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Atlantic Tropical Weather Discussion

AXNT20 KNHC 120549

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1249 AM EST Wed Dec 12 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 0000 UTC surface analysis and satellite imagery through 
0530 UTC. 


Atlantic Gale Warning: A stationary front extends from 32N60W to
31N64W, where it becomes a cold front. The cold front continues to
29N68W to eastern Cuba. A reinforcing cold front extends from
32N69W to 29N74W to 28N77W. Scattered moderate convection is N of
29N and E of 67W, along and N of the initial front, with 
scattered showers from 27N-29N between 65W-68W. A recent scatterometer
pass from 12/0100 UTC shows gale force winds N of 28N within 90 
nm behind and 180 nm ahead of the reinforcing front. Seas are 
also 12 to 15 ft in this same area. Gale force winds are expected
to persist across the northern waters near and E of the 
reinforcing front through early this morning before diminishing
around 1200 UTC today. Elsewhere W of the initial front, N of 26N
and east of 76W, fresh to strong NW to N winds will continue
through this morning, while fresh to strong southerly winds ahead
of the front will diminish by late this afternoon. Please read 
the latest High Seas Forecast under AWIPS/WMO headers 
HSFAT2/FZNT02 KNHC for more details.

Gulf of Mexico Gale Warning: A cold front is forecast to enter the
NW Gulf on Thu near 1200 UTC. The cold front will reach a position
from the Mississippi Delta to Tamiahua, Mexico on Thu night, 
reach from the Florida Big Bend to the E Yucatan Peninsula on Fri 
morning and pass through the Straits of Florida Fri night. Strong
to near gale force winds will develop ahead and west of the 
front, reaching gale force Thu night into Fri over most of the 
waters. Gale force winds are likely to extend to Veracruz, Mexico
and adjacent waters. Please read the latest High Seas Forecast 
under AWIPS/WMO headers HSFAT2/FZNT02 KNHC for more details.


The monsoon trough extends from the coast of Sierra Leone near
09N13W to 05N16W to 04N20W. The ITCZ continues from that point to
03N30W to 00N40W to the coast of Brazil near 00N49W. Scattered 
moderate convection is noted from 00N-04N between 05W-23W, and
from 02N-05N between 23W-40W. Scattered showers are seen from
00N-08N between 40W and the coast of South America.


A weak surface trough is located in the SW Gulf from 23N97W to
19N95W. Otherwise, a 1028 mb high pressure is centered over the
western Florida Panhandle and S Alabama near 31N87W with a 
surface ridge extending across the entire Gulf. Low-level stratus
is noted in the SW Gulf of Mexico and Bay of Campeche.

Fresh to locally strong southerly return flow will prevail across
the western Gulf waters this morning through early Thu ahead of a
cold front entering the northwest Gulf on Thu near 1200 UTC. Gale
force winds are expected with this front over much of the Gulf
Thu night into Fri. Mainly fresh west flow is expected on Sat 
with seas diminishing to less than 8 ft Sun.


A stationary front extends from eastern Cuba near 21N76W to 18N81W
to Honduras near 15N88W. Scattered showers are noted near and west
of the frontal boundary. Water vapor imagery shows very dry air 
across the eastern Caribbean N of 14N and E of 69W, with more 
moderately dry air elsewhere over the eastern and central

Fresh to strong trade winds will prevail in the S central 
Caribbean through Sun night with nocturnal pulses to near gale 
force off the northwest coast of Colombia. Fresh to strong winds 
will spread N to western Hispaniola Fri morning as high pressure N
of the area strengthens. The stationary front from eastern Cuba 
to the Gulf of Honduras will gradually dissipate through late this
morning, and fresh to strong northerly winds west of the boundary
will diminish. Another cold front will enter the NW Caribbean on 
Fri afternoon with northerly fresh to strong winds west of the 
boundary. Fresh to strong N winds will increase to near gale force
within 60 nm of the coast of Nicaragua on Sat night as the front 
stalls from eastern Cuba to northern Costa Rica.


Please see the Special Features section for information on the
Gale Warning in the Atlantic associated with two cold fronts.

Otherwise, a ridge of high pressure extending from a 1027 mb high
pressure near 27N45W dominates the remainder of the basin E of 
the cold fronts. Isolated shower activity is noted mainly S of 
23N across the tropics outside of heavier activity discussed in 
the Monsoon Trough/ITCZ section.

A strong ridge will build N of the area on Thu ahead of the next 
cold front to come off Florida Fri evening. Strong to near gale 
force southerly return flow is expected north of the Bahamas 
beginning Thu night and continuing through Sun evening. Gale force
winds are likely over the NW waters Fri night. 

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