000 AXPZ20 KNHC 060924 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Wed Jun 6 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 0600 UTC surface analysis and satellite imagery through 0830 UTC. ...SPECIAL FEATURES... Tropical Depression TWO-E has continued to become better organized overnight and is now Tropical Storm Aletta, located near 14.1N 106.5W at 0900 UTC, moving W or 270 deg at 6 kt. Maximum sustained winds are 40 kt with gusts to 50 kt. Minimum central pressure is estimated at 1000 mb. Latest satellite imagery shows that strong thunderstorms continue to develop in a classic comma pattern, with the scattered to numerous strong thunderstorms noted within 120 nm NE and 210 nm SW semicircles. A west-northwestward and then westward motion with a decrease in forward speed are expected during the next several days as the system gradually strengthens to hurricane strength Thursday morning. Strong thunderstorms are expected to persist across the south and southeast periphery of this system through Thursday. Please refer to the latest NHC Forecast Advisory under WMO/AWIPS headers WTPZ22/MIATCMEP2, and the NE Pacific High Seas Forecast under WMO/AWIPS headers FZPN03/MIAHSFEP2 for the latest information on this system. ...TROPICAL WAVES... A tropical wave is moving across the Yucatan Peninsula and the eastern Tropical Pacific overnight, and extends along 89W-90W from the Yucatan to 06N, moving W 10-15 kt. The southern part of the wave is helping to enhance deep convection occurring to the south of the monsoon trough as described above. Scattered strong convection is increasing over sections of Costa Rica and Nicaragua. The wave is forecast to move across the far eastern Pacific waters through the end of the week. Low pressure is expected to form along or near the wave by Thursday. A tighter gradient behind the wave should is producing fresh winds across the Papagayo region. These winds should continue through the rest of this week, with some pulsing of them to moderate intensity expected at times. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 08.5N72W TO 10N84W TO 08.5N94W TO 12N102W, where it has fractured from Tropical Storm Aletta, then resumes from 11N111W TO 08N124W. The ITCZ then continues to beyond 07N140W. Beyond the strong convection near Tropical Storm Aletta, scattered strong convection is noted from 03.5N to 09N to the east of 84W, from 05.5N to 12N between 87W and 96W, from 07N to 10.5N between 106W and 118W, and from 06N to 08N to the west of 136W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A broad ridge extends from a 1026 mb high pressure system centered near 32N141W southeastward to near the Islas Revillagigedo. The typical low pressure trough will remain over the Baja Peninsula and Gulf of California through Fri. This pressure pattern will generally support moderate to fresh northwest winds west of the Baja Peninsula through Fri. Seas of 4-6 ft this morning are forecast to gradually build to 5-7 ft Thu and 6-8 ft Thu night and Fri in the waters offshore northern Baja California due to a new pulse of NW swell forecast to propagate through those waters. Inside the Gulf of California, generally southerly wind flow is expected to continue through Thu. Afternoon and evening sea breezes are forecast to dominate the Gulf for the next few days and will freshen the winds to around 20 kt along the coasts each day. Variable light to gentle winds are expected across the Gulf of Tehuantepec through Thu night, then a brief episode of fresh to strong northerly winds will flow across the Gulf of Tehuantepec Fri as a cyclonic circulation associated with low pressure is expected to form along or near the tropical wave described above begins to impact the waters downstream from the Gulf of Tehuantepec. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fuego Volcano in Guatemala may resume venting some ash in the coming days, but remains relatively quite since the major eruption on Sunday. Moderate to locally fresh nocturnal drainage flow across and downstream of the Gulf of Papagayo will be prolonged through Fri as a tighter gradient behind a tropical wave, presently along 89W, keeps these winds mostly in the fresh range. The monsoon trough meanders across the forecast waters near 10N. Gentle to moderate E winds are generally forecast elsewhere north of the monsoon trough through Thu night. Gentle to moderate southwest winds are forecast south of the monsoon trough through Sat. REMAINDER OF THE AREA... The surface ridge extending across the northern waters will gradually shift W during the next few days. Fresh trades will continue across the tropics to the south of the ridge, generally from 08N to 18N west of 125W through Fri. Model guidance indicates that these winds increase in coverage late Fri as the Aletta tracks in a general northwesterly motion. Northerly swell producing seas to around 8 ft propagating through the NE waters N of 27N between 118W and 125W will gradually subside by early Wed afternoon. Long period SW swell crossing the Equator from the southern Hemisphere will cause seas near the Equator between 95W and 136W to build to 8 ft on Wed night. This area of 8 ft seas will continue to propagate northward and merge with the area of 8 ft seas associated with Aletta by Fri evening. The area of 8 ft seas will expand to include almost all of the basin to the south of 23N between 100W and 130W during this time frame. $$ Stripling