000 AXPZ20 KNHC 150319 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 319 UTC Thu Feb 15 2018 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. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: High pressure ridging southward across eastern Mexico and the adjacent waters, to the east of the Sierra Madre Oriental range, is supporting gale force winds offshore and across the Gulf of Tehuantepec. The gale force winds will diminish Thu by afternoon as the ridging weakens, with a round of strong to near gale force winds Thu night, and then fresh to strong winds pulsing each night thereafter. Gulf of Papagayo Gale Warning: Offshore northeast winds will pulse to minimal gale force in the offshore Gulf of Papagayo waters, with brief possible lulls during the afternoon hours. A surrounding area of fresh to strong winds, including the Gulf of Fonseca will also persist. Downstream seas will build to 8-11 ft during the strongest winds through Thu evening. Winds are expected to decrease below gale force by Fri afternoon, with pulsing fresh to near gale expected each night thereafter through the weekend. Please refer to the East Pacific High Seas Forecast under AWIPS/WMO headers HSFEP2/FZPN03 KNHC for more details on both gale warnings. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 10N82W to 04N97W. The ITCZ axis continues from 04N97W to 05N110W, then resumes from 10N128W to 07N140W. No significant convection is noted. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for more details on the gale warning in the Gulf of Tehuantepec. Light and variable winds and seas of 2 ft or less will prevail across the Gulf of California through tonight, becoming northerly and increasing to moderate to locally fresh Thu through Fri as the pressure gradient tightens. The gradient will then weaken this weekend allowing for conditions to once again improve. Looking ahead, a cold front will approach southern California and Baja California Norte by the end of the weekend, with southwest flow ahead of it increasing to 20-30 kt in the far northern Gulf into next Mon. Fresh northwest swell of 6-8 ft will also propagate into the open Pacific waters of Baja California Norte. Elsewhere across the open Pacific offshore waters of Mexico, light to moderate winds will prevail through the next several days, except pulsing to fresh offshore of Cabo Corrientes Fri night through Sun. Seas will mainly be 4-6 ft in mixed southwest and northwest swell. Scattered showers associated with an inverted trough southwest of the area will continue to move to the northeast across the waters north of 20N ahead of a deep associated mid to upper level trough. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please see the Special Features section above for more details on the gale warning in the Gulf of Papagayo. For the Gulf of Panama, fresh to strong northerly winds will continue to extend southward along the Azuero Peninsula with a locally tight pressure gradient. These winds will persist through Fri afternoon, even approaching 30 kt around 06Z tonight. Elsewhere, gentle to moderate offshore flow will prevail north of 09N, and light to gentle south-southwest winds will generally prevail south of 09N. REMAINDER OF THE AREA... Low pressure of 1011 mb is near 17N124W with a surface trough extending from 24N118W to the low to 12N126W. Associated scattered moderate convection is within an area bounded by 23N110W to 15N113W to 08N120W to 12N125W to 21N125W to 26N112W to 23N110W. This convection is streaming off to the northeast ahead of a deep mid to upper level trough which extends from 32N125W to 17N123W to 10N110W, and around a large upper level anticyclone positioned over central Mexico near 22.5N103W. Recent scatterometer data showed fresh to near gale force winds from 17N to 25N within 180 nm northwest of the trough along with 8-11 ft seas. The pressure gradient between the trough and high pressure well northwest of the area is supporting moderate to fresh trades elsewhere north of the convergence zone and west of 120W, with associated fresh seas of 8-9 ft in mixed swell. The low is forecast to gradually dissipate through the end of the week while moving southwest-west, with the trough weakening as well. This will allow for the pressure gradient and trades to weaken, with the residual seas subsiding through the upcoming weekend. $$ Lewitsky