000 AXPZ20 KNHC 100243 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sat Aug 10 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 0215 UTC. ...TROPICAL WAVES... A tropical wave with axis along 91W north of 05N is moving westward at 10-15 kt. Large clusters of scattered moderate to strong convection are over the southeastern section of Mexico and over much of Guatemala. Isolated showers and thunderstorms are elsewhere within 60 nm of wave axis. A tropical wave with axis along 98W from 05N to 17N is moving westward at about 10 kt. A well noted mid-level cyclonic circulation consisting of broken to overcast mainly mid-level clouds is along the wave axis near 15N98W. This wave remains embedded in a very moist environment per latest TPW satellite animation imagery, and is associated with a broad area of low pressure. Latest satellite imagery shows that the earlier observed deep convection associated with this wave has significantly dissipated. Only isolated showers and thunderstorms are occurring from 12N to 16N between 97W and 101W. Similar activity is out ahead of the wave from 12N to 16N between 101W and 104W. Scattered showers and thunderstorms are just inland the coast of Mexico between 99W and 102W. Locally heavy rainfall can be expected along portions of the southern and southwestern coast of Mexico during the weekend. An area of strong northeast to east winds along with wave heights reaching to 8 ft is within 60 nm west of the wave from 14N to 15N. These winds and wave heights are forecast to diminish late tonight, but there is a possibility they may last longer depending on future development of the wave and increased deep convection associated with it. This area of disturbed weather has a medium chance of tropical cyclone formation through the next five days. Please see the latest eastern North Pacific Ocean Tropical Weather Outlook for more information. A tropical wave with axis along 113W from 05N to 18N is moving westward at 10-15 kt. This wave is also embedded in a very moist atmospheric environment per latest TPW satellite animation imagery. Scattered showers and thunderstorms are gradually increasing within 120 nm east of the wave from 11N to 13N. Isolated showers and thunderstorms are elsewhere within 120 nm either side of this wave. Fresh southerly flow within 120 nm east of the wave from 09N to 13N has build wave heights to a peak of 8 ft there. The wave is forecast to remain in a very moist and unstable atmospheric environment during the next few days as it moves in a generally westward motion. This environment is expected to become more favorable for development of this wave through the middle of next week. Before then, expect strong southerly winds to develop within 90 nm or so east and southeast of the wave, with wave heights reaching a maximum of 9 or 10 ft. Please see the latest eastern North Pacific Ocean Tropical Weather Outlook for more information. A tropical wave with axis along 126W from 04N to 17N is moving westward near 15 kt. No deep convection is presently noted with this wave. Low pressure of 1011 mb is centered along the monsoon trough axis near 13N105W. Latest satellite imagery shows scattered moderate to strong convection within 180 nm of the low in the W quadrant and within 60 nm of the low in the SE quadrant. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from a 1011 mb low over northern Colombia southwestward to 08N79W and continues northwestward from there to 13N91W to 14N97W to 13N101W to low pressure near 13N105W 1011 mb, then to 12N115W to 11N123W and to 10N129W, where latest scatterometer data indicates that it transitions to the ITCZ and continues to 09N134W and to beyond 10N140W. Aside from convection related to the 1011 mb low described above, scattered moderate to isolated strong convection is within 180 nm south of the monsoon trough between 107W and 110W, and also within 60 nm south of the monsoon trough between 130W and 136W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface trough extends across the mid-section of the Baja California Peninsula this afternoon. The earlier fresh to strong southeast to south winds over the northern Gulf of California have diminished to fresh speeds this evening. The pressure gradient will tighten just enough to allow for these winds back to fresh to strong speeds late around 12Z on Sat, but will only be brief at these speeds as they will then diminish back to fresh speeds Sat afternoon and be in the moderate to fresh range through Sun before diminishing further to mainly gentle speeds late Sun into early next week. Gentle to moderate northwest winds continue over the Baja California offshore waters, between the aforementioned trough and a 1022 mb high pressure center that is analyzed near 29N137W. This high pressure center will remain nearly stationary through early next week, with little change in offshore wind and sea conditions. Looking ahead, fresh northerly winds will pulse across the Gulf of Tehuantepec beginning on Sun and increase to fresh to strong speeds on Mon, with wave heights building to around 7 ft. Long- period southerly swell will continue to impact the southern waters, with another set expected to propagate through the region from Sat night through early next week. The wave heights for the combined seas will remain at less than 8 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The pressure gradient across the western Caribbean Sea and Central America will continue to support fresh to occasionally strong northeast to east winds pulsing across the Gulf of Papagayo through early next week, with resultant wave heights building to maximum of about 8 or 9 ft on Mon. Moderate southwest flow will persist south of the monsoon trough, elsewhere, with scattered showers and thunderstorms expected off the coast of Central America through the next few days. Recent and current satellite altimeter passes reveal wave heights reaching a peak of 8-9 ft between Ecuador and the Galapagos Islands. These wave heights will change little through the weekend, and then subside early next week. REMAINDER OF THE AREA... Please refer to the Tropical Waves section, for more information regarding an area of disturbed weather just along and offshore the coast of southern Mexico. High pressure anchored by a 1022 mb high center near 29N137W covers the forecast waters north of 20N. Scatterometer data from this afternoon depicted gentle to moderate trades present between the ridge and the monsoon trough/ITCZ region. The scatterometer data also depicted moderate to fresh south to southwest winds south of the monsoon trough, roughly from 07N to 10N between 109W and 122W, where wave heights are reaching to near or at 8 ft as indicated by the latest satellite altimeter data pass across that area. Elsewhere, gentle to moderate winds southerly winds remain across the high seas domain. The latest satellite altimeter data pass revealed wave heights in the range of 8-10 ft south of a line from 02S120W to 01N108W to 01N98W to 02S91W and to 03.4S83W. As a rather significant southern hemispheric swell event continues, swell generated by this event will continue to cross the equator roughly between 83W and 131W through the weekend. This swell is forecast to propagate northward, reaching as far north as 11N between 110W and 122W. Mixed swell over the far western part of the area is south of 12N and west of 135W. This swell is forecast to reach northward to near 14N by Sun. The wave heights will begin to lower early next week as the southern hemispheric southerly swell energy slowly decays. $$ Aguirre