000 AXPZ20 KNHC 122059 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2045 UTC Tue Sep 12 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 1800 UTC surface analysis and satellite imagery through 2030 UTC. ...SPECIAL FEATURES... Tropical Depression 15-E centered at 15.6N 117.5W at 2100 UTC moving W or 265 degrees at 12 knots. The minimum central pressure is estimated 1004 mb. The maximum sustained winds are 30 kt with gusts to 40 kt mainly over the NW semicircle. Scattered moderate to strong convection is observed within 150 nm over the NW quadrant and within 300 nm across the NW and SW quadrants of the depression's center. Easterly upper-level wind shear is expected to limit the potential for much intensification of the depression during the next few days. The depression is forecast to move W and strengthen to a minimal tropical storm within 24 hours and then gradually weaken to a remnant low within 3 days near 15.6N122.7W. For additional information refer to NHC forecast advisories under WMO/AWIPS headers WTPZ25 KNHC/MIATCMEP5. Active convection persists along the monsoon trough and is being aided by a broad zone of strong SW monsoon winds. A surface low is forecast to develop by tomorrow afternoon along the trough in the vicinity of 103W and may develop quickly into a tropical cyclone within the next two days. Another surface low is forecast to develop further W along the trough in the vicinity of 112W where global models suggest another tropical cyclone could develop during the next several days. Global models also indicate that very active convection will continue along and south of the trough during the next several days. Currently strong S to SW winds are occurring from 07N-12N between 109W-115W, where seas are running 8 to 12 ft in cross equatorial southerly swell. The broad zone of strong monsoon winds and seas of 8-11 ft and higher will continue across the general area for the next few days as the trough and associated weather drift slowly northward. These areas of low pressure have a medium chance of tropical formation during the next 48 hours. ...TROPICAL WAVES AND TROPICAL LOWS... A 1010 mb low is embedded in the monsoon trough at 11N134.5W with isolated moderate convection within 90 nm of the low center. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 13N88W to Tropical Depression 15-E to low pres near 11N135W 1010 mb to beyond 11N140W. Scattered moderate convection is noted from 10N to 15N between 95W and 114W, and near the low from 10N to 13N between 133W and 137W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A NW to SE oriented trough will meander E to W across the Baja California Peninsula and the Gulf of California with a surface low developing intermittently along the trough axis over the far northern Gulf waters, and perhaps also over the central Gulf of California. A W to E orientated ridge will meander from 27.5N128W to 22N115W through the middle of the week, with a moderate W to NW breeze forecast across the EPAC waters S and W of the Baja California Peninsula through Thu night, with 5 to 6 ft seas. Gulf of California...Light, mostly NW winds expected through the next 24 hours. Gulf of Tehuantepec: Moderate nocturnal drainage flow is forecast through the period. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to locally fresh southwesterly monsoonal flow expected this week. Combined seas are currently 6 to 8 ft primarily due to cross-equatorial swell that is forecast to subside today with seas forecast less than 8 ft tonight. REMAINDER OF THE AREA... See the Special Features section above about T.D. 15-E and the other areas of active weather with potential to become tropical systems. A surface ridge extends from 32N140W to 23N135W with light to locally moderate anticyclonic flow expected elsewhere N of the monsoon trough and W of 115W through the middle of the week. $$ ERA