[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120527
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
127 AM EDT Thu Jul 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
0515 UTC.

...SPECIAL FEATURES...

...Hurricane Chris...

The center of Hurricane Chris is located near 39.6N 63.0W at
12/03Z, or about 300 nm south of Halifax, Nova Scotia. Chris is
moving toward the northeast, or 50 degrees, at 25 knots. On the
forecast track, the center of Chris will pass near southeastern
Newfoundland on Thursday. The estimated minimum central pressure
is 980 mb. The maximum sustained wind speed is 75 kt with gusts to
90 kt. Additional weakening is forecast fro Chris during the next
few days, and it will become a post-tropical cyclone by Thursday
afternoon. Numerous moderate convection is observed from 37N-44N
between 60W-66W. Please read the latest NHC forecast/advisory
under AWIPS/WMO headers MIATCMAT3/WTNT23 KNHC for more details.

...Gale in the Caribbean...

A tight pressure gradient will develop across the southern
Caribbean inducing gale-force winds from 11N-13N between 70W-
76W in 24 hours. These conditions will continue through the next
12 hours. Fresh to strong winds will prevail across the area
after this. Refer to the High Seas Forecast product, under the
AWIPS/WMO headers HSFAT2/FZNT02 KNHC, for more details.

...TROPICAL WAVES...

A tropical wave extends its axis along 27W from 05N-15N. The wave
is moving west at 20-25 kt. Scattered showers are noted along the
wave's axis. This wave coincides with a good surge of moisture
based on the TPW product, and model diagnostic guidance also
confirms its presence.

A tropical wave has its axis along 43W from 07N-20N, moving west
at 15-20 kt. Saharan dust follows this wave inhibiting convection
at this time. Satellite imagery indicates some inverted-V pattern
in the cloud field associated with this wave.

A low amplitude tropical wave extends its axis along 63W from
08N-15N, moving west 10-15 kt. Saharan dust surrounds the wave
inhibiting convection. GFS computer model suggests an increase in
moisture in association with this wave reaching the central
Caribbean by Friday.

Another tropical wave is moving across the western Caribbean. Its
axis along 84W from 10N-21N, moving west at 10-15 knots. GOES-16
RGB Geocolor shows African dust behind the wave's axis covering
the basin all the way to the Lesser Antilles. Scattered moderate
convection prevails from 11N-18N between 82W-88W.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal sections of The
Gambia near 13N17W to 09N40W. The ITCZ extends from 10N46W to
08N54W to 10N62W. Aside from the showers related to the tropical
wave along 27W, no significant convection is observed at this
time.

...DISCUSSION...

GULF OF MEXICO...

A surface trough is analyzed over the southwestern Gulf and
extends from 22N93W to 19N93W. A surface ridge prevails across the
remainder of the basin anchored by a 1018 mb high centered over
the NW Gulf near 27N94W. Scattered showers are noted over the far
east Gulf waters along 26N enhanced by an upper-level low.

High pressure is forecast to prevail across the northern Gulf
waters through the upcoming weekend. A surface trough will move
westward off the Yucatan Peninsula each evening through Sun, and
enhance nocturnal winds over the SW Gulf, producing moderate to
fresh NE-E winds and seas of 3-4 ft. Winds and seas will slightly
increase in association with this trough by Sat night.

CARIBBEAN SEA...

Two tropical waves are moving 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 section above for details.

Scatterometer data depicts moderate to fresh winds across the
basin, with fresh to strong winds over the central portion of the
basin south of 14N between 72W-74W. The Atlantic high pressure
will build across the region behind the tropical wave with axis
along 84W to freshen tradewinds across the central Caribbean
waters.

Convection will continue to flare-up during the day over the SW
Caribbean, mainly south of 11N, due to the presence of the
monsoon trough. This convective activity is affecting parts of
Panama and Costa Rica.

ATLANTIC OCEAN...

As of 0300 UTC, Hurricane Chris is centered north of the forecast
area near 39.6N 63.0W. Swells generated by Hurricane Chris are
expected to affect portions of the coasts of North Carolina and
the mid-Atlantic states during the next few days. These swells
could cause life-threatening surf and rip current conditions.
Refer to the section above for more details.

A large area of cloudiness and disorganized showers and thunderstorms
associated with the remnants of Beryl is located over the Bahamas
and extends northwestward over the western Atlantic for a few
hundred miles. A surface trough is analyzed in this area from
29N72W to 27N76W. Little or no tropical cyclone development is
expected today, but conditions could become a little more
favorable later in the week and over the weekend while the
disturbance moves slowly northward and northeastward over the
western Atlantic. The latest Tropical Weather Outlook gives this
system a low chance of tropical cyclone formation during the next
48 hours. A recent scatterometer pass clearly indicates the wind
shift associated with the aforementioned surface trough. Wind and
seas could be higher near tstms. Lightning density indicates
frequent lightning within the observed convection.

Surface ridge prevails across the remainder of the Atlantic
forecast area, anchored by a 1037 mb high pressure centered near
NW of the Azores near 43N33W. The ridge extends into the NE
Caribbean.

The Saharan Air Layer (SAL) from CIMSS shows a new surge of
African dust over the eastern Atlantic, and behind the tropical
wave along 43W.

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

$$

ERA
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