Pacific Discussion

  • NHC East Pacific Tropical Weather Discussion
    by (nhcwebmaster) on March 19, 2018 at 4:06 PM

    000 AXPZ20 KNHC 191605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Mon Mar 19 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 1200 UTC surface analysis and satellite imagery through 1545 UTC. ...SPECIAL FEATURES... Gale Warning: A weakening cold front over the far northwest portion of the area along a position from 30N134W to 22N140W is preceded by strong southerly flow north of 25N and within 300 nm to its east, along with seas of 8 to 10 ft. A deepening surface low pres system currently northwest of the area will drop southeastward tonight behind this initial cold front, and drag a second cold front into the discussion area accompanied by a strong to near gale southwest-west-northwest wind shift. The pressure gradient will tighten around the southwest semicircle of the low increasing the westerly winds to minimal gale force winds in the range of 30 to 35 kt over the discussion waters west of the front near 1200 UTC on Tue, with the associated seas of 16 to 20 ft. The low pres will lift north of the area on Tue afternoon, with associated winds diminishing to 20 kt or less south of 32N on Wed evening. The associated NW swell, in the form of 7 to 10 ft seas, will propagate southeastward through the waters covering the area west of a line from the Central Baja peninsula to 17N140W on Sat. Please refer to the Pacific high seas forecast for more details on this upcoming event under AWIPS/WMO headers MIAHSFEP2/FZPN03 ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 08N82W to 04N90W to 06N102W, where latest scatterometer winds indicate the ITCZ axis begins and continues to 06N120W to 06N140W. Scattered moderate isolated strong convection is noted from 04N to 09N between 107W and 124W and within 165 nm S of the trough E of 94W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A north-northwest to south-southeast ridge extending from 30N121W to 17N110W to 13N94W will shift slightly to the southwest through Tue. Fresh to locally strong northerly winds will set up south of 25N and east of the ridge briefly today and tonight with the pressure gradient then relaxing some on Tue. Light to gentle northerly winds and 3 to 4 ft seas are then expected west of the Baja Peninsula through Wed. Gulf of California: Moderate to fresh northwest flow is forecast across the southern half of the gulf waters today, with narrow swaths of strong northwest winds expected across the far southern gulf waters late tonight. Seas may build to 6 ft in the longer fetch waters. Gulf of Tehuantepec: Strong north flow will surge through the gulf waters on late Tue night, increasing to minimal gale force Wed night. Gale conditions are then expected to continue through Thu morning, with seas building to a maximum of around 11 ft downstream from the gulf near 14.5N95.5W on Wed night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to locally strong NE nocturnal winds will diminish to moderate winds this afternoon, then increase to strong winds again briefly on Tue night with seas building to 7 ft downstream. A stronger drainage event is forecast to begin on Wed night, and persist into the upcoming weekend. Gulf of Panama: Fresh northerly winds will diminish to moderate winds this afternoon. Fresh to strong north nocturnal winds are expected to resume on Wed night. Elsewhere, gentle to moderate offshore flow will prevail N of 07N while light to gentle SW winds are forecast S of 07N. REMAINDER OF THE AREA... Please see see Special Features Section above for details on upcoming gale force winds to impact the far NW portion of the area in the short-term. A very progressive pattern will continue to impact the the northwest portion of the area well into this week. The deep layer low pres system located to the northwest of the area and its related trough is preceded by mid to upper level moisture in the form of overcast cloudiness. Areas of rain along with scattered showers and isolated thunderstorms under upper level divergence that is present to the the east and southeast of this low have moved over the area north of about 27N and west of 120W. These clouds and precipitation will continue advancing eastward towards the general area of southern California and also northern and central Baja California through Wed per model moisture guidance fields. $$ Aguirre/Ramos […]