000 AXPZ20 KNHC 171514 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1420 UTC Sat Sep 17 2016 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 FEATURES... Low pressure of 1007 mb centered near 13.5N106.5W has a high probability of developing into a tropical cyclone during the next 48 hours. Convective activity has increased over the northwest quadrant of the system center with numerous moderate and isolated strong convection noted from 13N to 18N between 105W and 110W. A gale warning has been issued in anticipation of increased winds associated with an intensifying low. See the latest high seas forecast under AWIPS/WMO headers MIAHSFEP2/FZPN03 KNHC for more details on the gale warning. See the latest tropical weather outlook for the eastern north Pacific for more on the potential for tropical cyclogenesis. ...TROPICAL WAVES... The axis of a tropical wave is near 91W north of 05N to Guatemala. This is the same tropical wave which spawned Tropical Storm Ian in the Atlantic. Scattered moderate isolated strong convection is noted from 08N to 12N between 90W and 93W associated to this tropical wave. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N85W to 09N89W to 15N100W to low pres near 13.5N106.5W to 10N123W to 11N129W to 10N140W. Scattered moderate isolated strong convection is noted from 08N to 12N between 90W and 93W associated with a tropical wave as noted above. Scattered moderate convection was noted from 11N to 16N between 96W and 101W. Scattered moderate isolated strong convection was noted within 60 nm of the monsoon trough west of 126W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface ridge extends just west of the offshore waters off the coast of Baja California reaching near the Revillagigedo Islands. The pressure gradient between this ridge and troughing over the Gulf of California is maintaining gentle to moderate winds over the offshore waters of the Baja California Peninsula. There is a high probability that low pressure southwest of the coast of Mexico will develop into a tropical cyclone as mentioned above in the special features section. Also mentioned above, a gale warning is in affect for some of the offshore zones in anticipation of the development of this system. This system is forecast to move west of the Baja California Peninsula within a few days...and continue to parallel the coast afterwards. The tropical wave discussed above will help to freshen winds over the Gulf of Tehuantepec during the late night and early morning hours tonight. Winds will continue to pulse over the next several days as high pressure builds over the Gulf of Mexico and tightens the pressure gradient between the area of high pressure and low pressure within the monsoon trough. Winds will reach near 25 kt during the overnight hours. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to occasionally fresh winds are expected north of the monsoon trough. Gentle to moderate southwest winds are expected south of the monsoon trough. Combined seas of 4 to 6 ft will prevail in long period cross- equatorial SW swell. REMAINDER OF THE AREA... High pressure of 1027 mb centered northwest of the area near 34N146W extends a ridge southeast to near 19N111W. The pressure gradient between the ridge and the remnant circulation of Orlene, centered near 20N129W, is supporting winds in the 20 to 25 kt range. The low level circulation will continue to shift westward and weaken over then next couple of days, diminishing winds to 20 kt or less late Sunday night. The circulation will shift west of the forecast area Monday. Seas north of this remnant circulation are reaching near 11 ft, as indicated by a recent altimeter pass. Seas will continue to subside over the next few days, falling below 8 ft by Tuesday. $$ AL