AXNT20 KNHC 081002
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Thu Dec 8 2022
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 0600 UTC surface analysis and satellite imagery through
Central Atlantic Storm Warning: Showers and thunderstorms have
increased since last evening near a large non-tropical area of 980
MB low pressure located over the central subtropical Atlantic
about 850 miles east-southeast of Bermuda, near 29N51W. Numerous
moderate to scattered strong convection is now present in the NE
semicircle, N of 25N between 43W and 53W. However, the system
remains embedded within a frontal zone, that consists of an
occluded front that extends E to 29N38W. Numerous moderate to
isolated strong convection is noted along and N of this boundary.
The occluded front expected to become more pronounced later today
as the low begins to move ENE at around 20 kt toward colder
waters and interact with a mid-latitude trough. Therefore, while
the system could show some subtropical characteristics today, its
chances to fully transition to a subtropical or tropical cyclone
appear to be decreasing.
Currently, a large area of gale force winds is associated with
this low N of 23N between 44W and 60W. Within these gales is a
zone of storm force winds of 50 kt in the NW quadrant, from about
29N to 32N between 51W and 56W. As the low moves ENE today,
similar wind speeds and areas are expected into the afternoon,
before winds subside below storm force this evening, yet gales
continue through the week. There is an extensive area of rough,
extremely hazardous seas in association with this storm-force low.
Seas in excess of 20 ft reside N of 22N between 44W and 64W, with
seas of 30 to 32 ft peaking in the area where storm force winds
are occurring. An even broader area of seas of 12 ft or greater is
located N of 19N between 40W and 70W, with large northerly swell
already approaching the Lesser Antilles and Puerto Rico.
Significant non-tropical development of this low is expected
during the next couple of days, however, the risk for subtropical
or tropical development is now low. More information about this
system, including the associated Storm Warning, can be found in
the High Seas Forecasts issued by the National Hurricane Center at
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the Offshore
Zone Forecasts at https://www.nhc.noaa.gov/text/MIAOFFNT3.shtml
The monsoon trough extends from the coastal border of Sierra
Leone and Guinea near 09N13W to 07N17W. The ITCZ continues from
07N17W to 05N46W. Scattered moderate convection is observed from
01N to 09N, between 28W and 45W.
GULF OF MEXICO...
A 1025 mb surface high is centered near the Florida Big Bend,
causing gentle winds and 1-3 ft seas in the NE Gulf. This feature
is also supporting areas of dense fog in the northern Gulf that
will linger today. In the southern Gulf, easterly winds are
moderate to fresh with 3-5 ft seas. In the western Gulf, SE winds
are moderate with 2-4 ft seas.
For the forecast, high pressure will meander in the vicinity of
the NE Gulf through the forecast period. Gentle to moderate mainly
SE winds will prevail into Mon night.
The pressure gradient between subtropical high pressure in the
western Atlantic and lower pressure over Colombia is generating
fresh to locally strong NE winds in the central and western
Caribbean Sea, including the Windward Passage. In the E Caribbean,
gentle to moderate N winds prevail. Seas in the central and W
Caribbean are 5-7 ft and seas in the E Caribbean 3-4 ft except 5-8
ft of N swell through the Mona and Anegada Passages.
For the forecast, a strong low pressure system currently over the
central Atlantic will continue to deepen during the next few
days, maintaining NE-E winds across much of the forecast waters.
Fresh to pulsing strong NE winds will affect the Caribbean
Passages, the lees of the Greater Antilles, and offshore
Colombia into Fri night. Large NE swell across the central
Atlantic will move through the Caribbean Passages and Tropical
Atlantic waters through Sat.
Please read the Special Features section above for details on a
storm force low pressure system, affecting the waters north of 18N
between 35W and 75W.
Elsewhere, a weak pressure pattern prevails off central and
northern Florida, with gentle winds and 4-6 ft seas in the far
western Atlantic. In the eastern Atlantic, a cold front extends
from the Canary Islands to 22N24W, where it transitions to a
stationary front and continues NW to connect to the occluded front
that is associated with the low pressure described in the Special
Features section. Scattered moderate convection is impacting areas
along and within 90 nm of the frontal boundary. To the north of
the front, fresh W winds and seas of 9 to 14 ft dominate. South of
this front, a 1015 mb high pressure centered just N of the Cabo
Verde Islands is leading to light to gentle winds and seas of 5 to
For the forecast W of 55W, large long-period north to northeast
swell will impact the Atlantic waters and Caribbean Passages
between the southeastern Bahamas and the E Caribbean producing
high seas into the start of next week, with large E swell reaching
the Florida offshore waters N of 26N early Fri through Sat.