Tropical Weather Discussion
Issued by NWS
Issued by NWS
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311 AXPZ20 KNHC 200940 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Fri Sep 20 2024 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 0930 UTC. ...TROPICAL WAVES... A tropical wave over the far western Caribbean has its axis near 87W. It extends southward across western Honduras to just west of Costa Rica, and it is moving westward at about 10 kt. Numerous moderate to strong convection and tstms are affecting the offshore waters from Costa Rica to El Salvador. A tropical wave has its axis along 103W from 05N to 17N. It is moving westward at 10 to 15 kt. Scattered moderate convection is from 08N to 15N between 96W and 107W. A tropical wave has its axis along 121W from 06N to 18N moving westward at about 10 kt. Scattered moderate convection is from 07N to 15N between 119W and 127W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from northwest Colombia to 12N87W to 13N109W to 09N125W. Aside from the convection associated with the tropical waves, scattered moderate to isolated strong convection is from 08N to 16N between 106W and 118W. Scattered moderate convection is from 06N to 14N west of 131W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A broad surface ridge extends southeastward into the region. Gentle to moderate northwest to north winds are over the Baja California offshore waters with slight to moderate seas. Along the Gulf of California, light to gentle winds are ongoing, except for moderate to fresh SW winds in the northern Gulf N of 29N. Light to gentle winds and moderate seas are elsewhere. For the forecast, the Pacific ridge will remain in place and fluctuate into the weekend. Gentle to moderate northwest to north winds over the Baja California offshore waters will increase to fresh speeds this evening and continue through late Sat night, then diminish to gentle to moderate speeds afterward into Mon night. Ongoing moderate to fresh SW winds in the northern Gulf of California will diminish to gentle speeds Sat and then prevail through Tue night. An active monsoon trough will support mainly moderate to fresh W to SW winds across the outer SW Mexican offshore waters Fri night through Tue night. Looking ahead, an area of low pressure could form well to the southwest of the SW coast of Mexico late this weekend. Environmental conditions appear conducive for some slow development of this system thereafter as it slowly moves generally northward. Regardless of development, strong to near gale force winds and rough seas are forecast to affect the outer offshore waters SW of Cabo San Lucas starting Mon night and continuig beyond mid week. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh southwest to west winds are ongoing south of the monsoon trough and across the Central America offshore waters S of 10N. Seas are 4 to 6 ft in south to southwest swell. In the Papagayo region, moderate to fresh NE to E winds are ongoing along with moderate seas. Gentle to moderate SE to S winds are observed between the coast of Ecuador and the Galapagos Islands. Otherwise, heavy showers and thunderstorms are over the majority of the Central America offshore waters, except scattered showers in the Gulf of Panama. Seas are up to 10 ft in the areas of strongest convection offshore Costa Rica. For the forecast, moderate to fresh southwest to west winds south of the monsoon trough will change little through Sun night, then increase to fresh to strong speeds across the offshore waters from Costa Rica to Guatemala Mon through Tue night. Seas will build during this time in a mix of southwest swell and westerly wind swell. The monsoonal flow is expected to become very active, and dominate the region today into early next week. This pattern will generate increasing westerly wind waves moving into the area waters. Periods of very active weather are also expected across the waters north of 06N through the weekend and possibly into next week. ...REMAINDER OF THE AREA... Surface ridging extending from a 1027 mb high that is centered well northwest of the area extends east-southeastward to the Baja California Peninsula offshore waters. The pressure gradient between the ridge and the monsoon trough to the south is resulting in moderate to locally fresh NE trade winds and moderate seas south of about 24N and west of 130W. South of the monsoon and a 1008 mb low near 13N109W winds are fresh to strong from the SW and seas are 7 to 8 ft in long-period southeast swell. Seas are 5 to 6 ft in long-period southerly swell elsewhere S of the monsoon. For the forecast, little overall change is expected over the open Pacific waters west of 120W for the next several days as the aforementioned ridge dominates the region. Southwest to west monsoonal winds will continue to become well established through the weekend as the monsoon trough lifts very slowly northward. Moderate to fresh southwest to west winds, with small areas of locally strong winds near active thunderstorms will generally develop from 05N to 12N and east of 120W through the weekend. Seas within this wind regime will build to around 7 to 10 ft east of 120W during that time. $$ Ramos