- NHC East Pacific Tropical Weather Discussion
by nhcwebmaster@noaa.gov (nhcwebmaster) on December 6, 2019 at 9:20 PM000 AXPZ20 KNHC 062120 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2120 UTC Fri Dec 6 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A cold front that currently extends across the NW Gulf of Mexico will continue moving SE through Sat, and high pressure will build over eastern Mexico behind the front. The enhanced pressure gradient will support gale force gap winds over the Gulf of Tehuantepec from late tonight through Sat night. Seas will peak between 12-14 ft downstream of the Gulf on Sat night, then subside on Sun as the pressure gradient weakens and wind speeds diminish to fresh to strong speeds. Looking ahead, another gale force gap wind event could affect the Gulf of Tehuantepec Wed and Wed night as a stronger cold front crosses the Gulf of Mexico. See latest NWS High Seas Forecast issued by National Hurricane Center under AWIPS/WMO headers HSFEP2/FZPN03 KNHC or at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 06N77W to 07N90W to 06N108W to 08N114W. The ITCZ continues from 08N114W to 10N130W to beyond 09N140W. Scattered moderate isolated strong convection is noted within 180 nm of the monsoon trough east of 86W. Scattered moderate convection is occurring from 03N to 07N between 104W and 108W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for more details on the Gulf of Tehuantepec Gale Warning. Earlier scatterometer data showed fresh to locally strong NW winds across the central and southern Gulf of California between a low pressure trough over western Mexico and a high pressure ridge over the Baja California offshore waters. These winds will persist through Sat, then diminish to moderate speeds on Sun. Elsewhere, light to gentle winds prevail across most of the offshore waters, except for moderate northerly winds over the Gulf of Tehuantepec. Large NW swell will enter the Baja California Norte waters Sat, with offshore seas building to 8-11 ft by Sat night. This swell will continue spreading SE across the region Sat night through Sun night, then decay Mon into Mon night. The pressure gradient over Baja California will strengthen early next week, resulting in fresh northerly winds offshore and over the Gulf of California. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The latest GOES-16 satellite imagery and available lightning data reveals scattered moderate to strong thunderstorms near the monsoon trough over the offshore waters of Costa Rica, Panama, and Colombia. Locally stronger winds and higher seas can be expected in and near thunderstorms. Strong NE to E winds will pulse across and downstream of the Gulf of Papagayo through Wed, with seas peaking between 8-9 ft downstream of the Gulf each morning. Fresh SW winds off the coast of Colombia will diminish by Sat night. Otherwise, gentle to moderate S to SW monsoon flow will persist across the offshore waters of Costa Rica, Panama, Colombia, and Ecuador during the next several days. REMAINDER OF THE AREA... A cold front extends across the NW waters from 30N128W to 27N131W to 23N140W. Recent scatterometer data indicates moderate to fresh W winds prevail from 28N to 30N west of the front, with stronger winds noted north of the forecast area. An 18 UTC altimeter pass highlights seas of 20-21 ft near 30N134W, with 8-12 ft seas in NW swell extending SE to 26N133W. This front will continue moving eastward across the northern waters tonight, then stall and weaken west of 120W Sat into Sat night. Very large NW swell associated with this system will continue propagating SE through the weekend. Seas will remain greater than 12 ft over the northern waters through Sat, then subside Sat night through Sun. Looking ahead, another cold front will approach the NW portion of the discussion area on Mon, introducing another set of NW swell into the NW waters through the middle of next week. $$ Reinhart