AXPZ20 KNHC 280920
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
920 UTC Thu Jul 28 2016
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
Tropical Storm Frank is centered near 23.6N 123.7W at 0900 UTC
Jul 28, moving west-northwest or 290 degrees at 8 kt. The maximum
sustained winds have diminished to 35 kt with gusts to 45 kt. The
estimated minimum central pressure has risen to 1005 mb.
While winds remain at tropical storm force, there convection has
diminished substantially as Frank continues to move over cooler
water. Scattered moderate convection is noted within 90 nm of the
center. Frank is expected to weaken to a remnant low sometime on
this morning. Refer to the latest NHC forecast advisory under
AWIPS/WMO headers MIATCMEP2/WTPZ22 KNHC for more details.
Also refer to the latest high seas forecast under AWIPS/WMO
headers MIAHSFEP2/FZPN03 KNHC for more details on the wave
forecasts associated with Frank.
...TROPICAL WAVE...TROPICAL LOW...POST-REMNANT LOW GEORGETTE
A tropical wave north of 11N along roughly 112W/113W is analyzed
just to the west of an associated 1009 mb surface low pressure
area along the monsoon trough near 11N109W. Scattered moderate to
isolated strong convection is noted within 180 nm in the eastern
semicircle of the low pressure. This low has a medium chance of
developing into a tropical cyclone within 5 days.
A second tropical wave will start to move off the Central American
coast late today, slow as it moves across the Gulf of Tehuantepec
late Friday into early Saturday, and reaching 100W Sunday. Fresh
gap wind flow will follow the tropical wave through the Gulf of
Tehuantepec Saturday night.
The post-tropical remnant low of Georgette was centered near
21N132W moving west northwest at 7 kt. The minimum central
pressure is estimated to be 1010 mb. A recent scatterometer pass
indicated 20 to 25 kt winds within 150 nm of the northern
semicircle of the low pressure. Seas are likely 8 to 10 ft in the
area of stronger winds. The low is expected to dissipate later
today with winds and seas diminishing below 20 kt and 8 ft
respectively through tonight.
..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
A monsoon trough extends WNW from the pacific coast of Costa
Rica near 09N84W to 10N91W to 1009 mb low pressure near 11N109W to
09N125W. The ITCZ continues form 09N125W to 07N130W to beyond
08N140W. Scattered moderate isolated strong convection was noted
within 120 NM of the axis between 118W and 123W.
North of 15N and east of 120W:
Deep layer moisture has increased across the region in the wake of
Frank, now well west of the area. This is contributing to
scattered moderate to isolated strong convection along the length
of the Gulf of California this morning. Numerous moderate to
scattered strong convection is also noted within 120 nm off the
southern coast of Mexico from roughly the Gulf of Tehuantepec
through Acapulco. Otherwise, light to gentle winds prevail across
the region. The subtropical ridge will build across the waters
north of 20N through Saturday, allowing a slightly tighter
pressure gradient between the building ridge and resident
troughing over the Baja California peninsula, resulting in fresh
southerly winds across the central and Gulf of California
Saturday, and up to 25 kt possible over the far northern Gulf
early Saturday with 4 to 6 ft seas. Fresh gap wind flow is also
possible through the Gulf of Tehuantepec by Saturday night in the
wake of a tropical wave passing across the region, with seas to 6
ft. Looking ahead, slightly stronger gap wind pulses may follow
during overnight hours through Early next week with seas to 8 ft.
South of 15N and east of 120W:
Aside from the surface low near 11N109W mentioned above, the main
issue is fresh gap winds in the Gulf of Papagayo this morning.
This may repeat tonight in the wake of a tropical wave moving
across Central America. The pulses are brief, and significant
wave heights will likely not exceed six feet. A weak surface low
associated with the tropical wave will likely form along the
monsoon trough by late today, aided in part by the gap winds. No
significant development is anticipated with this low as it tracks
westward along the monsoon trough over the next couple of days.
Looking ahead, long period southwest swell of 5 to 8 ft will move
into the offshore waters off Central America starting Saturday.
This may cause periods of confused seas to 8 ft in the areas of
easterly gap wind plume, and possibly rough surf and the potential
for rip currents along the coastline.
West of 120W:
See section above for information on the remnant low of
Georgette and Tropical Storm Frank that will pass westward
through the northern portion of this discussion area through
Friday. Northeast swell of 6 to 8 ft will persist across the far
northwest portions of the discussion area through Friday,
primarily north of 25N and west of 135W.