NHC Tropical Weather Discussion (East Pacific) National Hurricane Center - Tropical Weather Discussion (East Pacific)

  • NHC East Pacific Tropical Weather Discussion

    000 AXPZ20 KNHC 140927 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 927 UTC Fri Dec 14 2018 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: Gale force winds follow a cold front moving across the Gulf of Mexico this morning. The front will move quickly southeastward through the Bay of Campeche to initiate strong gap winds into the Gulf of Tehuantepec by early afternoon, followed by gale to strong gale force winds by late afternoon. Computer model guidance suggests that these gales will continue through the weekend and will last until Mon afternoon. Peak winds are forecast to be around 40 kt on Sat as corresponding seas quickly building to near 18 ft. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 07N77W to 06N105W. The intertropical convergence zone extends from 06N105W to 09N133W. Scattered moderate convection is active from 05N to 08N east of 80W, and from 04N to 07N between 92W and 94W. Scattered moderate convection is also ongoing from 18N to 21N between 127W and 130W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 1022 mb high pressure centered near 28N121W is maintaining generally light to gentle breezes across the Pacific waters off Baja California. A scatterometer satellite pass from 0445 UTC showed fresh to strong NW flow along the Gulf of California, between troughing just inland of the eastern shore of the Gulf of California and a wedge of high pressure reaching from the Great Basin to north central Mexico. Meanwhile a shot of long period NW swell is entering the area from the west, currently just reaching Guadalupe Island and the northern coast of Baja California Norte. NW swell up to 9 ft will dominate the offshore waters off the entire Baja California coast through the Revillagigedo Islands by tonight, followed by reinforcing NW swell through Sun. Looking ahead, a cold front will reach the northern coast of Baja California by Mon night, accompanied by more substantive reinforcing NW swell, bringing seas of 12 to 18 ft to the entire offshore area of Baja California and into the Revillagigedo Islands by late Tue. Swell of this size and period will present hazardous seas for mariners, as well as cause very powerful and dangerous surf along the Pacific reefs and beaches. A mid to upper level disturbance is approaching the area from the west, and may bring a few showers to the central and southern portions of the Baja California peninsula and Gulf of California tonight into Sun. An associated weak cold front will move into OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo...Fresh gap winds will pulse to around 20 kt tonight before returning to fresh to strong during the overnight and early morning hours Sat night. These conditions will then persist through Mon night as high pressure builds north of the region. Seas are expected to max out near 10 ft Sun morning. Gulf of Panama...Fresh northerly winds across and downstream of the Gulf will slowly diminish through Sat, then become fresh from the north Sat night through Sun. Elsewhere, gentle to moderate winds will persist on either side of the monsoon trough through the remainder of the week, with seas remaining in the 4-6 ft range. REMAINDER OF THE AREA... Earlier altimeter passes indicated seas of 7 to 9 ft still evident near Clipperton Island, consisting of NE and E swell generated from by recent Central American gap winds. This continues to subside and shrink in areal extent. This area should subside below 8 ft through the early morning. Farther west, a persistent surface trough extends from 07N137W to 20N128W. A scatterometer pass from 0630 UTC showed fresh to strong winds on the northern end of the trough, facing 1022 mb high pressure centered near 28N121W. This sampled an area of fresh to strong trade winds estimated to be active from 15N to 20N between 125W and 140W. Recent satellite-derived wave height data indicate seas as high as 12 ft. The high will weaken through the morning ahead of an approaching cold front, allowing the trade winds to diminish to around 20 kt through late today. The cold front currently passing 30N140W is accompanied by a new round of NW swell with seas of 12 to 15 ft. The front will slow then dissipate trough Sat, with the swell subsiding as well. Elsewhere NW swell in excess of 8 ft will more or less dominate the waters west of 110W through Sun. Very large NW swell, in excess of 20 ft, will enter NW portions of the forecast area early Sun in conjunction with the arrival of a second, stronger cold front. Seas of 12 ft or higher could encompass almost all of the forecast waters N of 07N and W of 115W by Tue morning. $$ Christensen […]