000 AXPZ20 KNHC 192205 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Tue May 19 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 2145 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from a 1009 mb low over northwestern Colombia near 10N76W west-southwest to across northern Panama/southern Costa Rica, then to the coast at 09N84W and to 09N90W to 10N100W to low pressure center near 10N111W 1008 mb and to low pressure near 08N125W 1008 mb, where latest scatterometer data indicates that it transitions to the ITCZ to beyond the area at 07N140W. Scattered moderate to isolated strong convection is seen from 04N to 10N between 78W-81W, also within 120 nm south of the trough between 111W-118W, between 110W-115W and within 60 nm north of trough between 120W-124W. Scattered moderate convection is within 120 nm south of the trough between 91W-99W and between 105W-110W. Similar activity is within 60 nm north of the ITCZ between 129W-135W, between 137W-140W and also within 30 nm of the trough between 85W-88W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A weakening cold front extends from the southwestern U.S. to over the northern Gulf of California. It continues southwestward as a trough to 25N120W. Mainly gentle west winds are south of the front to near 29N, while gentle to moderate north winds are north of the front. Wave heights in the northern Gulf are low, in the 1-3 ft range. Rather strong high pressure building east- southeast over these waters will support fresh to strong winds and wave heights to 10 ft north of Cabo San Lazaro through Wed night. Farther south, local drainage flow along with a modest increase in the high pressure over the Gulf of Mexico is allowing for fresh north gap winds through the Gulf of Tehuantepec this morning. These winds will become light and variable this afternoon as the high pressure shifts eastward while weakening. Elsewhere, gentle to moderate mainly westerly breezes persist over Mexican offshore waters, with wave heights of 4-6 ft due to southwest swell. Agricultural fires are occurring over some sections of western Mexico as clearly being observed in satellite imagery. The resultant smoke is the densest just inland the coast. The imagery depicts smoke and haze spreading westward across the offshore waters from near Puerto Angel to near Manzanillo. These conditions may reduce visibility over these waters through at least Wed. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... North of the monsoon trough, generally light to gentle winds are present, whereas south of the trough, moderate south and southwest winds are confirmed by recent ship observations and earlier overnight scatterometer data. Wave heights across this area are in the 4-6 ft range. The earlier observed shower and thunderstorm activity that was along the coast of northern Central America this morning has diminished during the day, but with ample deep-tropical layer moisture in place along with favorable winds expect for similar activity to re-develop during the overnight hours. Scattered showers and isolated thunderstorms currently over the offshore waters should remain active through tonight, and perhaps increase in coverage late tonight. Looking ahead, gentle to moderate winds will persist much of the week. The monsoon trough will likely remain active, leading to more significant showers and thunderstorms for the waters offshore Colombia, Panama, and Costa Rica through at least Thu. REMAINDER OF THE AREA... A weakening cold front extends from the central Baja California Peninsula southwestward to 25N120W, where it becomes a trough to 23N130W and to 22N140W. Strong high pressure is building east-southeast across the northern and central waters. The high pressure is anchored by a 1030 mb high center that is well northwest of the area near 36N144W. Northwest swell in the wake of the cold front is producing peak wave heights to 10 ft. This swell will begin to decay in about 42 hours allowing for these wave heights to lower to 8 ft in mixed northwest and south swell. Northwest swell producing wave heights to a peak of 9 ft is confined to the western half of the area from 06N to 19N and west of 116W. This swell will decay to a peak of 8 ft by early Wed afternoon in northwest swell and change little through Thu as it mixes with a northeast swell component. Farther south, scattered strong thunderstorms are quickly increasing within 30 nm of a line from 13N107W to 12N111W to 11N114W. This activity is associated with a weak trough in that general area further aided by a mid-level shortwave trough that is passing just to its northeast. Scattered showers and thunderstorms are also increasing near the 1008 mb low that is on the western edge of the monsoon trough near 08N125W. Satellite imagery shows a small circulation consisting of low-level clouds with this low. The pressure gradient between this low and the strong ridging over the northern and central waters is allowing for fresh winds to exist within about 180 nm north of the low. The low will continue in a general westward motion through Thu. $$ Aguirre