000 AXPZ20 KNHC 080927 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 927 UTC Wed Nov 8 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 0600 UTC surface analysis and satellite imagery through 0915 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec: Nocturnal drainage flow will continue to pulse from strong to near gale force today through tomorrow. Winds are forecast to increase to minimal gale force late Thu afternoon or early evening as high pressure surges down eastern Mexico with an advancing cold front. Gales will then pulse for the foreseeable future through the upcoming weekend and into early next week. Winds will approach strong gale by the end of the weekend as the pressure gradient tightens slightly. Seas will build to 10 to 15 ft during the gale force winds. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N83W to 08N105W to low pressure near 10N117W to low pressure near 12N133W to 08N140W. Scattered moderate and isolated strong convection is from 06N to 08N between 80W and 82W, from 07N to 10N between 93W and 96W, from 07N to 10N between 98W and 101W, and also within 180 nm either side of the axis between 121W and 129W. Scattered moderate and isolated strong convection is from 04N to 07N within 90 nm of the coast of Colombia, including the approach to the Panama Canal. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge will dominate the waters W of Baja California through the rest of the week, while a trough will meander between the coast of NW Mexico and the Gulf of California. Moderate to locally fresh NW to N flow will prevail across the waters W of Baja California, increasing to fresh to locally strong offshore of the northern waters Thu night through Fri. A cold front is expected to weaken before reaching the area on Friday, but the associated long-period NW swell inducing seas in the range of 8 to 10 ft will propagate southeastward across the waters N of 23N and to the W of Baja California on Friday, then spread southward through all the waters W of Baja on Saturday while subsiding slightly. Gulf of California: Moderate to locally fresh NW winds will continue through the morning. The pressure gradient will tighten a little resulting in a narrow swath of fresh to locally strong NW winds from 25N to 28N by the afternoon. The pressure gradient will relax with moderate NW flow only to the S of 26N by Thursday evening. Mainly light and variable winds and seas of 2 ft or less will then prevail for the end of the week into the upcoming weekend, becoming moderate out of the NW by the end of the weekend. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: moderate to locally fresh N to NE winds will pulse during the overnight hours through early Thu, with seas building to 5 or 6 ft downstream near 11N87W. Light and variable winds and 4 to 6 ft seas, are expected elsewhere to the N of 09N, while moderate to locally fresh southerly winds and 5 to 7 ft seas, are forecast S of 09N through the remainder of the week and the upcoming weekend. REMAINDER OF THE AREA... A 1014 mb surface low is near 30N125W. A dissipating stationary front that occludes into the low extends from 30N122W to 23N129W. Scattered moderate convection is within an area bounded by 30N123W to 30N118W to 26N123W to 28N125W to 30N123W. The low is forecast to dissipate during the next 24 hours. A 1010 mb surface low is analyzed in the monsoon trough near 10N117W. Scattered moderate and isolated strong convection is within 180 nm in the SW semicircle of the low. A surface trough is analyzed just N of the monsoon trough from 22N126W to 13N131W. Scattered moderate and isolated strong convection is from 13N to 18N within 180 nm E of the trough axis. A cold front is forecast to reach a position from near 32N138W to 29.5N140W by early afternoon, followed by a new set of long period NW swell. The front will reach from near 30N130W to 27N140W by late tonight, then will begin to dissipate from 30N130W to 27N136W by late Thu night. The remnants will then drift NW as a trough into the early part of the weekend. A new front will breach just SE of 30N140W by Sat afternoon, but will quickly stall before eventually merging with the old frontal trough into Sun. The associated long period NW swell, with resultant seas of 8 to 13 ft will propagate southeastward through the northern and central forecast waters while gradually decaying and shrinking in coverage Thursday night through Friday night, at which time seas in the range of 8 to 10 ft are expected to be confined to the waters N of 12N and W of 114W. The swell will then slowly subside to less than 8 ft throughout the waters by early next week. $$ Lewitsky