000 AXPZ20 KNHC 220721 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sun Dec 22 2024 Tropical Weather Discussion for the eastern Pacific Ocean from 03.4S to 30N, east of 120W including the Gulf of California, and from the Equator to 30N, between 120W and 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 0700 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: The pressure gradient between high pressure over eastern Mexico and low pressure within the eastern north Pacific monsoon trough will support gale-force gap winds in the Gulf of Tehuantepec through tonight. Seas during the warning event will peak at 12 to 15 ft. The high pressure will shift east by early Mon, with the pressure gradient loosening. This will diminish winds below gale force early Mon with fresh to strong northerly pulses thereafter into mid-week. Please see the latest NWS High Seas and Offshore Waters Forecasts issued by the National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and https://www.nhc.noaa.gov/marine/offshores_eastpac.php for more details. Significant NW swell: A complex and powerful low pressure north of the area will generate several rounds of large NW swell that will propagate into the area through next week. This morning, seas greater than 12 ft cover the waters NW of a line from 30N120W to 10N136W, with seas peaking near 17 ft along 30N between 127W and 135W. The rough to very rough seas will continue to spread SE, covering the waters from west of Baja California near Punta Eugenia to 08N132W early this evening when a reinforcing set of NW swell arrives with peak seas of 21 ft near 30N140W. Please see the latest NWS High Seas Forecast issued by the National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N84W to 06N91W to 06N104W. The ITCZ extends from 06N104W to 07N123W to beyond 06N140W. Widely scattered moderate convection is noted from 03N to 09N between 77W and 98W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please read the Special Features Section for information on a Gale Warning in the Gulf of Tehuantepec, and significant NW swells that will impact the waters offshore Baja California through next week. Aside from those conditions, high pressure prevails over the waters west of the Baja California peninsula. The pressure gradient between this area of high pressure and a trough over Mexico is supporting with gentle to moderate winds across much of the forecast waters, except moderate to locally fresh offshore Baja California. Seas are in the 5 to 7 ft over the open waters off Mexico, except building to 7 to 10 ft well offshore Baja California Norte, and 2 to 4 ft over the Gulf of California, except 2 ft or less over the northern Gulf. For the forecast, other than the aforementioned Gale Warning in the Tehuantepec region and significant NW swell, winds will pulse to moderate to fresh at times offshore Baja California, then fresh to strong from Cabo San Lazaro northward starting Wed night, with gentle to moderate winds across the remainder of the waters. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The pressure gradient between a surface ridge over the northwestern Caribbean Sea and the EPAC monsoon trough is supporting fresh to strong NE gap winds and seas of 5 to 7 ft in the Papagayo region. Light to gentle winds prevail elsewhere N of the monsoon trough, except well offshore Guatemala where moderate to fresh winds are downwind from a Gulf of Tehuantepec gap wind event, with similar winds near the Gulf of Fonseca. South of the monsoon trough, gentle to moderate southerly winds and 3 to 5 ft seas in moderate S to SW swell prevail, mixed with NW swell from the Gulf of Tehuantepec gap wind event. Active convection is present offshore Panama and Costa Rica as described in the Monsoon Trough/ITCZ section above. For the forecast, the pressure gradient between high pressure over the western Caribbean and the eastern north Pacific monsoon trough will support pulsing fresh to strong NE gap winds in the Papagayo region into early Wed, then moderate to fresh thereafter. Gales in the Tehuantepec region will support northerly swell and rough seas well offshore Guatemala through the remainder of the weekend. Elsewhere, winds will be moderate or weaker with moderate seas through mid-week, pulsing to moderate to fresh in the Gulf of Panama at times. Seas may build mid-week in NW swell. ...REMAINDER OF THE AREA... Please read the Special Features section about large NW swell over the waters north of the ITCZ/monsoon trough through the next several days. A frontal boundary is just north of the waters with fresh to strong SW winds creeping just northwest of 30N140W. High pressure at 1025 mb is ahead of the front over our area near 26.5N128W per a recent ASCAT scatterometer pass. Light to gentle anticyclonic winds are elsewhere north of 22N and east of the front to 123W. The pressure gradient between the area of high pressure and lower pressure in the vicinity of the ITCZ is supporting moderate to fresh winds north of the ITCZ to 22N and west of 118W per recent ASCAT scatterometer data, locally to strong. Across the remainder of the open waters, including south of the ITCZ, gentle to moderate trades prevail. Aside from the large swell discussed above, seas are mainly in the 5 to 8 ft range. For the forecast, other than the NW swells discussed in detail in the Special Features sections, little change in winds are forecast over the next several days, while a front manages to push SE of 30N140W by early Mon, decaying over the northern waters into mid-week. Meanwhile, seas of 8 ft or greater will cover most of the waters west of 110W by early next week, and then west of 95W by mid-week. $$ Lewitsky