AXPZ20 KNHC 210402
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Mon Sep 21 2020
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
Based on 0000 UTC surface analysis and satellite imagery through
Tropical Depression Seventeen-E is centered near 16.1N 109.3W at
21/0300 UTC or about 410 nm south of the southern tip of Baja
California moving west-northwest at 9 kt. The estimated minimum
central pressure is 1005 mb. Maximum sustained wind speed is 25
kt with gusts to 35 kt. Last GOES-17 visible imagery indicates
that this system remains poorly organized as evident by its
center being exposed as a small swirl of low-level clouds just
to north of a large area of deep convection. This convection
consists of the scattered moderate to isolated strong type from
10N to 17N between 109W-114W, and of the scattered moderate type
intensity from 10N to 16N between 105W-109W. The depression is
forecast to maintain its current motion during the next few days
and become a tropical storm by Tue. Please read the latest HIGH
SEAS FORECAST issued by the National Hurricane Center at website-
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest
Tropical Depression Seventeen-E NHC Forecast/Advisory and Public
Advisory at www.hurricanes.gov for more details.
A tropical wave has its axis along 134W from 03N to a 1009 mb
low near 10N134W and north to 18N134W. It is moving westward at
10-15 kt. Scattered showers and isolated thunderstorms are
180 nm either side of the wave from 09N to 12N.
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
The monsoon trough axis extends from northwestern Colombia to
10N86W to 10N95W and to 13N102W, where it ends. It resumes at
13N116W to 12N126W to low pressure near 10N134W 1009 mb and to
09N136W, where latest scatterometer data indicates that it
transitions to the ITCZ to beyond the area at 10N140W. Scattered
moderate convection is within 180 nm south of he trough between
84W-85W, within 60 nm south of the ITCZ west of 138W and within
30 nm south of the trough between 134W-138W.
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...
The gradient induced by weak deep layer ridging between Baja
California and 125W is supporting mainly moderate northwest
to north winds off Baja California Norte with combined seas to
6 or 7 ft. Winds and seas will diminish some through Tue, except
within about 300 nm southwest of the southern tip of Baja
California, where much high winds and seas on the periphery of
Tropical Depression Seventeen-E can be expected.
Farther south, fresh to strong winds will pulse in the Gulf of
Tehuantepec region through the next couple of days. Elsewhere, a
weak pressure pattern across the region will result in mainly
gentle to moderate winds and slight seas.
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and
WITHIN 750 NM OF ECUADOR...
Gentle to moderate south to southwest winds continue south of
the monsoon trough. Elsewhere, gentle winds prevail north of the
monsoon trough. Combined seas are currently in the 5-6 ft range
in a mix of wind waves and southerly swell.
Scattered small clusters of moderate convection are along and
just some areas of Central American coast. This activity is
more concentrated near Costa Rica.
REMAINDER OF THE AREA...
A surface trough along 136W from 18N to 24N continues to break
up the subtropical ridge and supporting gentle moderate trade
winds farther south into the deep tropics. The ridge will
gradually build eastward north of 20N through mid week, and
trades will strengthen somewhat between the ridge and the monsoon
Farther east, seas of 8-9 ft are within an area along the
monsoon trough between 105W and 117W. These seas are a result
of the fresh to strong southwest to west winds that are occurring
in the southern part of the broad cyclonic circulation associated
to Tropical Depression Seventeen-E. In addition, persistent
long-period southwesterly is present within this area as well
further contributing to the build up of these seas.