National Hurricane Center
231
AXNT20 KNHC 311653
TWDAT
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1253 PM EDT Tue Jul 31 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
1645 UTC.
...TROPICAL WAVES...
A tropical wave is in the E Atlc with axis extending from 06N-17N
along 22W, moving W at 10-15 kt. The wave is in a low deep layer
wind shear environment, however is being severely affected by a
Saharan Air Layer outbreak as depicted by GOES-16 RGBs and CIRA
LPW imagery. Shallow moisture and middle level diffluence support
scattered showers S of the monsoon trough from 05N-09N between
20W-28W.
A tropical wave is in the central Atlc with axis extending from
07N-18N along 35W, moving W at 10-15 kt. The wave is in a low
deep layer wind shear environment, however is being severely
affected by Saharan Air Layer dry air and dust as depicted by
GOES-16 RGBs, low-level water vapor and CIRA LPW imagery. No
convection is associated with this wave at this time.
A tropical wave in the central Atlc with axis extending from 07N-
17N along 51W, moving W at 15-20 kt. The wave is being supported
by a middle to upper level inverted trough and is mainly in a dry
air environment as depicted by GOES-16 RGBs and CIRA LPW imagery.
Moderate moisture in the southern wave environment associated with
the ITCZ support scattered moderate convection from 07N-12N
between 50W-53W.
A tropical wave is in the central Caribbean with axis extending S
of 20N along 76W, moving W at 15-20 kt. The wave is mainly in a
strong deep layer wind shear environment and Saharan dust is noted
across the central Caribbean in GOES-16 RGBs imagery. However,
CIRA LPW imagery show abundant low level moisture associated with
this wave, which along diffluence aloft support scattered moderate
convection between Colombia and S Panama S of 12N. An upper-level
low centered E of Jamaica support isolated showers across
Hispaniola and the Windward Passage.
A tropical wave is moving off the Yucatan Peninsula into the E Bay
of Campeche. Its axis is S of 22N along 91W, moving W at 10-15 kt.
The wave is being supported by a middle-level inverted trough that
along with shallow moisture support scattered showers in the SW
Gulf S of 23N E of 92W.
...MONSOON TROUGH/ITCZ...
The monsoon trough extends from the coast of Africa near 18N16W
to 09N21W to 09N28W to 09N34W. The ITCZ begins near 09N38W and
continues to 09N49W, then resumes W of a tropical wave near
10N52W and continues to the coast of Venezuela near 09N61W. Aside
from the convection associated with the tropical waves, scattered
showers and isolated tstms are from 08N-11N E of 17W and from
06N- 13N between 50W-62W.
...DISCUSSION...
GULF OF MEXICO...
The Atlc subtropical high continues to extend a ridge axis SW
across the Florida Peninsula to the central Gulf, thus supporting
light to gentle south-southeasterly flow. CIRA LPW imagery show
very moist air at the lower levels across the basin, which is
being advected from the Caribbean by the return flow. This moist
environment along with diffluence aloft support scattered showers
and tstms N of 23N E of 90W. In the E Bay of Campeche, a tropical
wave support scattered showers. See tropical waves section for
further details. Otherwise, scattered heavy showers and tstms are
within 90 nm off the SE coast of Texas and SW coast of Louisiana
associated with a frontal system N of the area and anchored by a
1013 mb low in NE Texas. This front is forecast to come off the
coast of Texas Wed morning, stall from SW Louisiana to near
Tampico, Mexico Thu morning and weakening to a surface trough late
Thu night. Showers are forecast to continue in the aforementioned
regions through early Fri.
CARIBBEAN SEA...
Abundant shallow moisture is in the NW and central Caribbean as
noted in CIRA LPW imagery. This moisture along with middle to
upper level diffluence is supporting scattered showers and tstms N
of 18N between 79W-86W. Similar convection is in the SW basin S of
12N between 74W-84W, which is associated with the EPAC monsoon
trough that connects to a 1010 mb low off the coast of Colombia
near 10N76W. An upper level low off the E coast of Jamaica support
isolated showers over western Dominican Republic, Haiti and the
Windward Passage. GOES-16 water vapor and RGB imagery show dry air
and dust across the E basin, which in part is hindering the
development of convection. A new tropical wave is forecast to
move across the Lesser Antilles Thu with showers for the Windward
Islands. Another tropical wave will move into the E Caribbean on
Sunday with showers.
ATLANTIC OCEAN...
Three tropical waves move across the basin...see section above.
Otherwise, the Atlc subtropical high dominates the basin, thus
supporting mainly fair weather conditions. Surface ridging will
dominate the central and eastern Atlantic through the next couple
of days providing stable and dry conditions.
For additional information
please visit http://www.hurricanes.gov/marine
$$
Ramos
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A Hugh plume of African Sahara dust has moved off the African coast
due to mid to upper level low that has moved off shore kicking up
the dust. There are no signs of tropical cyclone formation at this time.
RTW
