AXPZ20 KNHC 190359

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Tue Jan 19 2021

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 0300 UTC.


The monsoon trough extends from the coast of Costa Rica near 09N84W to 08N92W to 06N106W. The ITCZ continues from near 06N106W to a 1010 mb low near 07N119W to 09N129W to 07N140W. Scattered moderate isolated strong convection is noted from 04N to 09N between 90W and 103W, from 05N to 13N between 105W and 118W, and from 05N to 15N between 122W to 140W.


Gentle to moderate winds will prevail across the offshore waters of Baja California and SW Mexico. A 1008 mb low pressure area near 30N118W will drift eastward tonight with gentle to moderate westerly winds expected south of Punta Eugenia overnight. Deep layered low pressure will sink southward tonight through Tuesday and intensify as it merges with the 1008 mb low. Fresh south to southwest winds will develop across most of the Baja waters by Tue. The low will sink slowly eastward Tue night through Wed and produce fresh to strong south to southwest winds through Wed afternoon. By Wed into Thu, the low is expected to weaken with winds diminishing quickly as it moves onshore across Baja Norte Thu evening. Large NW swell propagating through the Baja waters during this time will maintain seas in excess of 8 ft through Thu and 10-11 ft or greater across the outer waters of Baja Norte Tue through Wed.

Gentle southerly winds generally prevail across the Gulf of California waters this afternoon. As the surface low pressure deepens offshore of Baja Norte, south to southwest winds will become fresh to locally strong across central and north portions of the Gulf by Tue afternoon through Wed. Seas will build to near 6 ft during this time. Winds and seas will diminish significantly on Thu.

The pressure gradient across the Tehuantepec region continues to gradually weaken this afternoon, with strong northerly winds expected across the Gulf north of 13N with seas 8-11 ft. The supporting high pressure across the Gulf of Mexico will shift NE through Tue and act to gradually weaken the local pressure gradient. Expect fresh to strong winds to pulse nightly through early Fri with downstream seas peaking at 8 to 10 ft each early morning.


Fresh offshore gap winds will pulse to strong across the Papagayo region nightly through early Fri. Moderate northerly winds will pulse to fresh across the Gulf of Panama through early Thu. Mainly gentle to moderate winds are forecast elsewhere. Seas will build slightly from west to east in mixed long period S and NW swell Wed through early Fri.


High pressure north of the area extends a ridge into the northwest forecast waters. The pressure gradient between the ridge and lower pressures near the convergence zone is supporting moderate to fresh trade winds north of the convergence zone to near 18N west of 120W. Seas in this area are in the 8-11 ft range in a mix of NW swell and NE to E wind waves and are expected to persist through midweek.

The developing low pressure offshore of Baja California Norte on Tue will support an area of fresh to strong northerly winds on the western side of the low, N of 25N between 120W and 131W, early Tue through Wed. Seas will build to 14 ft through Wed as NW swell mixes with the wind wave generated by the low pressure.

Large NW swell continues moving south and east across the open waters of the northeast Pacific with seas up to 14 ft near 30N125W. NW swell will maintain seas greater than 8 ft over much of the forecast waters west of 100W through Tue night. The swell will subside south of 20N and west of 115W by Thu, while fresh northerly swell develops north of 20N in association with the deepening area of low pressure. Seas will subside throughout the open waters by the end of the week with the next significant northerly swell event expected to arrive by the weekend.

$$ AReinhart