[Tropical] Tropical Weather Discussion

EMWIN Server emwin at nashvilleweather.net
Wed Apr 12 17:36:00 CDT 2023


AXNT20 KNHC 122235 CCA
TWDAT

Tropical Weather Discussion...Corrected
NWS National Hurricane Center Miami FL
1805 UTC Wed Apr 12 2023

Corrected satellite imagery time

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 1200 UTC surface analysis and satellite imagery through
1730 UTC.

...SPECIAL FEATURE...

Gulf of Mexico Gale Warning: A tight pressure gradient between low
pressure of 1010 mb centered in the central Gulf near 26N89W, with
associated warm and stationary fronts and high pressure to its
north and northeast east has resulted in a tight pressure
gradient that is bringing strong to near-gale force east winds
with gusts to gale-force over most of the north-central and NE
Gulf waters. A recent ASCAT data pass over the NE and eastern Gulf
clearly depicted these winds. These winds are forecast to
generate seas in the range of 8-12 ft. Some of the observations
from buoys and oil platforms over these areas of the Gulf have
begun to reflect these wind conditions. The strong to gale-force
winds will continue over the north-central and NE Gulf through
tonight as the low tracks generally northward. The low will move
inland over the U.S. north- central Gulf Coast on Thu. Once the
low moves inland, marine conditions will improve Thu afternoon
and evening. Please read the latest High Seas Forecast issued by
the National Hurricane Center at
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for further
details.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis enters the Atlantic off the coast of
Liberia near 06N11W and continues to 02N16W to 02N24W and to
01N30W, where latest scatterometer data indicates that it
transitions to the ITCZ and continues to just below the Equator
near 40W. Numerous moderate to strong convection is noted within
240 nm south of the trough between 17W-22W and within 180 nm
north of the trough between 18W-24W. Scattered moderate to
isolated strong convection is within 180 nm north of the trough
between 13W-17W and within 180 nm south of the trough between
22W-29W.

...GULF OF MEXICO...

Refer to the section above for details on a Gale Warning that
is currently in effect for the north-central and NE Gulf.

The low pressure of 1010 mb centered near 26N89W, and that
is described above under Special Features has a warm front
extending from it to 27N88W and southeast to 25N85W, where it
transitions to a stationary front that extends southeastward
across the middle Florida Keys. Plenty of lift exists along and
north of the warm and stationary fronts, where the atmosphere is
very unstable. In addition, divergence aloft to the east of the
upper-level low that is retrograding westward over southwestern
Louisiana is also present. Latest satellite imagery shows
extensive cloudiness denoting the shield of rain that is
present to the north and northeast of the low pressure and
associated warm and stationary fronts. Extensive areas of rain
along with embedded scattered to numerous showers and
thunderstorms are underneath these clouds. A trough also extends
from the low to near 26N96W and another one from the low to near
23N86W. Scattered showers moving southward are seen from 25N to
28N between 89W-96W.

Elsewhere outside the areas impacted by the Special Features
system, generally gentle to moderate winds are over the western
part of the Gulf, while moderate to fresh northeast winds are over
the NW Gulf, light and variable are south of the warm front and
gentle east to southeast winds are south of the stationary front,
except for moderate to fresh east to southeast winds over the
Straits of Florida. Seas outside the impacted Special Feature
system range from 4-7 ft over the western Gulf south of 26N, 7-10
ft southwest of Louisiana due to a northeast to east swell and 6-8
ft over the central Gulf. Lower seas of 2-4 ft are over the
southeastern Gulf and southern Gulf south of 22N and west of the
Yucatan Peninsula.

For the forecast, the 1010 mb low pressure over the central Gulf
near 26N89W will move inland over the U.S. north-central Gulf
Coast on Thu. Expect improving marine conditions in its wake.
For the weekend, a cold front is forecast to enter the western
Gulf which will cause winds and seas to increase over the
western and Gulf and over the western part of the central Gulf.

...CARIBBEAN SEA...

Ridging aloft and weak surface high pressure across the area is
maintaining general dry and stable conditions throughout the
basin as continues to suppress deep convection from developing.
Only isolated showers moving westward in the trade wind flow are
seen north of about 12N and east of 81W. Moderate to fresh
easterly trade winds are evident in the south-central and
southeastern Caribbean, along with seas of 3-6 ft, except for
higher seas of 5-7 ft from 11N to 15N between 72W-80W, and
lower seas of 2-4 ft elsewhere per a few altimeter data passes.

For the forecast, the Atlantic ridge located just north of
the northeastern Caribbean will sustain a moderate trade-wind
regime across the eastern and central Caribbean through the
weekend, except for fresh to strong in the south-central
Caribbean, north of Colombia. Fresh to strong winds will pulse in
the Gulf of Honduras Fri night and Sat night. Moderate northerly
swell related to a frontal boundary currently across the western
Atlantic will enter the Mona Passage and northeastern basin today,
and then spread southward into the southeastern basin through Thu
before dissipating by the weekend.

...ATLANTIC OCEAN...

A cold front extends from near 31N52.5W to 25N62W, where it
becomes a stationary front to central Bahamas and continues
northwestward to the middle Florida Keys. Scattered showers and
thunderstorms are north of 28N and east of the front to 50W.
Scattered showers and isolated thunderstorms are near and north of
the cold and stationary fronts to near 29N, however, north of the
stationary front and west of 70W scattered to numerous showers
are present. This activity reaches northward to near 29N. Fresh to
strong easterly winds are north of the stationary front, while
mostly fresh northeast winds are northwest of the cold front. Seas
over these waters are 9-11 ft. The remainder of the western
Atlantic behind the cold front is under moderate to fresh
northeast to east winds and seas of 8-10 ft. Moderate to fresh
southwest winds and seas of 6-9 ft are east of the cold front,
especially north of 22N and west of 57W.

The rest of the tropical Atlantic is dominated by a broad
subtropical ridge positioned SW of the Azores. The tight pressure
gradient between this ridge and lower pressures in NW Africa
support fresh to strong northeast winds north of 22N and east of
35W, with the strongest winds occurring north of 24N and east of
30W. Seas over these waters are in the 7-10 ft range. Moderate or
weaker winds and moderate seas prevail elsewhere.

For the forecast W of 55W, fresh to strong northeast winds north
of the aforementioned stationary front will prevail north of 25N
and west of 68W through this early this evening. Rough seas north
of 25N produced by large northeast swell should gradually subside
tonight. The cold front will continue slowly moving eastward
through Fri, while the stationary front should gradually weaken
and dissipate. In response, winds and seas should subside further
Thu and Fri.

$$
Aguirre
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