000 AXPZ20 KNHC 020830 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Mon Oct 2 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 0730 UTC. ...SPECIAL FEATURES... South of Southwestern Mexico (EP98): Shower and thunderstorm activity has become more concentrated in association with a developing area of 1009 mb low pressure along a tropical wave located several hundred nautical miles south of the coast of southern and southwestern Mexico near 11N102.5W. Scattered moderate isolated strong convection is noted within 120 nm of the center. Scattered moderate convection is also noted in two separate bands well away from the center, between 210 nm and 360 nm in the NW quadrant, and between 180 nm and 420 nm in the SW quadrant. Winds earlier were likely 20 kt or less but may be higher now with seas of around 8 ft. Environmental conditions appear conducive for additional development, and a tropical depression is expected to form in the next day or two while it moves west-northwestward to northwestward at about 10 kt. The system has a high chance of tropical development within the next 48 hours. Please refer to the latest NHC Tropical Weather Outlook at hurricanes.gov for the latest on this system. ...TROPICAL WAVES... Please refer to the Special Features section above for information on a tropical wave along 102W/103W (EP98). ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N74W to the broad area of low pressure near 11N102.5W to low pres near 12.5N123.5W to 12N130W. The ITCZ extends from 12N130W to beyond 13N140W. Scattered moderate isolated strong convection is noted from 03N to 15N between 77W and 94W, from 04N to 11N between 94W and 100W, and from 12N to 16N between 113W and 119W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Refer to the section above for details on a developing area of 1009 mb low pressure near 11N102.5W. A weakening cold front extends across the northern portion of the Gulf of California from SE central Arizona through 29N112W to 26N119W. Surface ridging prevails elsewhere across the offshore waters of Mexico. Fresh to strong S-SW winds prevail in the northern Gulf of California on either side of a post-frontal trough from 31.5N113.5W to 30.5N115W per a recent ASCAT scatterometer pass. Fresh to locally strong N-NE winds are in the Gulf of Tehuantepec. Winds are mainly moderate or weaker elsewhere, locally moderate to fresh nearshore Baja California from Punta Eugenia southward. Seas are 4-6 ft across the open waters. In the Gulf of California, seas are 4-7 ft in the northern Gulf, and 1-3 ft elsewhere. For the forecast, other than the potential for tropical cyclone formation with the developing area of low pressure near 11N102.5W, moderate seas will not vary much into the middle of the week. Moderate to fresh N winds will pulse in the immediate area of the Gulf of Tehuantepec, mainly at night. Fresh to strong SW winds in the northern Gulf of California will diminish later this morning. Moderate to fresh winds will pulse nearshore Baja California from near Punta Eugenia southward today into Tue. Winds will be moderate or weaker elsewhere through the week. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Winds are moderate or weaker across the offshore waters. Seas are 4-6 ft across the offshore waters, except 3-5 ft offshore Colombia and Panama. Scattered thunderstorms are along the coast and offshore from Colombia and Panama W-NW. For the forecast, winds will be moderate or weaker across the offshore waters through most of the week, except moderate to fresh from the Equator to 06N this afternoon through Tue, then from 04N to 10N from Tue night through Wed morning. Seas will not vary much through Mon night, then will build slightly where the moderate to fresh winds are. New southerly swell will build seas slightly offshore Ecuador to the Galapagos Islands by mid- week. Looking ahead, a broad area of low pressure could form a few hundred miles south of the coast of Central America toward the end of this week. Thereafter, environmental conditions are forecast to be favorable for gradual development of this system, and a tropical depression could form by next weekend as it moves slowly westward to west-northwestward. ...REMAINDER OF THE AREA... Refer to the section above for details on a developing area of 1009 mb low pressure near 11N102.5W. A weakening cold front extends across the northern portion of the open waters from near Punta Eugenia in Baja California through 24N127W to 27N140W. Winds just behind the front have diminished slightly and are now mainly moderate. Seas of 7-10 ft in northerly swell are N of the front. Recent ASCAT scatterometer data showed low pressure embedded in the monsoon trough near 12.5N123.5W with moderate to fresh winds in the NW semicircle. Seas are around 8 ft with those winds. Winds are moderate or weaker elsewhere. Seas are 7-10 ft in SE swell S of 10N and W of 95W, and 5-7 ft across the remainder of the open waters in mixed swell. For the forecast, other than the potential for tropical cyclone formation with the developing area of low pressure near 11N102.5W, the weakening cold front will gradually dissipate. Associated seas will slowly subside through the early part of the week. The low pressure area embedded in the ITCZ near 12.5N123.5W is forecast to continue to produce moderate to fresh winds and seas to 8 ft on the NW side before weakening mid-week. Winds of moderate or weaker will prevail across the remainder of the open waters through the next several days. Meanwhile, southerly swell of 7-9 ft will wax and wane through the week from around the Equator southward. $$ Lewitsky