000 AXPZ20 KNHC 090215 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Mon Mar 09 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 0000 UTC surface analysis and satellite imagery through 0200 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A tight pressure gradient over the Isthmus of Tehuantepec due to high pressure ridging that extends southwestward from the southeastern U.S. to southern Mexico interacting with lower pressure to the south of Mexico continues to bring strong northerly gale force winds across the Gulf of Tehuantepec region. Peak significant wave heights are in the 10-14 ft range across the Gulf of Tehuantepec. In addition, the area of high sea state, with peak significant wave heights reaching up to 12 ft, have propagated to the south and southwest of the Gulf region to near 11N97W primarily due to resultant north to northeast swell. These gale force winds will diminish to minimal gale force by early Mon afternoon, then diminish to just below gale force later in the afternoon as the gradient slackens some, then pulse back up to gale force early Mon night. A slight tightening of the gradient should allow for these winds to reach back to strong gale force by early on Tue then diminish back to minimal gale on Tue afternoon. Model guidance indicates that these winds will pulse back up to gale force Tue night before diminishing to fresh to strong northerly winds Wed through Thu. 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 09N85W to 05N89W to 01N95W, where earlier scatterometer data indicated that the ITCZ begins and continues to 02N105W to 05N117W and to 08N129W where it is briefly interrupted by a trough that extends from 22N126W to 13N128W to 06N129W. It resumes at 08N132W and continues to beyond the area at 07N140W. A second ITCZ is analyzed from 02S86W to 04S97W to 02S109W. Scattered moderate convection is noted within 120 nm north of the first ITCZ axis between 124W and 129W. 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. A weak 1019 mb high pressure center is analyzed near 29N119W. The related gradient is allowing for light to gentle winds, in anticyclonic fashion, to be present over these waters. Wave heights are in the range of 4-6 ft range in a northwest swell attributed to a large extra-tropical low pressure system with attendant fronts that is well to the west of the California coast this afternoon. Slightly higher wave heights are in the northern part of these waters. A sub-tropical jet stream branch (atmospheric river type feature) is transporting ample mid and upper-level moisture in the form of overcast to broken clouds to over most of the Baja California Peninsula, the Gulf of California and into northwestern Mexico. Embedded areas of rain along with scattered showers and isolated thunderstorms are possible underneath these clouds. These clouds are observed from 20N to 28N and east of about 122W. The high pressure center is forecast to be shunted eastward toward the central Baja California Peninsula by late tonight n response to the approaching aforementioned extra-tropical low pressure system and attendant front. This high center is expected to then dissipate early on Mon. The low pressure system and attendant fronts is expected to weaken as it tracks southeastward during the next few days. The weakening low is expected to cross the region around the middle of the 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 has resulted in 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 to near 10 ft downstream of the Gulf each morning during the next few days. 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. Elsewhere, mixed northeast and southwest well 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 change little during the next couple of days as long period southerly swell reaches these waters on Monday. REMAINDER OF THE AREA... A strong cold front extending from a low pressure system north of the area enters the discussion region near 30N135W and extends southwestward to 28N 140W. West to northwest winds of 20-30 kt along with wave heights in the range of 10-16 ft are present behind the front. This low is weakening the usual subtropical ridge over the region, resulting in light to moderate trades across the deep tropics. A weak trough is noted from 22N117W to 19N124W, while another trough is seen along a position from 18N125W to 13N128W. Latest satellite imagery shows small clusters of scattered moderate convection from 09N to 12N between 122W and 127W. This activity is quickly moving eastward. Winds associated with the second trough are expected to remain in the gentle to moderate range through Mon, while northeast to east winds near the first trough are currently in the moderate to fresh range, but model guidance has them increasing to fresh to strong speeds by early this evening as the pressure gradient between it and the high pressure system west of Baja California tightens. These winds are forecast to expand in coverage through early Mon along with resultant wave heights building to the range of 8-10 ft. These conditions then diminish begin to diminish Mon as the high pressure system dissipates. Looking ahead, the cold front will continue to move eastward across the northern and central waters through Mon in association with the low pressure system. Strong to near gale force winds behind the front will build seas up to 12-20 ft north of 25N and west of 130W by Mon. The low is expected to track eastward and weaken through Mon night allowing for the cold front to also weaken. Large long-period northwest swell associated with this system will propagate southward during the next few days. $$ Aguirre