[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 141205
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 AM EDT Sat Jul 14 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 0600 UTC surface analysis and satellite imagery through
1145 UTC.

...SPECIAL FEATURES...

...Gale Warning off the coast of Colombia in the Caribbean Sea...

NE gale-force winds that were occurring from 11N to 12N between
74W and 75W during the overnight hours are diminishing to near
gale force this morning. Resultant seas with these winds are in
the 10-13 ft range. The pressure gradient will tighten up again
tonight on Sun night until daybreak on Mon to allow for NE gale
force winds to once again develop within the same area, and pulse
again from late on Tuesday night until sunrise on Wednesday
morning. Seas are expected to build to the range of about 10-14 ft
with these wind conditions. Please read the High Seas Forecast,
under the AWIPS/WMO headers HSFAT2/FZNT02 KNHC, for more details.

...TROPICAL WAVES...

A far eastern Atlantic broad tropical wave as seen in early
morning visible satellite imagery has its axis along 21W from 08N
to 18N, moving westward at 10-15 kt. Scattered moderate
convection associated with this wave is along its southern extent
tied mainly to the monsoon trough, and it is noted from 08N-10N
between 21W- 25W. Similar convection is behind the wave from 08N-
10N between 14W-16W and from 10N-12N between 17W- 19W.

A central Atlantic tropical wave has its axis extending from near
20N47W to 10N51W. This wave is observed as having a broad
inverted-V shape cloud structure as seen in satellite imagery as
it moves westward at 15-20 kt. The wave is passing through a
rather dry and stable environment, and is void of deep convection.
Only isolated showers and thunderstorms are seen behind the axis
from 08N-12N between 41W-45W.

An eastern Caribbean Sea tropical wave has its axis along 65W/66W
S of 19N, moving westward at 15 kt. The northern portion is
approaching the vicinity of Puerto Rico. Expect increasing
moisture with scattered showers and isolated to affect some areas
of the eastern Caribbean through tonight in the wake of the wave.
This shower and thunderstorm may be further aided by an upper-
level trough that extends from the Mona Passage to the far SW
Caribbean.

A central Caribbean Sea tropical wave has its axis along 75W,
moving westward at 15 kt. The northern extent of this wave is
passing across the Windward Passage. No significant deep
convective precipitation is noted in latest satellite imagery,
however isolated showers moving quickly westward are possible
near the wave axis.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal areas of Guinea
Bissau near 11N15W, to 10N20W and 10N28W. The ITCZ continues
from 10N28W to 09N32W 10N41W, 09N48W, 10N54W, and 08N60W.
Aside from convection associated with the tropical wave along 21W,
only scattered moderate convection is seen within 60 nm north
of the ITCZ axis between 59W-60W, and west to just inland
northeastern Venezuela.

...DISCUSSION...

GULF OF MEXICO...

A ridge continues to dominate the Gulf waters, with two weak high
pressure centers of 1021 mb located across the northern Gulf.
Under the influence of this system, mainly light to gentle
anticyclonic flow will prevail across much of the Gulf region
this upcoming weekend, with seas generally under 5 ft. Gentle to
moderate SE-S winds are expected across the western Gulf on the
western periphery on the ridge. According to the GOES-16 RGB
Geocolor imagery, African dust has reached the SE Gulf, including
the Yucatan Channel.

Weak high pressure will prevail across the area through
Wednesday. A surface trough will move westward off the Yucatan
Peninsula each evening through Wednesday. It will enhance
nocturnal winds in the SW corner of the Gulf. The northern part
of a tropical wave will move westward across the SW corner of
the Gulf today.

CARIBBEAN SEA...

Two tropical waves will continue to move across the basin. Refer
to the Tropical Waves section above for details.

A gale warning is in effect for the south-central Caribbean.
Refer to the Special Features section above for more information.

Saharan dust covers most of the Caribbean Sea, including the
Greater Antilles, where partly cloudy and hazy conditions
prevail.

A tropical wave along 74W/75W will move across the central
Caribbean Sea through Saturday night, and then across the
western Caribbean Sea on Sunday and Sunday night. An eastern
Caribbean Sea tropical wave will move through the rest of the
eastern Caribbean Sea on Saturday, and into the central
Caribbean Sea Saturday night. An Atlantic Ocean tropical wave
that is along 50W is forecast to reach the easternmost sections
of the Caribbean Sea by late Sunday/early Monday, and into the
central Caribbean Sea late Monday/early Tuesday, and then into
the western Caribbean Sea late Tuesday/early on Wednesday. High
pressure will build across the region behind each passing
tropical wave, in order to freshen trade winds across the
central Caribbean Sea.

ATLANTIC OCEAN...

An area of low pressure, associated with the remnants of Beryl, is
located about 250 miles west-northwest of Bermuda.  Although
upper-level winds are at best marginally conducive, this system has
become a little better organized today, and some additional
subtropical or tropical development is possible today as the low
moves north-northeastward at about 10 mph. By Sunday, the system
should reach colder water north of the Gulf Stream, where
additional development is unlikely. The latest Tropical Weather
Outlook gives this system a low chance of tropical cyclone
formation during the next 48 hours. A weak low of 1014 mb is
analyzed on the 0600 UTC surface map near 35N67W. Visible
satellite imagery reveals that the low level center is totally
exposeure due to the strong wind aloft.

A surface trough extends from the aforementioned weak low to
the NW Bahamas. The trough will move little through Sun night while
weakening. Scattered showers and isolated thunderstorms can be
expected along and southeast of the trough. A recent scatterometer
pass clearly indicates the wind shift associated with this trough.

The remainder of the Atlantic forecast area is under the influence
of the Bermuda-Azores High, with a center of 1034 mb located WNW
of the Azores near 39N38W. The ridge extends SW into the NE
Caribbean and the SE Bahamas. High pressure building westward
from the central Atlantic through Tue will support fresh to
strong trade winds south of 23N W of 65W. Winds will pulse to
strong north of Hispaniola at night this weekend.

A surface trough passes through 31N69W to 28N72W, to the NW
Bahamas. The trough will move little through Sun night while
weakening. Scattered showers and thunderstorms can be expected
along and SE of the trough to 25N. High pressure building westward
from the central Atlantic Ocean through Wed will support fresh to
strong trade winds south of 23N. The winds will pulse to strong
north of Hispaniola at night through the period.

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

$$
Ramos/Aguirre
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