000 AXPZ20 KNHC 070300 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 207 UTC Sun Jan 7 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 0230 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: Strong high pres ridging over the western Gulf of Mexico continues to support gale force N-NE winds over the Gulf of Tehuantepec. Winds will subside below gale force on Sun evening, then fall to moderate speeds by Mon morning as the ridging over the Gulf of Mexico weakens and shifts E. NE swell generated by the persistent strong winds will propagate downstream and maintain seas 8 ft or greater as far SW 10N100W tonight and 09N103W Mon morning. A cold front entering the Gulf of Mexico on Mon will provoke another gale-force gap wind event over the Gulf of Tehuantepec from around dawn on Tue to around dawn on Wed. Please refer to the latest high seas forecast issued under AWIPS/WMO headers HSFEP2/FZPN03 for additional details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 07N78W to 07N85W to 05N97W. The intertropical convergence zone continues from 05N97W to 07N110W to 08N124W to 10N129W. No significant convection is associated with the trough and ITCZ. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see Special Features section above for more details about the ongoing gale force wind event in the Gulf of Tehuantepec. Looking ahead, another gale force wind event is possible in the Gulf of Tehuantepec early next week as high pressure builds behind the next cold front forecast to move into the Gulf of Mexico. NW swell will propagate into the offshore waters off Baja California Norte Tuesday, with seas building to around 13 ft by Tue night. Elsewhere, relatively tranquil marine conditions are expected during the period. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Winds will pulse to 30 kt in the Gulf of Papagayo tonight, and again but much weaker Sunday night into early Monday as winds become fresh to locally strong. The Papagayo gap winds will diminish and remain light to moderate through Thu night. Light to gentle NE-E winds will prevail elsewhere to the N of 09N, with gentle to moderate S to SW winds expected S of 09N. REMAINDER OF THE AREA... The strong 1010 mb low pressure system centered near 28.5N130W has begun to weaken, which has allowed the gales in the NW quadrant of the low to subside. A warm front extends from 30N131W to the low, then continues as a stationary front to 25N130W to 20N131W. A second low has developed near 16.5N131W. This low has a trough curving SW from it to 08N139W. Both of these lows are supported by a sharp upper-level trough extending from 32N131W through a low centered near 24N136W to beyond 17N140W. The northernmost low is expected to weaken and dissipate during the next 24 to 36 hours as it drifts N to near 30N, allowing winds and seas in its vicinity to subside. However, the upper-level trough will support continued development of the southernmost low. By Sunday afternoon it will become the stronger of the two lows and be centered near 20N129W. The new low will lift north behind the first low, then weaken and dissipate as well by Mon afternoon. The area of seas associated with these systems will subside, but will be overtaken on Mon by longer period NW swell of 8 to 12 ft generated by a cold front entering the far NW waters. The NW swell will propagate SE and cause seas N of 10N and W of 115W to build to 8 ft or above by Wed evening. Please refer to the latest high seas forecast issued under AWIPS/WMO headers HSFEP2/FZPN03 for more details. The aforementioned area of low pressure splitting the subtropical ridge just to the W of 130W is supporting patchy rain from 19N to 30N between 126W and 130W. Scattered showers are evident from 12N to 16N between 125W and 129W. The subtropical ridge remains fairly week due the presence of the active low pressure areas, keeping trade- wind flow light to moderate W of 130W. $$ CAM