000 AXPZ20 KNHC 042216 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Thu May 4 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 1800 UTC surface analysis and satellite imagery through 2115 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning...A strong cold front moving across the Gulf of Mexico has reached the southwest portion of the gulf this afternoon and will move into the eastern Bay of Campeche tonight. High pressure is forecast to surge southward along the eastern Mexico coast in the wake of the front. Winds across the Gulf of Tehuantepec will quickly increase to fresh to strong from the N late tonight, then reach minimal gale force by around sunrise Friday. Gale force winds will then persist until around sunrise Saturday before diminishing to fresh to strong through Saturday evening. Maximum seas will build 13 to 14 ft Friday afternoon and night, then gradually subside to less than 8 ft by Sunday morning. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough axis extends from 09N73W TO 08.5N94W TO 07N113W. The ITCZ extends from 05N117W TO 06N135W. Scattered to locally numerous moderate to strong convection is noted from 03.5N to 11N between 87W and 102W. Scattered moderate to strong convection is noted within 240 nm N and 120 nm S of the ITCZ between 122W and 135W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the special features section for information on the Gulf of Tehuantepec Gale warning. Mainly light to moderate NW winds will prevail across the waters NW of Cabo Corrientes through Friday morning, with light to moderate W to SW winds prevailing E of Cabo Corrientes to Puerto Angel. Mainly light and variable winds currently prevail in the Gulf of California. Combined seas of 5-7 ft prevail in the open waters of the Pacific, with seas 2 ft or less in the Gulf of California except up to 4 ft near the entrance. A cold front will approach the SW United States and NW Mexico by the end of the week, then move across NW Mexico Friday night through Sunday. Winds will increase slightly across the Pacific waters of Baja California Friday through Saturday night ahead of the front, then become fresh to near gale force in the northern Gulf of California ahead of the front Friday night into early Saturday. Behind the front, fresh to strong winds are forecast offshore of Baja California Norte and in the northern Gulf of California. Seas will build to 8-12 ft in N swell N of 22N W of Baja California behind the front through early next week. Seas will build to 5-8 ft in the northern Gulf of California where the strong winds will occur. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle SW to W winds prevail S of 9-10N this afternoon, while gentle to moderate E to NE winds are occurring N of 10N. Only minor fluctuations in wind speed and direction are expected across the area through Sat, before some uncertainty in the forecast arises Sun through the middle of next week. Seas will remain mainly 4-6 ft in SW swell. Looking ahead, global models continue to indicate a chance for an elongated cyclonic circulation to develop about the current trough extending across the region. This may be the early beginning of the monsoon season. Global models also indicate that upper atmospheric conditions will become very conducive for sustained deep convection this weekend through the middle of next week across central America and the adjacent offshore waters as well as southeastern Mexico. The models are not in agreement in the development of a low pressure system developing within this larger elongated gyre, but do suggest that a surface low or two will eventually develop across the tropical eastern Pacific, between Central America and 95W late between Sunday and the middle of next week. Little movement of this possible low pressure area is expected initially, which could lead to very heavy rainfall across portions of the region from Costa Rica NW toward SW Guatemala. REMAINDER OF THE AREA... High pressure of 1016 mb centered near 22N127W extends a ridge to the E and W of the center. A weak trough extends into the area from 32N124W to 21N131W. An overall weak and broad pressure pattern results from these features with fairly tranquil marine conditions. Combined seas are 4-7 ft in mixed NWly across the majority of these open Pacific waters. A cold front has reached the NW corner of the discussion area near 30N140W this afternoon and will usher in fresh to strong northerly winds behind it as it moves ESE, and stronger high pressure builds in its wake. A new set of NW swell will also accompany the front with seas of 8 ft or greater covering much of the area N of 20N W of 120W this weekend. Moderate to fresh trades will cover this area for the early part of next week along with combined seas of 5-8 ft, except 8-14 ft seas over the NE portion due to stronger winds N of the area off southern California. $$ Stripling