000 AXPZ20 KNHC 132154 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Feb 13 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 2145 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A tight pressure gradient between high pressure ridge of 1025 mb over eastern Mexico and low pressure to the south of Mexico is allowing for a north gale to exist across the Gulf of Tehuantepec. A scatterometer pass covering half of the Gulf earlier today indicated peak winds of 35-40 kt. With the high pressure forecast to weaken and shift eastward through the next couple of days, the gradient will response by slackening. This will allow for the gale-force winds to diminish to a strong breeze early Thu and to gentle to moderate speeds Thu afternoon. Winds over the Gulf will become light and variable Thu evening. Peak seas are down to around 16 ft over the Tehuantepec region currently. Along with the winds forecast to diminish through the end of the week, the resultant seas will begin to subside beginning tonight. Seas will lower to 8 to 11 ft early Thu and to 8 ft in mixed northeast and northwest swell by late Thu night at which time Wave model guidance forecasts them to be confined from 04N to 10N between 97W and 108W. Please read the latest High Seas Forecast issued by the National Hurricane Center under AWIPS/WMO headers FZPN03/HSFEP2, or at the website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details on this gale warnings. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from a 1010 mb low over northwest Colombia to 06N77W and to 05N86W. The ITCZ extends from 05N86W to 03N110W to 05N124W and to 08N140W. Scattered moderate convection is noted within 60 nm north of the ITCZ between 90W and 94W, within 30 nm south of the ITCZ between 94W and 97W, and within 30 nm north of the ITCZ between 97W and 99W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features above for details on the ongoing gale force gap wind event in the Gulf of Tehuantepec. A weak high pressure of 1019 mb is centered to the southwest of the Baja California Peninsula at 24N115W. A weak pressure gradient over these waters is generally bringing light to gentle winds, in anticyclonic fashion, across the offshore waters of Baja California, with seas of 5 to 7 ft in northwest swell. A weakening cold front will move across the far northern waters west of Baja California Norte Thu night. The front will dissipate across central Baja and the Gulf of California on Fri. Moderate to fresh northwest to north winds will follow in behind the front, while gentle to moderate winds ahead of the front. Seas will build to near 16 ft to the west of Baja California Norte this weekend as northwest swell propagates into the area and northwest winds west of the Baja California increase to fresh to strong speeds. Elsewhere, light to gentle mainly northwest to north winds and seas in the 4 to 6 ft range will continue between the Gulf of Tehuantepec and Cabo Corrientes through Fri, then increase some on Sat mainly north of Manzanillo. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh winds over the Gulf of Papagayo will pulse to strong speeds tonight, then to mainly fresh speeds Thu afternoon through Sun. Elsewhere winds fresh breeze or weaker will prevail across the forecast waters through Mon. REMAINDER OF THE AREA... A vigorous cold front extends from a 996 mb low centered north of our area at 34N130W to 30N133W to beyond 22N140W. Scatterometer passes indicated that the S to SW winds ahead of the front and the NW to N wind behind the front were 25-30 kt south of 30N. The front will progress eastward, reaching Baja California late Thu with the winds gradually diminishing. A just-arriving altimeter pass reveals peak seas of 15 ft - primarily in NW swell - at our northwestern corner at 30N140W. 12 ft seas exist northwest of a line from 30N130W to 23N140W. With the wind forcing relaxing, the NW swell will progress southeastward, but gradually diminishing as well. A more vigorous NW swell event will reach our NW corner Fri night with a large area of 12 ft seas, peaking at 16 ft on Sat. This swell event will spread over much of our area bringing at least 12 ft seas as far south as 10N through Mon. Total precipitable water imagery shows ample deep-layer moisture streaming northeastward, currently reaching just west of Baja California. The moisture is being advected by southwesterly flow located ahead of a rather extensive upper-level trough axis extending from the NW United States southwestward to just N of Hawaii. The upper level trough supports the deep low pressure system. Areas of rain along with embedded scattered showers within these clouds, and are expected to last through the end of the week, and gradually shift into California. $$ Landsea