Tropical Weather Discussion
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AXNT20 KNHC 131052

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
552 AM EST Wed Dec 13 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 0600 UTC surface analysis and satellite imagery through
1015 UTC.

A cold front extends across the SW North Atlc from 32N72W SW to
the Florida peninsula near Key Biscayne and into the southern
Gulf of Mexico. Near gale to gale force winds are occurring
generally N of 29N on either side of the front as depicted on
earlier scatterometer passes from 13/0144 UTC and 13/0240 UTC.
The front is forecast to sweep eastward through Wednesday and
eventually lift N of the discussion area by Thursday. See the
latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/
FZNT02 KNHC for more details.

The monsoon trough extends from the African coast near 06N10W to
06N15W. The Intertropical Convergence Zone axis extends from
06N15W to 03N40W to the Equator near 47W. Scattered moderate
convection is from 03N-09N between 24W-54W.


The Special Features cold front mentioned above extends across the
extreme southern Florida peninsula and into the basin near 25N81W
extending W to 24N90W to 25N96W. A relatively dry and convection-
free front...this reinforcing front is providing moderate to
fresh N-NW winds E of 90W and gentle to moderate N winds W of 90W
this morning. A surface ridge influences much of the remainder of
the basin anchored by a 1026 mb high centered near Tampico and a
1025 mb high centered across southeastern Texas. As the cold
front shifts eastward through Wednesday night...ridging will
follow and provide light and variable winds on Wednesday. As the
ridge continues east...the re-establishment of southerly return
flow is anticipated Thursday.

A stationary front extends from the Windward Passage SW to near
12N80W. Widely scattered showers and isolated tstms are occurring
generally within 120 nm either side of the front. Much of this
convection is supported aloft by a divergent upper level pattern
on the northern periphery of an upper level anticyclone anchored
over eastern Panama near 09N78W. East of the anticyclonic
circulation...dry northerly flow prevails providing overall
stability to the central and eastern Caribbean this morning.
Overall gentle to occasional moderate trades are expected
Wednesday E of the front...while the front is forecast to
gradually weaken through Thursday.

Isolated showers are occurring across western portions of the
island this morning as a stationary front lies from the Turks and
Caicos through the Windward Passage to eastern Jamaica. The front
is expected to remain stationary and begin weakening through

Water vapor imagery indicates middle to upper level troughing
moving offshore of the eastern CONUS this morning supporting the
Special Features cold front extending from 32N72W SW to the
southern Florida peninsula near Key Biscayne. The reinforcing
cold front is expected to merge with a stationary front on
Thursday that is currently analyzed to the E-SE from 32N65W to
the Turks and Caicos islands to the Windward Passage region. The
reinforcing cold front remains relatively convection-free...while
isolated showers are occurring within 120 nm either side of the
stationary front. Farther east...a surface ridge influences much
of the central and eastern Atlc...anchored by a 1034 mb high
centered S of the Azores near 37N28W. However...within the
southeastern periphery of the ridge nearing the Cape Verde
Islands...a dissipating cold front extends from the coast of
Africa near 16N17W to 18N26W. The primary area of concern with
the front is the large area of strong to near gale force NE winds
generally N of 20N E of 33W. The pressure gradient associated
with this wind field is expected to relax by Friday.

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