000 AXPZ20 KNHC 091506 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1505 UTC Mon Mar 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 1450 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Overnight scatterometer data indicate that gale-force winds continue over the Gulf of Tehuantepec. These strong northerly winds are the result of strong high pressure over the western Atlantic, along with local drainage flow. Seas are estimated to be as high as 14 ft over and downstream of the Gulf region. Winds to gale force are expected to continue until early Wednesday before subsiding as the high over the western Atlantic weakens and shifts eastward. For more information please read the latest High Seas Forecast issued by the National Hurricane Center under AWIPS/WMO headers FZPN03 KNHC/HSFEP2 or at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for further details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A trough extends from 07N82W to 01N100W. The intertropical convergence zone continues from 01N100W to 06N117W to beyond 06N140W. Scattered moderate convection is noted from 03N to 05N between 92W and 97W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for details on an ongoing gale gap wind event in the Tehuantepec region. Winds remain generally light offshore of the Baja California peninsula and over the Gulf of California as weak high pressure remains situated over the region. Despite the low winds, seas have increased to 5 to 7 ft across much of the area due to a combination of northwesterly swell from a large low pressure area to the west and cross-equatorial southerly to southwesterly swell. A stream of moisture, with embedded showers and some thunderstorms, exist from 20N-27N. This activity is associated with a subtropical jet that lies above that area. Looking ahead, the weak area of high pressure is expected to shift eastward and weaken some more as the low currently near 31N 132W moves eastward closer to the region. This low is expected to weaken on its approach, but it should be strong enough to enhance southerly flow off Baja California Norte later today, with seas building to 8 ft. The winds and seas will diminish by the Wed as the weakening front and associated low move across the region. However, NW winds are expected to funnel over the southern Gulf of California and over the waters between Los Cabos and Cabo Corrientes late Tue through Wed ahead of the front. Pulses of fresh westerly gap winds are possible over the northern Gulf of California late Thu into Fri as the low moves eastward toward those areas. Meanwhile, farther south, long period southerly swell will dominate the Mexican offshore waters south of 20N through late week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: A tight pressure gradient between high pressure north of the area and lower pressure to the south continues to support northeast 20-30 kt winds across the Papagayo region. This flow tends to be the strongest during the early morning hours enhanced by drainage flow across the area. These winds will continue across the region through the middle of the week, with winds pulsing to near gale force each night and into the early morning hours. Wave heights will peak around 10 ft downstream of the Gulf each morning during the next few days. As the high shifts eastward and weakens over the western Atlantic, these winds should subside late in the week. Gulf of Panama: High pressure north of the area will maintain fresh to strong north to northeast winds over and downstream of the Gulf of Panama for the next few days. Wave heights with these winds are expected to reach up to 10 ft well downstream of the Gulf, mixing with a component of longer period southerly swell. Elsewhere, mixed northeast and southwest swell is resulting in a large area of high seas, up to 11 ft, across much of the waters off the coast of Central America. These wave heights are expected to only slowly subside during the next couple of days. REMAINDER OF THE AREA... A cold front, associated with a large low pressure system just north of the area, is currently analyzed from 30N127W to 22N140W. Earlier scatterometer and ship data indicate that strong NW winds, up to 30 kt, were occurring behind the front over the northwestern waters. Concurrent altimeter satellite passes show the seas of 12 to 18 ft behind the front, likely with a component of NW swell. A few showers and thunderstorms are occurring near the front, north of 28N and on the south side of the low north of 28N between 130W and 134W. An area of fresh to strong SE winds and seas to 9 ft are likely still occurring between high pressure off Baja California Norte and a trough in the deep tropics from 08N to 15N along 129W/130W. These winds and seas should diminish later today. Elsewhere, the weaken that normal subtropical ridge is resulting in light to moderate trades across the deep tropics. The surface low and associated front will weaken as they continue eastward during the next few days, reaching 120W by late Wed. This will allow winds to diminish over waters north of 25N. NW swell in excess of 8 ft will cover most of the area north of 10N and west of 120W by the middle of the week before subsiding. By late week, high pressure will build north of the area in the wake of the front and low, supporting fresh trade winds and seas to 8 ft in mixed swell over the deep tropics west of 120W. Farther east, seas from 8 to 11 ft cover a large area generally south of 12N between 90W and 115W. This is associated with confused seas related to a mix of longer period southerly swell and components of shorter period NE and E swell related to the persist gap wind events in Tehuantepec and Papagayo. These seas will gradually subside during the next few days as the gap winds diminish. $$ Cangialosi