[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281205
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
705 AM EST Sun Jan 28 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 0600 UTC surface analysis and satellite imagery through
1145 UTC.

...SPECIAL FEATURES...

Atlantic Gale Warning: A very tight pressure gradient exists
between a cold front that enters the discussion area at 32N41W to
22N52W, where it becomes a dissipating stationary front to 20N59W
and a shearline from there to just N of the coast of Hispaniola,
and strong high pressure of 1038 mb centered N of the area near
37N59W. This continues to produce a large area of near gale to
minimal gale force NE to E winds over the waters N of the front
and from 20N to 24N between 57W and 76W. Given the long duration
of these winds across an expansive fetch area, the resultant seas
have build to the range of 12 to 16 ft. These conditions are
forecast to continue through early this evening, at which time the
gradient should slacken enough to allow for the winds to diminish
to strong category, however, seas are forecast to remain quite
high in the 12 to 14 ft range with these winds. Fresh to strong
NE to E winds are elsewhere W of the front, including through the
Atlantic passages in the Bahamas except for strong to near gale
force winds across the Straits of Florida. These winds will become
fresh S to SW winds Sun night. Please see the latest NHC High
Seas Forecast under AWIPS/WMO headers FZNT02 KNHC for more details
on this event.

Central Atlantic Gale Warning: A storm center of 1012 mb N of the
area near 36N44W moving southward will reach near 30.5N45W by
early on Mon. A tight gradient between the low and strong
high pressure to its NW will bring minimal gale force northerly
winds to the waters N of 29N between 48W and 52W early on Mon.
Seas are forecast to be very large, 16 to 21 ft in N swell within
the area of gale force winds. By late Mon night, the low is
forecast to reach near 26N48W late Mon night while the ridge to
its NW weakens. The northerly winds at that time are then
forecast to be drop to just below gale force N of 25N between 48W
and 55W, with seas in the 12 to 15 ft range.

Caribbean Gale Warning: The combination of very strong high
pressure centered over the NW Atlantic and lower pressure over
South America is bringing minimal gale force NE to E winds near
the coast of Colombia, with seas in the 12 to 15 ft range. These
conditions will persist late at night and into the early morning
hours through Tue, and possibly well into next week. Please see
the latest NHC High Seas Forecast under AWIPS/WMO headers
MIAHSFAT2/FZNT02 KNHC for more details on this event.

Gulf of Mexico Gale Warning for the far SW portion: A weak 1018
mb low over southern Mississippi as of 09Z this morning will
rapidly track northeastward across the NE Gulf today, and push a
cold front through the eastern waters into early on Mon. Strong
high pressure ridging will surge southward in the wake of the
front over the western waters of the gulf. A tight pressure
gradient will set up in the far SW Gulf on Mon leading to strong
gale force NW to N winds that will affect the waters S of about
21N and W of 95W to along the coast of Veracruz. These winds are
expected to last into early Tuesday morning, with seas building
to the range of 9 to 13 ft. With the strong ridging then forecast
to weaken through the middle of next week, expect for these
strong gale force winds to significantly diminish along with seas
subsiding.

...MONSOON TROUGH/ITCZ...

The Monsoon Trough axis extends from the coast of Africa near
07N11W to 03N17W where scatterometer data indicates the ITCZ
begins and continues to 02N59W and along 01N westward to 44W.
Scattered moderate isolated strong convection is S of the axis
between the coast of Africa and 15W. Scattered moderate
convection is N of the axis within 60 nm of line from 02N31W to
02N38W, and also within 60 nm N of the axis between 42W-44W.

...DISCUSSION...

GULF OF MEXICO...

Please see the SPECIAL FEATURES section above for details
in reference to an upcoming gale event in the SW Gulf.

A tight pressure gradient between strong high pressure over the
eastern gulf waters and lower pressure to the W of there continues
to sustain a large area of fresh to strong E to SE winds E of
about 90W. The exception is in the Straits of Florida where E
winds are reaching up to 30 kt, however, these winds will
diminish further on Sun as strong ridging over the eastern Gulf
begins to weaken. An amplified upper level pattern is taking
shape across the region. A mid/upper level short-wave trough
moving across the NW and N central Gulf has aided in the
development of a weak 1018 mb low over southeastern Louisiana and
related stationary frontal boundary that trails from it
southwestward to just E of Brownsville. A surface trough is just
to the SE of the stationary front from 28N90W to 25N93W. As of
03Z, a cold front has reached the Texas coast from near Corpus
Christi northeastward to inland around Galveston. Latest radar
displays reveal scattered showers and thunderstorms with frequent
lightning along and within 120 nm of the Texas coast and within
180 nm S of the Louisiana coast. More concentrated scattered
shower and thunderstorm is related to the 1019 mb low and
attendant stationary front. This activity is occurring to the N of
26N and E to a line from the Florida Big Bend to 26N88W. This
activity is more directly being driven by the short-wave trough as
well as by the moist E to SE surface to low-level flow across the
eastern gulf. An area of scattered showers and isolated
thunderstorms are seen over the S central waters S of 25N between
85W and 89W, while isolated showers and thunderstorms are
elsewhere over the eastern gulf and near to within 60 nm of the NW
portion of the Yucatan Peninsula. The latest forecast calls for
the low to quickly track across the NE Gulf today, sending a cold
front through the eastern waters into early on Mon. Strong high
pressure ridging will surge southward in the wake of the front
over the western waters of the gulf. Until this upcoming weather
scenario is over, expect for scattered showers and thunderstorms
to plague much of the gulf through Mon.

CARIBBEAN SEA...

Please see the SPECIAL FEATURES section above for details regarding
the gale conditions near the coast of Colombia.

Fresh to strong NE winds prevail at the lee of Cuba. Fresh to
strong trades are occurring elsewhere across the basin, except for
the gale force winds near the coast of Colombia as described
above under SPECIAL FEATURES. A surface trough along the eastern
Yucatan Peninsula and Belize continue to support scattered
showers and isolated thunderstorm over the Gulf of Honduras.
Similar activity has developed over and just S of the Yucatan
Channel, and is lifting northward into the S central Gulf of
Mexico. Isolated showers and thunderstorms are noted over
Hispaniola being supported by upper level diffluent flow. Fresh to
strong NE winds will occur to the lee of Cuba, and through the
Windward Passage through early on Mon. Expect for low-level
moisture along with related scattered showers to continue to
impact the NE Caribbean, including Puerto Rico and nearby islands
through at least Mon as strong to near gale force NE winds with a
shearline that is located just to the N of the Greater Antilles
act to advect the moisture and shower activity towards that part
of the Caribbean.

ATLANTIC OCEAN...
Please see the SPECIAL FEATURES section above for details about
the gale conditions over a portion of the southern waters between
the Bahamas and a central Atlantic cold front.

A cold front enters the discussion area through 32N41W to 23N51W,
Where it becomes a dissipating stationary front to 21N60W and a
shearline from there to just N of the coast of Hispaniola.
Meanwhile, strong high pressure of 1038 mb is located well N of
the area at 39N60W. The resultant tight gradient support near
gale to minimal gale force winds along with large seas in the SW N
Atlc from the front N to 24N and between 57W and 76W. These
conditions are expected to continue through early this evening.
Latest satellite imagery shows areas of rain and scattered showers
within 120 nm E of the front N of 28N, and isolated showers and
weak isolated thunderstorms within 90 nm SE of the front from 24N
to 28N. Scattered showers are within 120-150 nm of the shearline
and stationary front portions. This shower activity, as stated
above under Caribbean Sea, will continue to press west-
southwestward towards the NE Caribbean through Mon.

Over the far western portion of the area, deep layer moisture is
increasing N of the Bahamas and W of 78W as the Gulf of Mexico
weak low pressure over southeastern Louisiana advances
northeastward, and new cold front along the Texas coast makes
headway across the Gulf of Mexico. Areas of rain along with
scattered showers are noted from along the central and NE Florida
coasts eastward from there for about 90-120 nm. The moisture, in
the form of mid/upper level overcast clouds will trend to spread
eastward through Mon in advance of the next cold front. This cold
front is expected to move offshore the SE United States coast on
Mon, and reach from near 32N73W southwest across the NW Bahamas
to the Straits of Florida on Mon night, then from 32N63W to
eastern Cuba by Tue night. Strong NW winds and building seas will
follow in the wake of this front.

Over the far eastern portion of the area, a ridge that extends
from a 1039 mb high pressure system centered near 43N18W
dominates the area E of the cold front maintaining rather stable
weather over much of the central and eastern sections of the area,
except for the far eastern portion S of 16N and E of 31W where
abundant mid and upper level clouds are streaming eastward towards
Africa ahead of a mid to upper level trough located N of 10N
between 30W and 40W.

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

$$
Ramos
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