000 AXPZ20 KNHC 222208 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Mon Oct 22 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Dangerous Hurricane Willa is centered near 19.7N 107.2W at 2100 UTC moving N at 7 kt. Estimated minimum central pressure is 929 mb. Maximum sustained wind speed is 140 kt with gusts to 170 kt. Willa has ingested some dry air into its core today which has disrupted the intensification, and produced a reorganization of the eyewall. Numerous strong convection continues within 90 nm across the N and 120 nm across the S semicircles, with scattered moderate to strong convection in bands elsewhere within 150 nm of the center except 240 nm across the SE quadrant. These rain bands on the eastern side of Willa will bring very heavy rainfall along the Pacific coast of mainland Mexico from Michoacan to southern Sinaloa during the next 48 hours. Willa is expected to continue northward this evening, then begin to gradually veer NE and across Las Tres Marias before sunrise early Tue, then accelerate and move inland to the south of Mazatlan in southern Sinaloa early Tue evening. Large swells generated by Willa will continue to reach the mainland Mexican coast between 100W and 108W through tonight, and into the southern third of the Gulf of California. These swells will produce very large and powerful surf and cause life-threatening rip current conditions. Please refer to local forecasts from the Meteorological Service of Mexico for specific information on heavy rainfall and flash flood potential from Willa. Refer to the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP4/WTPZ24 KNHC for additional details. Tropical Storm Vicente centered near 15.4N 101.5W at 2100 UTC moving WNW at 10 kt. Estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Scattered moderate to strong convection is occurring in bands within 120 nm N and 150 nm across the S semicircles. Vicente will continue on a general WNW track through the southern Mexican offshore waters into this evening then turn more NW and gradually weaken to a tropical depression through Tue afternoon as it approaches the Mexican coast near Manzanillo. Rainfall produced from Vicente as it moves ashore late Tue will move over areas already dumped on by heavy rain from Willa and may further compound flooding conditions. Refer to the latest NHC forecast/ advisory under AWIPS/WMO headers MIATCMEP3/WTPZ23 KNHC for additional details. ...TROPICAL WAVE... A tropical wave is analyzed N of 06N along 90W-91W. Scattered moderate to strong convection continues along the monsoon trough associated with the wave. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends W off the Caribbean coast of Colombia westward across Costa Rica near 09.5N84W to 08.5N94W TO 12N97W, where it breaks, then resumes SW of Hurricane Willa near 14N111W to surface low near 11.5N116.5W to 09.5N124W, where it transitions to ITCZ and continues on to beyond 10.5N140W. Widely scattered moderate isolated strong convection is observed within 60 nm N and 180 nm S of the trough and ITCZ west of 111W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features paragraph for details on Tropical Cyclones Vicente and Willa. W of the Baja California Peninsula...Gentle to locally moderate NW to N flow is expected through this evening when the pressure gradient will tighten, supporting moderate to locally fresh northerly flow W of the Baja California Peninsula on Tue into early Wed as Willa moves NE across Las Tres Marias and inland across southern Sinaloa. Large southerly swell from Hurricane Willa will propagate N through the waters W of Baja beginning this evening, and reaching as far N as 28N early Wed, before beginning to subside. Gulf of California: Light, mostly northerly flow is expected across the northern two-thirds of the Gulf through this afternoon when large southerly swell from Willa will propagate into the southern gulf waters, and then persist through late Tue night. Fresh to locally strong northerly winds are also expected across the gulf waters S of 24.5N late this afternoon into Wed as Willa passes just S of the Gulf entrance. Gulf of Tehuantepec...Fresh to locally strong northerly flow is expected through late this morning. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo...Pulses of fresh N to NE flow are forecast through Tue morning. Light northerly winds and 4 to 7 ft seas are forecast elsewhere N of the monsoon trough, while moderate to locally fresh southwesterly monsoonal flow, with 5 to 8 ft seas forecast through this afternoon, then mostly moderate SW flow and 4 to 7 ft seas are forecast through the middle of the week. REMAINDER OF THE AREA... Refer to the Special Features paragraph above for details on Tropical Cyclone Willa. A 1008 mb low near 11.5N116.5W will drift W for the next several days with fresh southerly flow, and 6 to 8 ft seas forecast within 300 nm SE of the low. This low has a low chance of becoming a tropical cyclone during the 5 days. A surface high will meander near 28N136W with moderate to locally fresh anticyclonic flow forecast across the tropical waters N of the monsoon trough and ITCZ, and W of 122W through the middle of the week. An area of 7 to 9 ft seas is observed across the tropical waters from 12N to 17N W of 128W. These conditions will gradually shrink in areal coverage and shift W through Wed morning. $$ Stripling