000 AXPZ20 KNHC 202144 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Tue Dec 20 2022 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 1800 UTC surface analysis and satellite imagery through 2030 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: High pressure will build southward along the eastern slopes of the Sierra Madre Mountains today as a central Gulf of Mexico low pressure system shifts eastward. As this happens, the gradient in southeastern Mexico will tighten as cold dense air surges southward toward the Gulf of Tehuantepec gap region. The resultant surge of northerly winds out over Tehuantepec will reach gale-force to 35 kt late this afternoon or early this evening, and is expected to last through Wed afternoon. Seas are forecast to build to 9-13 ft. Northerly winds will then gradually diminish Wed night. Seas will subside to below 8 ft by sunrise Thu. Please read the latest High Seas Forecast issued by the the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. Gale Warning in NW Part of area: A gale force low pressure center well west of the area contains an associated cold front along 148W. The low and associated front will shift northeastward through Thu, remaining NW of the forecast area. However, southerly winds to the east of the cold front are forecast to reach strong to near gale force, with a small area of gale force winds on Wed north of 27N and west of 137W. Seas of 15-18 ft are expected within the area of gale force winds in W swell. Winds will diminish in the area Wed night, and seas will subside to below 12 ft by Thu afternoon. Please read the latest High Seas Forecast issued by the 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 axis extends from 09N84W to 08N90W to 06N100W. The ITCZ continues from 06N100W to 08N125W to 09N140W. Scattered moderate convection is noted from 08N to 11N between 136W and 140W. Isolated moderate convection is seen from 04N to 07N between 77W and 80W, and from 07N to 10N between 125W and 130W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for information about an upcoming gale event in the Gulf of Tehuantepec from this evening through Wed. A recent ASCAT pass from 20/1623 UTC showed N winds up to 25 kt in the Gulf of Tehuantepec, where seas are currently 6 to 7 ft. Relatively weak high pressure ridging is present over the western portion of the Baja California offshore waters. Moderate N to NE winds are across the Baja California offshore waters. Fresh to strong NW to NNW winds are occurring in the Gulf of California south of 30N with 4-6 ft seas, while moderate to fresh winds prevail in the northern Gulf with 2-4 ft seas. Gentle or weaker winds and 3-5 ft seas prevail elsewhere. For the forecast, strong northerly winds in the Gulf of Tehuantepec will increase to gale force early this evening. Gales will last through Wed before diminishing Wed night into early Thu. Fresh to strong NW winds will continue in the Gulf of California through Wed before diminishing Wed night. Looking ahead, the next Tehuantepec gap wind event is expected Fri through the weekend. Gales could last from Fri afternoon through Sun night, with storm force winds possible on Fri night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh northeast to east winds are in the Gulf of Papagayo region, while moderate to fresh east winds extend offshore of Papagayo southwestward to 90W. Seas are 5-6 ft over these waters. Light to gentle winds prevail elsewhere north of the monsoon trough off of Guatemala and El Salvador, with seas of 4 ft. Gentle S-SW winds and seas of 3-5 ft are present south of the monsoon trough. For the forecast, fresh to strong northeast to east winds will continue to pulse in the Papagayo region through the rest of the forecast period. The strongest winds are mainly expected at night and into the mornings, when seas are expected to build to 6 to 7 ft. Gentle to occasionally moderate winds will continue elsewhere through the remainder of the week and the upcoming weekend. Seas will build to 6 to 8 ft on Wed well offshore western Guatemala due to swell from a Gulf of Tehuantepec gap wind event. A larger swell can be expected there Fri night through the weekend due to a stronger Gulf of Tehuantepec gap wind event. REMAINDER OF THE AREA... Please read the special features section above for details on a gale warning in the NW corner of the forecast area, from 27N to 30N between 137W and 140W. A cold front is west of the area along 148W. A recent ASCAT pass from 20/1942 UTC depicts strong SSE winds north of 26N and west of 138.5W, although strong winds likely extend as far south as 22N there. Seas of 7 to 9 ft are likely occurring within this strong wind area. Elsewhere, high pressure ridging prevails over the area between 115W and 135W from 20N to 30N. Light to moderate anticyclonic winds and 3-6 ft seas prevail across this area. Fresh trade winds are present from the ITCZ from 20N and west of 118W with 5-8 ft seas. For the forecast, moderate to fresh trade winds S of 20N and W of 120W are expected to change little through Thu. The low pressure and cold front described above in the special features section will continue to bring strong S winds through Wed night to waters from 22N to 30N between 134W and 140W, with seas reaching over 11 ft in this area. NW swell will migrate SE to near 130W by Wed night. Seas of 8-11 ft will extend elsewhere north of 05N and west of 130W through the end of the week. $$ Hagen