[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201754
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1254 PM EST Tue Nov 20 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.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends from the coast of Liberia near
05N09W to 0512W, where latest scatterometer data indicates the
ITCZ axis begins and continues to 05N21W to 03N30W to 05N37W and
to 04N45W. Scattered moderate convection is along and within 60 nm
north of the ITCZ axis. Scattered showers are within 90 nm either
side of the ITCZ axis between 12W and 17W.

GULF OF MEXICO...

In the upper-levels, broad troughing that extends from the Great
Lakes region of the U.S. to the far NW Gulf is keeping west to
southwest upper winds over the northern portion of the Gulf. At
the surface, a cold front is making headway the Florida panhandle,
and as of 15Z, it is analyzed from near Tallahassee, Florida
southwestward to 28N90W where it becomes stationary to 28N92W and
warm front to a 1019 mb low at 28N92W. A cold front extends from
the low to 24N95W and to inland Mexico at 21N97W. It continues
northwestward well inland Mexico. Satellite imagery shows
multilayer clouds with embedded scattered showers and isolated
thunderstorms within 150 nm southeast and south of the cold front
east of 90W, and also within 60 nm either side of the cold front
from 21N to 25N. Broken to overcast low clouds with areas of rain
and scattered showers are west and northwest of the cold front
west of 90W, except within about 30 nm of the Texas coast north of
Corpus Christi. A stationary front extends northeast to southwest
from the Atlantic to across central Florida to near 28N83W, where
it transitions to a trough to 24N86W. Scattered showers and
isolated thunderstorms are within 60 nm east of the trough north
of 25N, and within 90 nm west and northwest of the trough from 24N
to 25N.

As for the forecast, the 1019 mb low will dissipate by this
evening, while the cold front will become stationary from southern
Florida to the NW Gulf near 26N95W and to near Veracruz Mexico by
Thu Night. The trough over the eastern Gulf will dissipate by late
tonight.

CARIBBEAN SEA...

Water vapor imagery shows broad upper-level anticyclonic flow
covering just about the entire basin west of about 67W, with the
associated upper anticyclone centered over the far eastern Pacific
Ocean. Broad cyclonic upper-level flow is east of 67W. A mid-
level inverted trough extends from Panama to 15N82W and to near
18N83W. Scattered patches of low- level clouds moving quickly
westward with isolated showers are seen south of 20N west of 80W,
while scattered moderate isolated strong convection is confined to
the south of 13N west of 79W. This activity is more due to low-
level speed convergence of strong trades into an area of lighter
winds. Isolated moderate rainshowers are in broken low level
clouds, elsewhere, from 63W westward. Isolated showers also moving
quickly westward are elsewhere across the basin. An area of
scattered showers and thunderstorms is over the eastern Caribbean
from 12N to 15N between 66W and 70W. This activity is being
enhanced by a mid-level shortwave through.

As for the forecast, fresh to strong trades will continue along
the coast of Colombia through Thu. Large long period NE swell
over the Atlantic will continue to impact the waters east of the
Lesser Antilles through Wed afternoon.

ATLANTIC OCEAN...

A western Atlantic cold front enters the area near 32N74W and
continues to 29N77W, where becomes stationary to inland central
Florida near Coco Beach and continues to the west-central Florida
coast. Scattered showers and isolated thunderstorms are noted
north of 27N and west of 76W. This activity is being aided by
a mid to upper shortwave trough that is rounding the base of
a broad upper trough northwest of the area. A weak 1017 mb low is
centered at 30N71W, with a trough extending southwestward to
the central Bahamas and to the coast of Cuba at 22N78W. Scattered
showers and thunderstorms are ahead of the trough north of 28N
between 60W and 69W.

Over the far eastern Atlantic, a narrow upper-level trough extends
from near 32N08W to 22N12W and to an upper low at 11N18W. This
feature is sustaining a cold front that extends from a 1012 mb low
just north of the area at 33N15W, southwest from this low to
30N20W to a frontal wave at 29N30W and continues to 26N37W, where
it becomes a stationary front to 29N44W and to a 1019 mb low
north of the area at 32N53W. A trough extends from this low to
near 28N58W. A 1023 mb high is analyzed south of the stationary
front near 27N49W. Satellite imagery shows broken to overcast
mainly low and mid-level clouds along and within 60 nm south of
the cold front and frontal wave east of 30W. Patches of rain
and scattered showers are possible with these clouds. Isolated
showers are possible elsewhere along the stationary front and
with the trough that extends from the 1019 mb low. Relatively weak
high pressure is present over the remainder of the discussion
area.

As for the forecast, the trough that extends to the central
Bahamas and to near the coast of Cuba will dissipate by Wed. The
cold front over the northwest portion will move south over the
waters north and northeast of the Bahamas Thu through Fri night,
then become stationary Sat. A tight pressure gradient resulting
from strong high pressure that will build southward Fri through
Sat night will bring strong winds northeast of the Bahamas. Seas
outside the Bahamas will build to between 9 and 14 ft from Fri
through Sat night.

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

$$
Aguirre
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