AXPZ20 KNHC 220332
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Wed Jan 22 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 0 UTC surface analysis and satellite imagery through
Gulf of Tehuantepec Gale Warning: The edge of a Tue afternoon
Ascat pass suggested that strong gale force north to northeast
winds are occurring across the Gulf of Tehuantepec and adjacent
waters. Minimal gale force winds are well downstream of these
winds to near downstream to near 13N96W. Maximum wave heights
are up to around 18 ft within the area of the strong gale force
winds, while the leading edge of waveheights greater than 8 ft
in north to northeast swell reaches as far south as 04N98W. A
tight pressure gradient associated with strong high pressure
centered over southern Mexico will maintain the gale force winds
in the Tehuantepec region through late tonight. These winds will
begin to diminish Wed morning as the high pressure weakens and
the tight gradient begins to slacken. Winds will further
diminish through Wed afternoon as the high pressure over Mexico
weakens further. Residual swell welll downstream of the Gulf of
Tehuantepec will decay by Thu afternoon. Marine interests
transiting across or in the vicinity of the Gulf of Tehuantepec
through tonight should take necessary action to avoid hazardous
Please see the latest High Seas Forecast issued by the National
Hurricane Center under AWIPS/WMO headers FZPN03 KNHC/HSFEP2 or at
website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for
further details on this Gale Warning.
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
A surface trough axis extends from low pressure of 1007 mb over
northwestern Colombia near 10N75W southwestward to the coast at
06N77W, and continues to 08N84W to low pressure of 1009 mb near
07N87W and to 04N92W to 10N102W, where latest scatterometer data
indicates that it transitions to the ITCZ and continues to
06N118W to 08N125W and to beyond the area at 07N140W. Scattered
moderate isolated strong convection is noted within 180 nm south
of low and trough between 84W and 87W, and within 60 nm north of
trough between 90W and 94W. Scattered moderate convection is
within 120 nm north of the ITCZ west of 133W and within 60 nm
north of ITCZ between 105W and 112W.
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...
Please see the Special Features above for details on an ongoing
strong gale force gap wind event in the Gulf of Tehuantepec.
Weakening high pressure of 1023 mb is located near 28N135W, with
and an associated ridge extending southeastward across the Baja
California Sur waters. Gentle to moderate northerly winds
continue over the offshore waters between Cabo San Lazaro and
Cabo Corrientes, as well as over the southern Gulf of
California. Meanwhile, weakening low pressure has moved to over
the offshore waters west of Punta Eugenia near 28N118W. The low
will continue on a weakening trend and dissipate late tonight
into early Wed. Moderate to fresh northerly winds will develop
west of Baja California Wed into Thu as high pressure slides
eastward along 29N/30N. Elsewhere, expect moderate to fresh
northwest winds over the central and southern Gulf of California
Wed night through Thu night as high pressure and associated
tightening pressure gradient builds over the Great Basin region
of the U.S.
Long-period northwest swell is propagating through the Baja
California Norte waters this morning, with seas expected to build
to 8-10 ft north of Punta Eugenia tonight. The swell will
propagate SE across the region and reach the Revillagigedo
Islands Wed. Seas will gradually subside through Fri as the swell
decays. Another round of long period northwest swell associated
with an approaching cold front will reach the Baja California
waters beginning late Fri night and build seas to 8 ft or greater
there during the upcoming weekend.
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...
Mainly scattered moderate convection is observed over the
offshore waters of Costa Rica and western Panama this afternoon
due to atmospheric instability from a 1009 mb low pressure
centered near 07N87W. Showers and thunderstorms will likely
continue through tonight, as the weak low persists offshore and
the upper-level environment remains conducive for convection due
to the passage of a Kelvin wave.
Strong trades occurring over the southwestern Caribbean will
continue to support strong to near gale force northeast to
east winds over and downstream of the Papagayo region through
Thu morning. Winds will be strongest during overnight and early
morning hours assisted by nocturnal drainage. Waveheights will
build to 10 ft each morning during the period of peak winds.
Elsewhere, moderate to fresh northerly winds will continue in
the Gulf of Panama region this week and into the upcoming
Swell generated by a strong Tehuantepec gale force wind event
will impact the Guatemala and El Salvador offshore waters
through Wed night, with seas of 8-12 ft continuing through
REMAINDER OF THE AREA...
The presence of the weak 1018 mb low centered near 28N118W, as
described above, has disrupted the subtropical ridge over the
area, resulting in weaker trades in the deep tropics east of
Farther west, a broad area of fresh to strong northeast winds is
present roughly from 09N to 16N and west of 124W between the
ITCZ and high pressure building across the far northwest portion
of the area. These winds will likely continue for the next
couple days as the subtropical ridge strengthens and low-level
troughing remains north of the ITCZ roughly along 135W. Wave
heights greater than 8 ft due to long-period northwest swell
will dominate the region west of 117W by late tonight, with peak
heights of around 11-14 ft associated with the strongest winds.
By Thu afternoon, the leading edge of waveheights of 8 ft and
greater is expected to have reach as far southeast as 98W.
By early Thu, another set of long period northwest swell will
reach the northwest part of the area, then propagate
southeastward through the high seas during the upcoming
weekend while gradually decaying. The culprit cold front
is expected to be on the weak side as it moves across the
far northern waters Sat and Sun.