000 AXPZ20 KNHC 020226 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Mon Oct 2 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 0000 UTC surface analysis and satellite imagery through 0200 UTC. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends across Panama and Costa Rica to 1004 mb low pres near 14N93W to 1008 mb low pres near 12N114W to 10N130W to 10N124W to beyond 09N140W. Scattered moderate isolated strong convection is from 09N to 11N between 91W and 96W, and from 08N to 11N W of 135W. Scattered moderate convection is from 08N to 10N between 88W and 91W, and from 10N to 12N between 128W and 131W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh to locally strong gap winds will develop over the Gulf of Tehuantepec during the overnight and early morning hours through early Tuesday morning as a ridge persists across the western Gulf of Mexico and the eastern slopes of the Sierra Madre Mountains. Seas will build to 6-7 ft through early Monday morning, and to 7-8 ft by early Tuesday morning. Marine guidance continues to indicate increasing winds and building seas across the Tehuantepec area as an area of low pressure strengthens a couple hundred miles south of southeastern Mexico. Environmental conditions are expected to be conducive for gradual development over the next few days while the system moves slowly west- northwestward or westward. The latest Tropical Weather Outlook gives this low a medium change of formation through 5 days. A low of 1004 mb is already analyzed within the monsoon trough near 14N93W on the 0000 UTC surface map. Elsewhere, a ridge dominates the waters west of the Baja California Peninsula producing gentle to moderate northerly winds and seas of 4 to 5 ft. Northerly swell are propagating into the waters west of Baja California Norte, building seas to 8 to 9 ft. This will persist to Monday night, with seas subsiding to 7-8 ft on Tuesday. Fresh to locally strong S-SW winds are expected over the northern Gulf of California tonight and Monday as low pressure develops over the area. Seas over the northern Gulf will reach 6-7 ft during that time. The most recent scatterometer pass showed mainly moderate southerly winds across the Gulf of California N of 29N, and light and variable winds elsewhere. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... An active monsoon trough is currently across parts of Central America and adjacent waters with widespread convection. The trough will remain close enough to the coast, either inland or just offshore, to produce additional active convection over portions of Central America as well as the adjacent coastal waters during the next few days. As a result, locally heavy rain could be possible over higher terrain of portions of central America early this week. Winds and seas are expected to increase over the offshore forecast waters through the forecast period. Fresh to strong SW to W winds and seas of 8 to 11 ft are expected to affect the waters beyond 200 nm off the coast from Nicaragua to Guatemala Monday through Wednesday. Winds and seas will also increase across the offshore waters of Panama and Costa Rica Wednesday night and Thursday. Cross equatorial SW swell, with periods of 20 to 22 seconds are forecast to reach the waters between Ecuador and the Galapagos Islands Tuesday night, building seas to 7-8 ft by Wednesday night. REMAINDER OF THE AREA... High pressure of 1026 mb centered N of the area near 36N136W extends across the waters N of 18N W of 120W. The pressure gradient between the ridge and the monsoon trough is supporting moderate to fresh NE winds roughly from 15N to 25N W of 130W based on scattermeter data. The high pressure is forecast to move westward over the next 24 hours, reaching a position near 36N139W. The pressure gradient between the high and lower pressure inland over the SW of United States, and NW Mexico will produce N winds of 20-25 kt across the waters N of 28N between 122W and 128W by Monday morning. These winds combined with northerly swell propagating into the waters north of 24N between 120W and 130W through Tuesday will build seas to near 12 ft along 30N by Monday morning. Farther south, cross equatorial southerly swell will spread across the waters south of 02N between 105W and 135W by Tuesday, with seas building to 8-10 ft. $$ GR