[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 140012
TWDAT

Tropical Weather Discussion...Corrected
NWS National Hurricane Center Miami FL
805 PM Wed May 13 2020

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 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
2345 UTC.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the coastal sections of
Guinea near 11N15W and reaches to 06N20W, where scatterometer
data from this afternoon indicated that it transitions to the
ITCZ and continues to 05N28W to 02N36W to 01N42W and to the coast
of Brazil near 01S48W. Numerous moderate to strong convection is
seen within 60-90 nm of the trough between 16W-21W. Scattered
moderate to isolated strong convection is within 30 nm of the
ITCZ between 24W-28W, and also north of the ITCZ within 30 nm of
line from 05N30W to 03N36W. Similar activity is north of the
ITCZ within 30 nm of 04N48W.

GULF OF MEXICO...

A mid-level shortwave tough extending from the north-central
Gulf to the southeastern Gulf is moving eastward. At the surface,
ridging extends across the region from a 1028 mb high centered
off the U.S. Eastern Seaboard. A stationary front extends from
east of the Bahamas to the Straits of Florida along a position
from 24N80W to 24N85W. This is presently acting serving as the
focus for scattered showers and thunderstorms to persist across
the Straits of Florida as well as along and inland northwestern
Cuba and the over the southeastern Gulf waters to the south of
25N and east of 86W. Similar activity is noted over the northern
Gulf waters from 27N to 29N and between 90W-94W. With the mid-
level shortwave trough advancing eastward toward Florida through
the next couple of days or so, expect for the scattered shower
and thunderstorm activity to increase in coverage, while it lifts
northward across southern Florida and the adjacent Gulf waters.

Both buoy observations and the latest Ascat data indicate
moderate to fresh east to southeast winds across just about
the entire area, with the exception of the southeastern Gulf,
where a tighter gradient in place there along with wind gusts
from the aforementioned shower and thunderstorm activity is
producing strong east winds across those waters and peak wave
heights of up to 8 ft. Elsewhere, wave heights are in the range
of 4-7 ft except in the extreme NW Gulf where lower wave heights
of 2-4 ft are observed.

As for the forecast, the stationary front will weaken through
late tonight and dissipate by late Thu afternoon. The tight
gradient in place over the southeastern Gulf and over southern
Florida will maintain little change with winds over those water
through Thu night. Elsewhere, the moderate to fresh east to
southeast winds will continue through the upcoming weekend.
A weak cold front may approach the northern Gulf late on Mon
night.

CARIBBEAN SEA...

Mid-level ridging, with an axis stretching roughly from the
Honduras/Nicaragua northeastward to Puerto Rico, is providing
for light to moderate subsidence and associated drier air over
the western and central sections. Upper-level riding is over the
far eastern Caribbean. Its axis is identified to be along 63W,
and stretches north-northeastward well north of the Sea to the
central Atlantic. Strong subsidence and dry sinking air
accompanies this ridge from along the coast of Venezuela
northward to 17N and east of 69W. Only a few low cloud
streamers, with possible isolated showers, are seen east of 69W.
Afternoon scattered shower and thunderstorm fired up over the
interior of the western part of the Dominican Republic and in
some interior sections of central and eastern Cuba. With gradual
loss of day time heating, the activity appears to be weakening
except for that over eastern Cuba. Small patches of low clouds
moving west-northwestward with isolated showers are seen from
15N-18N and between 72W-76W.

Moderate to fresh trade winds are over the eastern and central
Caribbean, while gentle to moderate trade winds are over the
western Caribbean and fresh to strong trade winds over the south-
central Caribbean waters. Wave heights are in the 3-6 ft range,
with higher wave heights, up to 7-8 ft, offshore the northwest
coast of Colombia.

As for the forecast, a relatively weak pressure gradient will
strengthen later this week as high pressure builds north of the
area. The fresh to strong trade wind will change little over
the south- central Caribbean through the upcoming weekend. Northerly
swell over the Tropical N Atlantic waters south of 15N will
subside into Thu. Fresh winds will pulse over the Gulf of
Honduras from Thu night into early next week.

ATLANTIC OCEAN...

Westerly upper-level flow is over the western half of the area,
with an embedded sub-tropical jet stream branch that extends
from South Florida northeastward across the NW Bahamas and
eastward to near 26N61W. Another jet stream branch extends from
26N61W northeastward to north of 32N57W. A narrow mid to upper-
level trough is along a position from near 26N46W to an elongated
mid to upper-level low lifting northward at 18N52W and from the
low it extends south-southwest to near 08N56W. Moderate to strong
subsidence is within 240 nm west and 60 nm east of the low and
trough. A highly amplified mid and upper-level ridge, with a
crest north to near 24N41W, is to the east of these features to
25W. East of 25W, broad mid to upper-level troughing is the main
feature over this section of the area.

At the surface, a cold front enters the area at 32N56W and
continues southwestward to 29N62W, where it becomes stationary
to 25N69W and west-southwest to the Bahama Islands near 23N76W
and to the Straits of Florida at 24N81W and to 24N83W. A pre-
frontal trough extends from 28N59W to 22N68W. Scattered to
numerous showers along with isolated thunderstorms cover the
waters south of 27N and west of about 71W. A more concentrated
area of scattered showers and thunderstorms is along and within
120 nm north-northeast of the Cuban coast from 74W to 79W. In
addition to the nearby frontal boundary and jet stream energy
aloft in play, the occurrence of moist fresh to strong
northeasterly winds converging along the Cuban coast will
continue to sustain this activity through possibly Fri. Isolated
showers and thunderstorms are possible between the front and the
trough. Another trough is analyzed from 27N55W to 21N58W. Broken
low and mid-level clouds with isolated showers are seen from 21N
to 27N and between 54W-58W. Strong high pressure ridges southward
over the western Atlantic waters north of the stationary front.
The resultant tight gradient is allowing for fresh to strong east
winds and wave heights peaking to 8 ft over these waters.

In the eastern Atlantic, a cold front supported by the broad
mid to upper-level trough mentioned above, recently passed
the Canary Islands. It extends from near 32N10W to 27N16W
to 26N66W and northwestward to 30N35W. Isolated showers are
possible along this front. Otherwise, high pressure, anchored
by a 1026 mb high center just north of the area at 33N32W,
covers this part of the area. Light to moderate winds are noted
throughout the central and eastern Atlantic with wave heights
in the 4-7 ft range.

As for the forecast, the stationary front will will weaken through
late tonight and dissipate by late Thu afternoon. The strong
high pressure over the western waters will continue through Fri,
maintaining the tight gradient and fresh to strong east winds
and wave heights to 8 ft there. A broad area of low pressure is
expected to form near or just north of the Bahamas in a couple
of days, and likely develop into a subtropical depression or
storm this weekend while moving to the northeast over the
western Atlantic into early next week.

$$
Aguirre
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