000 AXPZ20 KNHC 251019 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Fri Jan 25 2019 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: The pressure gradient over SE Mexico has weakened slightly during the past several hours as high pressure ridging S over the Gulf from Louisiana and Texas slowly shifts E. However, high pres moving SE from the Central Plains will reinforce the ridge over the Gulf today and allow NE to N winds over the Gulf of Tehuantepec to increase to gale force around midday Friday through Sat morning. Thereafter, the ridge will shift toward the SE United States. Seas ranging 8-11 ft tonight will gradually build to around 12 ft during the gale force winds and then taper off Sat, then will subside more rapidly as the current gap wind event shuts down. The area of 8 ft seas generated by this event will spread well to the S and SW of the Gulf as far as 10N100W tonight and Fri, then subside. Another strong cold front will be entering the Gulf of Mexico on Sunday. Gales will be possible over the basin again by Sun night. 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. Developing Gale Warning: Deep layered upper troughing persisting across the western waters of the discussion area for the past several days has become N to S aligned along about 140W, from 35N southward into the tropics along 08N. This pattern combined with surface high pressure to the north is producing an area abundant low level moisture from the ITCZ northward to near 20N and between 110W and the trough along 140W. A 1007 mb surface low has developed near 11.5N133W and is embedded within the large area of convection described below in this very moist region. The low is forecast to lift northward today through Sun and will pull moisture and convection with it to beyond 20N through Sat. As the low moves northward, the pressure gradient will also tighten between the high to the north and the low, and gales are expected within about 270 nm across the NE semicircle of the low beginning Friday evening. Seas will build to 10-15 ft during this time. Please see 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 1010 mb low pressure centered over NW Colombia near 08N83W TO 02.5N94W TO 03.5N97W. The ITCZ continues from to 03.5N97W TO 04N98W TO 06.5N114W TO 07.5N126W. Scattered moderate isolated strong convection is occurring within 120 nm s of the trough between 85W and 90W, and from 07.5N to 12.5N between 110W and 126W. Scattered moderate isolated strong convection is occurring from 10N to 17.5N between 126W and 137W in association with the low pressure center near 11.5N133W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of California: Fresh to strong NW winds are occurring throughout most of the basin tonight. High pressure over the Great Basin will remain strong through Sat night and combine with lower pressure along the western slopes of the Sierra Madre Occidentales to maintain the pressure gradient over the Gulf of California. Seas associated with these winds will peak around 8 ft. Elsewhere, high pressure centered offshore of northern California is supporting a broad ridge extending south to 20N, which is producing moderate to fresh northerly winds west of the Baja California peninsula. Winds will diminish across this area Fri night and Sat morning as the high weakens and shifts north. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to strong NE winds will continue pulsing to at or just below 30 kt each night across the Gulf of Papagayo through Sun. Seas in this area will peak around 9 ft Fri morning. Gulf of Panama: Fresh N to NE winds will pulse over the Gulf will occur mainly at night and into the early afternoon through Sat. Winds could become locally strong Fri night. REMAINDER OF THE AREA... Broad 1032 mb high pressure centered near 41N133W ridges across the forecast waters north of 10N. A surface trough extends from the deep tropics near 07N137W to the low pressure described above near 11.5N133W to 14N131W. The pressure gradient between the ridge and the surface trough is generating fresh to strong trades between 10N and 20N W of 120W. Seas in this region are running between 8 and 12 ft. Model guidance suggests the area of fresh to strong winds will shift northward through the weekend with the low described above, and gradual diminish in areal coverage. The resultant fetch of winds is expected to generate seas as high as 15 ft near the low, while an extensive area of seas 8 to 11 ft in mixed NE and NW swell will cover the waters elsewhere generally N of 09N and W of 120W. This area of 8 ft seas will slowly retreat W to near 130W by Sun evening. $$ Stripling