 kt. The ASCAT
data also showed that the storm was a little larger than previously
thought.

The initial motion is now 285/12. Danny is on the south side of
the subtropical ridge. The dynamical models forecast the ridge to
weaken during the next 48-72 hours due to developing mid- to
upper-level troughs near Bermuda and over the northeastern
Atlantic. This should result in Danny continuing on a
west-northwestward track with a decrease in forward speed. After
72 hours, the trough near Bermuda should move northward and allow
the subtropical ridge to intensify. In response, Danny is expected
to turn westward with an increase in forward speed. The GFS had a
better initialization of Danny on the 1800 UTC run, and it now
forecasts a faster forward motion. Otherwise, there are no
significant changes in the track guidance since the last advisory.
Thus, the new forecast track is an update of the previous track and
lies near the consensus models and the center of the guidance
envelope.

Danny is forecast to be in an environment of light vertical wind
shear through the forecast period, and earlier Windsat data
suggest the storm has tight convective banding near the center.
In addition, the Rapid Intensification Index of the SHIPS model has
about a 50 percent chance of 25 kt of strengthening during the next
24 hours. However, there is abundant dry air near Danny,
particularly to the north of the storm, and the dynamical models
forecast Danny to encounter increasingly drier air through the
forecast period. The intensity forecast, which follows the overall
trend of the intensity guidance, calls for continued strengthening
through 96 hours, followed by a slight weakening due to dry air.
The new forecast has a higher peak intensity than that of the
previous advisory, but is not as intense as the SHIPS and LGEM
models. There are two alternative possibilities for this forecast.
The first is that rapid intensification occurs in the next 24 hours
before dry air entrains into Danny's core. The second is that
enough dry air starts entraining during the next 24 hours to cause a
slower rate of development than currently forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 19/0300Z 11.2N 38.8W 45 KT 50 MPH
12H 19/1200Z 11.6N 40.2W 55 KT 65 MPH
24H 20/0000Z 11.9N 41.7W 60 KT 70 MPH
36H 20/1200Z 12.3N 42.9W 70 KT 80 MPH
48H 21/0000Z 12.8N 44.1W 75 KT 85 MPH
72H 22/0000Z 13.5N 47.5W 85 KT 100 MPH
96H 23/0000Z 14.5N 51.5W 90 KT 105 MPH
120H 24/0000Z 15.0N 56.5W 85 KT 100 MPH

$$
Forecaster Beven

[gatorcane]

000
WTNT34 KNHC 191432
TCPAT4

BULLETIN
TROPICAL STORM DANNY ADVISORY NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 AM AST WED AUG 19 2015

...DANNY HEADING WESTWARD OVER THE CENTRAL TROPICAL ATLANTIC...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...11.2N 41.1W
ABOUT 1385 MI...2235 KM E OF THE LESSER ANTILLES
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
At 1100 AM AST (1500 UTC), the center of Tropical Storm Danny was
located near latitude 11.2 North, longitude 41.1 West. Danny is
moving toward the west near 12 mph (19 km/h), and a westward to
west-northwestward motion at a slightly slower forward speed is
expected during the next 48 hours.

Maximum sustained winds are near 50 mph (85 km/h) with higher gusts.
Some strengthening is forecast during the next 48 hours, and Danny
could become a hurricane by Friday.

Tropical storm force winds extend outward up to 70 miles (110 km)
from the center.

The estimated minimum central pressure is 1000 mb (29.53 inches).


HAZARDS AFFECTING LAND
----------------------
None.


NEXT ADVISORY
-------------
Next complete advisory at 500 PM AST.

$$
Forecaster Kimberlain

[gatorcane]

000
WTNT44 KNHC 191433
TCDAT4

TROPICAL STORM DANNY DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 AM AST WED AUG 19 2015

While there has not been much overall change to Danny's curved-band
cloud pattern, there is evidence in satellite imagery of
increased inner-core structural organization since yesterday. Cloud
top temperatures, however, have warmed in recent hours. The initial
intensity is held at 45 kt in agreement with the latest CI number
from TAFB.

There is nothing obvious that would impede gradual intensification
during the next few days, except for the possible entrainment of
dry air associated with a Saharan Air Layer following the cyclone
to the north. Around the time Danny approaches the Lesser Antilles
in 3 to 5 days, global models have divergent solutions regarding the
strength and position of the mid-oceanic trough, which will
ultimately affect Danny's intensity. The ECMWF shows upper-level
westerlies and even drier air associated with this feature holding
sway over the Caribbean region, while the GFS shows a relaxation
of the shear. The statistical guidance, strongly dependent on the
GFS forecast fields, continues to indicate a higher intensity, yet
the dynamical models suggest less overall intensification and even
weakening late in the forecast period. The GFS-based guidance seems
less likely relative to the other model solutions, especially given
the strength and persistence of the mid-oceanic trough thus far this
season. The intensity forecast is therefore reduced throughout
the forecast period but especially at later times and is close to or
just above the multi-model consensus ICON.

Recent fixes indicate that Danny's forward speed has decreased
slightly, and the initial motion estimate is 275/10. An enhanced
mid-oceanic trough, extending from the northeastern Atlantic to the
Caribbean Sea, is forecast to keep the subtropical ridge to the
north of Danny somewhat weak over the next few days. This should
result in Danny's continued movement toward the west or west-
northwest across the tropical Atlantic, albeit at a less than
climatological rate of speed. Later in the forecast period, large-
scale models are in agreement that there should be some re-
strengthening of the subtropical ridge, which would result in
Danny's moving at a slightly faster forward speed. The cyclone's
heading late in the forecast period should largely be a function of
the depth of the system. A weaker Danny would move westward faster,
as is the case in the ECMWF solution. A stronger system, like the
one that the GFS shows, would tend to gain more latitude. The
track forecast is adjusted southward this forecast cycle, based on
an initial re-positioning of the cyclone and with the expectation
that Danny could be somewhat weaker later in the forecast period.


FORECAST POSITIONS AND MAX WINDS

INIT 19/1500Z 11.2N 41.1W 45 KT 50 MPH
12H 20/0000Z 11.4N 42.6W 50 KT 60 MPH
24H 20/1200Z 11.9N 44.2W 55 KT 65 MPH
36H 21/0000Z 12.4N 45.8W 60 KT 70 MPH
48H 21/1200Z 13.1N 47.5W 70 KT 80 MPH
72H 22/1200Z 14.4N 51.5W 80 KT 90 MPH
96H 23/1200Z 15.6N 56.2W 75 KT 85 MPH
120H 24/1200Z 16.6N 61.5W 70 KT 80 MPH

$$
Forecaster Kimberlain

[cycloneye]

TROPICAL STORM DANNY DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
500 PM AST WED AUG 19 2015

Satellite imagery shows that Danny's deep convection collapsed late
this morning, with the experimental Saharan Air Layer (SAL) Meteosat
imagery suggesting that dry-air entrainment could be the cause.
Although visible satellite pictures still show a vigorous
circulation and some renewed convection, the system overall has lost
organization and become more embedded in the Intertropical
Convergence Zone since yesterday. With little change in the Dvorak
classifications, the initial intensity is kept at 45 kt in agreement
with the latest CI number from TAFB.

Given the current appearance of the cyclone, it might be that
dry air associated with the SAL intruding from the north and west
has become a greater impediment to intensification. Dry air aside,
other atmospheric parameters governing intensification would seem to
favor some strengthening during the next 2 to 3 days, and the
official forecast shows modest strengthening. After that time,
significantly drier mid-tropospheric air and an increase in westerly
flow aloft associated with an enhanced and persistent mid-oceanic
trough across the Caribbean region is expected to induce weakening
as shown in the ECWMF solution. There is a large discrepancy
between the statistical and dynamical model guidance, with the
GFS-based statistical guidance continuing to show more
intensification and the regional hurricane models showing only
modest strengthening followed by weakening. The official intensity
forecast is similar to but a little lower than the previous one at
later times, consistent with the multi-model consensus.

The cyclone has been moving generally west but at a slower forward
speed (280/08) in response to a weakening subtropical ridge to the
north of the cyclone. A west-northwestward motion is expected
during the next next 2 to 3 days, at which time an interesting
split in the model guidance occurs. The GFS shows a much stronger
representation of Danny moving west-northwestward near and north of
the Greater Antilles in 3 to 5 days. The ECWMF solution, on the
other hand, depicts Danny as a shallower feature from the start and
as a weakening cyclone as it nears the Lesser Antilles on a westward
track. The new forecast track maintains the philosophy of the
previous one by showing a general westward track in the extended
range, giving more weight to the ECMWF solution that shows
weakening.


FORECAST POSITIONS AND MAX WINDS

INIT 19/2100Z 11.5N 42.0W 45 KT 50 MPH
12H 20/0600Z 12.1N 43.2W 50 KT 60 MPH
24H 20/1800Z 12.6N 44.8W 55 KT 65 MPH
36H 21/0600Z 13.1N 46.3W 60 KT 70 MPH
48H 21/1800Z 13.8N 47.9W 65 KT 75 MPH
72H 22/1800Z 15.0N 51.8W 75 KT 85 MPH
96H 23/1800Z 16.0N 56.9W 70 KT 80 MPH
120H 24/1800Z 16.8N 62.0W 60 KT 70 MPH

$$
Forecaster Kimberlain

[cycloneye]

BULLETIN
TROPICAL STORM DANNY ADVISORY NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 PM AST WED AUG 19 2015

...DANNY JOGS WEST-NORTHWESTWARD...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...12.1N 42.7W
ABOUT 1270 MI...2040 KM E OF THE LESSER ANTILLES
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
At 1100 PM AST (0300 UTC), the center of Tropical Storm Danny was
located near latitude 12.1 North, longitude 42.7 West. Danny is
now moving toward the west-northwest near 10 mph (17 km/h) and this
general motion is expected to continue for the next couple of days.

Maximum sustained winds are near 50 mph (85 km/h) with higher gusts.
Some strengthening is forecast during the next 48 hours, and Danny
still could become a hurricane by Friday.

Tropical storm force winds extend outward up to 70 miles (110 km)
from the center.

The estimated minimum central pressure is 1000 mb (29.53 inches).


HAZARDS AFFECTING LAND
----------------------
None.


NEXT ADVISORY
-------------
Next complete advisory at 500 AM AST.

$$
Forecaster Beven


TROPICAL STORM DANNY DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 PM AST WED AUG 19 2015

Convection associated with Danny has increased in both coverage and
organization during the past several hours. Overall, though, the
storm still looks a little less organized than 24 hours ago. The
various satellite intensity estimates are unchanged since the last
advisory, so the initial intensity remains 45 kt. The cirrus
outflow is good in the northern semicircle and poor elsewhere.

Danny has turned to the right over the past several hours, and the
initial motion is now 295/9. A weak subtropical ridge north of the
cyclone is expected to steer Danny generally west-northwestward for
the next couple of days. After that, the ridge is forecast to
strengthen as a mid- to upper-level low currently near Bermuda
lifts out to the north. This should cause Danny to turn more
westward at a faster forward speed, with the center forecast to be
near the Leeward Islands by 120 hours. There is some spread in
the guidance during this time, with the UKMET, GFDN, GFDL and NAVGEM
models showing a more northward motion than the other guidance. One
change since the previous advisory is that the new GFS has shifted
southward and now lies closer to the ECMWF forecast on the south
side of the guidance envelope. The new track forecast, which is on
the south side of the guidance near the ECMWF/GFS/HWRF/GFS Ensemble
Mean solutions, is similar to the previous forecast.

Earlier Windsat data shows that Danny has a well-defined inner
core, and this, combined with a light-vertical wind shear
environment, should allow strengthening for the next three days or
so. However, experimental Saharan Air Layer (SAL) Meteosat
imagery continues to show abundant dry air not far from the storm
in the northern semicircle. Entrainment of this air is expected to
limit intensification, and this is reflected by a downward trend in
the intensity guidance. After 72 hours, the cyclone is expected to
encounter even drier air and southwesterly shear, which should cause
weakening. The new intensity forecast is identical to the previous
forecast through 48 hours and then shows slightly lower intensities
thereafter. It should be noted that the ECMWF and Canadian models
forecast Danny to weaken to a tropical wave by 120 hours, which is a
plausible alternative scenario given the forecast environment and
the small size of the cyclone.


FORECAST POSITIONS AND MAX WINDS

INIT 20/0300Z 12.1N 42.7W 45 KT 50 MPH
12H 20/1200Z 12.6N 43.9W 50 KT 60 MPH
24H 21/0000Z 13.1N 45.4W 55 KT 65 MPH
36H 21/1200Z 13.7N 47.0W 60 KT 70 MPH
48H 22/0000Z 14.4N 48.6W 65 KT 75 MPH
72H 23/0000Z 15.5N 53.0W 70 KT 80 MPH
96H 24/0000Z 16.0N 57.5W 65 KT 75 MPH
120H 25/0000Z 17.0N 62.5W 55 KT 65 MPH

$$
Forecaster Beven

[cycloneye]

BULLETIN
TROPICAL STORM DANNY ADVISORY NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
500 AM AST THU AUG 20 2015

...DANNY IN NO HURRY...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...12.2N 43.7W
ABOUT 1200 MI...1930 KM E OF THE LESSER ANTILLES
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES


TROPICAL STORM DANNY DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
500 AM AST THU AUG 20 2015

The cloud pattern resembles a tropical cyclone much more than 12
hours ago. An irregular Central Dense Overcast(CDO) has formed, and
the center continues to be remarkably well depicted in microwave
images. In fact, it has a much better structure than earlier. The
outflow remains fair. Dvorak numbers suggest that the winds are
still 45 kt. Danny has the opportunity to strengthen a little during
the next 2 to 3 days while embedded within very light shear. Models
in general, however, no longer intensify the cyclone as much as they
did in earlier runs and, in fact, the GFS and ECMWF weaken Danny to
a tropical wave in the eastern Caribbean Sea. The NHC forecast calls
for some intensification for the next 3 days, and calls for slight
weakening as Danny encounters high shear and dry air in the eastern
Caribbean Sea.

Microwave fixes indicate that Danny is moving toward the west or 280
degrees at 9 kt. A turn toward the west-northwest toward a weakness
in the subtropical ridge is expected soon. After 48 hours, most
of the global models forecast the subtropical ridge to expand
westward, forcing Danny to turn back to the west as indicated in the
NHC forecast. The multi-model consensus as well as the consensus of
the GFS and the ECMWF depict the expansion of the ridge, and bring
Danny to the eastern Caribbean, while the UK and the GFDL models
insist on taking the cyclone north of the islands. In summary, it
appears that a tropical cyclone or a perhaps a wave will be moving
over the Leeward Islands between 4 and 5 days.


FORECAST POSITIONS AND MAX WINDS

INIT 20/0900Z 12.2N 43.7W 45 KT 50 MPH
12H 20/1800Z 12.6N 44.9W 50 KT 60 MPH
24H 21/0600Z 13.5N 46.3W 55 KT 65 MPH
36H 21/1800Z 14.3N 47.8W 60 KT 70 MPH
48H 22/0600Z 15.0N 50.0W 65 KT 75 MPH
72H 23/0600Z 15.5N 54.4W 65 KT 75 MPH
96H 24/0600Z 16.3N 60.0W 65 KT 75 MPH
120H 25/0600Z 17.0N 65.0W 50 KT 60 MPH

$$
Forecaster Avila

[cycloneye]

HURRICANE DANNY DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 AM AST THU AUG 20 2015

Danny's cloud pattern has continued to improve since the previous
advisory, and a 10 n mi diameter eye has become embedded in the
center of a small central dense overcast. Water vapor imagery
indicates that upper-level outflow has become more symmetrical. The
initial intensity of 65 kt is based on NHC objective Dvorak
classifications of T4.1-T4.2 using an eye feature. Conventional and
microwave satellite images indicate that Danny is an unusually small
tropical cyclone.

Satellite fixes indicate that Danny is now moving west-northwestward
or 295/10 kt. The latest model guidance remains in very good
agreement on Danny moving west-northwestward for the next 48-72
hours toward a weakness in the subtropical ridge along 60W
longitude. A mid- to upper-level trough north of Bermuda is forecast
by the global models to begin lifting out to the north in 96-120
hours, which should allow the subtropical ridge to the north of
Danny to build back westward, forcing Danny on a more westward track
on days 4 and 5. The NHC official forecast track is essentially an
update of the previous advisory through 72 hours, but was shifted a
little north of the previous track after that in agreement with the
consensus model TVCN.

Danny's compact size makes it subject to significant fluctuations in
strength, both up and down, and such fluctuations are notoriously
difficult to forecast. Low-shear conditions are expected to
continue for the next 36 hours or so, which argues for some further
strengthening during that time. However, the cyclone continues to be
surrounded by dry mid-level air, which could penetrate into the core
and disrupt the intensification process. By 48 hours and beyond, the
vertical wind shear is forecast to become southerly to southwesterly
and increase to near 15 kt. As a result, Danny is expected to be
weakening as it approaches the Leeward Island. The official
intensity forecast calls for a peak intensity somewhat higher and
earlier than the previous advisory, ending up close to the IVCN
consensus model.

FORECAST POSITIONS AND MAX WINDS

INIT 20/1500Z 12.5N 44.8W 65 KT 75 MPH
12H 21/0000Z 13.1N 46.0W 70 KT 80 MPH
24H 21/1200Z 14.0N 47.6W 75 KT 85 MPH
36H 22/0000Z 14.7N 49.4W 75 KT 85 MPH
48H 22/1200Z 15.2N 51.5W 70 KT 80 MPH
72H 23/1200Z 16.0N 56.4W 65 KT 75 MPH
96H 24/1200Z 16.9N 61.7W 65 KT 75 MPH
120H 25/1200Z 18.0N 66.6W 55 KT 65 MPH

$$
Forecaster Stewart

[cycloneye]

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

...DANNY STRENGTHENS A LITTLE MORE...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...13.0N 45.7W
ABOUT 1030 MI...1655 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...990 MB...29.24 INCHES



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

[cycloneye]

BULLETIN
HURRICANE DANNY ADVISORY NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 PM AST THU AUG 20 2015

...DANNY CONTINUES WEST-NORTHWESTWARD OVER THE TROPICAL CENTRAL
ATLANTIC...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...13.4N 46.6W
ABOUT 970 MI...1560 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...990 MB...29.24 INCHES



HURRICANE DANNY DISCUSSION NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 PM AST THU AUG 20 2015

Danny continues to produce a compact central dense overcast, and
cloud tops are a little colder than earlier due to a recent burst of
convection in the eyewall. Coincidentally, the convective canopy
has intermittently been obscuring the tiny eye that was observed
earlier today. The initial intensity remains 70 kt based on a blend
of subjective Dvorak satellite estimates of T4.0/65 kt from TAFB and
T4.5/77 kt from SAB.

The hurricane continues to move west-northwestward, or 295/9 kt,
toward a break in the subtropical ridge located northeast of the
Leeward Islands. The track guidance shows this motion continuing
for another 36 hours, with Danny then turning westward and
accelerating from 48 hours through day 5 while the ridge builds
westward north of the Greater Antilles. With the exception of the
GFDL, GFDN, and NAVGEM--which insist that Danny will turn
northwestward before reaching the Leeward Islands--the other track
models are in agreement on a future track near or just south of the
northern Leeward Islands and Greater Antilles. This clustering of
the guidance required no significant changes to the official NHC
track forecast on this advisory cycle.

As has been mentioned in earlier discussions, Danny is susceptible
to sudden and possibly unexpected changes in intensity due to its
small size. Since vertical shear is expected to remain low for
another 24 hours or so, Danny could certainly strengthen some more
if it can avoid intrusions of dry air into the inner core. After
36 hours, an increase in westerly to southwesterly shear and a
decrease in mid-level relative humidities are expected to lead to
weakening, and Danny is forecast to weaken to a tropical storm
before it reaches the Leeward Islands. The updated NHC intensity
forecast is very similar to the previous one and remains close to
the IVCN consensus. It should be noted that given Danny's small
size, the weakening rate after 36 hours could be faster than
indicated in the official forecast.

A NOAA aircraft will be conducting a research mission in and around
Danny Friday afternoon, and an Air Force Reserve Unit reconnaissance
aircraft will investigate Danny Saturday afternoon.

FORECAST POSITIONS AND MAX WINDS

INIT 21/0300Z 13.4N 46.6W 70 KT 80 MPH
12H 21/1200Z 14.0N 47.9W 75 KT 85 MPH
24H 22/0000Z 14.7N 49.8W 75 KT 85 MPH
36H 22/1200Z 15.2N 51.9W 70 KT 80 MPH
48H 23/0000Z 15.6N 54.2W 60 KT 70 MPH
72H 24/0000Z 16.5N 59.3W 55 KT 65 MPH
96H 25/0000Z 17.5N 64.5W 50 KT 60 MPH
120H 26/0000Z 18.0N 69.5W 45 KT 50 MPH

$$
Forecaster Berg

[cycloneye]

HURRICANE DANNY DISCUSSION NUMBER 12
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
500 AM AST FRI AUG 21 2015

Danny has strengthened a little overnight. The eye of the compact
hurricane has become more distinct recently and the cloud tops have
cooled in the eyewall. The Dvorak classifications from TAFB and SAB
were both T4.5 at 0600 UTC, and the initial wind speed has been
nudged upward to 75 kt accordingly. The eye of Danny passed about
75 n mi south of NOAA buoy 41041 a few hours ago and winds at that
location were only around 20 kt, indicative of the very small size
of the wind field of this hurricane.

The cyclone continues to move west-northwestward at about 9 kt.
The relatively slow forward speed of the system is due to a trough
over the western Atlantic, which has weakened the subtropical
ridge. This trough is expected to lift northward in a couple of
days, allowing the ridge to build westward and strengthen. The
change in the steering flow should cause Danny to turn westward and
speed up this weekend and early next week. The track guidance
remains in good agreement, and the NHC forecast lies closest to the
consensus of the GFS and ECMWF models. The new forecast track is
just a tad to the north of the previous one at days 4 and 5, but is
otherwise just an update.

Danny is currently in a very low wind shear environment and over
warm water, and it is expected to remain in these favorable
conditions for about another 12-24 hours. Therefore, additional
strengthening is possible in the short term. Beyond that time,
however, the system is expected to move into an area of increased
southwesterly shear and drier air. These factors should induce a
weakening trend. The NHC intensity forecast is in best agreement
with the intensity model consensus IVCN. As mentioned in previous
discussions, the small size of the hurricane makes it susceptible to
sudden changes in intensity, which are difficult to predict.

A NOAA aircraft will be conducting a research mission in and around
Danny this afternoon, and an Air Force Reserve Unit reconnaissance
aircraft will investigate Danny Saturday afternoon. These data
will provide a better assessment of the intensity and structure of
the hurricane.

FORECAST POSITIONS AND MAX WINDS

INIT 21/0900Z 13.7N 47.4W 75 KT 85 MPH
12H 21/1800Z 14.3N 48.8W 80 KT 90 MPH
24H 22/0600Z 14.9N 50.8W 75 KT 85 MPH
36H 22/1800Z 15.5N 53.0W 65 KT 75 MPH
48H 23/0600Z 15.9N 55.3W 60 KT 70 MPH
72H 24/0600Z 16.7N 60.5W 50 KT 60 MPH
96H 25/0600Z 17.8N 65.7W 45 KT 50 MPH
120H 26/0600Z 18.5N 70.5W 40 KT 45 MPH...INLAND

$$
Forecaster Cangialosi

[drezee]

000
WTNT64 KNHC 211747
TCUAT4

HURRICANE DANNY TROPICAL CYCLONE UPDATE
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
200 PM AST FRI AUG 21 2015

...NOAA HURRICANE HUNTER AIRCRAFT REPORTS THAT DANNY IS A MAJOR
HURRICANE...

Reports from a NOAA Hurricane Hunter aircraft indicate that Danny
is now a Category 3 Hurricane on the Saffir-Simpson Hurricane Wind
Scale. The maximum winds are estimated to be 115 mph (185 km/h)
with higher gusts.

No additional intensification is expected, as Danny is moving into
an area of unfavorable upper-level winds, and a weakening trend is
expected to begin later today. Consequently, no adjustment to the
forecast intensities from the previous advisory is required.

SUMMARY OF 200 PM AST...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...14.3N 48.6W
ABOUT 900 MI...1450 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...115 MPH...185 KM/H
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...974 MB...28.76 INCHES

$$
Forecaster Beven/Roberts

[cycloneye]

HURRICANE DANNY DISCUSSION NUMBER 14
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
500 PM AST FRI AUG 21 2015

A NOAA Hurricane Hunter aircraft investigated Danny around
1600-1730 UTC. It found winds as high as 111 kt at the 12,000 ft
flight level and surface wind estimates from the Stepped Frequency
Microwave Radiometer as high as 104 kt. It also reported a
dropsonde central pressure of 974 mb. Based on these data, Danny
reached a 100-kt intensity at that time. Since then, the eye has
disappeared in satellite imagery, and the cyclone is showing signs
of being affected by southwesterly vertical wind shear. The
initial intensity is 100 kt for this advisory based on an expected
lag between the decay of the cloud pattern and the cyclone's
weakening. That being said, this intensity could be generous.

The initial motion is now 295/9. The subtropical ridge north of
Danny remains weaker than normal due to a deep-layer trough over the
western Atlantic. This trough is expected to lift northward during
the next couple of days, allowing the ridge to build westward and
strengthen. This evolution should cause Danny to turn more
westward with some increase in forward speed. The track guidance
is in good agreement with this scenario and forecasts Danny to be
near the Leeward Islands in about 72 hours, near Puerto Rico and
the Virgin Islands in about 84-96 hours, and in the vicinity of
Hispaniola by day 5. The new forecast track has a noise-level nudge
to the north of the previous forecast and is in best agreement with
the GFS and ECMWF models. It lies just south of the center of the
guidance envelope.

Danny has likely peaked in intensity based on the signs of shear in
the cloud pattern, stronger upper-level winds present west of the
cyclone, and abundant nearby dry air. Although it starts from a
higher initial intensity than the previous forecast, the new
intensity forecast still calls for Danny to weaken below hurricane
strength at about 48 hours. After that, the system should continue
to weaken as it moves near or over the Greater Antilles in close
proximity to an upper-level trough. The GFS/ECWMF/UKMET models
all forecast Danny to degenerate to a tropical wave by 120 hours, so
the new intensity forecast compromises between this extreme and the
SHIPS/LGEM models, which forecast a stronger cyclone at that time.

NOAA and Air Force Reserve Unit reconnaissance aircraft will
investigate Danny again Saturday afternoon. These data will provide
a better assessment of the intensity and structure of the hurricane.


FORECAST POSITIONS AND MAX WINDS

INIT 21/2100Z 14.5N 49.1W 100 KT 115 MPH
12H 22/0600Z 15.0N 50.5W 95 KT 110 MPH
24H 22/1800Z 15.5N 52.7W 85 KT 100 MPH
36H 23/0600Z 15.9N 55.2W 70 KT 80 MPH
48H 23/1800Z 16.3N 57.8W 60 KT 70 MPH
72H 24/1800Z 17.5N 62.5W 55 KT 65 MPH
96H 25/1800Z 18.5N 67.0W 50 KT 60 MPH
120H 26/1800Z 19.5N 71.5W 35 KT 40 MPH...INLAND

$$
Forecaster Beven

NNNN

[cycloneye]

BULLETIN
HURRICANE DANNY ADVISORY NUMBER 15
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 PM AST FRI AUG 21 2015

...DANNY WEAKENS TO A CATEGORY 2 HURRICANE...
...CONTINUED WEAKENING EXPECTED DURING THE NEXT FEW DAYS...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...14.8N 49.8W
ABOUT 810 MI...1305 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...110 MPH...175 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...977 MB...28.85 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.

Interests in the Leeward Islands and the Virgin Islands should
monitor the progress of Danny. Tropical storm watches may be
required for portions of the Leeward Islands and the Virgin
Islands on Saturday.



HURRICANE DANNY DISCUSSION NUMBER 15
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 PM AST FRI AUG 21 2015

After reaching its peak intensity earlier today, Danny appears to
be starting a weakening trend. There has been no eye in infrared
satellite imagery since about 1800 UTC, and a 2136 UTC WindSat pass
showed that a narrow swath of drier air had worked its way into
the inner core, eroding the southern eyewall. The shear analysis
from CIMSS at the University of Wisconsin indicates that a little
over 20 kt of southwesterly shear is now affecting Danny, and
dropsonde data from a NOAA G-IV surveillance flight revealed that
there was some light inflow into the western part of the circulation
between 300 and 400 mb. Dvorak final-T numbers from TAFB and SAB
were steady or decreased slightly from six hours ago; therefore,
the initial intensity is lowered slightly to 95 kt.

Vertical shear is expected to increase further during the next
couple of days, which should allow drier air in the surrounding
environment to penetrate into Danny's circulation. Therefore,
there is no change in the thinking that Danny should weaken as it
approaches and moves across the Leeward Islands and the Greater
Antilles during the forecast period. The SHIPS diagnostics is
currently showing only 10 kt of shear affecting Danny, and if the
shear is actually higher as shown by the UW-CIMSS product, then the
SHIPS and LGEM solutions probably keep Danny's intensity too high
during the next few days. The global models continue to depict
rapid weakening and show Danny degenerating into a surface trough in
3-4 days. As a compromise, the NHC intensity forecast is close to
the IVCN intensity consensus and a little bit lower than the
previous forecast. Danny is still expected to weaken to a tropical
storm before it reaches the Leeward Islands between 48-72 hours.

Danny's initial motion remains west-northwestward, or 295/9 kt.
The hurricane is forecast to accelerate and turn westward during
the next few days while the subtropical ridge builds westward over
the southwestern Atlantic. The bulk of the track guidance is
tightly clustered for the entire forecast period, and no
appreciable changes to the previous NHC track forecast were
required on this advisory cycle.

NOAA and Air Force Reserve Unit reconnaissance aircraft are
scheduled to investigate Danny and the surrounding environment
Saturday afternoon.

FORECAST POSITIONS AND MAX WINDS

INIT 22/0300Z 14.8N 49.8W 95 KT 110 MPH
12H 22/1200Z 15.1N 51.4W 85 KT 100 MPH
24H 23/0000Z 15.6N 53.8W 75 KT 85 MPH
36H 23/1200Z 16.0N 56.4W 65 KT 75 MPH
48H 24/0000Z 16.4N 59.0W 60 KT 70 MPH
72H 25/0000Z 17.6N 63.8W 55 KT 65 MPH
96H 26/0000Z 19.0N 68.5W 45 KT 50 MPH
120H 27/0000Z 20.0N 73.5W 30 KT 35 MPH

$$
Forecaster Berg

[cycloneye]

HURRICANE DANNY DISCUSSION NUMBER 16
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
500 AM AST SAT AUG 22 2015

Danny's cloud pattern consists of a central dense overcast with the
low-level center estimated to be on the southwestern side of that
feature due to southwesterly shear. Some fragmented curved bands
exist on the north side of the circulation as well. The initial wind
speed is lowered to 85 kt, but this could be generous as it
is slightly above the Dvorak CI-numbers. NOAA and Air Force Reserve
Unit reconnaissance aircraft are scheduled to investigate Danny this
afternoon and should provide a better estimate of its intensity.

The hurricane is moving west-northwestward at about 9 kt. A turn
to the west with an increase in forward speed is expected to begin
later today when the subtropical ridge to the north of the cyclone
builds westward and strengthens. This general motion is expected
to persist for the next several days taking Danny across the
Leeward Islands in 2 to 3 days, and near Puerto Rico and Hispaniola
in 3 to 4 days. The track model guidance remains in good
agreement, and the only change made to the previous forecast was a
slight northward adjustment at the latter forecast points.

Strong southwesterly winds aloft and a stable air mass are expected
to cause Danny to continue losing strength during the next several
days. In addition, the potential land interaction with the Greater
Antilles could contribute to the weakening. Although the guidance
agrees on the overall trend, there remains a significant discrepancy
between the dynamical and statistical model solutions on the
weakening rate. The GFS, ECMWF, and HWRF models show Danny weakening
quickly and opening up into a trough over the eastern Caribbean.
Conversely, the SHIPS and LGEM models show a slower decay. The NHC
intensity forecast is between these scenarios and is in best
agreement with the intensity model consensus.

Based on the current forecast, tropical storm watches will likely be
required later today for portions of the Leeward Islands and the
Virgin Islands.

FORECAST POSITIONS AND MAX WINDS

INIT 22/0900Z 15.2N 50.8W 85 KT 100 MPH
12H 22/1800Z 15.4N 52.6W 75 KT 85 MPH
24H 23/0600Z 15.8N 55.0W 65 KT 75 MPH
36H 23/1800Z 16.3N 57.6W 60 KT 70 MPH
48H 24/0600Z 16.8N 60.1W 55 KT 65 MPH
72H 25/0600Z 18.1N 64.9W 50 KT 60 MPH
96H 26/0600Z 19.7N 69.5W 40 KT 45 MPH
120H 27/0600Z 21.0N 74.0W 30 KT 35 MPH

$$
Forecaster Cangialosi

[cycloneye]

BULLETIN
HURRICANE DANNY ADVISORY NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 AM AST SAT AUG 22 2015

...DANNY STILL SLOWLY WEAKENING...
...TROPICAL STORM WATCH ISSUED FOR PORTIONS OF THE LEEWARD
ISLANDS...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...15.4N 52.0W
ABOUT 660 MI...1060 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...90 MPH...150 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...984 MB...29.06 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

The Meteorological Service of Antigua has issued a tropical storm
watch for Antigua, Barbuda, Montserrat, St. Kitts, Nevis, and
Anguilla.

The Meteorological Service of Curacao has issued a tropical storm
watch for Saba and St. Eustatius.

The Meteorological Service of St. Maarten has issued a tropical
storm watch for St. Maarten.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Watch is in effect for...
* Antigua, Barbuda, Montserrat, St. Kitts, Nevis, and
Anguilla
* Saba and St. Eustatius
* St. Maarten

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.

TCDAT4

HURRICANE DANNY DISCUSSION NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 AM AST SAT AUG 22 2015

Danny's cloud pattern is similar to that of six hours ago, with a
central dense overcast and some outer banding in the northeastern
semicircle. However, the size of the overcast has diminished with
the center getting closer to the edge. The initial intensity is
decreased to 80 kt based on decreasing satellite intensity
estimates and continuity from the previous advisory. However, this
could be generous. NOAA and Air Force Reserve Unit reconnaissance
aircraft are scheduled to investigate Danny this afternoon and
should provide a better estimate of its intensity.

The initial motion is now 285/10. There is no change in the
forecast philosophy from the previous advisory, with Danny expected
to turn westward and accelerate later today as the subtropical ridge
to the north of the cyclone builds westward and strengthens. This
general motion is expected to persist for the next several days
taking Danny across the Leeward Islands in about two days, and near
Puerto Rico and Hispaniola in 3 to 4 days. The track model
guidance remains in good agreement with this, and the forecast
track lies near the center of the track guidance envelope.

Danny is expected to move through a dry and stable air mass and
encounter moderate to strong southwesterly vertical wind shear for
at least the next three days. This should cause continued
weakening, and the cyclone is forecast to be a tropical storm as it
moves over or near the northeastern Caribbean Islands. The
intensity forecast becomes lower confidence at days 4 and 5 due to
the uncertainty in how much land Danny will encounter, disagreements
between the dynamical models over the forecast shear, and continued
divergence between the models forecasting Danny to dissipate and the
models forecasting it to survive. The latter part of the forecast
compromises between these extremes by showing a continued weakening
trend.

A tropical storm watch is being issued for portions of the Leeward
Islands at this time. Additional watches or warning may be
necessary for this area, as well as the Virgin Islands and Puerto
Rico, later today or tonight.


FORECAST POSITIONS AND MAX WINDS

INIT 22/1500Z 15.4N 52.0W 80 KT 90 MPH
12H 23/0000Z 15.7N 53.7W 70 KT 80 MPH
24H 23/1200Z 16.1N 56.1W 60 KT 70 MPH
36H 24/0000Z 16.6N 58.7W 55 KT 65 MPH
48H 24/1200Z 17.2N 61.3W 50 KT 60 MPH
72H 25/1200Z 18.5N 66.0W 45 KT 50 MPH
96H 26/1200Z 20.5N 71.0W 40 KT 45 MPH
120H 27/1200Z 22.0N 75.5W 30 KT 35 MPH

$$
Forecaster Beven

[cycloneye]

BULLETIN
HURRICANE DANNY INTERMEDIATE ADVISORY NUMBER 17A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
200 PM AST SAT AUG 22 2015

...HURRICANE HUNTER AIRCRAFT APPROACHING DANNY...
...NEW TROPICAL STORM WATCH ISSUED FOR PORTIONS OF THE LEEWARD
ISLANDS...


SUMMARY OF 200 PM AST...1800 UTC...INFORMATION
-----------------------------------------------
LOCATION...15.5N 52.4W
ABOUT 635 MI...1020 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...85 MPH...135 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...985 MB...29.09 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

The Government of France has issued a tropical storm watch for
Guadeloupe, St. Barthelemy, and St. Martin.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Watch is in effect for...
* Antigua, Barbuda, Montserrat, St. Kitts, Nevis, and
Anguilla
* Saba and St. Eustatius
* St. Maarten
* Guadeloupe, St. Barthelemy, and St. Martin

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
At 200 PM AST (1500 UTC), the center of Hurricane Danny was located
near latitude 15.5 North, longitude 52.4 West. Danny is moving
toward the west-northwest near 12 mph (19 km/h). A turn toward the
west and an increase in forward speed are expected later today or
tonight. On the forecast track, the center of Danny is expected to
be near the Leeward Islands by Sunday night or Monday morning.

Maximum sustained winds have decreased to near 85 mph (135 km/h)
with higher gusts. Additional weakening is forecast during the next
48 hours, and Danny is expected to weaken below hurricane strength
before it reaches the Leeward Islands.

Hurricane force winds extend outward up to 15 miles (30 km) from the
center and tropical storm force winds extend outward up to 60 miles
(95 km). U. S. Air Force Reserve and NOAA Hurricane Hunter
aircraft are currently enroute to investigate Danny.

The estimated minimum central pressure is 985 mb (29.09 inches).


HAZARDS AFFECTING LAND
----------------------
RAINFALL: Danny is expected to produce 2 to 4 inches of rain over
the Leeward Islands through Monday.


NEXT ADVISORY
-------------
Next complete advisory at 500 PM AST.

$$
Forecaster Beven

[cycloneye]

BULLETIN
HURRICANE DANNY ADVISORY NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
500 PM AST SAT AUG 22 2015

...HURRICANE HUNTER AIRCRAFT REPORT DANNY CONTINUING TO WEAKEN...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...15.8N 53.3W
ABOUT 570 MI...915 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...991 MB...29.27 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Watch is in effect for...
* Antigua, Barbuda, Montserrat, St. Kitts, Nevis, and
Anguilla
* Saba and St. Eustatius
* St. Maarten
* Guadeloupe, St. Barthelemy, and St. Martin

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.

Interests elsewhere in the U. S. and British Virgin Islands, Puerto
Rico, and the Dominican Republic should monitor the progress of
Danny. Additional watches or warnings may be required for portions
of these areas tonight or Sunday.


HURRICANE DANNY DISCUSSION NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
500 PM AST SAT AUG 22 2015

Satellite imagery and reports from Air Force Reserve and NOAA
Hurricane Hunter aircraft show that Danny continues to weaken. The
aircraft have reported that the central pressure has risen to at
least 991 mb, along with maximum surface wind estimates near 65 kt
from the Stepped Frequency Microwave Radiometer. Based on these
data, the initial intensity is decreased to 65 kt. The aircraft
data indicate that the center of Danny is tilted to the north or
northeast with height, as dropsondes released at the calm
flight-level center have consistently reported 50-60 kt easterly
surface winds. In addition, satellite imagery suggests that the
center is now at the southwestern edge of the convection. These
observations are likely due to ongoing southwesterly vertical wind
shear.

The initial motion is now 285/12, a little faster than before.
There is again little change in the forecast philosophy, with Danny
expected to turn westward tonight as the subtropical ridge to the
north of the cyclone builds westward and strengthens. This general
motion is expected to persist for the next several days taking Danny
across the Leeward Islands in about two days, and near Puerto Rico
and Hispaniola in 3 to 4 days. This part of the forecast track is
near the center of the guidance envelope and is similar to, but a
little faster than, the previous track. The dynamical models are
forecasting a mid- to upper-level trough to move into Florida and
the southeastern United States by 120 hours, and the track guidance
responds to this by showing a northwestward turn. The new forecast
track also shows a more northward motion at 120 hours, but it lies
to the south and west of the center of the envelope.

Danny is expected to move through a dry and stable air mass and
encounter moderate to strong southwesterly vertical wind shear for
at least the next three days. This should cause continued
weakening, and the cyclone is forecast to be a tropical storm as it
moves over or near the northeastern Caribbean Islands. The
intensity forecast becomes lower confidence at days 4 and 5. The
dynamical models forecast an upper-level low to form near central
Cuba. However, they do not agree on how this will change the shear
over Danny. The GFS continues forecasting significant shear, while
the ECMWF forecasts more favorable upper-level winds. It should be
noted that even with its more favorable shear forecast, the ECMWF
forecasts Danny to weaken to a tropical wave. Based on this and
the expectation that dry air will continue to impact the cyclone,
the intensity forecast calls for continued weakening at days 4-5.

There are no changes to the watches at this time. However,
additional watches or warnings may be necessary for portions of the
Leeward Islands, the Virgin Islands, and Puerto Rico tonight or
Sunday.


FORECAST POSITIONS AND MAX WINDS

INIT 22/2100Z 15.8N 53.3W 65 KT 75 MPH
12H 23/0600Z 16.1N 55.2W 60 KT 70 MPH
24H 23/1800Z 16.6N 57.9W 55 KT 65 MPH
36H 24/0600Z 17.1N 60.4W 50 KT 60 MPH
48H 24/1800Z 17.8N 62.9W 45 KT 50 MPH
72H 25/1800Z 19.5N 68.0W 40 KT 45 MPH
96H 26/1800Z 21.0N 72.5W 35 KT 40 MPH
120H 27/1800Z 23.0N 76.0W 30 KT 35 MPH

$$
Forecaster Beven