Tropical Weather Discussion
Tropical Weather Discussion NWS National Hurricane Center Miami FL 1501 UTC Tue Mar 21 2017 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. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The ITCZ extends from 03N95W to 02N105W to 04N125W to 03N140W. Scattered moderate to isolated strong convection is noted within 240 nm north of axis between 95W and 100W, between 110W and 115W, and between 120W and 130W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... In the Gulf of Tehuantepec, gale force winds are starting to diminish this morning as high pressure starts to weaken north of the area. However, the pressure gradient will remain tight enough to support strong to near gale force gap wind pulses through the Gulf of Tehuantepec tonight and Wednesday night with the assistance of local overnight drainage flow. Seas will will fluctuate up to 10 ft over the next couple of mornings with the near gale force pulses. A smaller and quicker pulse of strong gap winds is expected Thursday night, with generally moderate flow thereafter. Northerly swell generated by this gap wind event continues to propagate southward mixing with swell generated in the Gulf of Papagayo region as well as with cross equatorial southwest swell. This is resulting in combined seas of up to 9 ft in waters from from 03N to 12N between 90W and 105W. Seas will begin to gradually subside tonight. Elsewhere, a 1021 mb high pressure centered near 24N122W will maintain gentle to fresh northwest winds across the offshore waters west of Baja California through Wednesday evening with seas of 4 to 6 ft. A cold front is expected to push into northern Baja California by Wednesday night. A tight pressure gradient will result between the front and high pressure building behind it, thus supporting fresh to strong northwest winds off the Baja California coast Wednesday night through early Friday morning. Seas off Baja California will build to 6 to 9 ft during that period. Winds will also increase across the north and central Gulf of California with the frontal passage Wednesday night through Thursday, and across the southern Gulf of California Thursday afternoon through early Friday morning with seas to 8 ft in the southern Gulf of California. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... High pressure will prevail over the northwest Caribbean and Gulf of Mexico, which will allow for the continuation of fresh to strong gap winds across the Gulf of Papagayo through Friday with seas to 8 ft. Fresh to strong northerly winds are also expected in the Gulf of Panama and downwind to about 05N with seas less than 8 ft through Wednesday. Otherwise, light to gentle winds and combined seas of 3-5 ft are expected to continue the next several days elsewhere. Confluent low level flow is support moderate to strong convection along the ITCZ. REMAINDER OF THE AREA... High pressure of 1021 mb located near 24N122W will move little over the next 24 hours. A cold front extends from 30N126W to beyond 22N140W. This front will reach from 30N120W to 25N127W early Wednesday, then continue eastward into the northern Baja California peninsula and the northern Gulf of California through Thursday. Seas will build to 8 to 12 ft north of 25N and west of 130W in the wake of this front tonight. A third cold front is forecast to reach the northwest forecast waters early Friday morning, followed by a new round of northwest swell. Farther south, seas will build to 8 to 9 ft from 05N to 15N west of 120W by tonight in a broad mix of long period swell and shorter period trade wind waves. Scattered moderate to isolated strong thunderstorms are ongoing to the north of the ITCZ due to confluent flow in the lower levels and enhancement aloft from an upper level trough to the west.