000 AXPZ20 KNHC 090916 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Wed May 09 2018 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 0915 UTC. ...SPECIAL FEATURE... A persistent broad and elongated area of low pressure is analyzed as a 1010 mb surface low at 11N 122.5W, or about 1100 miles southwest of the southern tip of the Baja California Peninsula. Scattered moderate isolated strong convection is currently observed within 240 nm over the north, and within 90 nm over the southwest quadrants of the low. Environmental conditions are very favorable for this convection to organize into bands today leading to tropical cyclone formation. The system forecast to continue northwestward into an area of increasing unfavorable shear on Thu. A blend of global guidance results in a solution of a surface low, or tropical cyclone, near 12.5N125W tonight accompanied by minimal gale force winds mainly over the north semicircle. The low, or tropical cyclone, is forecast near 14N126W on Thu night with the winds then diminishing to near gale force within 75 nm over north semicircle. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends southwest from the Pacific coast of Panama at 09N78W to 05N93W, then the trough turns northwest to 11.5N117.5W where the trough turns abruptly southwest and through a surface low previously described at 11N 122.5W to 07N130W where scatterometer winds indicate a transition to an ITCZ which continues west to beyond 07N140W. Isolated strong convection is observed within 240 nm either side of a line from 02N80W to 07N98W. Scattered moderate isolated strong convection is observed from 04N to 13N between 105W and 118W. Scattered moderate isolated strong convection is observed within 45 nm either side of lines from 05N77W to 09N79W, from 07N81.5W to 10N86W, within 45 nm of 15.5N98W, and within 90 nm of 13N100.5W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A northwest to southeast ridge will meander about 250 nm seaward of northern Mexico the remainder of the week. Fresh northwest flow, and 5 to 7 ft seas currently north of 29N west of the Baja Peninsula will gradually increase as the pressure gradient tightens with locally strong winds forecast this afternoon through early Fri. The associated northerly swell will propagate as far south as 26N on Thu before beginning to subside from the south. Gulf of California: Light, mostly southerly flow forecast through the middle of the week, except moderate nocturnal drainage flow expected near gap areas. Guidance continues to suggest fresh to strong southwesterly flow developing along 30.5N on Fri, and continuing into early Sun. Gulf of Tehuantepec: Fresh to locally strong northerly winds will end around sunrise this morning. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate nocturnal winds will end after sunrise this morning. Gulf of Panama: Light to gentle northerly nocturnal flow is forecast through this week. REMAINDER OF THE AREA... Refer to special features section for a warning associated with a tropical low pressure developing near 12N123W. A weak cold front extending southwest from 32N130W to 23N140W will dissipate today. Long period northwest swell in the form of 7 to 10 ft seas across the area north of 13N west of 130W will subside to less than 8 ft on Thu. Seas of 8 to 11 ft are forecast across the subtropics, generally north of 24N east of 124W late in the week. $$ Nelson