000 AXPZ20 KNHC 140952 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Mon May 14 2018 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 0930 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from northwest Colombia to 08N79W to 07N93W to 08N100W, and northwestward from there to a 1010 mb low at 12N115W. It continues to 05N120W to 05N130W, where latest scatterometer data indicated it transitions to the ITCZ axis to beyond the area at 06N140W. Scattered moderate moderate isolated strong convection is seen within 180 nm south of the axis between 100W and 106W, and within 120 nm southeast of the axis between 116W and 120W. Scattered moderate convection is within 180 nm north and 120 nm south of the axis between 84W and 88W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A NW to SE oriented high pressure ridge is present across the offshore waters west of Baja California. It is bringing gentle to moderate northwest winds over those waters. These winds will continue through this afternoon, then increase to fresh speeds beginning tonight through Wed and to fresh to locally strong speeds Wed night as the ridge strengthens slightly, and while at the same time it begins to build east-southeastward. These winds are forecast to increase a little more to fresh to locally strong on Wed night. Seas will be in the 5-7 ft range through early Wed and build to 6-8 ft in a SW to W swell afterwards over most of the offshore waters, however, seas are in the 6-8 ft range in a NW swell over the offshore waters between 114W and 118W from the locations of Punta Eugenia to San Lazaro. Gulf of California: S to SW winds of 15-20 kt are over the northern sector of the Gulf of California from 30N to 31N west of 114W. These winds become light and variable tonight. Gentle to moderate NW winds will continue across the remainder of the Gulf through Wed, except for a brief instance of fresh to strong northwest winds near and along the coast of Mexico from 24N to 26N on Tue night. Gulf of Tehuantepec: Winds will briefly become northwest to north to moderate to fresh speeds this morning till early afternoon, then become SW to W at gentle to moderate speeds tonight. Winds will again briefly become NW to N at moderate to fresh speeds on Tue morning till the early afternoon hours. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: light to gentle winds will dominate the gulf most of the forecast period with seas of 4-6 ft in long period SW swell, building to 5-7 ft Wed night as another set of long period SW swell reaches the coast of Central America. Gulf of Panama: Gentle to moderate S to SW winds are forecast during the next several days, with seas of 4-6 ft in long period southerly swell, building to 5-7 ft Wed night as long period SW swell reaches the coasts of Panama and Colombia. Elsewhere, gentle to moderate southwest winds are expected to the south of the monsoon trough with axis roughly along 8N, with light to gentle variable winds north of trough. Seas are forecast to build to 6-7 ft in long period SW swell between Ecuador and the Galapagos Islands beginning on Tue. Overnight numerous strong convection that formed over the western half of Nicaragua and over southeastern EL Salvador has moved offshore, and is located from 10N to 13N to the E of 89W to just inland of these locations. This activity is moving southwestward under upper northerly flow found on the eastern periphery of an upper-level anticyclone centered near 16N100W. REMAINDER OF THE AREA... A ridge extends from the NW southeastward to near the Revillagigedo Islands. Low pressure, remnants of recent Tropical Depression One-E, is nearly stationary near 13N130W with a central pressure of 1012 mb. The small cyclonic circulation of the low is clearly exposed and becoming ill-defined with time. Moderate to fresh north to northeast winds are within 240 nm of the low in the NW quadrant and 180 nm in the NE quadrant. A swirl of low-clouds around the center is evident on satellite imagery over the area from 11N to 16N between 128W and 133W. Isolated showers are possible with these clouds. The low is forecast to weaken to a trough late on Tue as it drifts southward, and while at the same time the high pressure to its north begins to build southward. Decaying NW swell is propagating through the waters from 22N to 26N between 114W and 128W, where seas are peaking to 8 ft. As the swell energy continues to dissipate, expect these seas to subside to less than 8 ft by late tonight. Seas to 8 ft induced mainly by SW to W swell, combining to some extent with NE wind waves are present from 13N to 20N between 113W and 130W. An overnight altimeter pass captured some of the values of 8 ft. Seas to 8 ft in mixed SW and NW swell are within the area from 13N to 20N between 130W and 134W. These areas will gradually shift westward through Wed while shrinking in coverage. As previously mentioned, a 1010 mb low remains embedded within the monsoon through near 12N115W. The low is at the base of broad NE to SW aligned cyclonic circulation that covers the area from roughly 10N to 17N and between 109W and 120W. Deep convection is removed from the center of the low, and is identified as the scattered strong type within 120 nm of the low in the SE quadrant. Scattered moderate convection is NE of the low from 14N to 17N between 107W and 111W, and also within 30 nm of 15N114W. The majority of this activity is underneath the western periphery of a mid to upper-level ridge that extends from the anticyclone mentioned earlier that is near 16N100W west- southwestward to near 14N111W where it is interrupted by a mid to upper-level trough that stretches from east of the remainder area near 21N111W to 13N115W. Strong southwest winds ahead of this trough are keeping the deep convective activity displaced to the northeast of the low, for the time being. According to the global models, the low should persist over the next 48 to 72 hours as it tracks in a general west to west- southwest direction under the southern periphery of building high pressure. $$ Aguirre