000 AXPZ20 KNHC 240954 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 727 UTC Mon Jun 24 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 0600 UTC surface analysis and satellite imagery through 0920 UTC. ...SPECIAL FEATURES... A broad circulation centered a few hundred miles south of the Oaxaca coast of Mexico is becoming a little better organized this morning. Clusters of showers and thunderstorms continue to be active in the vicinity of the circulation along and north of the monsoon trough. Conditions surrounding this system are becoming slightly more favorable for development. Convection in the vicinity of this system is building in an area where deep layer easterly shear remains light to the S of an upper-level anticyclone over Mexico. Recent scatterometer data sampled this area well, and shows very broad gentle to moderate cyclonic flow. A coherent low pressure center is expected form by Mon, with gradual further development anticipated as the low moves WNW through mid week, parallel to the coast of Mexico and toward the Revillagigedo Islands. At a minimum, if this scenario happens, the low will bring strong winds, building seas, and increased thunderstorm activity to the offshore waters of southern Mexico between Punta Angel and Cabo Corrientes through the forecast period. Please refer to the latest NHC Tropical Weather Outlook under AWIPS/WMO headers MIATWOAT/ABNT20 KNHC or at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for further details. ...TROPICAL WAVES... A weak tropical wave with axis along 87W/88W north of 06N to El Salvador is moving westward at 10 to 15 kt. Numerous moderate to strong showers and thunderstorms are active mainly where the wave intersects the monsoon trough. This wave may eventually encroach on a low pressure area possibly forming off southern Mexico in the next day or two. A tropical wave has its axis along 116W from 04N to 14N. It is moving westward around 15 kt. No significant convection is noted with this tropical wave currently, although the wave continues to move through a very moist and unstable atmospheric environment. Convection is likely to increase along and near this wave over the 24 hours. A tropical wave is analyzed along 135W from 04N to 14N, approaching an area of upper divergence related to a sharp upper trough and cutoff low pressure between 135W and 140W. Scattered moderate and isolated strong convection has flared along the trough axis during the past several hours. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from low pres 1010 mb near 10N75W to 08N79W to 10N88W to 12N103W to 09N131W. The ITCZ continues from 09N131W to beyond 07N140W. Numerous moderate and scattered strong convection is seen within 60 nm of 07N79W and within 90 nm of 09N87.5W. Scattered moderate and isolated strong convection is noted elsewhere within 180 nm either side of the monsoon trough axis and ITCZ axis east of 137W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features section above for details regarding gradual development of broad low pressure S of Acapulco, with potential to develop into a tropical cyclone during the next few days. Farther north, a 0440Z scatterometer satellite pass indicated moderate NW winds funneling along the Pacific coast of Baja California Sur. This was on the eastern periphery of a ridge reaching SW across the waters west of Baja California to the Revillagigedo Islands. Various altimeter satellite passes indicated seas of 4 to 6 ft over the open offshore waters of Mexico. Aside from the potential impact of the developing low pressure over the outer offshore waters of southern Mexico, strong gap winds are possible in the wake of the developing low pressure over the Gulf of Tehuantepec Wed night through Fri night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate winds will continue for most areas, although pulses of fresh to strong NE to E gap winds will impact the Papagayo region through Fri night. Combined seas are primarily comprised of long period S to SW swell originating in the southern hemisphere. Recent altimeter satellite passes indicated seas of 5-7 ft adjacent to Central America and along the coasts of Colombia and Ecuador. The swell will maintain combined seas near these heights in these areas for at least the next several days. A tropical wave along 88W is triggering numerous moderate and scattered strong convection over the Gulf of panama and over the offshore waters just W of Costa Rica. This activity will most likely be attended by strong gusty winds and locally higher seas. REMAINDER OF THE AREA... A 1031 mb high pressure center is well north of the area near 40N139W. A ridge extends SE from this high to the Revillagigedo Islands. To the south of the high, the pressure gradient between the ridge and lower pressure over the tropics is supporting moderate NE to E trades to the north of the ITCZ and west of about 120W. Little change in the position of the high or the speed of trades is expected for the next several days. Waveheights in this area will generally run between 5 and 7 ft. Farther south, long-period cross-equatorial swell is maintaining waveheights of 8 to 9 ft to the south of 00N and W of 105W. This area of seas is slowly subsiding as the cross-equatorial swell decay. $$ CAM