000 AXPZ20 KNHC 131605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 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 1200 UTC surface analysis and satellite imagery through 1545 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A tight pressure gradient over southeastern Mexico resulting from the pressure difference between high pressure of 1027 mb over eastern Mexico and low pressure to the south of Mexico is allowing for strong north to northeast gale force winds to exist across the Gulf of Tehuantepec. 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 minimal gale force late tonight, then to strong speeds early Thu and to gentle to moderate speeds Thu afternoon. Winds over the Gulf will become light and variable Thu evening. Seas associated with this gale event are peaking to 18 ft this morning. 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. Eastern North Pacific Gale Warning: A tight pressure gradient between a ridge of high pressure to the west of the Baja California peninsula and low pressure of 994 mb located on the border of the discussion area near 32N133W is interestingly bringing minimal gale force south to southwest winds over quite a large area that covers the waters north of 26N and between 125W and 131W along with seas in the range of 9 to 14 ft. A cold front extends from the low southwestward to beyond the area at 23N140W. An Ascat pass from overnight late night clearly revealed gale force north to northeast winds behind the front. In addition, an satellite data indicated seas peaking to very near 18 ft behind the front. As the low pulls farther to the northeast during the remainder of the morning and into the early afternoon hours, the culprit pressure gradient will weaken and allow for the winds to lower below gale force. The large northwest swell behind the front will propagate southeast to south through the end of the week. The highest of the seas, to reach 11 or 12 ft, produced by the swell are forecast by Wave model guidance to be confined to the north of 26N on Thu and then to the north of 28N late Thu night and Fri. 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 both of these 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. Rather weak high pressure of 1018 mb is centered to the southwest of the Baja California Peninsula at 24N117W. 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 will be ahead of the front are will be prevail W 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 during the overnight hours through Thu, then to mostly fresh speeds Fri night. Gentle to moderate northerly winds will continue over the Gulf of Panama through Sat, becoming gentle Sat night. Light to gentle winds will prevail elsewhere across the forecast waters. REMAINDER OF THE AREA... Please refer to the Special Features above for details on the present ongoing gale force wind event over portions of the northwest and north-central discussion waters. Elsewhere, long-period northwest swell continues across the forecast waters, mixing with long-period cross equatorial southwest well. Seas of 8 ft or greater prevail over much of the waters W of 120W, with another area of 8 to 9 ft seas covering much of the waters from 00N to 10N W of 115W. Areal coverage of seas greater than 8 ft will continue to decrease today. The 8 ft seas will lower to less than 8 ft early on Fri. Satellite imagery shows ample deep layer moisture in the form of mostly mid and upper-level clouds, streaming northeastward to the west of a line from Baja California Norte to 10N132W, in strong southwest mid and upper-level flow. This flow is 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 mentioned above under the Special Features section. 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. $$ Aguirre