NHC Tropical Weather Discussion (East Pacific) National Hurricane Center - Tropical Weather Discussion (East Pacific)

  • NHC East Pacific Tropical Weather Discussion

    000 AXPZ20 KNHC 190912 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Fri Oct 19 2018 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... A broad area of low pressure is analyzed as two surface lows. The easternmost low is near 13N92W 1007 mb with scattered moderate isolated strong convection is observed within 180 nm of the low. The westernmost surface low is analyzed at 13.5N98W and estimated at 1007 mb. Scattered moderate isolated strong convection is observed within 210 nm west of the low. Strong northerly gap drainage winds are expected to continue through and downstream of the Gulf of Tehuantepec through this morning feeding into the westernmost surface low. This surface low has a high chance of developing into a tropical cyclone over the next 3 to 5 days as it tracks west-northwestward. Even if the convection does not organize into persistent banding, the pressure gradient is expected to tighten supporting near gale force winds within about 180 nm northeast of the low center by late this afternoon. There is some uncertainty is the model guidance and the adjustments to the track and strength of this low is likely. The easternmost surface low is becoming better organized. Although there is currently only a low chance of tropical cyclone development during the next 48 hours, the pressure gradient is forecast to strengthen with strong to near gale force winds expected within about 120 nm over the northeast quadrant by late Sat. Much uncertainty in the model guidance concerning this low. Refer to the latest East Pacific Tropical Weather Outlook under AWIPS/WMO header MIATWOEP/ABPZ20 KNHC for additional details. ...TROPICAL WAVES... A tropical wave previously analyzed north of 07N along 91W has lost identity. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends northwest off the Caribbean coast of Colombia at 10N76W to the Pacific coast of Nicaragua at 12N96W and then through surface lows at 13N92W and 13.4N98W, then the monsoon trough drops southwest to 12N108W, then turns northwest to 13.5N115W, then southwest again through another surface low at 12N119W to 09N125W, then turns west-northwest and continues to beyond 11N140W. Isolated moderate to strong convection is observed within 180 nm of the surface low at 12N120W. A surface trough is analyzed north of the monsoon trough from 10N139W to 15N137W and is accompanied by scattered moderate isolated strong convection within 330 nm east, and within 90 nm west of the trough axis. Isolated moderate to strong convection is noted elsewhere within 120 nm either side of a line from 05N78W to 11N89W to 10N95W to 12N113W to 08N120W to 09N140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features Paragraph above for a discussion on several synoptic features affecting the central and southern Mexico offshore waters during the next 3 to 5 days. A surface ridge will meander across the offshore waters from 23N117W to 17N109W for the next few days. Gentle northwest to north flow is expected north of 20N west of 110W through early Mon. The pressure gradient is then forecast to tighten supporting moderate northerly flow west of the Baja California Peninsula through the middle of next week. There is some forecast uncertainty due to two surface lows developing further south. Gulf of California: High pressure north of the area will support fresh to strong northerly winds across the gulf waters north of 29N through this morning. Gentle to moderate northerly winds are forecast across the remainder gulf waters through the upcoming weekend. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate southwesterly to westerly monsoonal flow will dominate the offshore waters through Sat night. Fresh southwest winds are expected to develop south of 05N east of 90W on Sat night with seas to 9 ft. These conditions will reach the coast of Panama early next week. Otherwise, showers and thunderstorms associated with the broad area of low pressure mentioned in the Special Features Paragraph above will continue to affect portions of Central America and adjacent Pacific coastal waters. REMAINDER OF THE AREA... Elsewhere, a surface ridge will meander from 12N131W to 23N117W through the upcoming weekend. A 1008 surface low is analyzed near 12N120W, and is expected to drift west for a day or so accompanied by fresh to locally strong winds and seas to 8 ft. An area of strong northeast trades is observed from 12N to 15N west of 132W, surrounded by seas to 10 ft in mixed swell across the discussion waters north of 11N west of 128W. These seas will gradually subside through the middle of next week. Long period southerly swell, in form of 8 ft seas, will enter the southern waters on Sat and propagate northeast to along 10N east of 120W through Sun. $$ Nelson […]