000 AXPZ20 KNHC 091551 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...TROPICAL WAVES... A tropical wave extends from the western Caribbean Sea southward across western Panama to near 05N81W, moving west around 10 kt. Associated convection is described below. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from low pressure over northern Colombia near 09N74W to low pressure near 07N93W to 13N104W to low pressure near 10N117W to low pressure near 10N130W to 08N134W. The ITCZ continues from 08N134W to 06N140W. Numerous moderate and scattered strong convection is noted within 10N86W to 05N89W to 02N78W to 09N74W to 10N86W. Scattered moderate and isolated strong convection is noted from 10N to 14N between 87W and 92W, from 05N to 08N between 93W and 97W, within 13N108W to 15N104W to 12N99W to 04N98W to 07N107W to 13N108W, from 09N to 11N between 110W and 112W, and from 04N to 08N between 135W and 140W. Scattered moderate convection is noted from 06N to 11N between 114W and 119W. 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 to strong levels early this morning along with seas up to 6 ft. Mainly gentle to moderate NW winds prevail elsewhere. Seas are 6-9 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 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 near gale thereafter. 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... Winds offshore of western Panama and Colombia will increase to 15 to 20 kt this afternoon 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 building 8-10 ft between Ecuador and the Galapagos Islands today. Similar wave heights, associated with the same swell event, are 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. 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 1026 mb high pressure near 32N134W 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 15N-22N and W of 130W. Recent altimeter satellite data show seas of 8-9 ft in mixed shorter period NE swell and long period southerly swell. Fresh northerly swell with seas of 8-9 ft is N of 20N and E of 126W. This swell will decay through tonight. The ridge is expected to weaken as a weakening cold front approaches 30N140W by late Wed night into 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. 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