TROPICAL WEATHER DISCUSSION BY NHC
305
AXNT20 KNHC 181804
TWDAT
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
204 PM EDT Sat Aug 18 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
1745 UTC.
...TROPICAL WAVES...
A tropical wave is in the E Atlc with axis extending from 07N-18N
along 23W, moving W at 10 kt. The wave is in a strong deep layer
environment and is being affected by dry and dust air intrusion
in the lower levels as depicted in GOES-16 water vapor and
enhanced IR imagery. These factors are hindering the development
of convection at the time.
A tropical wave is in the central Atlc with axis extending from
08N-20N along 39W, moving W at 15 kt. The wave is entering a low
deep layer wind shear environment, however is being severely
affected by Saharan dry air and dust, which hinder convection at
the time.
A tropical wave is in the E Caribbean with axis extending from
07N-18N along 62W, moving W at 15 kt. Both CIRA LPW and GOES-16
water vapor imagery show the northern wave environment being
affected by low level dry air, which is limiting the convection to
scattered moderate across the Windward Islands and SE Caribbean S
of 14N E of 65W.
A tropical wave is in the western Caribbean with axis extending
from 09N-20N along 79W, moving W at 15 kt. The wave is in a
moderate to strong deep layer wind shear environment and mostly a
dry enviromnent. Shallow moisture in the northern wave environment
and diffluent wind aloft support scattered showers and tstms from
18N-21N between 76W-81W.
...MONSOON TROUGH/ITCZ...
The monsoon trough extends from the coast of W Africa near 09N13W
to 06N26W to 10N40W. The ITCZ begins near 10N40W and continues to
08N50W to 10N58W. Besides the convection mentioned in the
tropical waves section, scattered heavy showers and tstms are off
the W coast of Africa from 06N-14N E of 20W.
...DISCUSSION...
GULF OF MEXICO...
The Bermuda high extends a ridge axis SW across Florida and the
entire Gulf reaching also eastern Mexico. The ridge is providing
return flow in the range of 5-10 kt across the region except in
the north-central Gulf where scattered heavy showers and tstms
enhance the wind to fresh. The area of convection is N of 27N
between 85W and 93W and is being supported by inflow of shallow
moisture from the Caribbean by southeasterly wind and middle level
diffluent flow. Surface ridging will prevail across the basin
through Wed. Showers over the N-central and NE basin are forecast
to continue through Sun morning.
CARIBBEAN SEA...
GOES-16 water vapor imagery at the lower levels show generally
dry, stable air across the basin. Besides dry air, moderate to
strong deep layer wind shear cover the western half of the
Caribbean, thus limiting the areas of convection. A tropical wave
moving S of eastern Cuba support scattered showers over central
and eastern Cuba adjacent waters. Another tropical wave moves
across the E Caribbean supporting showers in the SE basin. See the
tropical waves section for further details. CIRA LPW imagery show
regions of abundant shallow moisture in the basin that support
isolated showers in the Gulf of Honduras and N of 14N between
69W-73W, including Hispaniola. Otherwise, surface ridging
extending from the Atlantic to the northern half of the basin,
continues to support fresh to strong winds in the south-central
Caribbean. The center of high pressure SW of the Bahamas will
stall the next several days, which will allow the continuation of
these winds in the south-central basin. Showers will prevail in
the SE Caribbean through Sunday.
ATLANTIC OCEAN...
The Bermuda high and the Azores high covers most of the Atlc ocean
mainly supporting fair weather. A weakness in the ridge is
analyzed as a surface trough that extends from 30N54W SW to
27N60W. Scattered showers and tstms are within 120 nm either side
of the trough. Isolated showers are across the Bahamas. For
further information associated with the tropical waves, see
section above.
For additional information please visit
http://www.hurricanes.gov/marine
$$
Ramos
https://www.nhc.noaa.gov/
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A LARGE STRONG WAVE ABOUT TO EMERGE OFF THE COAST OF
AFRICA IS KICKING UP SAHARA DUST WEST OF THE ATLANTIC.
THERE IS THUNDERSTORM ACTIVITY ASSOCIATED WITH THIS WAVE
MAINLY OVER THE LAND AREA. MODELSSHOW A LARGE SWIRL
MOVING OFF COAST BUT NO THUNDERSTORMS ASSOCIATED WITH
THE WAVE. MORE THAN LIKELY DUE TO THE DRY AIR AND DUST
AHEAD OF THIS WAVE TO BE. ELSEWHERE IN THE TROPICS IT
REMAINS QUIET...RTW
