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Tropical East Pacific Satellite

NHC Tropical Weather Discussion (East Pacific)

National Hurricane Center – Tropical Weather Discussion (East Pacific)

NHC East Pacific Tropical Weather Discussion

853 AXPZ20 KNHC 211602
TWDEP Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Tue Aug 21 2018
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 1200 UTC surface analysis and satellite imagery through 1515 UTC. …TROPICAL WAVES…

A tropical wave along 86W is moving W around 10 kt. Isolated moderate convection is from 05N to 12N E of 90W. A tropical wave along 100W is moving W around 15 kt. Scattered moderate and isolated strong convection is from 05N to 14N between 93W and 110W.

A tropical wave along 118W is moving W around 10-15 kt. Scattered moderate and isolated strong convection is from 07N to 15N between 113W and 122W.

A tropical wave along 132W is moving W around 10-15 kt. Scattered moderate convection is from 06N to 17N between 126W and 136W.

…INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH… The monsoon trough extends from low pres 1010 mb near 10N75W to 08N83W to 09N100W to 12N125W. The ITCZ begins near 12N125W and continues to 12N131W then resumes near 12N133W and continues beyond 10N140W. Numerous moderate to isolated strong convection is from 03N to 08N east of 81W, from 07N to 11N between 122W and 127W and from 07N to 13N W of 135W.


OFFSHORE WATERS WITHIN 250 NM OF MEXICO… A surface ridge across the NE Pacific extends SE from a 1028 mb high centered near 42N140W and covers the forecast waters SE to near the Revillagigedo Islands. This ridge will support a weak to modest pressure gradient across the offshore waters of Baja California. Light to gentle NW winds are expected through Thu night before the ridge strengthens slightly and the pressure gradient tightens supporting then NW gentle to moderate winds along the Baja offshore waters. Seas will generally remain in the 3-4 ft range through Thu, then seas will increase to 5 ft over the offshore waters of Baja California Norte. Surface troughing over the Baja Peninsula will maintain a generally light wind regime over the Gulf of California through the weekend.

Strong N to NE gap winds will affect the Gulf of Tehuantepec tonight through Thu night, and are forecast to peak near 30 kt Thu night. Seas will build to 8 ft, increasing to 9 ft on Thu.


The monsoon trough will linger near 09N during the next few days. Winds on both sides of the trough axis will generally be light to moderate. The main exception to this will be over the Gulf of Papagayo, where moderate to fresh offshore winds will pulse to locally strong through Wed night. Seas are expected to remain 6-7 ft downstream of Papagayo during this time.

REMAINDER OF THE AREA… Elsewhere, the pressure gradient between ridging across the northern waters and the ITCZ will support mainly gentle to moderate trades and 4-6 ft seas in mixed swell N of the ITCZ and W of 120W through the weekend. A slightly tighter pressure gradient in the area from 13N-20N W of 130W will support NE to E moderate to fresh winds with seas to 7 ft.

Sea heights will be relatively low for most of the forecast area this week. A much more robust round of long period swell could arrive from the Southern Hemisphere toward the end of this week and cause seas near the Equator to begin building on Sat.