000 AXPZ20 KNHC 090242 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Fri Jun 9 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 LOWS AND WAVES... A tropical wave axis is along 106W from 05N to 15N, moving west about 13 kt. This wave has increased its forward speed slightly as it tracks through the southern periphery of mid/upper anticyclone located at 17N109W. The wave is moving into an area of less total precipitable water compared to that noted to its east. Only a small area of scattered moderate convection is noted within 120 nm west of the axis from 09N to 11N. Isolated weak showers and thunderstorms are east of the wave within 30 nm of 09N106W. In the wake of this wave over the eastern portion of the area, accumulated energy from previous waves in combination with increasing monsoonal background flow is forecast to gradually lead to a broad cyclonic gyre south of the southern coast of Mexico during the upcoming weekend, with increasing shower and thunderstorm activity expected there. A weak 1012 mb surface low is analyzed near 10N127W with a trough extending north-northeastward to near 14N127W. Satellite water vapor shows sharp upper trough axis just to the northwest of the low. Strong southwest winds associated with this trough are transporting mid to upper moisture north-northeastward to just west of the southern Baja California peninsula. This moisture is observed as broken high clouds within 90 nm either side of a line from 25N122W to 19N125W to 15N128W to 12N129W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A weak Monsoon Trough axis extends from a 1010 mb low located over NW Colombia to NW Costa Rica and Panama to offshore northern Costa Rica at 11N85W west to 11N95W and to 11N103W. A more defined monsoon trough is then analyzed from 10N106W to 07N115W, where scatterometer winds indicate that the ITCZ forms and extends northwestward through an embedded 1012 mb surface low at 09N128W, then continues westward to beyond 08N140W. Scattered moderate convection is observed south of the axis within 30 nm of a line from 08N90W to 08N95W, and also within 30 nm of the axis between 109W and 111W ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A northwest to southeast orientated ridge extends across the waters just west of the offshore zones, with the associated pressure gradient maintaining light to locally moderate northwest winds west of the Baja California peninsula north of 25N, and moderate to fresh west to northwest winds south of 25N. An Ascat pass from 1724Z Thursday afternoon highlighted a small area of strong west to northwest winds along and within about 60 nm of the coast of Cabo San Lucas. The pressure gradient will tighten on Friday with moderate to locally fresh northwest winds developing to the north of 25N. Another round of large nw swell in the form of 7 to 10 ft seas will arrive along 32N on Sunday, then propagate southward to along 30N by late on Sunday night. Wave model guidance suggests that this swell will reach southward to near 27N on Monday evening before it begins to decay. Gulf of California: Gentle to moderate southerly flow is expected north of 30N through Sat, then fresh to locally strong southwest winds are forecast from 30N to 31N beginning on Saturday, with seas building to about 5 ft. Light and variable winds are expected s of 30N through Mon night. Gulf of Tehuantepec: Moderate northerly drainage will briefly increase to fresh winds late tonight into Friday, then become light to gentle variable winds Friday afternoon. Mexican offshore waters elsewhere s of 23N: light to gentle west to northwest winds are expected, except for southeast to south winds near the coast and 3 to 5 seas are forecast through Mon night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate westerly winds and 4 to 6 ft seas are expected north of 08N, and moderate to fresh southerly winds with 5 to 7 ft seas forecast south of 08N through early Friday. Light to moderate southerly flow and 3 to 6 ft seas are then forecast through Monday night. REMAINDER OF THE AREA... A 1020 mb surface high is analyzed at 26N129W with a ridge extending southeastward to near 11N110W. Gentle to locally moderate anticyclonic flow is observed south of the ridge to along 10N. Moderate to fresh southwest flow is present to the north of the surface high, and also to the east of a weak cold front analyzed from near 32N129W to 27N140W. Gentle to moderate northerly flow is occurring to the northwest of the front. The front will lose its upper level support as broad upper troughing north of the area slides eastward. As a result, the front is forecast to become stationary from near 32N120W to 25N140W on Fri night and gradually wash out through Saturday night as a stronger area of high pressure builds southeastward over the northwest and central portions of the discussion area. $$ Aguirre