000 AXPZ20 KNHC 150807 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Mon May 15 2023 Tropical Weather Discussion for the eastern Pacific Ocean from 03.4S to 30N, east of 120W including the Gulf of California, and from the Equator to 30N, between 120W and 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 0710 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from Colombia near 09N74W to 05.5N95W to 05.5N112W. The ITCZ extends from 05.5N112W to beyond 04N140W. Numerous moderate and scattered strong convection is noted from 02S to 09N between 77W and 101W. Scattered moderate convection is noted from 04N to 07N between 138W and 140W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Weak high pressure ridging extends from NW to SE across the offshore waters of Mexico with gentle to moderate winds under this pattern, except for fresh to near gale-force N winds in the Gulf of Tehuantepec due to nocturnal drainage flow combined with a tight pressure gradient. Seas of 5-7 ft in S-SW dominate the open waters, mixed with NW swell offshore Baja California. In the Gulf of California, gentle to moderate SE-S winds and seas of 1-3 ft or less prevail, except 3-5 ft near the entrance. Hazy skies persist across the near and offshore waters from Las Tres Marias to Tehuantepec due to lingering smoke from ongoing agricultural fires with possible reduction in visibility to 5 nm. For the forecast, little change in the pressure pattern is forecast through Thu, and will maintain gentle to moderate winds area-wide. The exception will be a surge of fresh to near gale- force gap winds in the Gulf of Tehuantepec during the late night to early morning hours today, and again tonight into Tue, and also Fri night. Seas will build to around 8 ft during these winds. Moderate to fresh N winds are possible there late Thu night/early Fri. Moderate to fresh NW-N winds will pulse near Cabo Corrientes and Cabo San Lucas Thu night and Fri night due to a locally tight pressure gradient. Large cross equatorial southerly swell will arrive offshore Mexico late tonight/early Tue through Wed building seas to around 8 ft, with another yet weaker pulse of S swell arriving on Fri. Reduced visibilities in haze are possible in the S and SW Mexico offshore waters due to smoke produced by agricultural fires. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Numerous showers and thunderstorms are occurring across most of Colombia extending westward to across portions of Panama, and offshore from 02S to 08N. Model guidance indicates the potential for higher winds and seas with this convection. Fresh NE gap winds prevail across the Papagayo region and extend to near 88W. Gentle to moderate winds are elsewhere with 5-7 ft seas in S-SW swell offshore Ecuador, except building to 8 ft S-SW of the Galapagos Islands, and 3-5 ft elsewhere. Hazy skies persist from the Papagayo region to Tehuantepec due to lingering smoke from ongoing agricultural fires, with visibilities likely 5 nm offshore from the Gulf of Fonseca to El Salvador. For the forecast, strong thunderstorm activity is expected to persist across the waters from Panama southward through at least tonight with the potential for higher winds and seas. NE to E gap winds will pulse to fresh to strong across the Papagayo region through the early morning hours, then again Thu night/ early Fri and Fri night/early Sat. Building S-SW swell will reach from offshore Ecuador to the Galapagos Islands today with peak seas on Mon of 7-9 ft, then reach the nearshore waters of Central America early on Tue with peak seas of 7 ft there. New SW swell should reach the Galapagos waters early Thu, with seas building to 7-9 ft yet again across the offshore waters from Ecuador to the Galapagos Islands Thu night through at least Fri night. Reduced visibilities in haze are expected from the Guatemala to the Costa Rica offshore waters due to smoke produced by ongoing agricultural fires. ...REMAINDER OF THE AREA... A slow moving cold front extends from 30N136W to 24.5N140W, with a reinforcing trough behind it from 30N138.5W to 28N140W. Convection ahead of the front has diminished in the past several hours however showers are still likely occurring on either side. S-SW winds of fresh to strong just ahead of the front are now N of 30N, with moderate to fresh S of 30N. Associated NW swell of 8-10 ft is N of 21N and W of 135W as confirmed by recent altimeter data. Weak ridging prevails ahead of the front and N of the ITCZ with mainly gentle to moderate winds and 6-8 ft seas in mixed S and NW swell per recent altimeter passes. A set of S-SW swell with seas of 7-11 ft is S of 10N and W of about 93W, highest S of the Equator. For the forecast, the front will weaken and eventually stall from 30N135.5W to 24N140W late tonight, with associated seas subsiding to less than 8 ft by early Tue. Another weak front or trough will move into the NW waters by mid-week, with another pulse of NW swell building seas to 8-10 ft Wed and Wed night before decaying. Winds will increase slightly across the trade wind zone tonight and Tue, and again Fri night into the upcoming weekend, but otherwise, little change in winds is forecast through the next several days. Meanwhile, the S-SW swell will continue to propagate northward through the early part of the week, with combined seas of 7-10 ft dominating almost the entire open waters by late tonight/early Tue. The seas will then slowly decline through Wed. A new set of S-SW swell of 7-10 ft will reach the Equator Wed night, extending to near 10N Fri. $$ Lewitsky