[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121756
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1256 PM EST Mon Feb 12 2018

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 1200 UTC surface analysis and satellite imagery through
1730 UTC.

...SPECIAL FEATURES...

Caribbean Sea Gale Warning: A tight surface pressure gradient
between the strong surface ridge over the north Atlantic Ocean
and lower pressure over northwestern South America will continue
to support gale-force winds off the coast of Colombia. These
conditions are expected continue through late this week. Please
read the latest NHC High Seas Forecast under AWIPS/WMO headers
MIAHSFAT2/FZNT02 KNHC for more details.

...MONSOON TROUGH/ITCZ...

The Monsoon Trough axis enters the Atlantic through the coast of
Liberia, Africa near 05N09W and continues to 01N18W where latest
scatterometer data indicates the ITCZ begins and dips below the
Equator at 20W. It resumes southwestward to the coast of Brazil
near 05S36W. Scattered moderate convection is within 150 nm S of
the axis between 09W-14W, and within 90 nm S of the axis between
14W-18W.

...DISCUSSION...

GULF OF MEXICO...

As of 21Z, a cold front extends from near the Destin/Santa Rosa
area southwestward to 27N91W to 22N95W to inland the coast Mexico
just S of Veracruz. A pre-frontal trough is along a position from
27N90W to 23N96W to inland the coast of Mexico near Coatzacoalcos.
Another trough is ahead of the front along a position from 29N84W
to 27N88W. A 1027 mb high center is analyzed over eastern Mexico
near Ciudad Mante. Associated strong ridging is surging southward
across eastern Mexico and over the NW Gulf behind the cold front.
The pressure gradient between the ridge and the front is producing
fresh to near gale-force northerly winds over the western gulf
waters. The minimal gale force winds that were earlier observed
near the coast of Tampico diminished to strong winds as of 15Z.
Moist southerly winds advecting northward over the gulf from the
Caribbean in combination with a mid to upper shortwave trough
sliding eastward across the western Florida panhandle and far NE
Gulf continues to result in scattered moderate isolated strong
convection over the northern gulf waters along and to the E of
both the cold front and trough, roughly N of about 26N and between
84W-86W. Latest satellite lightning data reveals frequent strikes
primarily in the southern and central sections of this area of
convection. This activity may be attended by strong gusty winds as
quickly moves eastward. Elsewhere, isolated showers are along and
within 90 nm E of the pre-frontal trough. The scattered moderate
isolated strong convective activity is forecast to move E of the
Gulf of Mexico late tonight as the mid/upper trough slides to E of
NE Florida.

Strong high pressure over the north Atlc continue to extends SW
across the eastern half of the Gulf allowing for light to
moderate E to SE winds ahead of the front. Fresh easterly winds
are over the Straits of Florida. The cold front is forecast to
become stationary this afternoon from northern Florida to the
central Bay of Campeche while it weakens. The frontal remnants are
expected to lift back N as a warm front on Tue. The fresh to near
gale-force winds over the western waters will significantly
diminish tonight and through Tue. Seas associated with these winds
subside tonight into Tue as a ridge develops over the southeastern
United States. This pattern will support fresh east winds by mid
week.

CARIBBEAN SEA...

Please refer to the SPECIAL FEATURES section above for details
about the gale-force winds expected near the coast of Colombia.

The GOES-16 low to mid-level water vapor imagery continues to
suggest generally dry and stable atmospheric conditions continue
across the basin. Latest GOES-16 visible imagery depicts patches
of shallow moisture, in the form of broken to scattered low
clouds, advecting westward over much of the basin, including
portions of Hispaniola. Brief passing isolated showers are with
these clouds. A strong ridge N of the area anchored by a 1038 mb
high center over the N central Atlantic extends southward across
the northern half of the Caribbean, with the associated pressure
gradient supporting the continuation of fresh to strong trade
winds across the eastern and central basin as indicated by latest
scatterometer data. Seas are in the range of 12 to 18 ft near the
Colombia coast and 8 to 12 ft elsewhere. Fresh to near gale-force
are also occurring through the Atlc passages and will continue
through mid week. Otherwise, little change is expected through
mid-week.

ATLANTIC OCEAN...

Broad surface high pressure over the area is associated with a
1038 mb high center over the N central Atlantic at 35N48W moving
to the SW. The ridge is supporting fresh to strong E-NE winds
over most of the basin, except over NW forecast waters N of 24N
where E-SE winds are mainly moderate. An area of scattered showers
and isolated thunderstorms is noted over the tropical Atlantic
waters from 14N to 21N and between 45W and 60W in association
with broad mid to upper troughing that stretches from a cyclonic
circulation just SW of the Canary Islands to 23N40W to 21N52W and
as a shear axis from there to the northern Caribbean Sea. The
scattered shower and thunderstorm activity should move across
the Leeward Islands tonight through Tue night.

A cold front is forecast to move off the northeast Florida coast
by Tue morning. Scattered showers and thunderstorms are expected
to form out ahead of the front and impact the NW waters tonight
into Tue as a mid/upper level trough translates eastward from the
NE Gulf to NE Florida and the far NW waters. The front then will
stall before dissipating Thu morning. The next cold front is
forecast to enter the NW forecast waters by early Saturday
morning.

For additional information please visit
http://www.hurricanes.gov/marine

$$
Aguirre
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