526 AXPZ20 KNHC 092007 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Tue Jun 9 2020 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 1930 UTC. ...SPECIAL FEATURES... Volcanic Ash Advisory: Sangay Volcano in Ecuador near 02S78W is in a state of unrest and producing volcanic ash per the Satellite Analysis Branch in Washington, D.C. and per latest high resolution visible satellite imagery. Also, site SEGU (Jose Juaquin del Olmedo International Airport in Guayaquil, Ecuador) has reported volcanic ash for several observations. The volcanic ash plume is extending offshore of Ecuador to near 83W. Mariners are urged to exercise caution and report any observations to the National Hurricane Center by calling +1-305-229-4424. Please see the latest NWS High Seas Forecast at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for details. ...TROPICAL WAVES... A tropical wave extends from the western Caribbean Sea southward across western Panama to near 03N83W, moving west at 5 to 10 kt. Associated convection is described below. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from low pressure over northern Colombia near 10N75W to low pressure near 07N94W to 13N104W to low pressure near 10N119W to low pressure near 10N130W. The ITCZ continues from 10N130W to 06N140W. Numerous moderate and scattered strong convection is noted from 03N to 10N between the coast of Colombia and 89W. Scattered moderate and isolated strong convection is noted from 04N to 09N between 93W and 97W, from 05N to 15N between 100W and 106W, from 09N to 13N between 106W and 113W, from 07N to 08N between 114W and 116W, and from 06N to 08N between 126W and 130W. Scattered moderate convection is noted from 10N to 14N between the coast of Central America and 94W, and from 04N to 08N between 135W and 139W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Broad troughing extends from southern California to across the Baja California Peninsula with ridging extending to the west just beyond the offshore waters boundary. A locally tight pressure gradient is over the northern Gulf of California with NW-N winds at fresh levels per recent scatterometer data, along with seas up to 5 ft. Mainly gentle to moderate NW winds prevail elsewhere. Seas are 5-8 ft west of the Baja California Peninsula in NW swell, and around 6 ft elsewhere, except 3 ft or less in the central and southern Gulf of California. The swell west of Baja California will subside by tonight. The winds in the northern Gulf of California are already in the process of diminishing as the pressure gradient weakens. Ridging will dominate west of 100W for the remainder of the forecast period. The pressure gradient will tighten offshore of Baja California by the end of the week into the weekend due to troughing extending from the SW United States to NW Mexico, increasing NW winds to fresh to strong west of Baja California. Seas will build back to 6-9 ft as a result in fresh NW swell and wind waves. Conditions will improve by the end of the weekend as the pressure gradient weakens across the region. In the Gulf of Tehuantepec, mainly gentle to moderate onshore flow will prevail through Thu morning with 5-7 ft seas in long period SW and NW swell. By Thu afternoon, a locally tight pressure gradient will develop with winds becoming northerly at fresh to strong levels. Model guidance shows the potential for a gale force gap wind event by late Thu night into early Fri, then strong to near gale thereafter with overnight pulses to minimal gale. Seas will build to 10-13 ft during this time period due to the winds as well as long period southerly swell. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please read the Special Features section for more details about the Volcanic Ash Advisory offshore of Ecuador. Winds offshore of western Panama and Colombia at 15 to 20 kt will persist tonight due to a locally tight pressure gradient. Otherwise, mainly gentle to moderate S to SW winds will prevail across the offshore waters. Cross equatorial S-SW swell will continue to propagate across the region, with seas of 7-10 ft between Ecuador and the Galapagos Islands today. This set of swell is forecast to reach the offshore waters of western Panama and Costa Rica tonight into Wed, including also the Azuero Peninsula and the entrance to the Gulf of Panama, potentially causing hazardous surf conditions. Seas will finally subside to less than 8 ft by Sat night, however another southerly swell event is likely for the second half of the weekend. REMAINDER OF THE AREA... A ridge extends from 1027 mb high pressure near 31N137W to near 20N116W. The pressure gradient between the ridge and lower pressures in the vicinity of the ITCZ continues to support an area of moderate to fresh trade winds from 14N-22N and W of 128W. Recent altimeter satellite data show seas of 8-9 ft in mixed NE wind waves and long period southerly swell. The ridge is expected to weaken as a weakening cold front approaches 30N140W by early Thu. This will allow the trade winds to diminish slightly across most of the trade wind zone, however the development of a weak trough along the ITCZ west of 130W will keep the gradient tight enough to support fresh to locally strong trades winds from 10-20N and W of 130W into late week, with seas of 8-9 ft persisting. Fresh northerly swell with seas of 8-9 ft is N of 21N and E of 125W. This swell will decay through tonight, with a similar setup and conditions Sat night through Sun night. Long period southerly swell is breaching the equator, and will propagate across the waters S of 10N between 90W-110W through the end of the week. $$ Lewitsky