000 AXPZ20 KNHC 252205 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2031 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 1800 UTC surface analysis and satellite imagery through 2045 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: The pressure gradient over SE Mexico will begin to weaken as high pressure ridging extending S from the western Gulf of Mexico over SE Mexico shifts eastward. However, reinforcing high pressure moving SE from the Central Plains has boosted the pressure gradient over SE Mexico and caused the N to NE winds over the Gulf of Tehuantepec to increase to gale force. The gales will continue until around sunrise on Sat. Thereafter, the ridge will shift eastward toward the SE United States. Seas currently ranging between 8 and 12 ft will begin to subside Sat, then will subside to below 8 ft 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 12N98W tonight, 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. Gale Warning for the Far Western Waters: A strong mid to upper- level low is centered near 16N140W. A trough extends SE from this low to near 10N134W. The upper-level low and trough are supporting 1008 mb surface lows centered near 15N136.5W and 16.5N140W. Extensive tropical moisture feeding northward on the E side of this system is fueling scattered moderate and isolated strong convection within 90 nm either side of a line from 10N128W to 15N129W. Scattered moderate convection is occurring elsewhere within 300 nm either side of a line from 10N127W to 22N134W. Scattered moderate and isolated strong convection is evident within 120 nm in the NE semicircle of the low centered near 16.5N140W. The easternmost low is forecast to lift N through Sun and will pull moisture and convection with it to beyond 20N. As the low moves N, the pressure gradient will also tighten between the high to the north and the low, and gale force winds are expected within about 180 nm across the N and NE quadrants of the low beginning Friday morning. Seas will build to 10-15 ft during this time. This system will begin to weaken at all levels by Sat evening and allow winds and seas to subside. 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... Surface trough from 09N83W to 05N90W. The ITCZ continues from 05N90W to 04N92W to 05N106W to 07N113W to 07N120W to 09N124W. Scattered moderate and isolated strong convection is present within 90 nm either side of a line from 07N114W to 12N121W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of California: Fresh to strong northwest winds have subsided over all of the Gulf except between 27N and 29N. High pressure over the Great Basin will remain strong through early Sun and combine with lower pressure along the western slopes of the Sierra Madre Occidental to maintain the current tight pressure gradient and resultant strong northwest winds 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 northward. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to strong northeast 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 north to northeast winds will pulse over the Gulf will occur mainly at night and into the early afternoon through Sat. Winds may become locally strong tonight. REMAINDER OF THE AREA... Broad 1034 mb high pressure centered well north of the area near 45N127W ridges across the forecast waters north of 10N. The pressure gradient between the ridge, ITCZ and surface low near 15N is generating fresh to strong trades between 10N and 20N W of 120W. Seas in this region are running between 8 to 12 ft. Model guidance suggests the area of fresh to strong winds will shift northward during the weekend with the low described above, and while gradually diminishing 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 northeast and northwest swell will cover the waters elsewhere generally N of 09N and W of 120W. This area of 8 ft seas will slowly retreat westward to near 130W by Sun evening. $$ CAM