000 AXPZ20 KNHC 262057 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Aug 26 2020 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 1800 UTC surface analysis and satellite imagery through 1930 UTC. ...SPECIAL FEATURES... Tropical Storm Hernan is centered near 17.7N 105.8W at 26/2100 UTC moving NE at 5 kt. Estimated minimum central pressure is 1004 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Numerous moderate and isolated strong convection is noted within 90 nm in the S semicircle, and from 13N to 19N between 107W and 113W. A turn toward the N is expected tonight, followed by a turn toward the NW on Thu. The system is then expected to turn toward the W-NW on Fri. On the forecast track, the center of the tropical cyclone, along with the strongest winds and heaviest rains, is expected to remain just offshore of the SW coast of Mexico. A weakening trend is expected to begin late Thu night, and Hernan is forecast to become a remnant low Fri night. Please read the latest NHC Public Advisory at: https://www.nhc.noaa.gov/text/MIATCPEP3.shtml and Forecast/ Advisory at https://www.nhc.noaa.gov/text/MIATCMEP3.shtml for more details. Tropical Storm Iselle is centered near 15.5N 116.8W at 26/2100 UTC moving NE at 4 kt. Estimated minimum central pressure is 1001 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Numerous moderate and scattered strong convection is noted within 180 nm in the W semicircle. Iselle is moving toward the NE and this motion is expected to continue through Fri. Little change in strength is forecast during the next few days. Please read the latest NHC Public Advisory at: https://www.nhc.noaa.gov/text/MIATCPEP4.shtml and Forecast/ Advisory at: https://www.nhc.noaa.gov/text/MIATCMEP4.shtml for more details. A very active and strong monsoon trough extends across southern Mexico and Central America. Very heavy rainfall will continue through the week across these areas with the heaviest amounts expected across southern Mexico. This rainfall may cause dangerous and life-threatening flash flooding and mudslides, and river flooding. Refer to information issued by your local or national meteorological agency for details. ...TROPICAL WAVES... A tropical wave axis is near 9W/98W, moving westward at around 20 kt. Associated convection is described in the section below. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from Nicaragua near 11N84W to the vicinity of Tropical Storm Hernan to the vicinity of Tropical Storm Iselle to 10N130W to 11N140W. Other than the convection associated with Tropical Storm Hernan and Tropical Storm Iselle, scattered moderate and isolated strong convection is noted within 480 nm S-SW of the monsoon trough between 83W and 104W, from 16N to 18N between 111W and 116W, and from 07N to 11N between 126W and 140W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for details on Tropical Storm Hernan, Tropical Storm Iselle and a very heavy rainfall event over southern Mexico. Elsewhere, high pressure prevails over the waters W of Baja California. More tranquil weather conditions will likely return across the majority of the offshore waters by early next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Please see the Special Features section for details on a very heavy rainfall event over Central America. Moderate to fresh S-SW winds will prevail S of Costa Rica and Panama through the next several days, with gentle to occassionally moderate winds elsewhere. Moderate seas of 6-8 ft in mixed swell offshore of Central America will subside tonight. Long-period S-SW swell with seas of 7-9 ft will propagate into the waters offshore of Ecuador by early Thu, decaying by the end of the week. Another southerly swell event will approach the waters W of Ecuador Mon night. REMAINDER OF THE AREA... Please see Special Features section for details on Tropical Storm Iselle. Elsewhere, a weak cold front has slipped just E-SE of 30N140W. This front will stall out and dissipate during the next day or so. Otherwise, a ridge dominates the northern forecast waters N of 20N. Low pressure at 1009 mb is centered just W of the area near 11N141W. Associated winds and seas are confined to W of 140W. Elsewhere N of the monsoon trough, gentle to moderate winds prevail. Fresh to locally strong SW winds prevail S of the monsoon trough between 95W and 120W. No significant wind or swell events are anticipated through Sun, with the potential for a northerly swell event with seas of 8 ft or greater reaching S of 30N by Sun night into early next week, decaying beginning late Mon night. $$ Lewitsky