000 AXPZ20 KNHC 151010 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sun Jan 15 2017 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 0930 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A tight pressure gradient generated due to the combination of high pressure that extends from the Gulf of Mexico to southeastern Mexico with lower pressures to its south will begin to weaken this morning. The resultant north to northeast minimal gale force winds across portions of the Gulf of Tehuantepec will diminish to 25-30 kt this morning and 20-25 kt by early this afternoon. These winds diminish further tonight into Monday as the surface high pressure weakens and the pressure gradient relaxes. Northeast swell will produce waveheights of 8-9 ft downstream of the gulf to 12N between 94W-96W this morning, and into early this afternoon before subsiding to less than 8 ft this evening. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 04N78W to low pressure near 02N81W 1010 mb to 02N89W. ITCZ axis extends from 04N89W to 04N96W to 06N110W. It resumes at 08N124W to beyond 07N140W. Scattered moderate convection is seen within 180 nm north of the axis between 130W-134W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for information on the Gulf of Tehuantepec Gale Warning. A 1012 mb low pressure is located over the far northern Gulf of California near 30N113W with an occluded front southeast to over Sonora Mexico near 28N111W. A cold front then extends from 28N111W southwest to across the central section of the Gulf of California, to over the southern portion of Baja California Sur and continues as a weakening cold front to near 20N116W. The front will move south of Baja California Sur and the Gulf of California by late this morning or early this afternoon. Seas to 8 ft will prevail behind the front off Baja California Norte. The front will gradually dissipate from near Cabo Corrientes to Socorro Island Monday night. Fresh northwest winds behind the front will become moderate northwest to north winds today. Northwest swell producing combined waveheights in the range of 6- 8 ft will continue to propagate through the area about 120 nm off Baja California Norte through Tuesday, then diminish below 8 ft through mid week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo and along the south coast of Nicaragua, fresh to strong northeast winds will continue to pulse through early Monday afternoon before diminishing to fresh Monday night through Tuesday. Seas will build to 8 ft during the strongest winds. In the Gulf of Panama, strong north to northeast winds will diminish to fresh again this afternoon, then pulse from moderate to fresh through Monday morning and to become mostly moderate thereafter through Tuesday night. Seas in the range of 5-7 ft will subside to 4-5 ft on Monday. REMAINDER OF THE AREA... Strong high pressure is building south-southeastward in the wake of the cold front described above. The combination of this high pressure and lower pressures to its south, and with the added component of a couple of surface troughs (one from 05N126W to 11.5N123W the other one roughly within 120 nm to its east) has just recently begun to increase the trade winds in the deep tropics mainly west 120W through Tuesday. Strong northeast are presently confined from 12N to 15N between 124W-128W. Combined waveheights are currently in the range of 8-11 ft within this area, but will build to 10-12 ft by this evening at which time the strong northeast winds are forecast to be found from 12N to 17N west of 127W. By late Monday night the strong northeast winds are forecast to be located from 12N to 15N between 126W-133W, and from 11N to 19N west of 133W, with combined waveheights of 10-12 ft. latest satellite imagery shows scattered moderate isolated strong convection between the two troughs, and scattered moderate convection within 60 nm to the west of the western most trough. Converging trade winds in the lower levels along with jet dynamics aloft at the base of an exiting upper-level trough over the far eastern portion of the area continue to enhance scattered showers and a few thunderstorms along the ITCZ and a surface trough along 112W from 03N to 07N. Beyond 48 hours, global models are consistently suggesting that a large and deep low pressure system will move well to the north of the discussion area by the mid-week with the associated cold front possibly brushing the far northern waters of the discussion area. A northwest swell generated by this system is expected to arrive in the far northwest portion of the area by early Wednesday, with strong southwest winds expected to precede the cold front. $$ AGUIRRE