AXNT20 KNHC 241804

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
103 PM EST Sat Feb 24 2018

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 1745 UTC.


A system of low pressure over the NE Atlc will support a cold front forecast to extend from 31N35W to 28N48W by early Monday morning. A strong pressure gradient between this area of low pressure and surface ridging west of it will lead to the development of gale-force winds east of 41W. Gale conditions are forecast to prevail through Monday. For more details, refer to the NHC High Seas Forecast under AWIPS/WMO Headers MIAHSFAT2/FZNT02 KNHC.


The monsoon trough extends along 03N0W to 02N14W to 01N29W. The ITCZ continues from that point to 02N40W to the coast of Brazil near 01N50W. Numerous strong convection is N of the Equator between 05E-12W. Scattered moderate convection is within 90 nm either side of the monsoon trough between 12W-30W and within 120 nm N of the ITCZ W of 38W.



Fair weather prevails across the basin due to very dry conditions at the lower and middle levels as indicated by GOES- 16 water vapor imagery. This is supporting mainly clear skies basin-wide. CIRA microwave imagery at the lower levels show patches of shallow moisture advecting to the NW Gulf, which is supporting dense fog N of 26N W of 89W. A broad area of high pressure over the SW N Atlc extending a ridge SW across Florida and the eastern Gulf continue to support moderate to fresh SE flow across the basin, being the strongest winds W of 90W. No significant changes are expected through Sunday. On early Monday morning, a cold front is forecast to move over the northwestern waters from Louisiana to Brownsville, Texas to inland NE Mexico. By Monday afternoon, the front is forecast to extend from the Florida Panhandle to 27N94W to inland NE Mexico and then it will stall before it lifts northward along the Gulf coast through Tue night. Scattered to isolated showers will accompany this boundary.


Water vapor imagery from GOES-16 show deep layer dry air across the basin, which is supporting overall fair weather conditions. However, isolated to scattered showers are possible during the afternoon hours in the Greater Antilles as remnant shallow moisture associated with a former front advects from the north or SW N Atlc waters. An elongated upper level low centered NE of Hispaniola will support this convection and currently supports passing showers across Jamaica and southern adjacent waters. The other area where scattered to isolated showers are being reported is the SE Caribbean. Tropical Atlc moisture along with middle level diffluence support the convection in this section. In terms of winds, latest scatterometer data depict fresh trades across the central and eastern basin, with locally strong winds within 90 nm of the coast of Colombia increasing to near gale- force at night. Seas are highest near the coast of Colombia, up to 12 ft. Moderate to fresh trades are in the NW Caribbean. Looking ahead, winds and seas are expected to gradually lessen by Sunday morning as the high pressure system north of the area weakens.


Gale-force winds are forecast to develop over NE Atlc waters by early Monday morning. See the Special Features section above for further details. In the SW N Atlc, a broad ridge anchored by a 1028 mb high near 31N69W continue to support fresh to locally strong NE to E winds in the approaches of the Windward Passage and the eastern Great Bahama Bank. A low pressure system over the NE Atlantic continue to support a cold front that enters the area of discussion from 30N27W SW to 25N40W where it starts to weaken. Otherwise, a 1007 mb low and associated trough SW of the Canary Islands continue to weaken. Little change is expected over the remainder of the basin during the next day or two as the high pressure system remains stationary and while it weakens.

For additional information please visit http://www.hurricanes.gov/marine

$$ Ramos