{"msg": "440\nAXPZ20 KNHC 182201\nTWDEP \nTropical Weather Discussion\nNWS National Hurricane Center Miami FL\n2205 UTC Fri Sep 18 2026\nTropical Weather Discussion for the eastern Pacific Ocean from\n03.4S to 30N, east of 120W including the Gulf of California, and\nfrom the Equator to 30N, between 120W and 140W. The following\ninformation is based on satellite imagery, weather observations,\nradar, and meteorological analysis.\nBased on 1800 UTC surface analysis and satellite imagery through\n2145 UTC.\n...SPECIAL FEATURES...\nWestern East Pacific: Low pressure, Invest EP98, is centered near\n11N118W with a pressure of 1009 mb. This feature is part of a\nrather broad area of cyclonic circulation. Satellite exhibits \nnumerous moderate to isolated strong convection from 08N to 13N \nbetween 117W and 120W. Environmental conditions appear conducive for\ndevelopment of this system, and a tropical depression is likely \nto form this weekend as it moves westward across the western \nportion of the eastern Pacific. The low has a high chance of \ntropical cyclone formation through the next 48 hours.\nSouth of Southwestern Mexico: A tropical wave, Invest EP99, has its \naxis extending from near 16N105W to 06N106W, with low pressure of \n1010 mb, near 07N106W. This feature is part of a broad area low \npressure that is located about 700 nautical miles south-southwest of \nthe southwestern coast of Mexico. Satellite imagery depicts \ndisorganized scattered moderate to isolated strong convection within \nfrom 07N to 12N between 103W and 108W. Environmental conditions are \nconducive for development, and a tropical depression is likely to \nform late this weekend or early next week while it moves gradually \nnorthwestward off the coast of southwestern Mexico. This system has \na medium chance of tropical cyclone formation through the next 48 \nhours.\nPlease refer to the latest NHC Tropical Weather Outlook at \nwebsite: www.hurricanes.gov for more details on these Invests.\n...TROPICAL WAVES...\nThe southern portion of the axis of a western Caribbean Sea \ntropical is along 79W north of about 05N. It is moving westward \nnear 15 kt. Numerous moderate to strong convection is within 180\nnm west of the wave, and also from 03N to 05N between 79W and\n81W.\n...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...\nThe monsoon trough axis extends from northwest Colombia westward\nto across northern Costa Rica, and southwestward to 09N86W to \n09N100W to 06N101W to 06N111W to 10N114W to low pressure, Invest \nEP98, near 11N118W and to 12N126W. It resumes at 13N138W to \nbeyond 12N140W. Scattered moderate to isolated strong convection\nis within 300 nm north of the trough between 93W-103W, also \nwithin 300 nm south of the trough between 90W-102W and \nwithin 120 nm south of the trough between 120W-126W.\n...OFFSHORE WATERS WITHIN 250 NM OF MEXICO...\nThe pressure gradient between a ridge over the Gulf of America \nand the eastern extension of the Pacific monsoon is supporting \nstrong to near-gale force north to northeast gap winds across \nthe Gulf of Tehuantepec as was evident in satellite\nscatterometer from throughout the day. Seas with these winds are\n6 to 8 ft. Scattered to numerous showers and thunderstorms are \nover most of the offshore waters, especially east of about 101W. \nThe northern portion of tropical wave extends along 104W, \nnorthward to near 17N. The gradient related to high pressure west\nof the Baja California offshores is supporting moderate to fresh\nnorthwest winds N of Cabo San Lazaro. Moderate or weaker winds \nare elsewhere along with moderate seas, except for slight seas in\nthe Gulf of California. \nFor the forecast, winds will pulse to fresh to strong speeds in \nthe Gulf of Tehuantepec tonight becoming moderate north to \nnortheast winds Sat afternoon. Fresh to strong northwest winds \noffshore Baja California will diminish Sat afternoon. Northwest\nwinds over these waters are expected to briefly reach fresh\nspeeds Mon night into Tue. Otherwise, the environmental \nconditions of the tropical wave that extends from 6N105W to \n06N106W, with low pressure of 1010 mb, Invest EP99, near 07N106W \nare conducive for development, and a tropical depression is \nlikely to form late this weekend or early next week while it \ngradually moves north-northwestward and northward off the coast \nof southwestern Mexico. Regardless of development, this system is\nforecast to bring fresh to strong winds and moderate to rough \nseas to the Michoacan and Jalisco offshores Tue night into the \nmiddle part of next week.\n...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, \nAND WITHIN 750 NM OF ECUADOR...\nFresh to strong northeast to east winds prevail across the Gulf \nof Papagayo extending downstream to near 90W. Moderate easterly \nwinds from this gap event are affecting the outer offshores El \nSalvador and Guatemala. Moderate or weaker winds prevail \nelsewhere, except for moderate to fresh N winds in the Gulf of \nPanama extending to about 07N. Seas over the offshore waters \nare of moderate state due to a long-period southwest swell.\nFor the forecast, the pressure gradient between the ridge north \nof the area and the eastern Pacific monsoon will support pulsing \nfresh to occasionally strong easterly winds and moderate to rough\nseas across the Papagayo region into early Sat, then pulsing to \nmoderate to fresh speeds through early Sun. Moderate winds and \nseas will prevail elsewhere.\n...REMAINDER OF THE AREA...\nThe remnant 1008 mb low of former Tropical Depression Fifteen-E \nis located near 17N137W. A tight gradient between the low and \nhigh pressure to its north is bringing fresh to strong northeast\nto east winds over the waters from 19N to 27N west of 129W. Seas \nare 6 to 9 ft within this area of winds as interpreted from \nearlier satellite altimeter data passes. Satellite imagery\nshows numerous moderate convection within 180 nm of the low in \nthe NE quadrant and 90 nm of the low in the SE quadrant. Elsewhere,\nwinds are moderate or weaker and seas are of moderate state,\nexcept for rough state seas in the vicinity of Invest EP98. \nFor the forecast, see the Special Features section. Otherwise, \nenvironmental conditions appear conducive for some development of\nthe remnant low of former Tropical Depression Fifteen-E as it \nmoves westward to west-southwestward, and a tropical depression \ncould form well to the south or southeast of the Hawaiian Islands\nby the middle to latter part of next week.\n", "title": "Eastern Pacific Tropical Weather Discussion", "id": "1211428128462766082", "issued": "2026-09-18T22:05:00Z", "wmo": "AXPZ20", "source": "NOAA/NWS National Hurricane Center, received via the National Weather Wire Service", "page": "https://hurricane.terrapin.com/text/1211428128462766082"}