000 AXNT20 KNHC 060556 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1256 AM EST Mon Mar 6 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 0515 UTC. ...SPECIAL FEATURES... ...CARIBBEAN SEA GALE WARNING... The conditions starting at 06/0000 UTC: NE gale-force winds, and sea heights ranging from 10 feet to 17 feet, in the coastal waters of Colombia, from 10.5N to 12.5N between 74W and 77W. ALSO: NE gale-force winds, and sea heights reaching 11 feet, to the N of 18N between 73W and 76W, including in the Windward Passage. NE- to-E gale-force winds, and sea heights to 11 feet, to the N of 16N between 70W and 73W. Please read the latest NWS High Seas Forecast under the AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...ATLANTIC OCEAN GALE WARNING... The conditions starting at 06/0000 UTC: A cold front is along 31N49W 22N68W 21N60W 20N76W. NE-to-E gale- force winds and sea heights ranging from 8 feet to 12 feet in the open waters, to the S of 24N to the W of 74W. Please read the latest NWS High Seas Forecast under the AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...GULF OF MEXICO GALE WARNING... The conditions starting at 06/0000 UTC: NE-to-E gale-force winds, and sea heights ranging from 9 feet to 15 feet, to the S of 25N to the E of 83W, including in the Straits of Florida. Please read the latest NWS High Seas Forecast under the AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...ITCZ/MONSOON TROUGH... The Monsoon Trough passes through the coastal sections of Liberia near 06N10W, to 03N20W. The ITCZ continues from 03N20W, to the Equator along 30W and 36W, to the coast of Brazil near 03S42W. Convective precipitation: Isolated moderate to locally strong from 07N southward from 60W eastward. ...DISCUSSION... ...THE GULF OF MEXICO... A middle level to upper level trough is moving through the central sections of the Gulf of Mexico. Scattered to broken multilayered clouds and possible rainshowers are from 95W eastward. A surface ridge extends from the Florida Panhandle into the SW corner of the area. ...LOW LEVEL CLOUD CEILINGS AND WEATHER FOR THE OFFSHORE OIL PLATFORM SITES THAT ARE IN THE AREA WHOSE BOUNDARIES ARE FROM 27N NORTHWARD AND FROM 88W WESTWARD... LIFR: none. IFR: KMZG, KVAF, and KGRY. MVFR: KBBF, KBQX, KXIH, KHHV, KVAF, KHQI, KEHC, KGUL, KVQT, KGHB, and KATP. LOW LEVEL CLOUD CEILINGS AND WEATHER...FOR THE COASTAL PLAINS OF THE U.S.A. FROM THE DEEP SOUTH OF TEXAS TO FLORIDA... TEXAS: MVFR in the Lower Valley/the Deep South, and in Rockport. light rain in Victoria. MVFR from Bay City to the Houston metropolitan area and surrounding smaller communities, to Huntsville, and from Beaumont/Port Arthur to Jasper. LOUISIANA: MVFR in Slidell. MISSISSIPPI: light rain has ended for the moment in parts of the Hattiesburg metropolitan area. MVFR at the Stennis Airport. ALABAMA and FLORIDA: VFR. ...THE CARIBBEAN SEA... Upper level SW wind flow covers the area to the east of the line that runs from the SE coast of Nicaragua to SW Haiti. Upper level anticyclonic wind flow is moving across the area that is to the west of the aforementioned Nicaragua-to-Haiti line. NE wind flow from 600 mb to 800 mb spans the entire area. Rainshowers are possible, in areas of broken low level clouds, mainly from 70W eastward, and from 15N northward from 70W westward. The 24-hour rainfall amounts, for the period ending at 06/0000 UTC...according to the PAN AMERICAN TEMPERATURE AND PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...are: 0.20 in Guadeloupe. ...HISPANIOLA... NE-to-E wind flow from 600 mb to 800 mb is moving across the area. NE wind flow from 350 mb to 500 mb approaches the NE corner of Hispaniola. NW wind flow from 350 mb to 500 mb moves across Cuba toward Haiti. Rainshowers are possible inland and in the coastal waters. Comparatively drier air in subsidence is apparent in water vapor imagery across Hispaniola. SURFACE OBSERVATIONS...for Port-au-Prince in Haiti: VFR. for the DOMINICAN REPUBLIC: Barahona: VFR. Santo Domingo/La Romana/Punta Cana: VFR. earlier light rain in Santo Domingo ended a few hours ago. Santiago: moderate rain. MVFR. ceiling 1400 feet. Puerto Plato: VFR. The GFS MODEL forecast for 250 MB shows that SW wind flow will move across the area during the next 48 hours, with a ridge from the SW corner of the Caribbean Sea toward the NW corner of the Caribbean Sea. The GFS MODEL forecast for 500 MB shows that the wind flow will be from the NW, first with a W-to-E oriented ridge, and then later just with NW wind flow, for the rest of day one. Expect more NW wind flow for the first 12 to 18 hours of day two. Expect anticyclonic wind flow during the last 6 hours to 12 hours of day two, with an Atlantic Ocean to Hispaniola E-to-W oriented ridge. The GFS MODEL forecast for 700 mb shows that an anticyclonic circulation center moves from a position that is just to the E of the SE Bahamas to a position that is to the NE of Puerto Rico during the first 24 hours of the 48=hour forecast period. Expect NE to E to SE wind flow during day one. The anticyclonic circulation re-organizes itself and it remains quasi- stationary to the north of the Mona Passage for the first 12 to 18 hours or so of day two. Expect anticyclonic wind flow across Hispaniola during this time. Expect NE wind flow for the last half of day two. ...THE ATLANTIC OCEAN... Deep layer cyclonic wind flow, with a trough, covers the area from 20N from 40W westward. A cold front passes through 32N46W to 23N60W 20N70W, across northern sections of Hispaniola, to 20N77W between SW Cuba and Jamaica. An upper level trough extends from a 25N27W cyclonic circulation center, to 20N40W and 20N53W. A surface trough is along 29N24W 25N25W 20N26W. A surface ridge passes through 32N30W to 27N37W and 22N47W. A second surface ridge is along 25N58W 28N68W beyond 32N74W. For additional information please visit http://www.hurricanes.gov/marine $$ MT ...Caribbean Gale Warning... A strong pressure gradient between a high pressure anchored across the southeast CONUS and lower pressure analyzed across northwestern South America will support near-gale to gale force winds each night and early morning within about 90 nm of the northwest coast of Colombia. These conditions will continue through Wednesday night. See the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...Florida Straits/Windward Passage Gale Warning... Strong high pressure is centered across the southeast CONUS and continues to build in across the Florida Straits region behind a cold front analyzed from 26N56W to the eastern coast of Cuba near 21N74W. Near-gale to gale-force east winds will continue across the Straits and are expected to persist through early Monday. As the front moves east of the Windward Passage region by tonight into early Monday...near-gale to gale-force northeast winds are expected through the Windward Passage and adjacent Caribbean Sea waters. See the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends from the African coast near 07N12W to 00N23W. The Intertropical Convergence Zone extends from 02N23W to 03S42W. Isolated showers are observed within 100 nm on either side of the ITCZ mainly west of 35W. ...DISCUSSION... GULF OF MEXICO... A mid to upper-level shortwave trough is noted on water vapor imagery over the west Gulf waters and eastern Texas. While no lower-level or surface feature has materialized across this area, isolated showers are occurring between 88W-94W. Elsewhere, the southwestern periphery of a surface ridge prevails across the remainder of the basin anchored by a 1039 mb high centered across Virginia and North Carolina. Fresh to strong easterly winds are prevailing across the basin except over the Florida Straits (see section above for details). These conditions will to continue through Monday. Winds will gradually diminish through early Tuesday from west to east as the high center moves eastward into the west Atlantic region. CARIBBEAN SEA... Aside from the near-gale to gale-force winds forecast off the coast of Colombia during the next few days, the Caribbean is under the influence of dry and stable air aloft, along with fairly tranquil conditions at the surface. A few quick-moving isolated showers are possible across the Lesser Antilles, Puerto Rico, and Hispaniola as low level moisture continues to be transported by the fresh to strong trades. These conditions are expected to prevail through early Friday. The high pressure will be anchored across the west Atlantic region for much of the week ahead. ...HISPANIOLA... Water vapor imagery depicts strong subsidence over the island with west-southwesterly flow aloft. Low-level moisture transported by trade wind flow is supporting isolated showers this afternoon across the island and adjacent coastal waters. A cold front lies to the N along 21N/22N and will reach the island by tonight increasing the northeast winds into fresh to strong levels. These winds are forecast to persist through Wednesday night. ATLANTIC OCEAN... A cold front extends across the west/central Atlantic from 31N50W to 20N74W. A strong high pressure is building in the wake of the front centered over the North Carolina/Virginia boundary. The pressure gradient in the area is strong enough to support gale- force winds currently occurring across the Florida Straits area and soon to begin in the Windward Passage. Refer to the section above for details. To the east of the cold front, a pre-frontal trough extends from 25N57W to 20N63W. No significant convection is related to the trough at this time. The remainder of the basin is under the influence of a surface ridge anchored by a 1028 mb high centered near 34N22W. South of this feature, an upper-level low is reflected at the surface as a trough that extends from 28N29W to 22N30W. For additional information please visit http://www.hurricanes.gov/marine $$ MT