000 AXPZ20 KNHC 072205 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2123 UTC Tue Nov 7 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N85W to 09N90W to 09N100W to 11N110W to low pressure near 10N116W 1012 mb to 09N140W. Scattered moderate isolated strong convection within 60 nm S of axis between 116W and 118W, and within 30 nm of axis between 88W and 92W. Scattered moderate convection is within 60 nm of axis between 124W and 131W. ...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 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 Tehuantepec: Pulses of strong northerly drainage flow, with seas building to maximum of about 10 ft, are forecast through early Thursday. These northerly winds are then expected to increase to near gale force by late Thursday morning into early Thursday afternoon and to minimal gale force by late Thursday afternoon or evening. Gale force winds are forecast to persist through early Friday morning, with seas then building up to 10 or 14 ft. As the tight pressure gradient over southeastern Mexico slackens during Friday afternoon, the gale force winds will then diminish to below gale force and associated seas will subside some. The pressure gradient will tighten again by Friday evening ushering in another round of northerly gale force through the Isthmus of Tehuantepec and across the Gulf. Presently, it appears based on latest NAM/GFS model guidance that this next episode of gale force winds will be small in coverage. Gulf of California: moderate to locally fresh NW winds will continue through tonight. The pressure gradient will tighten a little resulting in a narrow swath of fresh to strong NW winds from 25N to 28N on Wednesday. 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. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Pulsing moderate to locally fresh N to NE winds are forecast during the overnight hours through Wednesday, 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. REMAINDER OF THE AREA... Water vapor imagery reveals a longwave trough that stretches from southern California southwestward to 32N126W to 25N135W and to an elongated upper low located at 16N140W. A very pronounced jet stream branch along the trough is attendant by strong SW winds that are advecting abundant overcast to broken mid and high level clouds northeastward towards northern and central Baja California as well as extreme southern California. These clouds extent within 480 nm to the SE of the trough axis. Isolated showers are possible underneath most of these clouds. At the surface, a 1016 mb low is analyzed near 31N126W, with a dissipating occluded front entering the forecast area near 30N123W and extending SSW to 26N124W to 20N130W. The low is forecast to continue to pull northeastward away from the discussion area through Wednesday. The front is expected to gradually dissipate by Wednesday evening. Another cold front is forecast to reach a position from near 32N138W to 29.5N140W by early Wednesday afternoon followed by a new set of long period NW swell. The front will then reach from near 32N131W to 28N135W and dissipating stationary to 28N140W. The associated long period NW swell, with resultant seas of 8 to 13 ft will propagate southeastward through the northern forecast waters while decaying. Seas of 8 ft or greater will cover the waters N of 14N W of 125W and N of a line from 21N119W to 14N125W by Friday afternoon, then begin to subside to near 8 ft beyond Friday as the swell area shrinks. $$ Aguirre