[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201003
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Tue Dec 20 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
0900 UTC.

...SPECIAL FEATURES...

NE Gulf of Mexico Gale Warning: A 1014 mb low pressure is in the
NW Gulf offshore SW Louisiana near 28N93W. A cold front extends
from the low to the western Bay of Campeche near 20N96.5W. A warm
front extends from the low center to south of Pensacola, Florida
near 29N87W. Numerous showers and scattered thunderstorms are
affecting the waters N of 23N and between 84W and 94W. Fresh to
strong cyclonic winds are observed N of 28N and W of 87W. Frequent
gusts to gale force are occurring in the coastal waters between
88W and 91.5W. Seas in these waters are 5-8 ft. The gradient
between the low and strong high pressure over the SE United States
will cause winds to gale force over the NE Gulf of Mexico this
afternoon. Seas will build to near 10 ft in the northern Gulf.
Gale force winds are also now forecast offshore Veracruz, Mexico
behind the front this afternoon and evening with seas of 8-10 ft.
The low will shift toward South Florida by late tonight while the
cold front slowly moves eastward, stalling and weakening by mid-
week. Fresh to strong N winds are expected elsewhere behind the
front through this evening. Scattered showers and thunderstorms
are expected with the low and front. Winds and seas will diminish
in the NE Gulf and SW Gulf late Wed into Thu.

SW N Atlantic Gale Warning: A cold front from 30N55W to 26N63W
continues as a shearline to across the Central Bahamas and the
Straits of Florida. A few showers are noted near the frontal
boundary, but no deep convection is evident. Moderate to fresh
N-NW winds are present behind the frontal boundary and north of
the shearline, with the strongest winds occurring near 27N70W.
Seas behind the cold front are 6-10 ft, with the highest seas
occurring N of 28N and E of 70W. The cold front will extend from
31N49W to 23N67W this evening. A low pres over the Gulf of Mexico
will cross South Florida tonight and move ENE near the NW Bahamas
Wed morning. The low pres is expected to develop gale force winds
on Wed as it continues east along 26/27N to the east of the
Bahamas, while seas build to 8-10 ft. These gales should diminish
by early Thu as the low nears 26N65W while becoming elongated. At
the same time, a second area of gales is expected to form Wed
morning to the east of N Florida, associated with a sharp surface
trough. Seas will build to 8-12 ft there. Winds will diminish to
strong by Wed evening off N Florida.

Please read the latest High Seas Forecast issued by the National
Hurricane Center at http://www.nhc.noaa.gov/text/MIAHSFAT2.shtml
for more details on both Gale Warnings.

...MONSOON TROUGH/ITCZ...

The monsoon trough reaches the Atlantic through 1008 mb low
pressure at the coast of Guinea near 11N14W to 05N18W. The ITCZ
continues from 05N18W to 10N35W to the coast of Brazil near
02N50W. Widely scattered moderate convection is noted from the
Equator to 07N between 10W and 48W.

GULF OF MEXICO...

Please read the Special Features section above for information
on the developing gales in association with the low pressure
system over the NW Gulf of Mexico, as well as offshore Veracruz,
Mexico.

Outside of the impacts of the low pressure mentioned above in the
Special Features section, high pressure over the eastern United
States dominates the rest of the Gulf of Mexico. Moderate to
locally fresh easterly winds are present E of 90W. Seas in these
waters are 3-6 ft, with the highest seas occurring in the Straits
of Florida. Moderate or weaker winds and seas of 3-6 ft are found
S of 25N and W of 90W ahead of the cold front.

For the forecast, looking ahead, a stronger cold front is
expected to move off the Texas coast Thu evening followed by near-
gale to gale force winds and rough to very rough seas across the
basin through Fri night, with strong gales possible off Veracruz.

CARIBBEAN SEA...

A strong ridge over the eastern United States extends southward
into the Caribbean Sea, maintaining fairly tranquil weather
conditions. The exception are isolated pockets of shallow
moisture traversing the basin in the trade flow. The pressure
gradient between the strong high pressure and lower pressure in
northern South America result in fresh to strong easterly trade
breezes in the central Caribbean, with the strongest winds
occurring offshore Colombia. Seas in these waters are 6-9 ft.
Moderate to locally fresh easterly winds were evident in earlier
satellite derived wind data in the eastern Caribbean. Seas in the
area described are 3-6 ft. Moderate or weaker winds and slight to
moderate seas are observed elsewhere.

For the forecast, surface ridging north of the region will
maintain fresh to strong NE to E tradewinds across the central and
SW Caribbean Sea through Sat night. Moderate to locally fresh
winds will prevail in the E Caribbean with gentle to moderate
winds in the W Caribbean. Moderate long-period N to NE swell will
continue to move into the tropical Atlantic waters for the next
several days. A cold front will move into the Yucatan Channel by
late Fri and reach from central Cuba to Belize by Sat night. Fresh
to locally strong winds and rough seas will follow the front.

ATLANTIC OCEAN...

Please read the Special Features section for details on SW N
Atlantic Gale Warnings.

Moderate to fresh SW winds are found ahead of the aforementioned
front, mainly N of 28N and between 43W and 56W.

The remainder of the tropical Atlantic waters are dominated by a
1023 mb high pressure system positioned near 27N38W. The pressure
gradient between this ridge and lower pressures in the deep
tropics result in moderate to fresh easterly trade winds S of 20N
and between Africa and the Lesser Antilles. Seas in these waters
are 6-9 ft with the highest seas occurring just WSW of the Cabo
Verde Islands. Moderate or weaker winds and moderate seas prevail
elsewhere in the basin, along with seas of 6-11 ft in northerly
swell.

For the forecast west of 55W, looking ahead, winds will become
more southerly Thu ahead of a stronger cold front expected to move
off the northeast Florida coast Fri, accompanied by strong to
near-gale force winds and rough seas. Gales are possible to the
east of northern Florida with this next front.

$$
Lewitsky
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