000 AXPZ20 KNHC 042205 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Tue Dec 4 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: Strong high pressure ridging southward along the eastern slope of the Sierra Madre mountains is helping to create a tight pressure gradient over southeastern Mexico. This is bringing strong to near gale force northerly winds across the Gulf of Tehuantepec. These winds will quickly increase to minimal gale force in a few hours. The gale force winds are expected to persist through early on Thu. The southern extent of the strong winds will reach as far S as 12N98W on Wed morning. Maximum waveheights with this event are expected to be in the range of 8 to 12 ft on Wed before subsiding some late on Wed. 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 axis extends from NW Colombia near 08.5N74W westward across the Gulf of Panama to 08N92W to 08N106W, where it transition to the ITCZ, and continues to 09N120W to 08N131W to beyond 08N140W. Scattered moderate convection is within 120 nm south of the trough axis between 85W and 89W, and within 90 nm south of the ITCZ between 116W and 120W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec...See special features paragraph above. Gulf of California: Fresh northerly winds across the Gulf will diminish to a light and variable breeze throughout by late Wed morning. Fresh to locally strong southerly flow is forecast north of 29N 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 is expected across the entire gulf waters on Sat. Fresh to locally strong northwest winds are expected across the southern gulf waters on Sun. Elsewhere: Light to gentle northerly flow, and 4 to 6 ft seas, are west 110W, except for higher seas in the 5 to 7 ft range north of 26N. Light to gentle northeast flow, and 3 to 5 ft seas are east of 110W. Winds will become southwest to west in the fresh range range west of Baja California Norte on Wed in advance of a cold front that will move across the northern portion of the area and weaken as it approaches the northern part of the Baja California Peninsula. It will be accompanied by long-period northwest swell, with seas in the 6 to 9 ft range. These seas will propagate southward while building to 8 to 10 ft are they reach to near 19N by late on Fri. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The Santa Maria Volcano located at 14.45N 91.33W has been observed on satellite imagery emitting steam and ash, and is spreading southwestward reaching the Pacific waters of Guatemala between 14N91.5W and near the Mexican border at 15N92W, extending west-southwestward 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 northeast swell will bring seas in the range of 6 to 9 ft as far west as 09N97W by early Fri. 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 north 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 cold front is analyzed from near 32N125W to 24N130W to 21N140W. High pressure is building eastward behind the front across the northwest part of the area. The cold front will reach to near 32N118W to 25N122W and to near 21N126W by early Thu as it weakens. Fresh to strong westerly winds, and large seas of 10 to 13 ft due to long- period NW swell will follow in behind the front. The weakening front will reach from the northern Baja Peninsula to 20N130W on Wed night, but only accompanied by only a moderate 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 is expected to reach 32N140W on Sat accompanied by strong winds shift and large post-frontal NW swell. $$ Aguirre