000 AXPZ20 KNHC 080234 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Thu Jun 8 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 0000 UTC surface analysis and satellite imagery through 0215 UTC. ...TROPICAL WAVES... A tropical wave axis extends along 98W from 11N to 16N, moving west at 10 to 15 kt. This wave is becoming more defined at the mid and upper levels with time. Convection was more prevalent in coverage a few hours ago, but recently has decreased and only scattered moderate convection remains to the east of the wave within 30 nm of 13N96.5W. Model potential vorticity diagnostics do not hold on this wave in the fields after Thursday morning as main left over energy begins to lag behind focusing to south of the Gulf of Tehuantepec in what appears will be a developing broad cyclonic gyre over the next few days. A tropical wave axis is along 110W from 09N to 15N, moving west at 10 kt. This wave is becoming rather ill-defined at the surface with time, and will most likely weaken during the next 48 hours. Last visible satellite imagery showed mostly overcast mid-level clouds from 09N to 15N between 106W and 114W. Isolated showers are possible underneath these clouds, while isolated weak thunderstorms are just to the east and south of these clouds. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The Monsoon Trough axis begins at a persistent surface low pressure over NW Colombia near 10N74W, and extends southwestward across the northern Gulf of Panama to 09N79W, then turns northwestward to across northern Costa Rica and Panama, then turns westward along 11N to 107W where it then dips southwest to 10N109W. Both latest satellite imagery and scatterometer data from Wednesday afternoon indicate that the ITCZ then continues from 10N109W to 07N117W to a 1008 mb low at 09N128W and to beyond the area at 09N140W. Scattered moderate to isolated strong convection is noted from 05N to 09N between 77W and 80W, and within 180 nm south of the axis between 122W and 124W. Scattered moderate convection is sen from 05N to 09N between 80W and 86W, within 120 nm north of the axis between 103W and 105W, and also between 126W and 129W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A 1020 mb high is center near 26N132W with related high pressure extending east-southeastward to just west of these offshore waters. The associated pressure gradient is maintaining light to locally moderate northwest winds west of the Baja California Peninsula to the north of 25N, and moderate to fresh west to northwest winds south of 25N. The exception is that locally strong west to northwest winds are expected during the overnight hours across the coastal waters near Cabo San Lucas tonight and on Thursday night. The pressure gradient will tighten on Thursday night with moderate northwest winds developing north of 25N. Another round of large northwest swell will produce seas of 7 to 9 ft along 32N by early on Sunday, and propagate southward to near 30N by Sunday night. Gulf of California: Gentle to moderate southerly flow is expected north of 30N through Saturday with guidance suggesting fresh to locally strong southwest winds from 30N to 31N on Saturday and Sun nights, with seas building to about 5 ft. Light and variable winds are expected to the south of 30N. Mexican offshore waters south of 23N, including the Gulf of Tehuantepec: Light to gentle west to northwest winds and 3 to 5 seas are forecast through Sun night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The monsoon trough extends east to west across the area between 08N and 11N, and is active with scattered showers and thunderstorms. Gentle to moderate westerly winds are expected north of 10N, and moderate to fresh southerly winds are forecast south of 10N through early Fri. Combined seas of 5 to 7 ft are expected to build to 6 to 8 ft in a southwest swell to the south of Panama and southern Costa Rica beginning early on Thursday and continuing into Friday. REMAINDER OF THE AREA... A 1020 mb surface high is analyzed at 26N132W with a ridge extending southeastward to near the Revillagigedo Islands. High pressure covers the area north of 15N and west of 114W. Gentle to locally moderate anticyclonic flow is occurring to the south of the ridge to along 10N, while moderate to fresh southwest flow is north of the ridge. The high will shift southward tonight allowing for a cold front, presently crossing the far northwest corner of the area. The front is forecast to reach a position from near 32N131W to 28N140W by early Thursday afternoon, then gradually become diffuse as it moves across the north-central and northwest portions of the area Friday through Saturday. The gradient behind the front will support mainly moderate north-northeast winds along with seas of 5 to 6 ft. $$ Aguirre