AXNT20 KNHC 171800

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 PM EDT Tue Oct 17 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 1715 UTC.


A cold front extends from central Florida to the Bay of Campeche in the SW Gulf. Strong high pressure west of the front supports 30-35 kt northerly winds south of 21N west of 95W. The front is expected to gradually weaken through Wednesday night with winds decreasing below gale force tonight. See the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/Vicinity KNHC for more details.


A tropical wave south of 13N along 54W is moving W at 10-15 kt. The wave coincides with troughing at 700 mb troughing and a maximum in 850 mb relative vorticity. Scattered moderate convection is from 08N-10N between 53W-57W.

A tropical wave south of 16N along 64W is moving W at 10-15 kt. The wave coincides with troughing at 700 mb troughing and a maximum in 850 mb relative vorticity. Widely scattered moderate convection is from 12N-15N between 61W-64W.

A tropical wave south of 16N along 80W is moving W at 10-15 kt. The wave coincides with broad 700 mb troughing between 75W-82W. Scattered moderate to strong convection is west of the wave axis from 09N-13N between 80W-84W.


The convergence zone continues to sag equatorward. The African monsoon trough extends from 09N13W to 08N25W. The ITCZ axis continues from 08N25W to 07N53W. Scattered moderate convection is from 06N-10N between 37W-47W..



The cold front mentioned above is supported aloft by an upper level trough pushing into the north-central Gulf. Scattered showers are occurring within 150 nm south and east of the front. It will become nearly stationary overnight then gradually become diffuse through Wednesday night. Fresh to strong N-NE winds will prevail behind the front through early Wednesday and then weaken through Thursday. Surface ridging is expected to remain in place across the basin the rest of the week.


Two low amplitude tropical waves are moving across the basin with scattered convection. See above. A nearly stationary 1007 mb low is centered near 10N76W, and the eastern extension of the Pacific monsoon trough is analyzed from 11N69W to 11N75W to 09N78W. An upper level anticyclone centered over the W Caribbean near 16N80W supports mostly dry air aloft across the region. Scatterometer data shows fresh E-SE winds in the eastern Caribbean, and gentle to moderate E-NE winds west of 75W. Moderate to fresh trades are expected to persist across the basin through Wednesday.


A disorganized line of showers is slowly moving over the middle of the island. Local sea breeze dynamics during afternoon and evening hours is expected to initiate showers and tstms across the island today. A tropical wave will move south of Hispaniola Wednesday and Thursday, increasing the potential for convection.


A cold front extends across the NW portion of the SW North Atlc from 32N74W to central Florida. Scattered showers are occurring within 180 nm NW of the front. A surface trough extends from a low near 34N67W to 24N73W. Scattered moderate isolated strong showers are well east of the trough within 90 nm either side of a line from 32N65W to 22N68W. A broad ridge anchored by high pressure centered near 33N37W dominates the remainder of the tropical north Atlantic, north of 10N and east of 65W.

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

$$ Mundell