[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 221740
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1240 PM EST Sun Dec 22 2019

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 1200 UTC surface analysis and satellite imagery through
1720 UTC.

...SPECIAL FEATURES...

For all three of the special features below, see the latest NWS
High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC
for further details.

NORTHEASTERN GULF OF MEXICO GALE WARNING...

A complex 1012 mb surface low pressure system centered in the NE
Gulf of Mexico near 29N87W is currently producing gale force
winds east 87W and north of 26N, according to the latest ASCAT
pass. Winds in the northeastern Gulf should decrease to below
gale force during the late afternoon or early evening hours today.

SOUTHWESTERN GULF OF MEXICO GALE WARNING...

A tight pressure gradient between the aforementioned low pressure
and high pressure over Mexico is leading to gale force winds in
the southwest corner of the Gulf of Mexico, south of 20N and west
of 95W. The winds are forecast to decrease to below gale force
by early this afternoon.

WESTERN ATLANTIC OCEAN GALE WARNING...

Gale force winds are expected to begin this afternoon for the
Atlantic waters offshore Georgia and northern Florida, mainly
north of 30N between 78W-81W. This is due to a strong pressure
gradient between the low pressure in the NE Gulf of Mexico and a
1030 mb high pressure near 36N66W. The gales will migrate slightly
eastward during the day on Monday, remaining north of 30N between
75W-79W. The gales are expected to end Monday evening for the
waters south of 31N.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coast of Sierra Leone
near 07N12W to 07N16W. The ITCZ continues from 07N16W to 04N21W to
02N37W to 01N49W. Scattered moderate convection is seen from
02N-05N between 34W-46W and from 03N-07N between 46W-54W. Isolated
moderate convection is from 02N-06N between 19W-34W.

GULF OF MEXICO...

Two Gale Warnings are over the Gulf of Mexico. See section above
for details. A potent upper-level disturbance over Louisiana is
fueling a strengthening surface low pressure system over the NE
Gulf of Mexico, described below.

A 1012 mb surface low is over the NE Gulf of Mexico near 29N87W.
A cold front extends southward from the low to 27N87W. A
stationary front continues from 27N87W to 22N87W. A warm front
extends eastward from the low to the big bend of Florida near
29N83W to Jacksonville Florida. Numerous moderate with embedded
isolated strong convection is within the area bounded by 31N87W
to 25N86W to 29N81W to 31N81W to 31N87W, including much of
northern Florida and the NE Gulf of Mexico.

A second, weaker surface low of 1015 mb is west of Key West near
25N83W. A surface trough extends SSW from the low to western Cuba
near 22N84W to 20N86W. A warm front extends E from the low to near
Key Largo Florida. Numerous moderate with embedded isolated
strong convection is to the east of the low along the warm front
from 24N-27N between 81W-83.5W, including over portions of SW
Florida. Isolated to scattered moderate convection is elsewhere
from the north coast of western Cuba to Lake Okeechobee between
80W-85W.

Winds and seas will diminish in the basin as the trailing cold
front sweeps southeast of the Gulf tonight and the low lifts
northeast toward the Georgia coast through late Mon. Weak high
pressure sets up in the wake of the front over the western Gulf
through mid week. Looking ahead, winds may increase over the
northeast Gulf by late Thu as a weak front approaches the region.

CARIBBEAN SEA...

A surface trough extends from a 1014 mb low near 25N84W to western
Cuba near 22N84W to 20N86W. Scattered moderate with isolated
strong convection is along and within 90 nm east of the trough
axis. In the far SW Caribbean, the east Pacific monsoon trough is
inducing scattered moderate with isolated strong convection south
of 11N and west of 76W, including over portions of Panama and
southeastern Costa Rica. GOES-16 low and mid-level water vapor
channels show that dry air covers the eastern and central
Caribbean Sea. The dry air is due to mid-level anticyclonic flow
and sinking motion. The latest ASCAT pass shows fresh winds over
the central Caribbean, with strong winds in the south-central
Caribbean.

A stationary front currently extends from a 1012 mb low in the NE
Gulf of Mexico to near 22N88W. This front will become a cold front
and will move through the Yucatan Channel and into the far
northwest Caribbean later today. The front will reach from the
central Cuba to the Gulf of Honduras by early Mon from eastern
Cuba to northeast Nicaragua by early Tue, before stalling and
weakening from Windward Passage to 13N81W through mid week. Some
coastal flooding is possible along the north coast of western
Cuba, including Havana, late Mon into early Tue, due to fresh to
strong NW winds behind the front over the eastern Gulf of Mexico.
Fresh to strong winds will also follow the front over the western
Caribbean. Elsewhere, the front and its parent low pressure will
shift into the western Atlantic to the north of the area,
displacing the subtropical ridge and allowing moderate trade winds
by mid to late in the week.

ATLANTIC OCEAN...

A 1012 mb low pressure in the NE Gulf of Mexico extends a
warm front to near Jacksonville Florida and just offshore the
Georgia coast. Scattered moderate convection is over the Atlantic
waters north of 29N and west of 69W, with isolated convection
from 28N-29N. Gale force winds are expected to begin this
afternoon offshore of northern Florida and Georgia. See section
above for details. Fresh to strong winds already cover the entire
area north of 20N west of 70W, with near gales north of 29N west
of 78W.

A cold front passes through 32N37W to 26N46W to 24N59W. A
stationary front continues from 24N59W to 23N71W to Key Largo
Florida. Scattered moderate convection extends from the front to
28N, and west of 73W, including the northwest Bahamas. The latest
ASCAT pass shows strong winds on both sides of the front north of
30N, between 35W-44W. A 1028 mb high is centered near 33N17W,
leading to ridging over the eastern Atlantic.

Deepening low pressure currently over the northeastern Gulf of
Mexico will move toward the Georgia coast by late Mon, with a
trailing cold front moving off the east coast of Florida. SE winds
will increase to gale force by late today off northeast Florida
ahead of the approaching low and front. The front will continue to
sweep eastward, reaching from 31N72W to western Cuba by early Tue
as the low slowly moves toward 31N76W. The low pressure will
weaken little as moves toward 29N65W by early Wed, with the front
extending to the Windward Passage. Looking ahead, winds and seas
diminish across the region after late Wed as the low and front
move farther east and weaken.

$$
Hagen
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