AXPZ20 KNHC 211024
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Wed Aug 21 2019
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 0600 UTC surface analysis and satellite imagery through
A 1007 MB low pressure system is located near 14.5N104.5W, or
about 250 nm south of Manzanillo, Mexico. This area of low
pressure is embedded within a large area of cyclonic winds that
cover the area between 96W and 112W. A large area of showers and
thunderstorms associated with this broad circulation continues
tonight, with a cluster of strong thunderstorms persisting near
the low. and suggesting that it is slowly becoming better
organized. Environmental conditions are favorable for further
development, and tropical cyclone is expected to form within the
next 48 hours. Global models suggest that gale force winds will
develop by Thu afternoon associated with this low. Currently,
numerous moderate and scattered strong convection is located
within 180 nm across the NW and 120 nm across the SE
semicircles, while scattered moderate to strong convection is
elsewhere from 06.5N to 18N between 94W and 118W. The low is
expected to move WNW at 10 to 15 kt through 24 hours, running
parallel and several hundred miles offshore the coast of central
Mexico, and then turn more NW and offshore of Baja California.
This system could still produce locally heavy rainfall leading
to flash flooding across the coastal states of Mexico from Oaxaca
to Jalisco over the next couple of days. Refer to the latest NHC
High Seas Forecast under AWIPS/WMO headers MIAHSFEP2/FZPN03 KNHC
for more details on the forecast of this low.
A tropical wave extends from the eastern Bay of Campeche S-SE
across far southeast Mexico and Guatemala to near 07N89W.
Scattered to numerous moderate to strong convection is occurring
ahead of this wave from 10N to the Mexican coast between 93W and
100W, while scattered moderate isolated strong convection is
elsewhere behind the wave from 05.5N TO 10N between 81W AND 93W.
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
The monsoon trough extends from 10N73W TO 08N80W TO 11.5N91W to
low pressure near 14.5N104.5W to 11.5N110W to 16.5N120W to low
pressure near 16N123.5W to near 12N139W. Scattered strong
convection is noted from 03N to 08.5N E of 79.5W. Scattered
moderate to strong convection is within 120 nm either side of
the trough between 130W and 140W.
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...
Please see the Special Features section for more details about
the low pressure area offshore of Manzanillo.
The pressure gradient between high pressure northwest of the
area and low pressure across the northern Gulf of California is
producing fresh to locally strong NW winds offshore of Baja
California N of 25N this morning, and is expected to continue
today before retreating to the NW late this afternoon and
evening. This will maintain seas of 5-7 ft in mixed NW to N
swell. Low pressure over the U.S. Great Basin will induce fresh
to strong SE to S winds over middle and north portions of the
Gulf of California Wed evening through Fri.
A middle to upper level trough extending from the SW Gulf of
Mexico WSW across central Mexico has maintained unstable upper
level conditions and is supporting ongoing moderate to strong
convection across the waters from Cabo Corrientes to the
Mazatlan area. This convection is expected to diminish this
morning. The trough will remain in place through tonight and is
expected to support another round of late afternoon and night
time convection across this area again Wed.
Overnight scatterometer data showed E to SE winds of 20 kt
between the low pressure center S of Manzanillo to the coast
between Puerto Angel and Manzanillo. Seas in this region are
ranging from 6 to 10 ft. Look from fresh to strong E to SE winds
and seas remaining in the 6-9 ft range through Thu as the low
moves parallel to the coast. Very active convection also across
this area will have the potential for strong wind gusts and
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...
A weak pressure gradient is expected to produce only gentle to
moderate winds across the region for the next several days. Long
period cross equatorial SW swell will reach the waters between
Ecuador and the Galapagos Islands today, building seas to 6 to 7
ft late today into Thu.
REMAINDER OF THE AREA...
A 1022 mb high pressure located near 30N133W extends a ridge
across the northern forecast waters. This system will remain
nearly stationary over the next 48 hours producing mainly gentle
to moderate winds N of 20N and W of 110W. The pressure gradient
between the ridge and lower pressures in the vicinity of the
monsoon trough will result in moderate to fresh trade winds S of
20N. The remnants of a low pressure center persist along the
monsoon trough near 16N123.5W. fresh winds to around 20 kt
surrounding this low are combining with mixed swell across the
region to produce seas of 6-8 ft from 15N to 17.5N between 124W
and 130W. This low will shift W and weaken through Fri.
Elsewhere winds are expected to increase S of the monsoon trough
through Thu night, particularly between 105W and 120W, in
response to the developing low pressure system offshore of
Manzanillo. As the monsoon through continues to lift northward
fresh to strong SW monsoonal winds will create wind waves that
will combine with SW swell to produce seas of up to 10 ft S of
15N between 100W and 120W through Thursday. Some northerly swell
will cross south of 30N to near 25N around 120W Thursday, with
seas around 8 feet expected.