232 AXPZ20 KNHC 281510 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1510 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURE... Tropical Depression Gilma centered near 15.2N 133.0W at 28/1500 UTC or 1290 nm E of Hilo Hawaii moving W at 10 kt. Estimated minimum central pressure is 1007 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. See latest NHC forecast/ advisory under AWIPS/WMO headers MIATCPEP3/WTPZ33 KNHC for more details. Gilma continues to encounter strong NW shear, and scattered moderate to strong convection is relegated to within 240 nm in the E quadrant. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP3/WTPZ33 KNHC for more details. ...TROPICAL WAVES... A tropical wave that was previously analyzed near 104W/105W has become diffuse and ill defined. A tropical wave extends along 122W from 02N to 16N moving W at 10 to 15 kt. Associated convection has diminished during the past several hours. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 11N86W to low pressure near 09N99W to 08N119W. The intertropical convergence zone axis extends from 07N125W to 12N131W. Also, scattered moderate and isolated strong convection is within 240 nm SW of Central America between 81W and 86W, and also within 180 nm SW of Mexico between 94W and 101W. ...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 later this morning, but are likely again tonight into early Sun. Elsewhere a trough persists from Baja California Norte southward to near Cabo Corrientes. 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. 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 one remaining tropical wave. 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. $$ Lewitsky