000 AXPZ20 KNHC 210247 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sun Aug 21 2016 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 0000 UTC surface analysis and satellite imagery through 0215 UTC. ...SPECIAL FEATURES... Tropical Storm Kay was is centered near 20.6N 113.3W at 21/0300 UTC or about 220 nm southwest of the southern tip of Baja California moving northwestward, or 305 degrees at 5 knots. The estimated minimum central pressure is 1000 mb. Maximum sustained winds are 45 knots with gusts to 55 knots. Latest satellite imagery shows that deep convection has impressively developed rather quickly over and near the center of Kay during the evening hours. The area of stable and dry noted Saturday afternoon entraining into the western portion of the circulation of the cyclone appears to have eroded, and latest water vapor imagery presently shows upper the level cirrus turning in anticyclonic fashion indicative of an upper anticyclone becoming established over Kay. IR imagery shows numerous strong convection within 45 nm southwest of the center, and scattered strong convection is seen elsewhere within 90 nm of the center in the southeastsemicircle, and within 60 nm of the center in the northwest semicircle. Kay is forecast to maintain its intensity as it reaches near 21.0N 114W early Sunday morning before it begins to weaken over cooler sea surface temperatures. The latest NHC advisory has Kay weakening to a minimal tropical storm intensity with wind speeds of 35 kt by Monday evening, then become a post-tropical remnant low by late on Tuesday. Please read the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP2/WTPZ22 KNHC for more details, and the latest public advisory MIATCPEP2/ WTPZ32 KNHC, for more details. ...TROPICAL WAVES... The southern portion of a tropical wave axis that extends from the western Caribbean Sea along 88W and south to western Honduras reaches south to near 09N. It is moving westward at about 15 to 20 kt. Weakening isolated moderate convection is within 120 nm west of the wave axis from 09N to 11N. This wave is forecast to reach near 90W early on Sunday, and to near 95W on Monday with its northern portion pushing through the Gulf of Tehuantepec and vicinity. The axis of a tropical wave is extends from 06N110W to 17N108W. Low pressure of 1007 mb is on the wave axis near 10N110W. Scattered moderate/isolated strong convection has recently developed from 08N to 09N between the wave and 112W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N79W to 09N92W to 11N100W to low pressure near 10N110W 1007 mb. Scattered moderate isolated strong convection is within 60 nm north of the axis between 82W and 85W, and within 90 nm south of the axis between 90W and 95W. Scattered moderate convection is within 120 nm of the axis between 105W and 108W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Tropical Storm Kay continues to impact the waters southwest of the tip of Baja California, and it is described in detail in the special features section. Light to moderate winds prevail outside of Kay in a relatively weak pressure pattern, which will persist into early next week. Combined seas of 4 to 7 feet outside of Kay will subside gradually early next week. The Gulf of Tehuantepec: northerly offshore winds will continue to pulse to fresh levels during the late night and early morning hours with nocturnal drainage flow. The northerly flow may briefly pulse to moderate to strong intensity late Monday night into Tuesday with passage of the forecast tropical wave as described above. Model guidance then suggests that the northerly flow may increase further to fresh to strong intensity on Wednesday and Thursday of next week as high pressure ridging from the Gulf of Mexico presses southwest across southeastern Mexico. Scattered moderate convection is occurring over and just along the east side of southern Baja California from 23N to 24N due to a shortwave trough lifting northeastward across the southern portion of the Gulf of California into northwest Mexico. This activity is expected to continue into tonight, and may be attendant by gusty winds. Similar activity is occurring just inland Mexico from near Acapulco to Los Mochis. Additional activity of same type intensity may develop over the offshore waters of the southern tip of Baja California late tonight, and into Sunday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Offshore winds will pulse to fresh levels in the Gulf of Papagayo and adjacent areas during the late night and early morning hours on Tuesday and on Wednesday. Light to moderate winds will prevail on either side of the monsoon trough. Combined seas of 4 feet to 7 feet will slowly subside through Monday as supporting long period south-southwest swell decays. Seas are expected to be about 5 to 6 ft downstream of the Gulf of Papagayo through Monday. A tropical wave, currently along 88W, is forecast to reach 90W early on Sunday and near 95W on Monday. ELSEWHERE... High pressure of 1030 mb centered northwest of the area extends a weakening ridge southeastward to 32N140W and to near 23N123W. The resulting weak pressure gradient is maintaining generally light to gentle winds with seas in the 4 to 6 ft range. These general conditions will prevail into Monday. Cross-equatorial mixed southeast and southwest swell, originating from a long- duration ongoing swell event in the South Pacific region, are forecast to propagate into the far southern waters of the high seas area beginning Sunday night south of a line from 02S120W to 02S110W to 03.4S106W. Resultant seas are forecast to be up to 8 ft. Wavewatch model guidance projects this area of swell to spread eastward to near 98W by Mon night. $$ Aguirre