000 AXPZ20 KNHC 180234 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Fri Oct 18 2019 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 0000 UTC surface analysis and satellite imagery through 0130 UTC. ...SPECIAL FEATURES... Tropical Storm Octave is centered near 9.8N 127.1W at 18/0300 UTC moving W at 3 kt. Estimated minimum central pressure is 1006 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Numerous moderate and isolated strong convection is noted within 210 nm in the SE semicircle and 120 nm in the NW semicircle of Octave. Octave is forecast to maintain strength through Fri before weakening back to a tropical depression this weekend. Octave is also forecast to not move much through the next few days. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP3/WTPZ23 KNHC for more details. Heavy Rainfall Event for southern Mexico: Moderate to fresh strong southwesterly monsoonal flow under a very moist and unstable atmosphere will gradually weaken through the remainder of tonight, and the heavy rainfall threat should begin to diminish somewhat. Until then, heavy rainfall remains possible over portions of southern Mexico from Chiapas to Jalisco. These rains could cause flooding and mudslides, especially in mountainous areas. Strong gusty winds are possible in and near showers and thunderstorms. Please monitor products from your local or national meteorological service for more details on this event. ...TROPICAL WAVES... The axis of a tropical wave is near 82W, from near the Colombia/Ecuador border to eastern Panama, moving W at 10-15 kt. Scattered moderate convection is noted mainly over western Panama and SE Costa Rica from 07N to 09N between 80W and 84W. The axis of a tropical wave is near 121W from 03N to 15N, moving W at 5-10 kt. No significant convection is noted. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from near the Costa Rica/Nicaragua border near 11N86W to across the Gulf of Tehuantepec to 16N98W to low pressure near 14N113W to 10N123W then resumes from 10N131W to 11N140W. Scattered moderate and isolated strong convection is noted from 10N to 15N between 93W and 97W, within 180 nm either side of the monsoon trough between 98W and 108W, and from 05N to 10N between 130W and 136W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please read the Special Features section for more details about a heavy rainfall event over southern Mexico. An area of low pressure that was previously analyzed about 75 nm S of Cabo Corrientes has opened up into a surface trough from 21N104W to 16N106W, with scattered moderate and isolated strong convection noted within 120 nm NW of the trough axis. This trough is expected to dissipate by the weekend. Moderate to fresh SW monsoonal flow and wave heights of 6-8 ft will remain to the S of the monsoon trough in the Gulf of Tehuantepec zone and vicinity through Sat. A ridge will build across the Baja California offshore waters in the wake of a dissipating cold front. A tight pressure gradient between this ridge and deep troughing which will develop over interior California will support gale force winds offshore of Cape Conception. Outer fresh to strong winds will manage to filter southward into the offshore zones of Baja California Norte later tonight through the weekend. Along with these winds, a set of large NW swell will propagate into the Baja California waters, with seas reaching a range of 10-14 ft by Sat. This swell will spread SE reaching the Revillagigedo Islands by Sat night and continuing through Sun night. The swell will then gradually decay early next week. Gulf of California: The pressure gradient will tighten across the region early next week as high pressure W of the area shifts NE. This will allow for NW flow to freshen in the northern and central Gulf. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate SW to W winds will change little through Fri. SW winds will become moderate to fresh S of the monsoon trough this weekend before diminishing somewhat early next week. These winds will help to build seas slightly for the weekend. REMAINDER OF THE AREA... Please read the Special Features section for more details about Tropical Storm Octave A 1010 mb area of low pressure is embedded in the monsoon trough near 14N113W. Scattered moderate and isolated strong convection is within 210 nm in the W quadrant of the low. This low is currently forecast to drift NE, eventually opening up into a trough this weekend. A large set of NW swell is propagating into the northern waters with seas currently 8-12 ft. This swell will continue to propagate SE, and seas will peak around 10-14 ft N of 24N between 118W and 128W Fri night into Sat, aided by fresh to strong winds which will spread southward from off the southern California coast. The edge of seas of 8 ft or greater will reach to 10N and W of 110W by Sat night into Sun. This swell will gradually decay early next week along with the fresh to strong winds which will diminish. Otherwise, a weak ridge extends across the waters S of the dissipating cold front and N of the monsoon trough. Mainly moderate to fresh trades are noted underneath the ridge as supported by recent scatterometer data, except for a small area of fresh to strong winds near 140W in the wake of a now departed surface trough. These conditions near 140W will shift westward tonight as the trough continues away from the area. $$ Lewitsky