National Hurricane Center
155
AXNT20 KNHC 061739
TWDAT
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
139 PM EDT Mon Aug 6 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
1730 UTC.
...SPECIAL FEATURES...
Gale warning over the south-central Caribbean...
A strong ridge over the E CONUS extending E to Atlc adjacent waters
W of 60W will tighten the pressure gradient in the south-central
Caribbean. Wind gusts reaching gale-force are expected starting
tonight, then sustained gale-force winds are forecast for the
Gulf of Venezuela on Tue night and along the coast of Colombia by
Wed night. Please see the National Hurricane Center Atlantic High
Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for
further details.
...TROPICAL WAVES...
A tropical wave is in the eastern Atlantic with axis extending
from 07N-18N along 35W, moving W at 10 kt. This wave continues to
be affected by Saharan dry air and dust intrusion, which is
limiting convection to the area where the wave meets the ITCZ from
09N-12N and west of 35W.
A tropical wave is in the central Atlantic with axis extending
from 01N-14N along 48W, moving W at about 10-15 kt. The wave
continues to be affected by intrusion of Saharan dry air and dust
as indicated by GOES-16 RGBs, water vapor and CIRA LPW imagery at
the lower levels. Shallow moisture in the vicinity of the ITCZ
supports scattered moderate convection mainly S of 10N.
A tropical wave is in the E Caribbean with axis S of 21N along
70W, moving W at 5-10 kt. The wave is in a very moist environment
at the lower levels as indicated by CIRA LPW and GOES-16 water
vapor imagery. The wave is underneath a diffluent environment
between an elongated upper-level low over the central basin and
S-SW flow to the E, which is supporting scattered showers N of
17N between 68W-72W.
A tropical wave is in the W Caribbean with axis S of 21N along
80W, moving W at 10 kt. CIRA LPW imagery shows shallow moisture
associated with the wave. Shallow moisture in the vicinity of the
monsoon trough supports scattered moderate convection mainly S of
10N.
...MONSOON TROUGH/ITCZ...
The monsoon trough enters the eastern Atlantic near 20N16W to
14N31W. The ITCZ begins W of a tropical wave near 10N38W and
continues to 08N46W, then resumes near 07N51W to 09N61W. Aside
from the convection related to the tropical waves, scattered
moderate convection is observed along the ITCZ.
...DISCUSSION...
GULF OF MEXICO...
A broad area of high pressure extends from eastern CONUS across
the basin. A surface trough extends across the northwest Gulf
along 96W and north of 27N. Scattered moderate convection is
observed with this trough mainly north of 25N and west of 94W.
Another trough extends across the Bay of Campeche with scattered
showers. Return flow provided by the surface ridge continues to
advect shallow moisture from the Caribbean and into the Gulf,
which is supporting scattered moderate convection across the
Yucatan Channel and south-central Gulf waters between 84W-90W.
A third surface trough is in the far east Gulf from the Florida
Big Bend to 29N84W with no significant convection at this time.
Expect for convection to continue across the west Gulf through
tonight. Isolated showers are forecast in the Bay of Campeche
through the middle of the week associated with a thermal surface
trough that will come off the Yucatan Peninsula at night. This
trough will also enhance the winds to fresh off the W Yucatan
Peninsula. Surface ridging is forecast to prevail through the week.
CARIBBEAN SEA...
GOES-16 RGBs continue to show a thin layer of Saharan dust moving
across most of the basin where strong deep-layer wind shear
prevails. This environment continues to suppress the development
of significant convection across the basin. However, shallow
moisture is across the basin supporting scattered showers within
90 nm off the southwest of Cuba. To the south, the monsoon trough
supports similar convection within 75 nm off Panama. A tropical
wave is in the W Caribbean lacking convection, while an upper-
level low over Hispaniola is supporting convection near the
northern portion of the wave currently along 70W. See the
Tropical Waves section above for further details. Fresh to near-
gale force winds in the south-central Caribbean are forecast to
increase to gale-force gusts in the Gulf of Venezuela and off the
coast of Colombia by tonight, then sustained gale-force winds
will develop through midweek. See the Special Features section for
further details.
ATLANTIC OCEAN...
Two tropical waves are moving across the basin. Refer to the
section above for details. A non-tropical, surface low pressure
system centered near 31N50W is interacting with a broad upper-
level low. Although the system is producing disorganized showers and
thunderstorms to the east and northeast of the center, environmental
conditions are expected to be only marginally conducive for the low
to acquire subtropical or tropical characteristics while it moves
north or north-northeastward over the next day or so. The low is
forecast to move over cooler waters by Tuesday night, and
development is not expected after that time. Southeast of this
low, a surface trough extends from it to 26N57W supporting
scattered showers and tstms N of 30N between 40W-50W. Aside from
the tropical waves, the remainder of the Atlc is under the
influence of surface high pressure that supports fair weather.
For additional information please visit
http://www.hurricanes.gov/marine
$$
ERA
https://www.nhc.noaa.gov/
470
ABNT20 KNHC 061740
TWOAT
Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Mon Aug 6 2018
For the North Atlantic...Caribbean Sea and the Gulf of Mexico:
A non-tropical low pressure system centered about 1100 miles
west-southwest of the Azores is interacting with an upper-level low.
Although the associated shower and thunderstorm activity has
increased during the past 24 hours, environmental conditions are
expected to be only marginally conducive for additional development
while the system moves north or north-northeastward over the next
day or so. The low is forecast to move over cooler waters Tuesday
night, and development is not expected after that time. Additional
information on this system can be found in High Seas Forecasts
issued by the National Weather Service.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...low...30 percent.
&&
High Seas Forecasts issued by the National Weather Service can be
found under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and
on the Web at https://ocean.weather.gov/shtml/NFDHSFAT1.shtml.
$$
Forecaster Brown
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No change in the tropics. Invest 97L has a chance for development
as it begins to track northeast away from present location. 97L
is only a threat to shipping... RTW
Please note that the latest guidance model for 18z has not yet been
released. So all I have is the 12z model run. I may not be able to
post this evening, so click on image to go to NHC and tropical tidbits
for latest info and models...RTW
