000 AXPZ20 KNHC 090928 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Tue May 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURE... The monsoon trough has become convectively active across the area east of 110W during the past few days, with multiple weak low pressure centers developing along the trough. Very active convection surrounds a low center near 08.5N91W this morning, and has begun to exhibit curving bands with embedded clusters of scattered to numerous thunderstorms. Animated satellite imagery shows evidence a developing cyclonic circulation. Global models indicate that upper level conditions will remain very favorable for active convection across this area through the remainder of the week, and the low center is expected to gradually become better organized. We are quickly approaching the beginning of the Northeast Pacific hurricane season, and this low has been assessed high potential for development into a tropical cyclone within the next 48 hours as it moves slowly WNW to NW. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N78W to low pres near 08.5N91W 1008 mb to another low pres near 10N106W 1008 mb to 05N113W. The ITCZ continues from 05N113W to 03N140W. Scattered moderate to strong convection is noted from 04N to 12N between 87W and 101W. Scattered moderate convection is noted within 30 nm either side of the ITCZ axis between 117W and 127W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gentle to moderate NW winds prevail over most of the Gulf of California, and moderate to fresh NW winds prevail north of 26N west of the Baja peninsula. Moderate W to NW winds generally prevail across the remainder of the forecast area NW of Manzanillo, except for fresh NW winds along the coast of Cabo San Lucas. Seas are in the 8-12 ft range in NWly swell over the offshore waters off of Baja California Norte, 1-3 ft over the Gulf of California, except 3-4 ft over far N portions, and 4-7 ft in the remainder of the forecast waters. Winds and seas will gradually subside across forecast waters through midweek. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh winds prevail over the forecast waters north of 07N while gentle to moderate winds prevail south of 07N. Seas are in the 4-7 ft range. An elongated cyclonic gyre associated with an active early season monsoon trough prevails over the region. Upper atmospheric conditions are conducive for sustained deep convection the next several days across central America and adjacent offshore waters to southeastern Mexico, while abundant moisture converges about the trough axis. Global models are in good agreement with the development of an area of low pressure within this larger gyre, as mentioned above, but disagree on the precise location and strength of the primary low later in the forecast period. Active convection over a large area may produce periods of heavy rain across portions of the region from Panama to SW Guatemala. This area will be monitored for heavy rainfall potential along adjacent coastal zones. REMAINDER OF THE AREA... High pressure centered north of the area near 34N140W extends a ridge southeast to near the Revillagigedo Islands. The pressure gradient between this area of high pressure and lower pressure over the SW United States is supporting fresh northwest to north winds over northern waters east of 120W. Large northerly swell generated by strong winds off the coast of California supports seas to 12 ft in the waters east of 130W. The area of high pressure will weaken during the next 48 hours as a cold front approaches the NW part of the discussion area. The front will stall and dissipate from 30N131W to 27N140W by Thursday night. $$ Mundell