000 AXPZ20 KNHC 072203 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Jun 7 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...TROPICAL WAVES... A tropical wave axis extends from 1009 mb low pressure embedded along the monsoon trough near 12N96W north to 16N96W, moving west at 10 to 15 kt. The southern portion of the wave is no longer defined at the surface as was depicted in earlier analyses as broad monsoonal southwesterly flow is evident over the eastern portion of the area per latest Ascat data. The remainder of this wave is becoming more defined at mid and upper levels with time. Scattered moderate to strong convection is noted within 60 nm of the low in the northeast and southwest quadrants. The low is forecast to dissipate within the next 12 to 18 hours. A tropical wave axis extends from 08N107W to a 1009 mb low pressure embedded along the monsoon trough near 12N107W and north to 16N107W, moving west at about 10 kt. Both the low and wave are appearing rather ill-defined at the surface with time as indicated by an earlier Ascat pass from this afternoon and model guidance. Latest satellite imagery shows mostly overcast mid level clouds from 10N to 14N between 107W and 111W. Isolated showers and rather weak thunderstorms are within this area of clouds. The low and wave are likely to become weaker at the surface through tonight and into Thursday. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The Monsoon Trough axis begins at a persistent surface low pressure over NW Colombia near 09N74W, and extends southwestward across the Gulf of Panama to 08N80W, then turns northwestward over and along to Pacific coast of Panama and Costa Rica to 10N86W, then turns westward through surface lows at 12N96W and 12N107W. Both latest satellite imagery and recent scatterometer data depict it dropping southwestward to 07N112W, where scatterometer winds indicate that the ITCZ forms, and continues to 07N120W and to 09N129W where it briefly ends before a trough that extends from 12N127W to 06N130W. The ITCZ axis then continues at 09N131W and continues to beyond the area at 09N140W. Scattered moderate to strong convection is noted within 60 nm either side of the axis between 97W and 99.5W. Scattered moderate to isolated strong convection is within 180 nm south and 120 nm north of the axis between 77W and 83W, and also within 120 nm north of the axis between 88W and 91W. This includes the coastal waters of El Salvador. Scattered moderate convection is within 60 nm south of the axis between 120W and 124W, from 05N to 10N between 124W and 128W, and from 10N to 11.5N between 126W and 129W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A 1020 mb high is center near 26N129W 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 to move into the area, and reach from near 32N131W to 28N140W on Thu. The front will become diffuse from near 32N120W to 26N140W on Fri night. $$ Aguirre