000 AXNT20 KNHC 100427 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1127 PM EST Thu Mar 9 2017 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 0000 UTC surface analysis and satellite imagery through 0345 UTC. ...SPECIAL FEATURES... A strong pressure gradient will remain in place across the SW Caribbean Sea off the coast of Colombia through the morning hours on Friday. Thereafter...winds are expected to diminish below gale force as the pressure gradient relaxes. See the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...ITCZ/MONSOON TROUGH... The Monsoon Trough axis extends from the African coast near 06N11W to 04N16W. The Intertropical Convergence Zone axis extends from 04N16W to 03N23W to 01N30W to the Equator near 41W then along the Equator to 50W. Isolated moderate convection is from 01N-04N between 19W-25W. Scattered moderate convection is S of 04N between 34W-52W. ...DISCUSSION... GULF OF MEXICO... While upper level ridging prevails over much of the Gulf basin this evening...mid-level energy embedded within weak troughing over the Rio Grande river valley is supporting a surface trough extending from 20N95W to 24N96W to 26N96W. The surface trough and mid-level shortwave trough is generating scattered showers and isolated tstms N of 23N W of 90W...and from 20N-23N between 93W- 96W in the vicinity of the surface trough axis. Otherwise...the remainder of the basin is under the influence of a surface ridge anchored by a 1022 mb high centered in the NE Gulf near 28N85W. Mostly moderate E-SE winds are expected through the overnight period into Friday. The next weak frontal boundary is forecast to skirt the north-central and NE Gulf waters Friday night increasing winds out of the N-NE briefly into moderate to fresh breeze levels through Saturday morning. High pressure will then once again influence the basin through the remainder of the weekend. CARIBBEAN SEA... Aside from the near gale to gale force conditions expected through the early morning hours on Friday off the coast of Colombia...two features continue to impact the basin. A surface trough is analyzed from western Nicaragua near 13N87W to 19N84W providing focus for isolated to widely scattered low-topped showers remaining generally S of 19N between 81W-88W...including interior portions of northern Nicaragua and much of Honduras. Farther east...a shear line extends from the central Atlc to the Lesser Antilles near Dominica then E to 15N71W. Fresh to strong E winds are occurring N of the shear line in addition to isolated showers. Elsewhere moderate to fresh trades prevail and are expected to persist through Saturday. ...HISPANIOLA... Most isolated shower activity lies within the adjacent coastal waters S of the island in the vicinity of a shear line extending along 15N/16N E of 72W. Otherwise...skies through the overnight hours into Friday are expected to be mostly clear with only a slight possibility of a passing isolated shower. ATLANTIC OCEAN... A broad middle to upper level trough is noted on water vapor imagery in the vicinity of 31N73W that supports a weakening stationary front from 32N70W to 29N78W. It continues dissipating within the influence of two ridges...one anchored by a 1022 mb high centered across the NE Gulf of Mexico near 28N85W and the other a 1029 mb high centered near 29N50W. The stronger ridge to the east across the central Atlc prevails across much of the area...however a shear line extends along 15N/16N W of 43W on the southern periphery of the ridge. Aside from fresh to strong E-NE winds occurring generally S of 22N between 35W-62W...isolated showers are noted within 150 nm either side of the shear line axis. Farther east...a middle to upper level low is centered near 28N32W and supports a cold front analyzed from 32N22W SW to 23N30W to 19N37W. Scattered showers and isolated tstms are occurring from 23N-34N between 20W-33W. For additional information please visit http://www.hurricanes.gov/marine $$ HUFFMAN