[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 090605
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 AM EDT Sun Jul 9 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 0000 UTC surface analysis and satellite imagery through
0545 UTC.

...TROPICAL WAVES...

A tropical wave extends from along the coast of Africa near 16N17W
to just offshore the coast to 12N17W and to near 07N17W. It is
moving westward at about 10 kt. Both water vapor imagery and
the Total Precipitable Water (TPW) imagery animation confirm
that deep tropical moisture continues to increase over and near
the environment of this wave, mainly attributed to it being
entrenched within a very pronounced monsoonal flow that has set
up along and off the coast of W Africa. With this moisture in
place, deep convection near the wave increased since 24 hours ago.
Scattered moderate to strong convection is seen west of the wave
axis from 09N-11N between 18W-20W. Scattered moderate isolated
strong convection is within 30 nm of 13N24W.

Another tropical wave is over the far eastern Atlantic with axis
extending from 18N26W to 12N30W to 09N31W, moving westward at
10-15 kt. This wave marks the leading edge of deep atmospheric
moisture that has increased between it and the wave just offshore
the coast of Africa. This is clearly evident on latest satellite
imagery, and further supported by the Total Precipitable Water
(TPW) loop animation. The wave has a very good signal at the 700
mb level as indicated in the GFS model guidance. The Meteosat 9
imagery continues to depict an extensive area of African Saharan
dry air and dust to its west. Deep convection directly associated
with this wave is very limited. Only weak isolated showers and
thunderstorms are within 90 nm east and 60 nm west of the wave
just north of where it intersects the monsoon trough axis.

A tropical wave, remnants of Tropical Depression Four, is over
the central Atlantic with its axis extending from 24N58W to
18N60W and to 12N59W, and is moving west-northwestward at 15-20
kt. The northern portion of the wave is under an upper trough
axis that extends from an upper low (TUTT) located near 29N56W.
The combination of diffluence aloft over this portion of the wave
and the availability of very deep moisture atmospheric
environment surrounding the wave as observed in the TPW loop
animation is supporting a large burst of deep convection
consisting of the strong type intensity from 20N-24N between 56W-
60W. Scattered showers and thunderstorms have recently developed
ahead of the wave within 60 nm of a line from 19N60W to 19N65W.
The 0052Z Ascat pass from last night revealed quite an impressive
area of 20-25 kt within 90 nm east of the wave axis from 20N-22N,
and within 120 nm west of the wave axis from 20N-23N. The wave is
forecast to move across the Leeward Islands this morning, pass
north of Puerto Rico this afternoon and tonight and move in the
general direction of the SE Bahamas Monday through Tuesday.
Expect scattered showers and thunderstorms with gusty winds to
affect mainly the NE Caribbean today and tonight, with the
majority of the activity shifting west-northwest towards the
general vicinity of the SE Bahamas and that of the northern and
eastern portions of Hispaniola Monday through Tuesday.

A tropical wave is over the central Caribbean Sea with axis
extending from near 21N72W to 15N74W to inland NW Colombia
at 11N74W, moving westward at about 13 kt. The latest water vapor
imagery shows subsidence and associated dry air over and around
the wave's environment, except south of 12N where moisture
becomes evident. Scattered moderate isolated strong convection
has recently developed just west of Haiti within 30 nm of 19N73W.
Scattered strong convection is over Colombia near the southern
extent of the wave. Otherwise, the subsidence aloft is allowing
for only isolated showers to exist within 180 nm either side of
the wave axis.

The northern portion of an eastern Pacific tropical wave reaches
to the far western portion of the SW Gulf. It is moving westward
at 10-15 kt. The wave is embedded in a very moist and unstable
atmospheric environment present to the east of sharp upper trough
axis located over central Mexico. Clusters of scattered moderate
isolated strong convection persist over much of the SW Gulf of
Mexico from 19N-23N between 95W-98W. The wave is forecast to
move inland Mexico this morning.

...ITCZ/MONSOON TROUGH...

The Monsoon Trough axis extends from 11N15W to 10N24W to 08N38W.
The Intertropical Convergence Zone extends from 08N38W to 04N52W.
Aside from the convection related to the tropical waves over the
far eastern Atlantic, scattered strong convection is south of the
axis within 30 nm either side of line from 05N32W to 06N36W and
within 90 nm north of the axis between 50W-52W. Scattered
moderate isolated strong convection is noted within 180 nm south
of the axis between 26W-30W.

...DISCUSSION...

GULF OF MEXICO...

A tropical wave is over the far western portion of the SW Gulf.
See above for details. In the upper levels, a small upper level
high is centered over the western Bay of Campeche near 20N94W,
with the associated anticyclonic flow covering the western half of
the Gulf. An upper level low is noted just north of NW Cuba, with
a trough extending N to near 28N86W. At the surface, a 1019 mb
high is centered over the north-central Gulf near 27N91W. The
associated anticyclonic wind flow consists of light to gentle
winds covers the area north of about 24N. The thermal trough that
moved offshore the Yucatan Peninsula on Saturday evening in
combination with upper level anticyclonic flow and a very moist
and unstable atmosphere has resulted in recently formed large
clusters of strong convection over the Bay of Campeche. Latest
mosaic radar imagery shows scattered showers and isolated
thunderstorms over the extreme SE Gulf and Straits of Florida
moving westward around 10 kt. The tropical wave will move inland
by this afternoon. Little change is expected in the present
weather pattern through late Monday.

CARIBBEAN SEA...

A tropical wave is moving across the central Caribbean. See
above for details. Scattered moderate convection is over W Cuba.
Scattered moderate to isolated strong convection is over the SW
Caribbean, Panama, Costa Rica, and S Nicaragua. 10-15 kt
tradewinds are over most of the Caribbean. Stronger winds
of 20-25 kt are near the coast of Colombia.  Expect the central
Caribbean tropical wave to move W over the next 24 hours with
convection. Also expect convection over the northern Leeward
Islands due to another tropical wave, the remnants of Tropical
Depression Four, within the next 24 hours.

...HISPANIOLA...

Scattered showers and thunderstorms recently developed over the
waters just west of Haiti due to the combination of an upper
level cyclonic shear axis extending east to west over the vicinity
of the island, and a tropical wave axis just west of Haiti as
mentioned above. Expect scattered showers and isolated thunderstorms
to affect some sections of the eastern and southern portions of
the island through Monday in moist easterly flow in the wake of
the wave. Also, expect the typical diurnal scattered shower and
thunderstorm activity over some of the interior sections through
early next week.

ATLANTIC OCEAN...

Three tropical waves are analyzed over the tropical Atlantic. See
above for details. Nearly stationary high pressure of 1030 mb is
centered well north of the area at 36N42W, with a ridge stretching
southwestward to 32N55W and to central Florida. An upper level low
(TUTT) is observed to be near 29N56W, with a trough reaching south
to 23N55W, then west-southwest as a cyclonic shear axis to 21N68W
and to 21N77W. Scattered showers and isolated thunderstorms are
seen from 24N-28N between 55W-57W and north of 26N between 51W-
55W. Scattered showers and isolated thunderstorms moving west-
northwest are over much of the western half of the area. The ridge
will begin to lift north on Monday. An extensive area of African
Saharan dust is situated over the eastern and central Atlantic E
of 55W, and is gradually shifting westward.

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

$$
Aguirre
This weather bulletin was brought to you by:
www.nashvilleweather.net