000 AXPZ20 KNHC 101605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sun Dec 10 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 1200 UTC surface analysis and satellite imagery through 1545 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Storm Warning: A very tight pressure gradient across the Isthmus of Tehuantepec as supported by a 1035 mb high center analyzed over N central Mexico will support storm force winds of 40-50 kt across the Gulf of Tehuantepec through late this morning, with in the 14-22 ft range. A large area of gale force winds of 30-40 kt is present elsewhere within 120 nm either side of a line from 16N95W to 14N96W to 12N98W, with seas in the 12-19 ft range. Fresh to strong NE-E winds extend downstream of the gulf to near 09N and 102W, where seas are 10-15 ft in NE swell. Seas 8 ft or greater are expected to propagate well away from the Gulf to near 105W today, and farther W to near 110W on Monday. The ongoing storm conditions are forecast to weaken to a strong gale by early this afternoon and continue into early Monday before weakening further to minimal gale force early on Tuesday. These conditions are forecast to continue through Wednesday night of the upcoming week. Gulf of Papagayo Gale Warning: The pressure difference between a very tight packing of isobars pressing southward across the northern portion of Central America associated with the 1035 mb high center over N central Mexico as analyzed on this morning's 12Z surface analysis and broad low pressure that exits over the remainder of Central America and SW Caribbean Sea has induced NE gale force winds of 30-35 kt through the Gulf of Papagayo. N-NE winds of 20-30 kt are elsewhere downstream from the gale force winds over an area from 07N-11N between 85W-88W. The aforementioned very tight isobaric packing will loosen enough to allow for these gale conditions to continue through early on Monday before diminishing to strong to near gale force NE winds late Monday night and to strong NE winds Tuesday. Seas of 8-10 ft will propagate to the SW well away from the gale force wind area reaching from 05N-11N between 86W-90W early on Monday, and from 04N-10N between 86W-91W early on Tuesday. with sea heights to 9 ft in NE swell. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The Monsoon Trough axis extends from along the coast of southern Costa NW to 10N89W to 07N100W to 09N110W to 10N118W to 08N126W to 09N135W, where scatterometer data from last night indicated the that Intertropical Convergence Zone (ITCZ) then begins and continues to beyond the area at 09N140W. Scattered moderate to isolated strong convection is 60 nm S of the axis between 113W- 115W. Scattered moderate convection is within 60 nm S of the axis between 130W-136W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Please see Special Features section above for details on an ongoing storm event. High pressure over the Great Basin will continue to support fresh to strong northerly winds over the northern Gulf of California today. N-NE winds funneling through the Baja California peninsula into the Pacific waters have diminished to 15-20 kt, with seas subsiding below 8 ft off the coast of Baja California tonight. Elsewhere gentle to moderate winds and 4-6 ft seas will persist through next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Please, see Special Features section above for details on an ongoing gale event. Strong high pressure ridging surging southeastward across northern central America in combination with low pressure over the remainder of Central America has resulted in strong to gale force NE winds through the Gulf of Papagayo and nearby waters. Large NE swell from a Tehuantepec gap wind event will spread across the offshore waters of Guatemala and El Salvador through Mon. Localized gap pulses of strong NE winds are possible off the coast of El Salvador and Guatemala, including Gulf of Fonseca beginning early today. REMAINDER OF THE AREA... A cold front is approaching the NW corner of the area. A tight pressure gradient between the front and high pressure over the northern waters is bringing strong S to SW winds to the NW of a line from 32N134W to 28N140W along with seas of 8-12 ft in a NW swell. The cold front will reach a position from near 32N138W to 28N140W this afternoon, with strong S to SW winds within 120 nm E of it N of 29N and seas 8-10 ft. This front will begin to weaken by early tonight from near 32N136W to 27N140W, with winds on either side of it becoming 15-20 kt. Seas of 11-15 ft in NW swell are expected W of the front while seas of 8-10 ft are expected within 180 nm SE of the front at that time. The front will dissipate by late Monday night, however, long period NW swell will produce seas of 8-11 ft to the N of 18N and W of a line from 32N126W to 18N127W. This swell will gradually decay through late Tuesday, with seas of 8-10 ft expected N of 13N and W of a line from 32N125W to 16N125W to 13N125W at that time. The pressure difference between a trough near 136W and the high pressure over the northern is forecast to result in strong NE-E winds beginning late Monday night from 13N-18N and W of 129W along with seas of 8-10 ft. This area of strong winds will shift to W of 130W by early on Tuesday, and diminish to 15-20 late on Tuesday. $$ Aguirre