000 AXPZ20 KNHC 251009 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Tue Oct 25 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... Hurricane Seymour has continued to move westward around 13 kt overnight, with a 10 nm wide eye appearing on and off throughout the night. The latest satellite images show a clearing eye and improved appearance in the core of Seymour, and the rapid intensification process is clearly underway. Seymour is located near 15.6N 113.8W 970 mb AT 0900 UTC with maximum sustained winds 100 kt gusting to 120 kt. Numerous strong convection is seen within 45 nm across the SW semicircle, while scattered to numerous moderate to strong convection is elsewhere within 120 nm of the eye. Arching rainbands of scattered to numerous moderate to strong convection spiral outward from Seymour to 270 nm across the NW and S quadrants. A west to west-northwest motion of Seymour is expected through this evening before it begins to turn toward the northwest Wednesday and Thursday and gradually weaken. The current rapid intensification trend is expected to continue today and Seymour is forecast to become a category 3 hurricane this afternoon near 16.0N115.9W, with maximum sustained winds near 115 kt, which will likely be its peak intensity. Although the forecast track keeps Seymour just outside of the Mexican offshore zones, fresh to strong winds and seas in the 8-10 ft range are expected to affect the southern part of zones PMZ023 through early this morning and PMZ015 through tonight. For additional details on Seymour, refer to the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25. A gale warning will remain in effect for the Gulf of Tehuantepec during the next 48 hours, as strong northerly winds will persist throughout the week across this region. By Thursday night into early Friday morning, the aerial extent of the gale force winds will increase as high pres builds across the western Gulf of Mexico. At that time, seas are expected to build to 10-14 ft. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N74W to 09.5N84W to 07N92W to 9N104W...where it remains separated from Seymour, then resumes from 13.5N118W to low pres near 14N128W. The ITCZ stretches from 10N133W to beyond 10N140W. Scattered moderate to strong convection is noted from 03N to 08N E of 82.5W, and within 60 nm N and 180 nm S of the trough between 90W and 104W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See special features for details on the persistent Gulf of Tehuantepec gap wind event. High pres of 1020 mb is centered near 28.5N120W and is producing light to gentle anticyclonic winds across the waters W of the Baja California Peninsula. Combined seas are 5-7 ft prevail N of 24N in NW swell. Seas increase to 8-11 ft across parts of forecast zones PMZ023 and PMZ115, particularly S of 20N...including the Revillagigedo Islands, due to moderate NW swell mixing with swell from Hurricane Seymour located just S of these forecast areas. The high pres will shift slightly N-NE during the next 24 hours. This will result in moderate NW winds across the offshore waters. Inside the Gulf of California, mainly gentle southerly winds prevail across the north half, while gentle N to NW winds prevail across far southern portions. As the high center shifts farther N-NE today, light to moderate NW winds will spill down the entire length of the Gulf of California and continue through Wednesday. Afternoon heating is likely to enhance winds near select coastal areas to 15-20 kt through the evening hours. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: NE winds will pulse to near 20 kt over the Gulf of Papagayo during the night time and morning hours over the next couple of days, then diminish to near 15 kt during the afternoon and early evening hours. Elsewhere gentle to moderate S to SW winds are noted S of the monsoon trough, while mainly gentle W to NW winds prevail N of the monsoon trough. Combined seas are in the 4 to 6 ft range, primarily in long period SW swell which is dominating the offshore waters. These marine conditions will persist over the next few days. REMAINDER OF THE AREA... A weak ridge dominates most of the north waters N of 20N, and is producing light to moderate anticyclonic winds between 20N and 30N. Outside Seymour, two weak low pres centers are noted along the monsoon trough, one is near 18N119.5W and the second one is near 14N128W. Seas are 6 to 8 ft in the vicinity of these lows as moderate NW swell is mixing with NEly wind waves. These lows will shift W and weaken further during the next 48 hours. A cold front is over the NW waters and extends from 30N132.5W to beyond 27N140W. Moderate to fresh SW winds are noted N of 28N ahead of the front to 127W. This front will become stationary later this extending from 30N135W TO 27.5N140W. At the same time...a second and stronger cold front will approach 30N140W. These fronts are forecast to merge by this evening and tonight. SW winds of 20-25 kt and seas of 8-9 ft are expected NW of a line from 30N132W to 27N140W by early Tue morning. A new pulse of long period NW swell will follow the merging cold front building seas behind the front to 10 ft by Wed afternoon. $$ Stripling