000 AXPZ20 KNHC 170812 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Tue Apr 17 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 0900 UTC. ...SPECIAL FEATURES... A gale warning remains in effect for the Gulf of Tehuantepec. Minimal gale force winds of 30-35 kt are still expected early this morning across the Tehuantepec region, then winds will diminish below gale force by late this morning. Seas of 10-14 ft will gradually subside to 8-11 ft by early this afternoon. An extensive swath of large N to NE swell generated by this gap wind event will continue to propagate well to the SW of the Tehuantepec area, covering roughly the waters from 03N to 14N between 93W and 110W by early this afternoon. Please refer to the East Pacific High Seas Forecast under AWIPS/WMO headers HSFEP2/FZPN03 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 07N77W to 08N84W to 05N90W. The ITCZ stretches from 05N90W to 08N108W to 07N120W to beyond 08N140W. Scattered moderate to isolated strong convection is from 05N to 07N E of 79W to the coast of Colombia. Scattered moderate convection is noted from 05N to 10N between 120W and 125W. Similar convection is also seen from 12N to 14N between 110W and 112W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A cold front is currently moving across the northern Gulf of California and the northern Baja California peninsula, and extends from 32N114W to 27N120W to 25N124W. Fresh to strong winds are noted ahead and behind the front over the Gulf of California, and behind the front over the offshore waters W of Baja California, particularly N of 28N E of 118W. These winds are forecast to diminish to 20 kt or less by this afternoon. Moderate to fresh NW-N winds are forecast across the offshore waters W of Baja California the remainder of the forecast period. However, winds will increase again to 20-25 kt N of Punta Eugenia Thu night and Fri due to a tight pressure gradient between a ridge over the northern forecast waters and lower pressures over the SW CONUS and Mexico. Seas in the 8-10 ft range W of Baja California will begin to gradually subside on Wed, with seas below 8 ft by late Wed. Gentle to moderate NW winds are expected to prevail across the Gulf of California Wed through Fri. Gulf of Tehuantepec: Please, see Special Features section above for details. Currently, marine guidance suggests another gap wind event, with minimal gale force winds, across the Gulf of Tehuantepec by late Thu as a strong high pressure builds southward across the central plains of U.S. and the Gulf of Mexico. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Pulsing fresh to strong NE-E winds are expected across and downstream of the Gulf of Papagayo during the late afternoon through early morning hours each day through Fri. Gulf of Fonseca: A recent scatterometer pass indicates northerly winds of 20-25 kt across the Gulf of Fonseca and downwind to near 12N. Tegucigalpa was reporting N winds of 20 kt. These winds are occuring behind a dissipating frontal boundary over the Caribbean Sea, and are forecast to diminish to 20 kt or less by this afternoon. Gulf of Panama: A couple of ship observations also indicate fresh to strong northerly winds across the Gulf of Panama. Fresh northerly winds are expected across the Gulf of Panama through Wed night. Elsewhere, light to gentle winds are expected through the forecast period, with a weak surface through extending along 08- 09N yielding light S to SW winds to its south. Seas in the 3 to 5 ft range will continue over most of the area. Cross equatorial SW swell will mix with residual swell from Papgayo tonight through Fri and raise seas to 5-7 ft S of 10N. REMAINDER OF THE AREA... As previously mentioned, a cold front is moving SE across the northern Baja California peninsula and extends from 32N114W to 27N120W to 25N124W. The front will dissipate across the NE waters today. A 1031 mb high pressure center located near 34N139W follows the front, and extends a ridge across the northern forecast waters, including the entrance of the Gulf of Califonia and Las Tres Marias islands. This system will weaken some over the next 24-48 hours, and then will be reinforcing by a stronger high pressure by late Thu. Large NW swell continues to propagate southeastward through the forecast waters, with max seas of around 11 ft based on altimeter data. This swell event is mixing with waves generating in the Tehuantepec area. As a result, seas of 8 ft or greater will cover most of the area W of 108W today. Cross equatorial SW swell is forecast to reach the southern forecast waters this morning. Marine guidance suggests that seas of 8-9 ft will dominate the waters S of 04N between 97W and 120W by early this evening. Seas are forecast to susbise to 8 ft or less across most of the area W of 120W by late Wed. At that time, seas of 8-10 ft are expected mainly S of 10N between 92W and 120W. $$ GR