[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 122244
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Mon Sep 13 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 31N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0000 UTC surface analysis and satellite imagery through
2230 UTC.

...SPECIAL FEATURES...

Tropical Storm Nicholas is centered near 22.8N 95.5W at 12/2100
UTC or 140 nm ESE of La Pesca Mexico moving NNW at 12 kt.
Estimated minimum central pressure is 1008 mb. Maximum sustained
wind speed is 35 kt with gusts to 45 kt. Numerous moderate to
isolated strong convection is noted within 210 nm in the northeast
semicircle and within 180 nm in the south quadrant of the center.
8 to 10 ft seas are noted within 120 nm in the northeast quadrant
of the low. Nicholas is expected to continue on a NNW track
through tonight, then slowly turn toward the N or NNE late Monday.
The center of Nicholas will pass near or just offshore the coasts
of northeastern Mexico and South Texas on Monday, and move
onshore along the coast of south or central Texas coast Monday
night or early Tuesday. Nicholas is expected to produce storm total rainfall of
8 to 16 inches, with isolated maximum amounts of 20 inches, across
portions of the middle and upper Texas coastal areas today through
the middle of the week. This will increase the chance of flooding
at urban and low-lying areas, and near rivers and streams. In
addition, the combination of a dangerous storm surge and the tide
will cause normally dry areas near the coast to be flooded by rising
waters moving inland from the shoreline.

Please read the latest High Sea Forecast issued by the National
Hurricane Center at website -
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest
Nicholas NHC Forecast/Advisory and Public Advisory at website -
www.nhc.noaa.gov/graphics_at4.shtml?start#contents

...TROPICAL WAVES...

An Atlantic tropical wave is along 30W from 03N to 21N, moving W
at 15 to 20 kt. Scattered moderate convection is noted from 08N
to 10N between 30W and 32W.

Another Atlantic tropical wave is near 51W from 05N to  22N
moving W 10 to 15 kt. Much drier air at mid levels are hindering
any significant convection near this wave.

A Caribbean tropical wave is along 70W from 21N southward across
the central Dominican Republic to NW Venezuela, and moving W at
15 to 20 kt. Enhanced by an upper-level low north of the
Dominican Republic near 21N69W, scattered showers and isolated
thunderstorms are occurring from 16N to 17N between 69W and 71W.

...MONSOON TROUGH/ITCZ...

A monsoon trough passes through the Gambia coast near 13N16W
to 05N40W. The ITCZ continues from 05N40W to 05N47W. Other than
the convection described in the Tropical Wave section, scattered
moderate convection is evident from 12N to 14N east of 17W.

The eastern end of the E Pacific monsoon trough is triggering
scattered showers and isolated thunderstorms across Panama and the
SW Caribbean Basin.

...GULF OF MEXICO...

Refer to the Special Features section above for details on newly
developed Tropical Storm Nicholas over the SW Gulf.

An earlier scatterometer satellite pass showed fresh to strong NW
winds along the coast of Veracruz, south of 20N, and fresh to
strong E to SE winds south of 24N and west of 90W converging into
T.S. Nicholas. Buoy data indicates seas are mostly 5 to 7 ft in
this area, outside of the main impact area of Nicholas. 3 to 5 ft
seas are noted elsewhere, except for 2 to 4 ft seas in the far
northeast Gulf. Scattered showers and thunderstorms are active
along a surface trough off the coast of Texas. Scattered showers
and thunderstorms are also noted over the far southeast Gulf, off
the Florida coast.

For the forecast, winds and seas will diminish over the western
Gulf by mid week after Nicholas moves inland, leaving gentle to
moderate E to SE winds across the basin, with 3 to 5 ft seas over
the western Gulf and 1 to 3 ft seas over the eastern Gulf.

...CARIBBEAN SEA...

Please see the Tropical Waves and Monsoon Trough/ITCZ sections
above for convection in the Caribbean Basin. Moderate to fresh
trades and seas of 4 to 6 ft persist across the basin, except for
mainly gentle trades and seas at 3 to 5 ft in the lee of Cuba.

For the forecast, fresh winds in the Gulf of Honduras will pulse
this evening. By tonight and into Mon morning, moderate to fresh
trades will prevail across the basin through the forecast period.

...ATLANTIC OCEAN...

A stationary front reaches from near Bermuda to Saint Augustine
Florida. Scattered showers and a few thunderstorms are evident
within 60 nm of the front east of 72W, ahead of a mid/upper level
trough moving eastward along the boundary. A few showers and
thunderstorms are also active over the Straits of Florida.
Scattered showers and thunderstorms are ongoing south of 22N
between 60W and 70W, associated with an upper low centered north
of the Dominican Republic. Farther east, a cold front reaches from
off Portugal to just west of the Canary Islands to 28N40W.
Moderate northerly winds and 4 to 6 ft seas are noted north of
this boundary, gentle to moderate winds and 3 to 5 ft seas are
noted north of 27N and west of 40W, and moderate to fresh trades
and 5 to 7 ft seas are noted elsewhere.

For the forecast west of 60W, a few showers and thunderstorms will
persist along the the frontal boundary as it will lingers through
Mon. An area of low pressure is expected to form north of the
southeastern or central Bahamas in a few days resulting from a
tropical wave interacting with an upper-level trough. Gradual
development of this system is possible, and a tropical depression
could form later this week several hundred miles southeast of the
Carolinas while it moves northwestward across the western
Atlantic. This system has a low chance of formation in the next 48
hours and a medium chance through the next 5 days.

$$
Christensen
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