[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 151657
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1257 PM EDT Fri Jun 15 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
1715 UTC.

...TROPICAL WAVES...

A tropical wave is in the E Atlantic, with axis extending from
13N29W to 03N30W, moving W at 10 kt. The wave shows up well as a
low amplitude moisture surge on the TPW product. The GOES-16
Geocolor RGB imagery shows the presence of the Saharan dust and
dry air N of the wave at 15N. Isolated moderate convection is
noted where the wave meets the ITCZ.

A tropical wave is in the central Atlantic, with axis extending
from 14N46W to 03N47W, moving W at 10-15 kt. The wave is well
depicted in the TPW product. Shallow moisture and isolated
showers are near the wave's axis.

A tropical wave is moving westward across the eastern Caribbean.
Its axis extends 61W/62W. African dust also surrounds the wave.
As a result, shallow moisture with embedded showers is associated
with the wave. Moisture related to this system will reach Puerto
Rico late today into tonight, and Hispaniola early on Sun,
increasing the likelihood of showers and isolated tstms.

A tropical wave is over the W Caribbean, with axis along 82W
from 10N-19N, moving W at 10-15 kt. Scattered showers and tstms
are seen over the SW Caribbean, likely a combination of the wave
and the proximity of the Monsoon Through. The wave will move
westward into Central America through Sat, helping to induce some
shower and tstm activity. The GFS model indicates plenty of
moisture over Central America this upcoming weekend.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Africa near 11N15W
to 06N25W. The ITCZ continues from 06N25W to 07N40W to 06N50W to
the coast of Guyana near 07N59W. Besides the convection mentioned
in the Tropical Waves section, scattered moderate convection is
noted within about 75 nm S of the monsoon trough between 14W-22W.
Similar convection is also seen from 07N-09N between 37W- 40W.

...DISCUSSION...

GULF OF MEXICO...

A surface trough is analyzed over the SW Gulf and extends from
23N95W to the central Bay of Campeche near 19N93W. Scattered
showers and isolated thunderstorms are noted over the western Gulf
under a SE wind flow. An upper-level low centered over the
western Gulf is helping to induce this convective activity. A
large area of cloudiness with embedded showers and tstms is
affecting the far SE Gulf, including parts of the Yucatan
Peninsula and the Yucatan Channel. This large area of moisture is
associated with a second and stronger trough, that will be added
to the 1800 UTC surface analysis. A ridge dominates the remainder
of the Gulf waters.

The surface trough across the Bay of Campeche and western Gulf
will shift WNW moving inland of Mexico by this evening. The second
and stronger trough will shift from the NW Caribbean through NW
Gulf tonight through Sun, accompanied by widespread convection. A
tightening pressure gradient E of this second trough will induce
fresh SE winds in west-central Gulf waters tonight, becoming
strong to near gale in the central Gulf this weekend, spreading W
through early next week.

CARIBBEAN SEA...

As previously mentioned, abundant cloudiness with embedded showers
and tstms are noted over the NW Caribbean, and parts of the
Yucatan Peninsula, including also the Yucatan Channel, and the
westernmost tip of Cuba. A diffluent pattern aloft is helping to
induce this convective activity. Scattered showers and tstms are
also seen over the SW Caribbean just N of Panama. Two tropical
waves are moving westward across the basin. Please, see Tropical
Wave section for details.

Recent scatterometer data provided observations of fresh to strong
winds across the central Caribbean, with seas of 10-11 ft. The
aerial extent of the strong trades, roughly between 70W and 83W,
will slightly diminish this weekend. However, winds are forecast
to increase to 20-25 kt across the Gulf of Honduras and the NW
Caribbean beginning tonight, in association with the above mentioned
surface trough moving from the NW Caribbean into the Gulf of
Mexico.

ATLANTIC OCEAN...

As of 1500 UTC, a surface trough is located E of Florida, and
extends from 31N77W to 27N80W. Scattered showers and tstms are
near and ahead of the trough. Farther E, a stationary front enters
the forecast region near 31N54W and extends SW to near 27N60W. An
upper-level low is generating some showers and isolated tstms just
E of the frontal boundary. The remainder of the Atlantic Ocean is
under the influence of a ridge, anchored by a 1030 mb high pressure
located SW of the Azores near 36N32W.

The trough offshore of northern and central Florida will be
overtaken by a backdoor cold front this weekend, which will move
S through early next week. The high pressure ridge located S of
these boundaries will sink southward ahead of the features. New
high pres is forecast to build from N of the area by Tue.

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

$$
GR
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