000 AXPZ20 KNHC 080908 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 908 UTC Sun Mar 8 2020 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... Gulf of Tehuantepec Gale Warning: Strong gale force winds continue across the Gulf of Tehuantepec as high pressure over eastern Mexico maintains a tight pressure gradient across the Isthmus of Tehuantepec. The strong gales have diminished slightly from the storm force winds active earlier. The significant wave heights have subsided accordingly as well. The 12 ft or greater wave heights have propagated to the south and southwest of the Gulf region primarily due to a northeast swell to as far as 09N- 10N based on altimeter data from today. The gale force winds will continue to pulse through early next week. Please read the latest High Seas Forecast issued by the National Hurricane Center under AWIPS/WMO headers FZPN03 KNHC/HSFEP2 or at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for further details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 05N83W to 01N94W. The intertropical convergence zone continues from 01N94W to 07N125W to 08N140W. A second ITCZ segment extends from 03S90W to 01N105W. No significant convection is noted. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for details on a gale warning in the Tehuantepec region. 1020 mb high pressure centered just west of Guadalupe Island is maintaining generally light winds across Mexican waters north of 20N. There may be fresh to strong SW winds over the far northern portions of the Gulf of California currently. Land-based observations do not support this so far, but there is a weak boundary moving across the area, and it is plausible the winds have strengthened accordingly. These winds will be short-lived however. The boundary will shift east through early morning, allowing winds to diminish. Light to moderate winds persist farther south off Mexico, outside of the Tehuantepec area. Seas are 4 to 6 ft in open waters primarily in NW swell north of 20N, with a larger component of SW swell south of 20N. Upper jet dynamics may be supporting some shower activity across central Gulf of California and northern Baja California Sur. The high pressure will dissipate this morning ahead of a cold front approaching the region from the west. The front will slow and weaken today, before dissipating later this evening over Baja California. A large extra-tropical low pressure system and attendant occluded cold and warm fronts is presently located well to the northwest of the discussion area. This system will track southeastward reaching near 31N130W on Mon at which time it will track in a more eastward motion pushing the frontal system toward the Baja offshore waters. Fresh to strong SE to S winds will develop offshore of Baja California Norte ahead of the cold front, which will likely cross the region through mid-week while weakening. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: A north to south tight pressure gradient remains in place across Central America and the northwest Caribbean. Along with overnight drainage flow, this is producing strong northeast winds across the Papagayo region this morning, as shown in a recent scatterometer satellite pass. These winds will continue across this region through the middle of next week, with winds pulsing to near gale force each night. Wave heights will peak to around 11 ft downstream of the Gulf each morning for the next several days. Gulf of Panama: High pressure north of the area will maintain fresh to strong north to northeast winds over and downstream of the Gulf of Panama for the next several days. Wave heights with these winds are expected to reach to about 9 or 10 ft well downstream of the Gulf. Elsewhere, large northwest swell associated with the ongoing Gulf of Tehuantepec gap wind event is producing 10-16 ft seas offshore of Guatemala, with seas greater than 8 ft encompassing the waters off El Salvador in mixed NW and E swell. Seas well offshore will remain greater than 8 ft for the next several days in combined Tehuantepec and Papagayo swell, along with long period southerly swell that will reach the waters by Mon. REMAINDER OF THE AREA... A cold front is moving across the waters north of 25N currently, followed by a strong front approaching the area from the northwest. The second front is associated with a deep layer low just north of the area moving eastward. Strong westerly winds likely accompany the second front over discussion waters north of 25N and west of 135W. Ship observations also confirm NW swell in excess of 8 ft is accompanying both front over waters north of 20N and west of 130W. The cold fronts are breaking up the normal subtropical ridge over the region, resulting in only moderate trade wind flow across the deep tropics. The lack of any major convergence in the trade wind belt is limiting significant convection in the tropical waters. Farther east, mixed swell from the Tehuantepec and Papagayo gap wind events is propagating well downstream of the source regions, with seas 8 ft or greater roughly north of 05N between 90W and 105W.Seas 8 ft or greater will encompass the waters south of 12N between 90W and 110W by late today as gap wind swell mixes with long period southerly swell propagating across the southern waters. For the forecast, the first front will shift east and weaken today. The stronger reinforcing front cold front will continue to move eastward across the waters north of 20N through tonight in associated with low pressure that will move to near 31N133W by Mon morning. Strong to near gale force winds behind the front will build seas to 12-20 ft north of 25N and west of 130W by Mon. The low pressure is expected to track eastward through early next week and pull the cold front across the waters roughly north of 20N. Large long- period northwest swell associated with this system will propagate southward through the middle of next week. $$ Christensen