000 AXPZ20 KNHC 061605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sun Aug 6 2017 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 1545 UTC. ..TROPICAL WAVES... A tropical wave axis is along 99W north of 08N, moving west at 10-15 kt. Both long-term satellite imagery and the CIMSS tropical precipitable water imagery (TPW) animation distinctly denotes the wave signature through time from the past 48 hours to the latest imagery time. In addition, middle to upper level potential vorticity guidance from the GFS has a very good handle on the wave position. The 700 mb streamline analysis from the GFS suggests that troughing over and near the location of the wave. The TPW reveals that the wave axis marks the leading edge of very deep moisture that just about covers the far eastern portion of the area from 07N to 16N west to the wave. The wave is moving through the southern periphery of upper level ridging associated with a large anticyclone centered over Baja California at 27N112W. Latest satellite imagery shows scattered strong convection in cluster type formation to the east of the wave from 13N to 14N. Scattered moderate isolated strong convection is east of the wave within 30 nm of 12N98W. Lightning density data indicates frequent lightning with some of the observed convection. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N84W to 10N92W to 08N102W to 08N109W to 09N116W. Another monsoon trough axis extends from 18N115W to 14N120W to 12N130W to 10N135W, where scatterometer data indicates the ITCZ begins and continues to beyond the area at 09N140W. Scattered to numerous strong convection is within 60 nm either side of the trough between 93W and 96W, within 60 nm north of the trough between 87W and 91W, and from 09N to 14N between 99W and 102W. Scattered strong convection is within 60 nm either side of the trough between 108W and 111W, within 60 nm south of the the trough between 87W and 91W, and within 60 nm south of the trough between 99W and 105W. Scattered moderate isolated strong convection is within 60 nm of the trough axis between 102W and 108W, and within 60 nm south of the trough axis between 115W and 119W. Scattered moderate convection is within 60 nm south of the trough axis between 130W and 133W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A low pressure system, remnants of recent Tropical Eleven-E, is centered near 21N112W with a pressure of 1010 mb. It is nearly stationary at the present time. Isolated showers and thunderstorms are removed far to the northwest from the center within 30 nm of 22N114W. Scatterometer data from the overnight hours highlighted 20 to 25 kt winds within about 90 nm of the low center in the NE semicircle. Since then, these winds have diminished in coverage to within 60 nm of the low in the NE quadrant with seas of 8 to 9 ft. The low will continue to weaken through this evening with seas subsiding to less than 8 ft. A ridge will dominate the offshore waters to the west of northern and central Baja California. Expect gentle to moderate NW to N winds and seas in the range of 4 to 5 ft west of the Baja California peninsula. Gentle to locally moderate southerly flow will prevail across the Gulf of California. Gulf of Tehuantepec: moderate to locally fresh northerly winds will become light and variable winds by late this afternoon through tonight, then become moderate northerly winds early on Monday, with the assistance of nocturnal drainage flow. This winds will decrease to light to gentle winds Monday afternoon and become moderate southwest to west winds Monday evening, and through Monday night before backing around to the northwest late Monday night into early Tuesday. Wave model guidance has been consistently suggesting that a new set of long-period southerly swell, with the leading edge containing a period of 20 to 21 seconds, is forecast to reach the coast of Mexico south of Cabo Corrientes on Tuesday. This scenario will bring the potential for large breaking waves as it reaches shallow waters along the coast of Mexico on Tuesday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The Gulf of Papagayo: gentle to moderate southwest to west winds will change little offshore the Gulf of Papagayo through Tuesday with seas of 5 to 6 ft in southerly swell. Moderate southerly winds are expected to the south of the monsoon trough, with gentle and variable winds to the north of the monsoon trough, with seas generally in the 4 to 6 ft range. A set of long-period southerly swell, with a leading edge period of 20 to 21 seconds, is forecast to reach the waters between Ecuador and the Galapagos Islands early Monday, and the coast of Central America on Tuesday. Seas are expected to build to the range of 6 to 7 ft mainly over the offshore waters of northern Costa Rica and western Panama on Tuesday, with some potential for large breaking waves as it reaches shallow waters along the coast. REMAINDER OF THE AREA... A surface ridge that extends across the northern and central portions of the area from 32N140W to 25N125W to near 20N118W will remain about stationary through early on Monday, then begin to build southeastward through the middle part of the week. This will cause the remnant low of Tropical Depression Eleven-E to weaken to a trough while shifting southeastward to the waters west of Manzanillo by that time. Weak low pressure is expected to form on the monsoon trough near 12N137W by early on Monday, and move little through Tuesday. Moderate to locally fresh trades also are expected between the southern periphery of the ridge and monsoon trough/ITCZ and expected weak low, mainly from about 12N to 20N and west of 125W, with associated seas in the range of 5 to 7 ft. $$ Aguirre