000 AXPZ20 KNHC 160240 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sun Jun 16 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 0230 UTC. ...TROPICAL WAVES... A tropical wave with axis along 102W from 05N to 16N is moving westward at about 15 kt. Earlier observed deep convection near this wave has weakened to isolated showers and thunderstorms from 13N to 16N between 98W and 100W. This activity may flare up again to scattered type convective activity late tonight as instability in the vicinity of the wave attributed to a the tail- end of a mid to upper-level trough may provide may help in developing the convection. A tropical wave with axis along 120W from 04N to 15N is moving westward at about 15-20 kt. Scattered moderate convection is occurring within 120 nm east of the wave from 12N to 15N as the wave moves through a moist environment found to the south of high pressure, both at the surface as analyzed at 00Z, and aloft as indicated by models and as noted by dry air in water vapor imagery. The previous tropical wave that was along 139W has recently moved west of 140W. In its wake, satellite imagery shows isolated showers and thunderstorms from 05N to 13N west of 134W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from NW Colombia to across the Gulf of Panama west-southwest to a 1010 mb low pressure near 08N85W and from there to 11N96W to 11N103W to 11N112W, where latest scatterometer data indicated that it transitions to the ITCZ briefly ending at 11N118W. It resumes to the west of the tropical wave analyzed along 120W at 11N122W and continues to 08N139W. Scattered moderate to isolated strong convection is noted within 120 nm north of the ITCZ between 122W and 124W, and also within 60 nm south of the ITCZ between 124W and 125W. Scattered moderate convection is within 60 nm south of the trough between 81W and 84W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The pressure gradient between a high pressure ridge west of Baja California and a low pressure trough along the Baja California peninsula is maintaining moderate northwest to north winds across most of the adjacent offshore waters where seas remain in the 4-5 ft range. Winds and seas off Baja California will change little through early on Mon as the ridge remains over offshore waters. However, winds will pulse to fresh speeds near the coast during the evening hours through Sun night mainly in the region between Punta Eugenia and Cabo San Lazaro. Low pressure is expected to cover a rather expansive area over the southwestern United States and along California by late Mon afternoon in response to a sharpening mid/upper-level trough that will pass over those regions. This will result in a weakening of the ridge allowing for offshore wind speeds to briefly diminish through middle part of the upcoming week. Mainly moderate southeast to south winds were captured by an Ascat pass over the southern half of the Gulf of California. These winds will diminish slightly early on Sun. By late Sun night, gentle to moderate southeast to south winds will be over the entire Gulf and through Mon. These winds then become light and variable on Tue and through Wed evening. Winds will increase to fresh speeds over the far northern part of the Gulf Mon night before diminishing to moderate speeds early on Tue. Long-period southwest swell is reaching the Mexican offshore waters, however, with most of the energy spent already, the seas will remain in the 5-6 ft ft range through the middle of the upcoming week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to strong nocturnal offshore winds will continue pulsing across the Gulf of Papagayo region through the middle part of the upcoming week, with seas peaking around 7-8 ft downstream of the Gulf. Otherwise, fairly tranquil conditions will persist off Central America under a weak pressure pattern. Gentle to moderate south to southwest flow with scattered showers and thunderstorms will prevail south of the monsoon trough through Sun night and early into next next week. Long-period southwest swell propagating through the southern waters will build the waveheights to 8 ft between Ecuador and the Galapagos Islands through the remainder of this weekend. Wave model guidance suggests that another set of south to southwest swell will propagate through the southern waters west of 85W Tue night through Thu building waveheights there to a peak of 8 ft again before they begin to subside late on Thu. REMAINDER OF THE AREA... A high pressure ridge prevails across the northern waters. Moderate to fresh northeast winds are between the ridge and the ITCZ west of 120W. Seas in this region are generally 5-7 ft based on the latest altimeter data. Moderate to locally fresh trades are expected to persist mainly south of 20N through the remainder of this weekend and into early next week as a couple of tropical waves moves south of the ridge. Long period southwest swell will continue to propagate through high seas areas east of 120W through Sun night. Seas will remain 8 ft or greater south of the Equator through the middle of the upcoming week, as a reinforcing set of southwest swell is expected to reach the far southwestern waters by Mon night. Expect 8-10 ft seas south of the Equator and west of 100W by Tue. Elsewhere, northwest to north swell will impact the far northern waters west of about 125W beginning on Mon night and continuing through Wed night as strong high pressure builds southward to the north of the area and while low pressure lingers offshore California. Waveheights associated with the swell will likely build to 8-10 ft north of 28N. $$ Aguirre