000 AXPZ20 KNHC 041554 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Dec 04 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 1500 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: Strong post-frontal high pressure building across the Gulf of Mexico this morning will surge across the Gulf of Tehuantepec during the next several hours, to produce strong northerly winds that will quickly increase to 30 kt shortly after noon time, and then reach minimal gale force late this afternoon. Gale conditions are then expected to persist through near sunrise on Thu. The southern extent of strong winds will reach as far S as 12N98W on Wed morning, with maximum seas occurring then at around 14 ft. Winds will diminish to 20 kt or less on Fri evening. The next gap event will begin on Sun morning with strong gale conditions developing on Sun night. .INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from NW Colombia near 08.5N74W westward across the Gulf of Panama to 10N90W to 10N99W to 08N110W, where it transition to ITCZ, and continues W to beyond 07.5N140W. Scattered moderate isolated strong convection is observed within 270 nm S of the trough between 78W and 107W, and within 210 nm N and 120 nm S of the ITCZ between 116W and 138W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec...See special features paragraph above. Gulf of California: Fresh northerly winds across the full length of the gulf waters overnight has built seas to 5-6 ft across central portions this morning. Winds will gradually diminish to moderate this afternoon and then to a light and variable breeze throughout by late Wed morning. Fresh to locally strong southerly flow is forecast N of 29.5N on Wed evening, ahead of a pre-frontal trough that will pass through the northern gulf waters on Wed night and Thu, followed by the associated cold front early Fri, with fresh northerly flow forecast briefly behind both the trough and the front. Gentle to locally moderate northerly flow expected across the entire gulf waters on Sat. Fresh to locally strong NW flow expected across the southern gulf waters on Sun. Elsewhere: Light to gentle northerly flow, and 4 to 6 ft seas, are expected W of 110W this morning while light to gentle northeast flow, and 3 to 5 ft seas, is expected E of 110W, as perturbation along the monsoon trough along 105W moves westward. Low level winds will gradually clock to the S across the waters W of Baja Norte tonight ahead of a cold front arriving at 32N120W on Wed, and reaching the extreme northern Baja Peninsula early Thu, accompanied by long-period NW swell in the form of 7 to 9 ft seas. These seas will propagate S reaching the W shore of the southern Baja Peninsula late Fri, then begin to subside from the N on Sat with seas less than 8 ft by Sun afternoon. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Volcanic ash originating from the Fuego Volcano in Guatemala has ended this morning. However, nearby Santa Maria Volcano located at 14.45N 91.33W has been observed on satellite imagery emitting steam and ash overnight through this morning, and is spreading southwest and reaching the Pacific waters of Guatemala between 14N91.5W and near the Mexican border at 15N92W, extending WSW to near 13.8N93.5W. This ash is dispersing quickly and is thought not to be falling to the surface. However, local mariners are urged to exercise caution across this area and the volcano remains active. Gulf of Papagayo...Nocturnal pulses of fresh to locally strong NE winds are expected across and downstream of the Gulf through Fri night, with peak winds in terms of areal coverage forecast for Wed Night through Thu night. The resultant NE swell in the form of 6 to 9 ft seas will reach as far WW as 09N97W on Fri morning. Elsewhere: The monsoon trough will meander between 08N and 10N this week with light to gentle variable flow, and 3 to 5 ft seas, forecast N of the monsoon trough, and moderate southwesterly monsoonal flow, and 4 to 6 ft seas, forecast S of the monsoon trough. REMAINDER OF THE AREA... A surface high has collapsed near 28N121W, with the remaining NE to SW ridge expected to will shift SE and weaken during the middle of the week. This is occurring ahead of a cold front currently extending from 30N127.5W TO 22.5N140W, that will continue to move E, reaching a position from 32N122W to 23N133W tonight while preceded by strong SW flow to the N of 29N within 150 nm E of the front. Fresh to strong westerly winds, and large 8 to 15 ft seas due to long-period NW swell, is forecast tonight W of the front. The weakening front will reach from the northern Baja Peninsula to 20N130W on Wed night, but only accompanied by only a moderate SW-W-NW wind shift. However the associated leading edge of 8 ft, or greater, seas will reach from 32N120W to 10N140W early Thu, and from the southern tip of the Baja Peninsula to the equator at 130W on Fri night. Another cold front will reach 32N140W on Sat accompanied by strong winds shift and large post-frontal NW swell. $$ Stripling