000 AXPZ20 KNHC 250244 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 046 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 0000 UTC surface analysis and satellite imagery through 0200 UTC. ...SPECIAL FEATURES... 1008 mb low pressure centered 210 miles south-southwest of Acapulco Mexico continues to become a little better organized in its overall cloud pattern depiction. Environmental conditions surrounding this system are slowly becoming more favorable for development, and the low pressure may intensify into a tropical depression within the next couple of days as it tracks in west- northwest motion parallel to the coast of Mexico and toward the general vicinity of the Revillagigedo Islands. At a minimum, if this 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 weak tropical wave with axis along 93W from 03N to 13N is moving westward at 10-15 kt. A few showers and thunderstorms are evident near the wave, on an outer band east of the low pressure south of the Gulf of Tehuantepec, from 12N to 14N between 94W and 96W. A tropical wave is along 110W from 05N and 15N. A small area of convection is noted where the tropical wave intersects the monsoon trough, but overall the tropical wave is in an area of fairly dry air, west of the developing low pressure. A tropical wave with axis along 120W from 04N to 15N, moving westward at 15-20 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. A tropical wave with its axis extending along 138W from 04N to 14N. The wave is under an area of upper- level divergence related to a sharp upper-level trough situated between 135W and 140W. No significant convection is noted. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 08N78W to low pressure near 13N102W to 08N115W to 10N135W. The ITCZ is west of 140W. Scattered moderate convection is noted from 08N to 12N between 108W and 112W, and from 06N to 09N between 122W and 132W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features section above for details regarding gradual development of a low pressure system a few hundred nm to southwest of Acapulco , with potential to develop into a tropical cyclone during the next few days. A ridge axis extends southeastward, from high pressure centered well to the northwest of the area, to near the Revillagigedo Islands. The associated pressure gradient is allowing for generally moderate northwest winds to exist over the offshore waters west of Baja California Sur, with the exception of moderate to fresh winds near the southern tip of the peninsula. Earlier altimeter data revealed waveheights in the range of 4-6 ft over 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 in the wake of the developing low pressure over the Gulf of Tehuantepec Wed night through Fri night, possibly reaching 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 Fri night. Combined seas are primarily comprised of long-period south to southwest swell originating in the southern hemisphere. Recent altimeter satellite passes indicated waveheights in the range 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 with axis along 91W is producing shower and thunderstorm activity over the waters west of Costa Rica and norther Panama. For further details on this activity see the Tropical Waves section above. REMAINDER OF THE AREA... A 1026 mb high pressure center is well north of the area near 37N140W, with a ridge extending southeastward to the Revillagigedo Islands. To the south of this high, the pressure gradient between the ridge and lower pressure over the tropics is allowing for generally moderate northeast to east trades to exist north of the ITCZ and west of about 125W. 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 in the range of about 5-7 ft. Farther south, long-period cross-equatorial swell is maintaining waveheights of 8-9 ft to the south of a line from 01S120W to 03.4S104W. As the swell energy begins to decay tonight, this area of waveheights will respond by slowly subsiding through Wed. $$ Christensen