Tropical Weather Discussion
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086
AXPZ20 KNHC 192212 CCA
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC TUE SEP 19 2017

Tropical Weather Discussion for the eastern Pacific Ocean from
the Equator to 32N, east of 140W. The following information is
based on satellite imagery, weather observations, radar, and
meteorological analysis.

Based on 1800 UTC surface analysis and satellite imagery through
2115 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION NORMA NEAR 21.9N 115.0W 1006 MB AT 2100 UTC
SEP 19 MOVING WNW OR 290 DEG AT 6 KT. MAXIMUM SUSTAINED WINDS 30
KT GUSTS 40 KT. WIDELY SCATTERED MODERATE CONVECTION IS NOTED
WITHIN 45 NM NW AND 75 NM SE SEMICIRCLES. Norma is expected to
move slowly NW and gradually lose tropical characteristics in
the next 24 hours as it moves over cooler waters and into more
stable atmospheric conditions. Associated winds and seas will
slowly wind down during the next 2 days before the low
dissipates Thu.

POST-TROPICAL CYCLONE OTIS NEAR 18.6N 128.7W 1008 MB MOVING WSW
AT 5 KT. MAXIMUM SUSTAINED WINDS 30 KT GUSTS 40 KT. No
convection is associated with the remnants of Otis at this time.
However, sufficient pressure gradient exists between this low
center and a surface ridge to the NW to create strong NE to E
winds 20 to 30 kt WITHIN 180 NM across the NW SEMICIRCLE, where
seas are 8 to 12 ft. The low will continue to move WSW during
the next 2 days and gradually dissipate, with an area of fresh
to strong NE to E winds and seas 8 to 9 ft accompanying it
through Thu.

...TROPICAL WAVES...

A tropical wave is propagating across the eastern Pacific Ocean
just to the west of the Gulf of Tehuantepec, along 95-96W N of
07N. Scattered moderate to strong convection is from 10N to 16N
between 92W and 104W. Global models suggest that a low pressure
center could develop across this region in a few days.

..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

Monsoon trough extends from 10N85W to 13N100W to 12N120W to
13N140W. Scattered moderate convection is from 03N to 08N
between 77W and 84W. Scattered moderate to strong convection is
from 07N to 12N between 87W and 91W. Scattered moderate to
strong convection is from 12N to 16N W of 132W.

...DISCUSSION...

To the North of 15N and to the east of 120W:

A broad surface ridge extends SE into the region and passes
through 32N128W to near 25N118W. Anticyclonic wind flow covers
the area N through NW of the lows of Norma and Otis. A surface
trough is in the northernmost part of the Gulf of California,
where fresh northerly winds prevail across the nearshore waters
of Baja California Norte. The surface pressure gradient that
exists between the ridge and the trough is supporting gentle to
moderate N to NE winds, and seas in the range from 5 feet to 7
feet. The ridge will continue to build during the next few days,
which will freshen winds off the Baja California coast with seas
building to 6 to 8 feet.

To the South of 15N and to the east of 120W:

A tropical wave across the W Caribbean is moving into the far
eastern waters. Light to gentle monsoonal flow prevails to the
south of the monsoon trough, while gentle to moderate
southeasterly trade winds prevail to the south of the monsoon
trough. Light to gentle northeasterly trade winds prevail to the
north of the monsoon trough for the next few days. Southwesterly
swell continues to propagate across the area with seas in the 6
to 8 foot range from 100W westward, and in the 4 to 6 foot range
from 100W eastward.

Elsewhere to the west of 120W:

A 1031 mb high pressure center is located near 38N149W and
extends S and SE into the waters N of 25N. The surface pressure
gradient that exists between this high pressure, and the lower
pressure that is in the vicinity of the monsoon trough, will
maintain moderate to fresh trade winds to the N of 21N west of
130W, with sea heights in the 8 foot to 10 foot range. The ridge
will prevail in the northern waters during the next few of days
with these general conditions persisting.

$$
Stripling



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