[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 202323
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Sun Feb 21 2021

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 1800 UTC surface analysis and satellite imagery through
2300 UTC.

...SPECIAL FEATURES...

Caribbean Gale Warning: The combination of strong high pressure
building north of the area and the typical low pressure found
over northern Colombia will support gale force northeast to east
winds near the coast of Colombia beginning on Sun night and
continuing through the middle of the upcoming week. Wave heights
with these are expected to be in the 7-10 ft. Please read the
latest NWS high seas forecast issued at the National Hurricane
Center at website: https://www.nhc.noaa.gov/text/MIAHSFAT.shtml
for more details.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the coastal sections of
Sierra Leone near 08N13W to 07N17W, where latest scatterometer
data indicates that it transitions to the ITCZ to 02N30W and to
below the equator at 01S44W. Scattered moderate to isolated
strong convection is within 180 nm south of the ITCZ between 20W-
26W, and within 60 nm north of the ITCZ between 22W-29W. Scattered
moderate convection is within 120 nm north of the ITCZ between
30W-36W, and also well south of the ITCZ within 30 nm of line
from 02S25W to 01S29W.

GULF OF MEXICO...

A 1030 mb high pressure center is analyzed over extreme
southwestern Louisiana, while a 1032 mb high is analyzed over
southwestern Alabama. Associated strong high pressure has build
over the entire basin in the wake of the recent cold front that
is presently stationary over the northwestern Caribbean Sea.
Latest ASCAT data passes show moderate to fresh northeast winds
over the eastern Gulf, and mainly moderate northeast to east
winds gentle over the central Gulf. Buoy observations in the
western Gulf are reporting moderate to fresh southeast winds
there. Wave heights are in the range of 5-7 ft in the eastern
Gulf, except for up to 8 ft near the Yucatan Channel and 4-6 ft
elsewhere.

The present high pressure is controlling the wind regime
throughout and keeping the atmosphere stable as dry air has
advected over the Gulf behind the cold front. Only scattered to
broken low clouds are noted south about 29N. A pocket of
overcast low clouds is identified to be in the Bay of Campeche,
where scattered showers are possible.

As for the forecast: The high pressure area will shift eastward
to the Atlantic Ocean on Mon in response to the next cold front
to approach the area. This front is forecast to move over the NW
Gulf early Mon morning. It will move across the rest of the Gulf
through Tue night. Scattered showers and a few thunderstorms may
be possible with this front. Beyond the forecast time frame, yet
a third cold front may reach the NW Gulf by early on Thu.

CARIBBEAN SEA...

Please see the Special Features section above for details on a
Gale Warning for pulsing gale-force winds off the coast of
Colombia.

A stationary front extends from west-central Cuba to the Gulf of
Honduras at 16N86W. Latest ASCAT data revealed strong to near
gale-force northwest winds west of the front and south of 19N to
the Gulf of Honduras. Wave heights there are in the range of 6-8
ft. Elsewhere west of the front, the ASCAT pass along with
recent buoy data indicate fresh northerly winds over those waters
along with wave heights of 7-10 ft in a north swell. Fresh to
strong trade winds are noted over the south-central Caribbean
elsewhere outside the vicinity of the Colombia, where strong
northeast to east winds are present when not pulsing to gale
force at night as mentioned above. Wave heights with these winds
are in the range of 6-9 ft, but will be lightly higher at night.
Moderate trade winds are noted elsewhere over the eastern
Caribbean.

Patches of low-level moisture, in the form of broken to scattered
shallow low-level clouds, are moving quickly westward in the
trade wind flow over the areas north of 12N east of 70W, and
north of 14N west of 70W. Isolated to scattered showers may be
possible with some of these clouds.

As for the forecast: The stationary front will weaken tonight
and dissipate by Sun evening. High pressure north of the area
building in the wake of the front will support fresh to strong
northeast winds east of 80W into Mon.

ATLANTIC OCEAN...

A cold front extends from near 32N66W southwestward to the
central Bahamas and to west-central Cuba. Buoy observations over
the western Atlantic are reporting fresh to strong north to
northeast winds west of the front, except for strong northwest
winds between the front and 70W. Wave heights resulting from
these winds are in the range of 7-10 ft, but are slightly lower
west of 70W. A few ship observations in the area are reporting
similar wind speeds like that from the buoys. Latest ASCAT data
showed moderate to fresh south to southwest winds ahead of the
front north of 26N, with wave heights of 6-8 ft. Latest GOES-16
satellite imagery depicts overcast to broken low and mid-level
clouds within 50-60 nm either side of the front. Scattered
showers are possible underneath these clouds. Cold-air
stratocumulus clouds are observed elsewhere to the northwest of
the front suggestive of cold air advection that is filtering in
over the northwest part of the area behind the cold front.

Available partial ASCAT data passes suggested that an eastern
Atlantic anticyclone is located at 27N42W. It was analyzed with a
pressure of 1023 mb at 18Z. A ridge axis stretched from it west-
southwestward to the central Bahamas. Another ridge axis extends
from the anticyclone east- southeastward to just inland the
coast of Western Sahara, Africa near 23N15W. The latest ASCAT
data confirmed that there are mainly fresh northeast to east
trade winds south of the ridge axis between 33W and the Lesser
Antilles. Gentle to moderate east to southeast winds are seen in
the ASCAT data from 20N-25N between 30W-76W, and gentle to
moderate north-northeast winds are over the far eastern Atlantic
from 16N-22N between 20W-30W. Light and variable winds are in the
vicinity of the 1026 mb anticyclone. Wave heights elsewhere east
and southeast of the aforementioned cold front are in the range
of 5-7 ft due to mainly an east-southeast swell.

Over the far eastern Atlantic, a cold front extends from near
32N14W southwestward to the western part of the Canary Islands
and to 24N32W. Fresh northwest to north winds as captured by
morning ASCAT pass to be present north of this, while fresh
to strong southwest winds were seen in the same ASCAT pass to be
present east of the front north of 27N. Altimeter data passes
from during the day reveal wave heights in the range of 10-15 ft
due to a northwest to north swell east of a line from 32N49W to
24N35W. This swell is forecast to begin to decay through early
Sun allowing for these large wave heights to subside to around
8-12 ft through late Sun.

As with the forecast regarding the western Atlantic cold front:
It will move southeastward across the open Atlantic Ocean
tonight through Sun night, then begin to weaken and become
stationary along roughly 23N across the central Bahamas through
Mon night. High pressure in the wake of the front will support
fresh to strong northeast to east winds across the western
Atlantic tonight through Mon morning. The next cold front will
move off the northeast Florida coast Mon night and reach from
Bermuda to the Straits of Florida by mid-week. Strong to gale
force southwest winds and building wave heights are expected
ahead of the front north of 29N early Tue and through and Tue
night.

$$
Aguirre
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