000 AXPZ20 KNHC 091605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Wed Aug 9 2017 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 1545 UTC. ...TROPICAL WAVES... A tropical wave axis is along 89W from 04N to 15N, moving west at 10 to 15 kt. The CIMSS total precipitable water (TPW) imagery animation depicts extensive moisture along and east of the wave to the coast of Central America. The wave position coincides well with potential vorticity guidance from the GFS model. The latest satellite imagery shows that scattered moderate isolated strong convection has increased since the overnight hours within 120 nm either side of the wave from 10N to 10N. The interaction with energy associated with this wave and the monsoon trough axis in its vicinity is forecast to gradually develop a broad cyclonic gyre over the far eastern part of the area to the southwest of Central America by the end of the week and into the weekend. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... Monsoon trough axis extends from 09N79W to 09N85W to 08N90W to 10N94W. Another monsoon trough segment extends from 13N102W to low pressure near 13N106W 1010 mb to 11N120W to 09N128W to 10N132W to 12N140W. Scattered strong convection exists from 04N to 08N between the coast of Colombia and 80W. Scattered moderate to isolated strong within is 120 nm south of the trough axis between 112W and 115W, and between 118W and 125W. Scattered moderate convection is within 180 nm south of the trough axis between 126W and 132W, and also within 30 nm of the trough axis between 134W and 140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The Gulf of California: mainly gentle to occasionally moderate southerly flow will prevail. Expect northerly wind flow in the southern part, just after 48 hours. The sea heights will be 2 feet or less, except up to 4 feet near the entrance. Gentle onshore winds and 4 to 6 feet sea heights will prevail across the offshore waters through Saturday, with the possibility of pockets of 6 to 7 ft seas between Manzanillo and the southern tip of Baja California fro Friday night to Saturday as the gradient tightens between an expected area of low pressure or trough and the Mexican coastline. Beyond Saturday, a forecast southerly swell is expected to build seas to the range of 6 to 9 ft over some portions of the offshore waters. Gentle to moderate northwest to north flow will prevail across the offshore waters of Baja California into early Friday, along with seas of mainly 4 to 6 ft. As mentioned above, it is possible that an area of low pressure or a trough may form within the area defined from 13N to the southernmost point of Baja California between 100W and 110W beginning around Friday and through the upcoming weekend, and track in a general west to northwest motion. Uncertainty remains with regards to the strength and impacts of any associated marine conditions. Scattered moderate within 120 nm of the coast of Mexico between Puerto Angel and Cabo Corrientes is mainly attributed to the daily nocturnal occurrence of convection that forms just inland of the Mexican coast. This activity will gradually weaken through this afternoon, and is expected to develop again tonight near the same geographic locations. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate southerly winds are expected to the south of the monsoon trough, with gentle and variable winds are expected to the north of the monsoon trough. Seas are expected to be in the range of 4 to 6 ft. The long-period southerly swell that is inducing occasional waves of 7 to 8 ft or higher over coastal areas of Costa Rica and Panama will begin to decay today, and continue through Friday. A new and extensive set of cross-equatorial swell is forecast by wave model guidance to cross 03.4S east of 120W, on Friday afternoon. It will possibly reach the coastal waters of Panama and Costa Rica between 80W and 88W late on Sunday night, and possibly reach the coastal waters that are between El Salvador and Mexico between 90W and 102W by sunrise on Monday. It is possible that the sea heights may range from 7 to 10 feet across the offshore waters, except in the lee of the Galapagos Islands. REMAINDER OF THE AREA... A weak and broad ridge anchored by a 1023 mb high center north of the area at 39N137W extends from 32N135W to 25N124W to near 29N114W. Gentle to moderate trades prevail north of the monsoon trough region, with moderate to fresh southerly winds to the south of the monsoon trough region. The wave heights are 4 to 5 ft to the north of the monsoon trough region, and 5 to 7 ft to the south of the monsoon trough region. Little overall change in these marine conditions is expected into the upcoming weekend. $$ Aguirre