000 AXPZ20 KNHC 081606 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1516 UTC Wed Feb 8 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 Gale Warning: Strong broad high pressure will build and move across the Mississippi Valley Thursday night extending south across the Gulf of Mexico and southwestward along the eastern section of Mexico. This will create a tight pressure gradient along southern Mexico that will lead to the development of gale force winds starting late Thursday night through Friday night. Please see the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFEP2/FZPN03 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The ITCZ axis is ill-defined along 01N and west of 110W. No significant convection is presently observed. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Moderate to fresh northwest winds are across the central and southern Gulf of California, and off the Baja California peninsula between a 1022 mb high pressure centered near 30N121W and a trough of low pressure extending along western Mexico and the Gulf of California. Seas are in the 4-6 ft range in the central section of the Gulf of California, 3-5 ft elsewhere in the gulf south of 28N and 1-2 ft north of 28N. Seas are in the 5 to 7 ft offshore the Baja California peninsula. The pressure gradient will further increase along the Gulf of California today as broad high pressure over central United States builds southward across northern Mexico. The pressure difference between the high pressure and the trough along western Mexico and the Gulf of California will result in fresh to strong northwest winds over the central Gulf of California beginning this morning and through Thursday morning with seas building up to 7 ft in the central gulf waters. These seas will subside later on Thursday and through Friday as the high pressure then shifts eastward. The fresh to strong northwest winds will become light and variable winds on Friday. NW swell will propagate into the waters off Baja California Norte early Saturday with seas building to the range of 6-8 ft on the northern offshore waters west of Baja California Norte. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The pressure gradient between high pressure ridging extending southwest from the central Atlantic to the western Caribbean Sea and lower pressures over the southwestern Caribbean Sea and Central America in combination with overnight drainage flow will support pulses of fresh to strong northeast winds through the Gulf of Papagayo during the nighttime hours through Friday. Model guidance continues to suggest that new broad and strong high pressure north of the area Thursday will allow a much stronger pulse and longer lasting of gap winds through the Gulf of Papagayo Thursday night into early Friday, with a plume of seas to 8 ft reaching to roughly within 300 nm to the west and southwest of the Gulf of Papagayo with seas reaching a range of 8-9 ft by Friday night. Presently, northerly flow through the Gulf of Panama is in the moderate to fresh reaching reaching south to near 04N between 79W and 81W with seas of 3-5 ft. Model guidance also shows these winds increasing to the fresh to strong range by late on Friday, with seas building to 8 ft. These winds will spread southwestward by that time with an additional small swath of similar winds expected to plume southwest from the Peninsula de Azuero. Overnight convection off the coast of Colombia is weakening some, however the surface trough along the coast of Colombia south of 04N should help set off new convection again tonight. REMAINDER OF THE AREA... A cold front is approaching the far northwest corner of the discussion area. Strong to near gale force south to southwest winds with seas of 9-16 ft driven by a large NW swell train are confined to the northwest of a line from 32N131W to 25N140W, with the largest of these in the far northwest portion of the area. The cold front will reach a line from 32N137W to 27N140W by around 21Z this afternoon, with strong to near gale force south to southwest winds ahead of it north of 27N and east to 134W along with seas of 11-15 ft. Strong west winds with seas of 12-6 ft in NW will follow in behind the front. As the front moves farther east across the northwest portion of the area through early Thursday, the 1022 mb high center near 30N122W will be shunted to the northeast some. The front will weaken as it reaches from 32N127W to 22N137W, and become statioanry from there to 20N140W by early on Thursday, with a post-fronal trough following it from near 32N136W to 27N140W. By Thursday afternoon, the front will continue to weaken along a position from 32N128W to 23N135W and statioanry to 20N140W, while the post-frontal trough is expected to lose its identity. Seas in the range of 8-13 ft in NW to N are expected to cove an extensive area to the northwest of a line from 32N125W to 22N133W TO 07N130W to 10N140W at that time. Jet dynamics aloft are supporting scattered showers and a few thunderstorms west of 130W as well. The winds will diminish tonight as the main support aloft for the front lifts out. Lingering northwest swell of 8 to 14 ft will propagate through the area north of 06N and west of 125W through Thursday night. $$ Aguirre