[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 150940
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
540 AM EDT Sat Apr 15 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 0600 UTC surface analysis and satellite imagery through
0930 UTC.

...SPECIAL FEATURE...

Low pressure over the southwest north Atlantic near 22N66W will
dissipate tonight as it moves northeast. The remnants of this low
will then merge with a newly formed center of low pressure near
28N57W, which will be dragged by a cold front racing towards the
central Atlantic. Strong high pressure building behind the cold
front will tighten the gradient, thus supporting gale force winds
of 35 kt N of 30N between 52W and 56W Saturday night...increasing
to 40 kt on Sunday. Please refer to the high seas forecast under
AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details.

...ITCZ/MONSOON TROUGH...

The Monsoon Trough extends across the western Africa coast near
05N10W to 02N15W. The Intertropical Convergence Zone continues
from 02N15W to 01N30W to 0N50W. Scattered moderate convection and
isolated tstms are within 120 nm either side of the ITCZ and S of
the Monsoon Trough.

...DISCUSSION...

...THE GULF OF MEXICO...

Broad surface high pressure anchored by a 1030 mb high over NW
Atlc waters continue to extend a ridge axis SW across the Florida
peninsula and Gulf of Mexico. This is supporting moderate to fresh
easterly-southeasterly flow across the basin according to latest
surface and scatterometer data. Water vapor imagery show middle to
upper level dry air across the western basin and a short-wave
trough over the north-central gulf. Diffluent flow east of the
short-wave trough aloft along with shallow moisture being
advected from the SW N Atlc support isolated showers over the NE
basin. Showers are also occurring off the western Yucatan
peninsula where a thermal trough extends from 22N89W to 18N91W.
No major changes expected through Monday morning.

CARIBBEAN SEA...

The pressure gradient between strong high pressure over the west
Atlantic and lower pressure over northern Colombia continue to
support fresh to strong winds from 10N to 12N between 74W and 77W.
This synoptic pattern is expected to continue over the weekend.
Water Vapor and CIRA LPW imagery continue to show very stable
conditions over the western Caribbean while SW winds aloft
advects moisture from South America to the eastern basin. Moisture
is also being advected from the tropical Atlc waters to the NE
Caribbean by SE flow associated with an area of low pressure in
the SW Atlc waters. All this moisture along with middle level
troughing across the region may induce the development of showers
mainly over the NE basin...including Puerto Rico, the Virgin
Islands and the Leeward Islands. Shower activity for this region
and Hispaniola may increase late today and Sunday as the tail of
a cold front pass to the N of the Islands.

...HISPANIOLA...

Low and upper level dry air across the area continue to support
fair weather this morning. However, the remnants of an area of
low pressure over the SW Atlc will merge with a cold front, which
tail will pass just north of the Island Sat through Sun
supporting the development of showers.

ATLANTIC OCEAN...

The 1012 mb center of low pressure near 22N66W continues to weaken
this morning while a new center of low pressure developed NE of it
near 28N57W. The former low will dissipate tonight as it moves
E-NE to merge with the new area of low pressure. These areas of
low pressure are being supported by a broad middle to upper level
trough, which also supports a cold front that extends from 30N61W
to 28N65W. The cold front is forecast to merge with the area of
low pressure tonight and gale force winds will develop as strong
high pressure builds behind the front. See the special features
section for further details. Otherwise, a cold front continues to
weaken over NE Atlc waters from 30N25W to 22N32W with isolated
showers within 90 nm either side of the boundary.

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

$$
Ramos
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