[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 250000
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
700 PM EST Tue Jan 24 2017

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 1800 UTC surface analysis and satellite imagery through
2315 UTC.

...SPECIAL FEATURES...
A strong area of low pressure analyzed at 986 mb just S of Long
Island near 40N72W has an associated cold front extending into
the discussion area near 32N64W. The front continues SSW to
26N69W to the N coast of Haiti then SW to the coast of Costa Rica.
Gale force SSW winds are occurring N of 23N within 120 NM east of
the cold front over the SW North Atlc. Gale force winds are
forecast to remain associated with the front into Thu. In
addition...a surface trough is analyzed W of the cold front from
32N69W to 25N70W. Near gale force WNW winds are occurring
generally N of 29N with this feature and are expected to continue
into Wed. See latest NWS High Seas Forecast under AWIPS/WMO
headers MIAHSFAT2/FZNT02 KNHC for more details.

...ITCZ/MONSOON TROUGH...
The Monsoon Trough extends from the African coast near 08N13W to
05N18W. The Intertropical Convergence Zone axis extends from
05N18W to 01N30W to the Equator near 42W and continues to the
coast of South America near 01S46W. Widely scattered moderate
convection is S of 05N between 40W-46W.

...DISCUSSION...

GULF OF MEXICO...
Mid- to upper level ridge dominates the entire Gulf with axis
along 88/89W. Strong subsidence was noted over the southern half
of the Gulf with some upper level moisture streaming along the
Gulf coast. The ridge supports clear skies over the entire Gulf
and light anticyclonic surface flow E of 94W. A 1017 MB surface
high was located over northeastern Yucatan. Moderate to fresh SSE
winds are occurring W of 94W to the Texas coast. These southerly
winds will gradually spread eastward through Wednesday as the next
cold front is expected to emerge off the Texas and Louisiana
coasts by the afternoon. Winds behind the front will shift
northerly as high pressure builds in across the lower Mississippi
River valley Thursday into Friday.

CARIBBEAN SEA...
Large anticyclone was centered over the East Pacific near the
equator along 85W with associated anticyclonic NW flow prevailing
over the Caribbean W of 70W with more westerly flow E of 70W.
Water vapor imagery indicated very dry and stable air in place
over the entire basin. However...a middle to upper level trough
is noted N of the basin over the SW North Atlc that supports a
cold front analyzed from Haiti SW to the coast of Costa Rica
near 10N83W. With upper level dynamics fairly stable...the front
continues to carry broken to occasional overcast skies and
possible shallow low-level isolated showers within 90-120 NM
either side of the front. Farther east...weak low-level
convergence is generating cloudiness and possible isolated showers
across the eastern Caribbean...however no significant deep
convection is expected. Otherwise...the front has disrupted the
usual trade wind flow with generally light to moderate southerly
winds E of the front...and light to moderate northerly winds
expected W of the front through Wednesday as the front progresses
to the east.

...HISPANIOLA...
The proximity of the front over Haiti has resulted in broken to
overcast low clouds with possible isolated showers over the
island. The cold front is expected to continue eastward over the
island tonight and early Wed before high pressure builds in across
the region with drier conditions expected. The 12Z rawindsonde
from Santo Domingo showed some increase in moisture below 750 MB
with deep layered westerly flow.

ATLANTIC OCEAN...
A negatively-tilted middle to upper level trough is noted on
water vapor imagery over the SW North Atlc with axis extending
from a mid-level vorticity maximum near 40N72W through 32N65W to
a base near 25N62W. The troughing supports a cold front extending
from 32N64W to 25N65W to the north coast of Haiti near 20N72W and
into the SW Caribbean Sea. As mentioned in the Special Features
section...near gale to gale force wind are occurring on both side
of the front at this time. Scattered showers and isolated tstms
are occurring N of 25N within 150-180 NM E of the front...while
isolated showers are occurring within 120 nm E of the front S of
25N. Mostly fresh to strong W to NW winds are occurring across
the remainder of the SW North Atlc to the W of the front. High
pressure is expected to build in across the region through
Wednesday night gradually ushering in light to moderate
anticyclonic winds. Farther east...the remainder of the central
and eastern Atlc is under the influence of a pair of surface
ridges. One surface ridge is anchored by a 1022 mb high centered
near 28N48W and the other is a 1027 mb high centered near 32N18W
extending a ridge axis SW to 20N40W. A weak surface trough along
32N34W to 26N43W separated the areas of high pressure.

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

$$
Cobb
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