000 AXNT20 KNHC 121655 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1155 AM EST Thu Jan 12 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 1200 UTC surface analysis and satellite imagery through 1630 UTC. ...SPECIAL FEATURES... A 1010 mb partially occluded low is centered 25N53W that is supported aloft by a middle to upper level low nearly collocated with the surface feature near 26N51W. The associated cold front extends from the low S-SW to 22N51W to 18N54W to the Lesser Antilles near Dominica and into the SE Caribbean Sea. Near gale to gale force NE winds are occurring across the discussion waters within 660 nm of the low center in the NW quadrant. Latest scatterometer pass around 12/1300 UTC confirms the large area of increased winds due to the strength of the pressure gradient. See latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/ FZNT02 KNHC for more details. A strong pressure gradient between lower pressure across South America and a ridge anchored across the SW North Atlc is generating near gale to gale force winds in the SW Caribbean Sea this afternoon. These conditions are expected to pulse during the late night and early morning hours through Sunday. See 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 10N14W to 02N23W. The Intertropical Convergence Zone axis extends from 02N23W to the Equator near 28W the along the Equator to 44W. Isolated moderate convection is S of 04N between 04W-12W...and S of 04N between 26W-51W. ...DISCUSSION... GULF OF MEXICO... Middle to upper level ridging remains anchored across the eastern Gulf waters that supports surface ridging with axis extending from the Florida peninsula SW to southern Mexico near 20N97W. Moderate to occasional fresh E-SE winds are occurring across the basin this afternoon with mostly fair skies noted on visible satellite imagery. This overall synoptic pattern is expected to persist through the remainder of the week and into the weekend. The next front is not expected until Tuesday night into Wednesday. CARIBBEAN SEA... West-southwesterly flow aloft prevails over the basin between broad upper level troughing over Central America and the adjacent east Pacific region and an upper level ridge anchored over northeastern South American continent. Another middle to upper level low is also noted on water vapor imagery centered over the central Atlc near 26N51W supporting a shear line analyzed from 16N58W W-SW across Dominica to 14N70W to 11N83W. Scattered showers and isolated tstms are occurring from 11N-14N between 81W-84W...with isolated showers elsewhere within 90 nm either side of the shear line. In addition...strong to near gale force NE winds are occurring in close proximity to the coast of Colombia due to a strengthened pressure gradient across the region. Otherwise...fresh to strong trades persist elsewhere. The shear line boundary is expected to remain nearly stationary or drift slightly eastward through the overnight hours and become diffuse into Friday. ...HISPANIOLA... Fresh to strong NE winds prevail across the island and adjacent coastal waters this afternoon. This wind field is due to a relatively strong pressure gradient across the region and SW North Atlc waters. Isolated showers are expected to continue as the NE flow persists through the remainder of the week into the weekend. ATLANTIC OCEAN... A middle to upper level low is centered near 26N51W that supports a nearly collocated 1010 mb surface low...as mentioned in the Special Features section above. The associated cold front extends from the low S-SW to 16N57W and becomes a shear line into the eastern Caribbean Sea. Scattered showers and isolated tstms are occurring from 19N-31N between 44W-56W with isolated showers elsewhere within 90 nm either side of the cold front and shear line boundary. The remainder of the SW North Atlc is under the influence of a surface ridge anchored by a 1035 mb high centered N of Bermuda near 37N64W. Mostly moderate to fresh NE to E winds prevail on the southern periphery of the ridge which are forecast through Sunday. The low pressure area along the front is expected to drift southward through the remainder of the week and weaken well E of the Lesser Antilles by Saturday night into Sunday. Farther east...a surface trough extends from 15N42W to 23N37W providing focus for isolated showers within 60 nm either side of the boundary. This area of activity continues to be enhanced by marginal middle to upper level diffluence. For additional information please visit http://www.hurricanes.gov/marine $$ HUFFMAN