457 AXPZ20 KNHC 280912 CCA TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 912 UTC Sat Jul 28 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 0830 UTC. ...SPECIAL FEATURE... Tropical Depression Gilma centered near 15.1N 132.4W at 28/0900 UTC or 1360 nm E of South Point Hawaii moving W at 11 kt. Estimated minimum central pressure is 1007 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. Gilma continues to encounter strong NW shear, and scattered moderate convection is relegated to within 120 nm in the southeast quadrant of the depression. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP3/WTPZ33 KNHC for more details. ...TROPICAL WAVES... A tropical wave is analyzed along 104W from 05N to 16N and is estimated to be moving west at 20 kt. Scattered moderate and isolated strong convection is currently noted within 180 nm east of the wave axis. A tropical wave extends along 120W from 08N to 16N moving W at 10 to 15 kt. Scattered moderate convection is noted from 10N to 15N between 120W and 123W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N78W to 09N115W. Scattered convection is noted from 05N to 09N between 85W and 90W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Latest reports from Salina Cruz indicate fresh northerly gap flow is ongoing. This is due to local drainage effects interacting with a relatively tight pressure gradient between higher pressure over the Gulf of Mexico and lower pressure far south into the tropical Pacific. These gap winds will diminish by mid morning, but are likely again tonight into early Sun. Elsewhere a trough persists from Baja California Norte southward to 20N120W. This is resulting in a fairly weak pressure pattern across the open offshore waters of Mexico. Scatterometer data show light to gentle NW winds in most areas, with moderate NW winds funneling off the Cabo San Lucas. Seas are generally 3 to 5 ft. A persistent deep thermal low over the Colorado River valley is supporting moderate southerly flow across the Gulf of California. Strong and moist mid level NE flow across the Sierra Madre Occidental has been supporting clusters of thunderstorms over the inland mountains, some of which are making into the southern Gulf of California. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate easterly flow is expected through early early next week. Gentle to occasionally moderate E winds are forecast elsewhere N of the monsoon trough which is meandering between 08N and 10N. Moderate to locally fresh southerly winds are forecast S of the monsoon trough into early next week accompanied by 5 to 7 ft seas. REMAINDER OF THE AREA... See the special features section for information on Tropical Depression Gilma and the tropical waves section for details on two tropical waves. Otherwise, ridging will persist north of 20N west of 120W through the period, supporting moderate N to NE winds and 5 to 7 ft seas in that area. Moderate to locally fresh southerly forecast elsewhere S of the monsoon trough or roughly 10N for the next several days. $$ Christensen