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000
AXPZ20 KNHC 261549
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Thu Jul 21 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
meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through
0945 UTC.

...SPECIAL FEATURES...

Hurricane Frank is centered AT 21.2N 116.6W, or about 445 miles
wsw of the southern tip of the Baja California Peninsula, at
1500 UTC, moving slowly wnw, or 290 degrees at 08 kt. The
maximum sustained winds have increased to 65 kt with gusts to 80
kt. The estimated minimum central pressure has dropped to 989
mb. Currently, scattered moderate isolated strong convection is
observed within 150 nm se, and within 90 nm over the nw
semicircles of the center. Frank has likely peaked in strength
as a minimal hurricane, and is forecast to begin a weakening
trend within 24 hours. Refer to the latest NHC forecast advisory
under AWIPS/WMO headers MIATCMEP2/WTPZ22 KNHC for more details.

Tropical Storm Georgette is centered at 18.4N 128.6W at 1500
UTC, moving nw, or 305 degrees at 03 kt. Maximum sustained winds
are currently 60 kt with gusts to 70 kt. Estimated minimum
central pressure is at 987 mb. A large eye became noticeable
over the past few hours, and surrounded by scattered moderate
isolated strong convection within 60 nm over the se semicircle,
and within 90 nm over the nw semicircle. Georgette is expected to
continue to weaken as both oceanic and atmospheric conditions
become less favorable and the cyclone accelerates. Refer to the
latest NHC forecast advisory under AWIPS/WMO headers
MIATCMEP3/WTPZ23 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 these systems.

...TROPICAL WAVE...

A tropical wave is analyzed n of 09N along 101.5W, and has been
moving w at about 12 kt. Scattered moderate isolated strong
convection is noted from 10-15N within 180 nm e, and within 120
nm w of the wave axis. Expect this tropical wave to lose
identity over the next day or so.

..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

A monsoon trough extends wsw from the pacific coast of Colombia
at 08N78W to 07N83W, then turns nw to 10N88W to 09N95W to
11N109W where scatterometer winds indicate a transition to an
ITCZ. The ITCZ extends sw to 08N130W, then resumes sw of
Georgette at 14N136W to 12N140W. Scattered moderate isolated
strong convection is observed along the pacific coast of
Colombia, Panama and Costa Rica within 30 nm either side of a
line from 03N78W to 07N78W to 07N81W TO 10N86W. Similar
convection is noted within 60 nm either side of a line from
05N88W to 08N94W to 09N106W, within 150 nm either side of a line
from 10N113W to 08N127W, and within 60 nm of 13.5N137W.

...DISCUSSION...

N of 15N e of 120W:

Tropical storm force winds associated with tropical cyclone
Frank will move w of 120W on on Wed, and associated seas of 8 ft
or greater will shift w of 120W on Wed night. See special
features above additional information on Frank.

A w to e orientated surface ridge will build from 21N120W to
15N106W in the wake of tropical cyclone Frank. The weak gradient
ne of the ridge will support light to gentle nw winds through
the upcoming weekend, with seas of 4-6 ft.

A nnw to sse orientated trough will meander e and w over the
Baja California Peninsula, and the northern Gulf of California
this week, supporting light and variable winds across the Gulf
of California waters through Fri. A gentle to moderate southerly
flow is expected to begin on Fri night, and will persist through
Sat across the gulf waters.

Moderate northerly flow expected late Thu night into the early
daylight hours on Fri, and then again late Fri night into Sat
morning with seas building to about 6 ft. Model guidance is
suggesting a slightly stronger drainage flow on Sat night into
Sun morning, with seas building to 8 ft.

S of 15N e of 120W:

See section on tropical wave.

Moderate e winds are expected across, and just downstream of the
Gulf of Papagayo during the overnight hours tonight and on Wed
night, then guidance is hinting at fresh e drainage flow on Thu
night as a surface low develops near 10N91W. The low should move
westward through the upcoming weekend, with increasing chance
of tropical cyclone formation later in the week.

Long-period cross-equatorial sw swell, in the formed of combined
seas of 6-8 ft, is forecast to propagate n across the equator
between 100-115W on Thu, and reach along 08N between 90-115W on
Sat before beginning to subside. Combined seas are forecast to
less than 8 ft on Sun.

W of 120W:

See special features above for information on tropical cyclones
Georgette and Frank that will pass westward through the northern
portion of this discussion area through this upcoming weekend.
Combined seas of 6-9 ft, primarily due to mixing swell, are
expected to surround the large seas near the cyclone, and cover
the waters elsewhere to the n of 12N through the upcoming
weekend.

$$
Nelson

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