000 AXPZ20 KNHC 182154 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sun Mar 18 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...SPECIAL FEATURES... Gale Warning: An initial cold front over the far northwest portion of the discussion area is preceded by strong southerly flow with seas of 7 to 9 ft. A deepening surface low pres currently well northwest of the area will drop southeastward to near 32N140W on Mon night behind this initial cold front, and drag a second cold front into the discussion area accompanied by a strong to near gale southwest-west-northwest wind shift. The pressure gradient will tighten around the southwest semicircle of the low increasing the westerly winds to 25 to 35 kt minimal gale force across the discussion waters from 29N to 30N west of 139W at 0900 UTC on Tue, with the associated seas of 12 to 18 ft forecast from 26N to 32N between 136W and 140W. The low pres will lift north of the area on Tue night with associated winds diminishing to 20 kt or less south of 32N on Wed evening. The associated northwest swell, in the form of 7 to 10 ft seas, will propagate southeast across the discussion waters covering the area west of a line from the Central Baja peninsula to 06N140W on Sat. Please refer to the Pacific high seas forecast for more details on this upcoming event under AWIPS/WMO headers MIAHSFEP2/FZPN03 ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough is analyzed from 08N82W to 05N101W where scatterometer winds indicate an ITCZ develops, and continues W to beyond 05N140W. Scattered moderate isolated strong convection is noted within 150 nm of 05.5N85W and within 30 nm of lines from 10.5N116.5W to 09.6N123W and from 04N121.5W to 05.5N130W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A north-northwest to south-southeast ridge extending from 30N121W to 17N110W to 13N94W will shift slightly southwest on Mon and Tue. Fresh to locally strong northerly winds will set up south of 25N and east of the ridge briefly on Mon and Mon night with the pressure gradient then relaxing some on Tue. Light to gentle northerly winds and 2 to 4 ft seas are then expected west of the Baja Peninsula through Thu night, with large northwest swells arriving at 30N120W on Fri. Gulf of California: Moderate to fresh northwest flow is forecast across the entire gulf waters tonight through Mon, with narrow swaths of strong northwest winds expected across the far southern gulf waters late Mon. Seas may build to 6 ft in the longer fetch waters. Fresh to locally strong northwest to north flow expected across the open Pacific waters from 18N to 23N east of 110W through late Mon night with seas building to 8 ft. Gulf of Tehuantepec: Strong north flow will surge through the gulf waters on Tue evening, increasing to minimal gale force late Wed. Gale conditions are then expected to continue through Thu morning, with seas building to 13 ft downstream near 14.5N95.5W on Wed night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to locally strong NE nocturnal winds expected tonight and again briefly on Tue night with seas building to 7 ft downstream. A stronger drainage event is forecast to begin on Wed night, and persist into the upcoming weekend. Gulf of Panama: Fresh northerly winds are expected tonight. Fresh to strong north nocturnal winds are expected to resume on Wed night. Elsewhere, gentle to moderate offshore flow will prevail N of 07N while light to gentle SW winds are forecast S of 07N. REMAINDER OF THE AREA... Refer to the Special Features Section above. $$ Nelson