000 AXPZ20 KNHC 070229 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Tue Feb 7 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The ITCZ axis extends from 02N104W to 03N120W to 04N137W. Scattered moderate convection is WITHIN 210 nm N of axis between 110W and 115W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Winds in the Gulf of Tehuantepec have diminished to 20 kt or less with seas 0f 3-4 ft. The next Gulf of Tehuantepec gap wind event, with gale conditions possible, is expected late Thursday night as strong high pressure builds southward across the Gulf of Mexico in the wake of a cold front. High pressure of 1020 mb centered near 26N121W extends a ridge southeastward to near the Revillagigedo Islands. The pressure gradient between the ridge, and weak troughing over the Gulf of California is supporting gentle to moderate northerly winds off the west coast of the Baja California peninsula. Seas in this area are in the 5-6 ft range. Light to gentle winds and seas 2 ft or less prevail over the Gulf of California, while gentle to moderate winds and seas 4-6 ft prevail off the southwest coast of Mexico, with the exception of moderate to fresh NW winds within about 60 nm of the coast between Manzanillo and Cabo Corrientes. The high pressure is forecast to remain nearly stationary over the next 24 hours, but strengthen slightly. It is then forecast to lift northward to near 32N121W by Wednesday afternoon. As this takes place, the pressure gradient between the associated ridging and the trough over the Gulf of California will tighten some allowing for fresh to strong NW-N winds to materialize off the west coast of the Baja California peninsula as well as central portion of the Gulf of California Tuesday night and Wednesday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The pressure gradient between high pressure centered over the southeast United States and the equatorial trough over the eastern north Pacific is supporting fresh to strong gap winds over the Gulf of Papagayo, but mainly during the overnight and early morning hours, with the assistance of the nocturnal drainage flow. This weather pattern is forecast to persist most of the forecast period. Northerly winds in the 15-20 kt range are expected across the Gulf of Panama and downstream to near 4N- 5N at night. Winds are forecast to increase again across these two gap wind regions Thursday night into Friday as a strong high pressure settles over the southeast United States. Otherwise, light and variable winds and 4-6 ft seas will prevail elsewhere. REMAINDER OF THE AREA... A ridge, associated with the aforementioned high pressure of 1020 mb continues to dominate the northern waters. Long period NW swell propagating through the northwest portion of the area is producing seas in the range of 8-12 ft range there. This swell train with a leading edge period of 17 to 18 seconds will reach from Los Cabos to the Equator at 128 tonight, and the Revillagigedo Islands late tonight into Tuesday morning, and to near 100W on Wednesday. A relatively tight pressure gradient between the above mentioned high pressure center and lower pressures in the vicinity of the ITCZ is supporting an area of moderate to fresh trades north of the ITCZ to near 20N. Seas are in the 8-10 ft rande within the area of the trade winds based of altimeter passes. these marine conditions are expected to persist over the next couple of days. The most recent scatterometer pass and a couple of ship obseravtions showed SW winds in the 20-30 kt range across the NW waters, mainly NW of a line from 30N135W to 26N140W. These winds are forecast to further increase to minimal gale force, particularly between 0600-1200 tonight, and again Tuesday night. As a result, a gale warning was issued with this forecast package. Seas are forecast to build to 16-18 ft with the strongest winds. These marine conditiones will be assiociated with a series of deep low pressure centers with attendant cold fronts approaching the NW corner through Wednesday. This will maintain a very tight pressure gradient across the NW part of the forecast region. One of these cold fronts will enter the forecast waters by Wednesday afternoon, reaching from 30N136W to 25N140W by Wednesday evening. At that time, expect fresh to strong winds on either side of the front with seas up to 18 ft in the wake of the front. $$ GR