[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 041057
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
657 AM EDT Sat Apr 4 2020

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
1045 UTC.

...SPECIAL FEATURES....

Atlantic Gale Warning: Gale conditions are forecast for a portion
of the northern waters of the central this afternoon and continue
until early Sunday. A cold front, associated with a deep and
complex low pressure system north of the area, will bring gale
force west to northwest winds to the waters north of about 30N
and between 61W and 66W along with wave heights in the range of
15-18 ft. These conditions will shift northeast of the forecast
waters during Sun morning as the cold front pushes farther
eastward across the central Atlantic and while the broad gale-
force wind field tied to the complex low pressure system lifts
northeast of the area. Please read the latest High Seas Forecast
product, under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC, or at
website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more
details.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends from the coast of Sierra Leone
near 08N14W to 04N20W, where overnight scatterometer data
indicated that it transitions to the ITCZ axis and continues to
03N30W to the equator at 38W and to the coast of Brazil near
01S47W. Scattered moderate to strong convection is within 120 nm
north of the ITCZ axis between 24W-28W, and within 60 nm of the
ITCZ axis between 20W-24W and also between 28W-33W. Scattered
moderate to isolated strong convection is within 30 nm of the ITCZ
axis between 33W-38W and between 18W-20W. Scattered moderate
convection is just north of the ITCZ axis within 30 nm of a line
from 01N40W to 01N48W.

GULF OF MEXICO...

The earlier cold front over eastern Texas has become stationary as
of 04/0900 UTC from Houston to vicinity Corpus Christi and
southwestward from there to just eats of Laredo. Both satellite
imagery and regional NWS radar displays reveal scattered to
strong thunderstorms inland over southern Texas and extending
out to the far western Gulf waters from 26N-28N. This activity
is being supported by pretty decent upper-level jet dynamics.
Patches of rain with scattered showers are over some sections of
the central and NW Gulf areas. This is due to abundant moisture
seen on TPW imagery and upper-level diffluence in the area located
ahead of an upper-level trough over the central U.S. Weak high
pressure over the eastern Gulf is maintaining gentle winds across
much of the eastern Gulf. Moderate easterly winds are noted over
the western Gulf, except for fresh to strong east to southeast
winds over the south-central Gulf due to the gradient associated
with the thermal trough emerging off the west coast of the Yucatan
Peninsula. Smoke from agricultural fires in southern Mexico may
be causing minor limitations to visibility over the SW Gulf.

The weak high pressure over the eastern Gulf will shift eastward
through Sat night in response to low pressure and the
aforementioned stationary front, which will begin to move
eastward as a cold front later this morning. The front is
expected to reach the Texas coast Sat, then become stationary
before it lifts back north as a warm front Sun. This front will
trigger showers and thunderstorms over the far NW Gulf Fri night
through Sat night. High pressure from off the Carolina coast will
slide southward early next week setting up an east to west ridge
across the area. This will allow for generally light to moderate
east to southeast winds over the basin through Wed night. Fresh to
strong winds will pulse each evening north and west of the
Yucatan Peninsula through the period as thermal troughs emerge off
the Peninsula to across SW Gulf.

CARIBBEAN SEA...

A rather weak pressure gradient is noted across the basin under
very dry aloft as indicated by the strong subsidence signal in
water vapor imagery. These means there is considerable lack
moisture in the Caribbean, with the exception of the SE part,
including the coast of South America, where scattered to broken
low clouds with possible isolated showers are present. The TPW
satellite animation detects this moisture. Overnight scatterometer
data shows moderate to fresh east winds south of 14N and between
61W-78W, with the exception being a small area of strong
northeast to east winds along and near the coast of Colombia. The
scatterometer shows gentle to moderate east winds elsewhere,
except for a pocket of fresh winds over the eastern part of the
Gulf of Honduras.

Winds over the basin will gradually increase through the middle
of next week as high pressure rebuilds over the western Atlantic.
Fresh to strong winds will pulse each night during the forecast
period beginning Sat night over the Gulf of Honduras and especially
along the coast of Colombia. Fresh to strong northeast winds are
expected through the Windward Passage Mon night and again Tue
night.

ATLANTIC OCEAN...

Gale force winds are forecast for a section of the northern-
central waters beginning this afternoon. See Special Features
section above for details on this event.

A cold front, associated with a complex low pressure system
located well north of the area off New England and the mid-
Atlantic region, extends from near 32N60W to 25N70W. This is the
cold front that will be followed by gale force winds beginning
this afternoon as described above under Special Features.
Meanwhile, a second, slow-moving cold front, that is also tied to
the same complex low pressure system, is analyzed from 32N41W to
26N55W and to just inland the northern part of Hispaniola.
Overnight scatterometer data nicely depicted an extensive area of
strong west to northwest winds north of 29N and west of the first
cold front to 72W, while fresh west to northwest winds are
elsewhere north of 27N between the cold front and 74W. Strong west
winds are about 240 nm east of the first cold front. A satellite
altimeter pass captured wave heights to 13 ft near 29N30N, and
another pass captures wave heights to 12 ft north of 27N and
between 56W and 60W.

Latest satellite imagery shows broken to overcast low and mid-
level clouds along and within 150 nm southeast of the slow moving
cold front. Patches of rain along with scattered showers are
possible underneath these clouds, mainly north of 28N where upper-
level jet stream dynamics could assist in keeping this activity
active. Fresh to strong southwest are within 180 nm southeast of
this slow-moving cold front.

Long-period north swell is propagating through much of the
central and western Atlantic waters, namely east and northeast
of the Bahamas. A weak 1017 mb high is centered at 23N41W. The
related pressure gradient is allowing for generally light to
moderate winds in the 14N-24N latitude band across the entire
Atlantic and Caribbean. In the far eastern Atlantic, a weak cold
front extends from 32N14W to across the Canary Islands and to near
24N18W. Lack of atmospheric forcing due to dry sinking air aloft
as seen in water vapor imagery, and along with dust in this area
of the Atlantic is suppressing shower and thunderstorm activity
with this front.

The cold front that extends from 32N60W to 25N70W will quickly
reach from near 32N57W to 23N69W by late tonight and from near
32N50W to 23N66W by late Sun night. The slow-moving cold front
will move to east of the Leeward Islands near 18N62W by Mon
morning. Gale conditions are expected near 30N64W from this
afternoon till early Sun as a deep low pressure system centered
southeast of New England drops southeastward passing just east of
Bermuda Sun morning. North swell generated by the low will produce
very large seas across the waters east and northeast of the
Bahamas through the weekend. Seas will gradually subside through
early next week as the swell decays. High pressure will shift
southward over the north-central waters Mon night into Tue. It
will then shift southeastward through Wed night as a cold front
moves across the NW waters. The front will be preceded by
increasing south to southwest winds and accompanied by scattered
showers and thunderstorms.

$$
Aguirre
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