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TROPICAL STORM DANNY FORECAST/ADVISORY NUMBER 5

NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015

1500 UTC WED AUG 19 2015

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

TROPICAL STORM CENTER LOCATED NEAR 11.2N 41.1W AT 19/1500Z

POSITION ACCURATE WITHIN 20 NM

PRESENT MOVEMENT TOWARD THE WEST OR 275 DEGREES AT 10 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1000 MB

MAX SUSTAINED WINDS 45 KT WITH GUSTS TO 55 KT.

34 KT...... 60NE 30SE 0SW 40NW.

12 FT SEAS..100NE 50SE 20SW 40NW.

WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL

MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 11.2N 41.1W AT 19/1500Z

AT 19/1200Z CENTER WAS LOCATED NEAR 11.1N 40.7W

FORECAST VALID 20/0000Z 11.4N 42.6W

MAX WIND 50 KT...GUSTS 60 KT.

50 KT... 20NE 20SE 0SW 20NW.

34 KT... 60NE 30SE 0SW 40NW.

FORECAST VALID 20/1200Z 11.9N 44.2W

MAX WIND 55 KT...GUSTS 65 KT.

50 KT... 30NE 20SE 0SW 20NW.

34 KT... 60NE 50SE 20SW 50NW.

FORECAST VALID 21/0000Z 12.4N 45.8W

MAX WIND 60 KT...GUSTS 75 KT.

50 KT... 30NE 20SE 20SW 30NW.

34 KT... 70NE 50SE 40SW 70NW.

FORECAST VALID 21/1200Z 13.1N 47.5W

MAX WIND 70 KT...GUSTS 85 KT.

50 KT... 40NE 20SE 20SW 40NW.

34 KT... 70NE 60SE 50SW 70NW.

FORECAST VALID 22/1200Z 14.4N 51.5W

MAX WIND 80 KT...GUSTS 100 KT.

50 KT... 40NE 30SE 20SW 40NW.

34 KT... 80NE 70SE 60SW 70NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM

ON DAY 4 AND 200 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY

OUTLOOK VALID 23/1200Z 15.6N 56.2W

MAX WIND 75 KT...GUSTS 90 KT.

OUTLOOK VALID 24/1200Z 16.6N 61.5W

MAX WIND 70 KT...GUSTS 85 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 11.2N 41.1W

NEXT ADVISORY AT 19/2100Z

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FORECASTER KIMBERLAIN

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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

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