000 AXPZ20 KNHC 250912 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 654 UTC Tue Jun 25 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 0840 UTC. ...SPECIAL FEATURES... 1008 mb low pressure centered 240 miles SSW of Acapulco Mexico continues to gradually develop as its cloud pattern shows increasing organization. Environmental conditions surrounding this system are slowly becoming more favorable for development, and the low has a high chance of becoming a tropical depression within the next couple of days as it tracks WNW parallel to the coast of Mexico and in the general direction of the Revillagigedo Islands. At a minimum, if this forecast scenario happens, the low will bring strong winds, building seas, and increased thunderstorm activity as well as squalls to the offshore waters of southern Mexico between Acapulco 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 tropical wave entering the eastern Pacific from the Caribbean has an axis extending N from 05N79W over the Gulf of Panama to 17N79W, moving W around 20 kt. Numerous moderate and scattered strong convection is seen within 90 nm of 04N78W. A weak tropical wave with an axis along 94W from 03N to 13N is moving westward around 15 kt. There is no significant convection currently associated with this feature. A tropical wave has an axis along 111W from 05N and 11N and is moving W between 15 and 20 kt. A small area of convection is noted in the vicinity of the tropical wave in convergent SW winds S of the monsoon trough. Convection on the N side of the wave is being inhibited by a dry air mass advecting S to SW from the interior of Mexico. A tropical wave has an axis along 121W from 03N to 14N, moving westward around 10 kt. Despite being in an area of deep layer moisture, no significant convection is evident near the wave, as this is in an area of mid to upper northerly subsidence. Scattered convection is active however just west of the tropical wave along the monsoon trough. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N74W to low pressure 1008 mb near 14N102.5W to 08N119W to 10N135W. The ITCZ continues west of 140W. Numerous moderate and scattered strong convection is present within 90 nm of 04N78W. Scattered moderate and isolated strong convection is noted from 05N to 17N between 100W and 107W. Numerous moderate and scattered strong convection is seen from 07N to 10N between 125W and 127W. Scattered moderate and isolated strong convection is found elsewhere within 180 nm of the monsoon trough axis W of 107W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features section above for details regarding the gradual development of a low pressure system a few hundred nm SW of Acapulco. This system has a high chance of developing into a tropical cyclone during the next couple of days. A ridge axis extends SE from 1024 mb high pressure centered well to the NW of the area near 36N141W to near the Revillagigedo Islands. The pressure gradient on the E side of this ridge is supporting moderate NW winds over the offshore waters W of Baja California Sur. Recent altimeter data revealed waveheights in the range of 4 to 6 ft for the 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 over the Gulf of Tehuantepec Wed night through Sat night, possibly peaking at minimal gale force Thu night and Fri. 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 Sat. The plume of gap winds could extend W from the Gulf of Papagayo as far W as 100W by Fri evening. Seas within the plume are expected to range between 8 and 10 ft. Combined seas are primarily comprised of long period S to SW swell originating in the southern hemisphere. Recent altimeter satellite passes indicated waveheights ranging between 5 and 7 ft adjacent to Central America and along the coasts of Colombia and Ecuador. The long period swell will maintain combined seas near these heights in these areas for at least the next several days. A tropical wave with an axis along 79W is producing shower and thunderstorm activity over the Gulf of Panama and the waters along the Colombia coast. For further details on this activity see the Tropical Waves section above. REMAINDER OF THE AREA... A 1024 mb high pressure system is centered well N of the area near 36N141W. A ridge extends SE from the high to the Revillagigedo Islands. To the south of this high, the pressure gradient between the ridge and lower pressure over the tropics is generating moderate northeast to east trades north of the ITCZ to about 20N 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 S, long-period cross-equatorial swell is maintaining waveheights around ft to the S of 02S and W of 110W. As the swell energy continues to decay, this area of 8 ft seas will respond by slowly subsiding through Thu. A new round of cross- equatorial swell will cause seas S of 05N between 105W and 125W to build to between 7 and 9 ft by Sun evening. $$ CAM