000 AXPZ20 KNHC 271529 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1529 UTC Mon May 27 2019 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. ...SPECIAL FEATURES... ...Heavy Rainfall Potential Over Central America... A large low level cyclonic circulation that is typical for this time of the year, called a Central American Gyre, is forecast to persist across the far eastern tropical Pacific and Central America for the next several days. This will continue bringing abundant moisture and areas of heavy rainfall across portions of Central America. Computer model forecasts have begun to indicate the chance for a further increase in moisture and instability associated with this feature Tue through Wed, which could lead to a very significant rainfall event. Life-threatening flash flooding and mudslides will be possible in areas of mountainous terrain. Please refer to your local meteorological service for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N78W to 1008 mb low pressure near 09N89W to 13N97W to 06N135W. The ITCZ extends from 06N135W to beyond 07N140W. Scattered moderate to strong convection is noted from 06N to 10N between 85W and 88W. Scattered moderate isolated strong convection was noted from 07N to 12N between 97W and 98W. Scattered moderate convection was noted from 05N to 07N between 127W and 132W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A weak cold front reaches across the central portion of the Gulf of California, just south of Tiburon Island, then over the northern portion of Baja California Sur and into the eastern Pacific just south of Punta Eugenia. The front is supported by a deep layer low north of the area moving through the Great Basin into the Rockies. Strong SW gap winds were active behind the front over the Gulf of California along 30N ahead of the front, which have shifted to NW earlier over the northern Gulf as the front moved through the region. Ship observations and an earlier scatterometer satellite pass indicated fresh to strong NW winds off the southern portion of Baja California Sur between Cabo San Lucas and Cabo San Lazaro. Farther south, fresh to strong gap winds are also ongoing through the Gulf of Tehuantepec, between lower pressure farther south into the tropics, and high pressure over central Mexico. These gap winds were supporting a plume of showers and thunderstorms during the early morning hours, merging with a line of showers parallel to the coast due to overnight drainage flow. Recent altimeter data show seas 5 to 6 ft in open waters, except closer to 8 ft near Guadalupe Island due to NW swell. The cold front moving into the central Gulf of California and the northern portion of Baja California Sur will dissipate through this evening. The strong winds across the northern Gulf of California behind the front will diminish early today accordingly. Elsewhere, high pressure will build across the offshore forecast waters north of 20N to produce fresh to locally strong NW to N winds off Baja California through Tue night. The ridge weakens thereafter, allowing winds to diminish. Seas will subside accordingly as well, except for off the northern coast of Baja California Norte where another round of NW swell will approach the region. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please see the Special Features section for more information about the Central American Gyre, which will continue to bring locally heavy rains to parts of Central America and the adjacent offshore waters through at least mid week. Gentle to moderate SW to W winds prevail south of the monsoon trough, with seas in the 4-7 ft range. Moderate to locally fresh winds, and seas in the 5-6 ft range prevail N of the monsoon trough. Low pressure of 1008 mb embedded within the broad gyre will meander offshore the coast of Nicaragua the next couple of days. The monsoon trough will lift northward through the early part of the week, with southerly monsoon flow strengthening, potentially to 20-25 kt by Tue. Seas will build to 8-12 ft by mid week in this enhanced monsoon flow and southerly swell. REMAINDER OF THE AREA... A ridge extends from 1027 mb high pressure centered northwest of the area near 32N139W through the Revillagigedo Islands. The pressure gradient between the ridge and lower pressure in the vicinity of the ITCZ is supporting moderate to fresh NE winds across much of the area north of the ITCZ and west of 120W. Moderate to fresh winds will continue to prevail over this area the next several days. SW cross equatorial swell will dominate the forecast waters south of 10N and west of 95W for the next few days, with new swell arriving late Tue. Seas 8 ft or greater will cover much of the forecast waters south of 10N between 85W and 115W by late Tue. $$ Christensen