[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201757
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Thu Apr 20 2023

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 1200 UTC surface analysis and satellite imagery through
1700 UTC.

...MONSOON TROUGH/ITCZ...

A monsoon trough enters the Atlantic through the coast of Guinea-
Bissau just south of Bissau then southwestward to 04N21W. An ITCZ
extends westward from 04N21W across 03N30W to 04N40W. Numerous
moderate to scattered strong convection is occurring near both
features from 01N to 07N between 10W and 23W. Scattered moderate
to isolated strong convection is observed farther west near the
ITCZ south of 06N between 23W and 40W.

...GULF OF MEXICO...

A surface ridge stretches west-southwestward from a 1025 mb high
over southern Georgia to just north of Tampico, Mexico. Convergent
easterly winds are causing scattered showers and isolated
thunderstorms at the southeastern Gulf, including the Florida
Straits and northwestern coast of Cuba. Moderate with locally
fresh E to SSE winds and 3 to 5 ft seas are found across the
entire Gulf.

For the forecast, the subtropical ridge positioned between the
southeastern United States and Bermuda, and lower pressures over
Mexico will continue to enforce moderate to fresh SE to S return
flow over the Gulf of Mexico through Fri. The diurnal trough
forming over the Yucatan will promote strong E winds over eastern
Bay of Campeche tonight. Agricultural and seasonal fires over
Mexico and Central America result in smoke and haze over the the
southwestern Gulf and the Bay of Campeche. Mariners may experience
reduced visibility in these waters. Winds will diminish across
the Gulf on Fri. A cold front that is expected to enter the
northwestern Gulf Fri night. Moderate to fresh N to NE winds will
prevail behind the front on Sat. By Sun morning, the dissipating
front will extend from southwest Florida to near the Texas-Mexico
border. Looking ahead, as a surface ridge builds to the north of
the Gulf, fresh to strong E to SE winds are expected on Sun and
Mon over most of the western and central Gulf.

...CARIBBEAN SEA...

A 1022 mb Mid-Atlantic High near 28N49W sustains a relatively
fair trade-wind regime for much of the basin. The southern end of
a surface trough is triggering scattered showers and isolated
thunderstorms over eastern Cuba and northeast of Jamaica. Fresh
with locally strong NE to E winds and seas of 6 to 8 ft are
present at the south-central basin, north of Colombia. Gentle to
moderate ESE winds and seas at 2 to 4 ft are noted at the
northwestern basin. Moderate easterly winds with 4 to 6 ft seas
prevail for the rest of the basin.

For the forecast, the Mid-Atlantic High will weaken over the next
couple of days. This will allow the fresh to strong NE to E trades
over the south-central Caribbean and fresh E trades over the Gulf
of Honduras to diminish by Fri. Elsewhere, winds and seas will be
quiescent through early next week.

...ATLANTIC OCEAN...

A dissipating stationary front curves southwestward from a 1019 mb
low east of Bermuda across 31N58W to northeast of the Bahamas at
29N74W. Patchy showers and isolated thunderstorms are seen up to
40 nm along either side of this feature. A surface trough over the
central and southeast Bahamas is coupling with an upper-level low
east of the Florida-Georgia border near 31N77W to trigger
scattered showers and thunderstorms from 21N to 26N between 68W
and 75W. Another surface trough north of Sao Luis, Brazil near
03N43W is generating widely scattered moderate convection south
of 05N between 40W and the coast of Brazil. Convergent trades are
creating similar conditions near the coast of Guyana, Suriname
and French Guiana. Refer to the Monsoon Trough/ITCZ section for
additional convection in the Atlantic Basin.

Moderate with locally fresh ENE winds and 4 to 6 ft seas in
moderate NE to E swell are found near the stationary front, north
of 27N between 65W and the Florida-Georgia coast. Farther
southeast, light to gentle E to SE winds and seas of 3 to 5 ft are
present from 21N to 27N/31N between 50W and 65W. For the central
and eastern Atlantic, light to gentle winds and seas of 5 to 7 ft
in moderate N swell are evident north of 20N between the African
coast and 50W, including the Canary Islands. To the south, gentle
to moderate with locally fresh NNE to NE trades and seas at 6 to 8
ft exist from 03N to 20N/21N between the central African coast and
Lesser Antilles. Light to gentle southerly and monsoonal winds
with 4 to 6 ft seas prevail for the remainder of the Atlantic
Basin.

For the forecast west of 55W, the aforementioned stationary
front should dissipate later today. A surface trough/low is
likely to develop by Fri night and persist through Sun east of the
Bahamas. These features should strengthen trades between Bermuda
and the Bahamas on Sat and Sun, allowing for fresh to strong
winds and building seas peaking near 9 ft, before weakening on
Mon. A weak cold front should move off the coast of northeast
Florida Sat night, then dissipate north of the Bahamas by Mon.
Moderate north swell is anticipated to impact the waters south and
southwest of Bermuda east of 60W beginning on Sat.

$$

Forecaster Chan
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