000 AXPZ20 KNHC 131002 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sun Sep 13 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... newly upgraded Tropical Storm Karina is located near 17.4N 113.8W 1003 mb. Maximum sustained winds 35 kt gusts to 45 kt moving NW at 10 kt. Scattered to locally numerous moderate to strong convection is seen within 330 nm NW and 300 nm SW quadrants, and continues to spread to within 30 nm of the center of the T.S. across the southern semicircle. Environmental conditions appear conducive for gradual intensification as it moves W-NW to NW. Further modest strengthening is expected through late Tue before cooler sea surface temperatures will lead to gradual weakening. Tropical storm force winds and seas to around 12 ft will spread across the outer offshore waters of southwest Mexico and just west of the Revillagigedo Islands early during the next several hours, then shift directly across Clarion Island and the surrounding waters midday through Sun evening. For more information, see the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPEP1.shtml and Forecast Advisory at https://www.nhc.noaa.gov/text/MIATCMEP1.shtml. ...TROPICAL WAVES... A tropical wave extends along 91W across Guatemala into the eastern Pacific, moving westward at 10 kt. Associated convection is described below. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N75W to 13N92W to 18N105W, then resumes from low pres 1007 mb near 16N119W to 12N128W to 11N140W. Scattered moderate isolated strong convection is noted from north of 06.5N to the coastlines between 80W and 99W, and from 08N to 12.5N between 102W and 108W. Scattered moderate convection is noted from 09N to 12N between 121W and 127W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for more details on Tropical Storm Karina. SE winds of 20 to 30 kt and seas 8 to 11 ft will shift NW across the outer offshore waters west of Cabo Corrientes and across western portions of the Revillagigedo Islands during the next several hours and then shift NW and out of the offshore waters late this afternoon. Southerly swell from Karina will spread northward across the Baja California offshore waters later today through early next week. Overnight scatterometer data show gentle to moderate west to northwesterly winds over the Baja California waters. Earlier convection noted near the entrance to the Gulf of California has ended. Elsewhere, light to gentle winds prevail along the coast of southern Mexico, where altimeter data indicates seas are 4-6 ft. Modest pulses of moderate to locally fresh northerly gap winds are expected overnight and Sun night over the Gulf of Tehuantepec. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Gentle to moderate S to SW winds persist south of the monsoon trough, which extends across the offshore waters roughly along 10N-11N. Elsewhere, winds remain gentle north of the trough near the coast of Guatemala, El Salvador, and Nicaragua, except for higher gusts in monsoon trough convection across the waters of Costa Rica, Nicaragua and El Salvador. Combined seas remain 4-7 ft in wind waves and background S to SW swell. Gentle to moderate monsoonal flow will prevail over the waters generally S of 10N for the next several days. Combined seas may slightly increase in the waters E of 90W Tue night through Wed as S to SW swell moves across the region. REMAINDER OF THE AREA... Increasing winds and seas will be seen southeast of Clarion Island this morning and spread northwestward over the next several days as Tropical Storm Karina moves west-northwestward away from the coast of Mexico and strengthens to a strong Tropical Storm. Elsewhere, 1007 mb low pressure along the monsoon trough near 17N119W and is depicted in satellite imagery as a small cyclonic swirl. This low will likely become absorbed in the southwestern portion of Tropical Storm Karina during the next few days. A weak and narrow high pressure ridge extends across the NW portion from 1020 mb high pressure near 30N130W to 26N140W. South of the ridge, mainly moderate NE trades prevail across the waters north of the monsoon trough, with smaller pockets of fresh winds noted in scatterometer data between 120W and 130W and north of 18N. Combined seas are generally 5-7 ft based on recent altimeter data, peaking at 8-9 ft within the fresh flow. A broad area of fresh to locally strong monsoonal flow is shown south of the trough between 110W and 125W, with seas generally 6-9 ft in this region. Decaying, long-period S to SW swell lingers across the waters E of 120W, with 7-8 ft combined seas south of the equator. Looking ahead, new southerly swell may move across the southern waters during the early to middle parts of next week. $$ Stripling