Tropical Weather Discussion
Issued by NWS
AXNT20 KNHC 191801
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 PM EDT WED OCT 19 2016
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
A non-tropical 1004 mb surface low is centered northeast of the
Turks and Caicos near 25N69W with a surface trough extending
from 28N63W through the low then across the Turks and Caicos
through the Windward Passage to 19N76W. Clusters of scattered
moderate to isolated strong convection are from 19N-28N between
54W-67W. Scattered showers and isolated thunderstorms are within
90/120 nm of a line from 26N70W to over the Bahama Islands near
23N75W. The heavy convection is to the east of the low/trough
due to strong westerly winds aloft. The upper level winds are
expected to become more conducive for development and there is a
medium chance of sub-tropical or tropical formation in the next
48 hours as the low moves northwest through tonight, then north-
northeast before merging with a cold front this weekend.
Regardless of development, locally heavy rainfall is possible
over Hispaniola, Puerto Rico, and portions of the northern
Leeward Islands through tonight. Please see the Tropical Weather
Outlook under AWIPS/WMO headers MIATWOAT/ABNT20 KNHC for more
Tropical wave in the east Atlantic extends along 34W/35W from 7N-
14N moving west near 15 kt over the past 24 hours. Wave
coincides with a 700 mb trough and is embedded within a high
amplitude surge of moisture. Clusters of scattered moderate to
isolated strong convection are from 7N-13N between 30W-37W.
The Monsoon Trough extends across Africa into the east Tropical
Atlantic near 14N17W then along 8N23W to 8N38W where the ITCZ
begins and continues along 7N46W to South America near 5N53W.
Scattered moderate to isolated strong convection is from 9N-10N
between 27W-30W. Large clusters of scattered moderate convection
are from 1N-8N between 18W-32W and from 7N-17N between 42W-46W.
...GULF OF MEXICO...
A broad upper ridge dominates the Gulf this afternoon with an
upper ridge axis extending from the east Bay of Campeche to an
upper high along the coast of Florida near Apalachicola Bay
continuing along the eastern seaboard to North Carolina. Strong
subsidence and dry, stable air aloft dominates the Gulf east of
90W. A surface ridge extends over the north Gulf anchored by a
series of 1021 mb highs over South Carolina, south Georgia, and
north Alabama. The easterly surface flow through the Straits of
Florida are generating scattered showers within 45 nm of 23N
between 81W-87W. The southerly surface flow around the surface
ridge is bringing isolated showers dotting the coastal waters of
Louisiana and scattered showers within 45/60 nm of a line from
23N94W to 29N92W. A mid level trough is in the east Bay of
Campeche supporting a surface trough that extends from 21N94W to
the coast of south Mexico near 18N92W with scattered showers and
possible isolated thunderstorms within 60 nm of the surface
trough. The surface ridge will persist through tonight then will
retreat east ahead of a cold front that will move into the
northwest Gulf Thursday. The front will race east reaching from
central Florida to the Yucatan peninsula by Friday night then
pass through the Straits of Florida Saturday night.
A broad upper ridge anchored over Honduras extends an upper
ridge axis east along 15N69W then into the central Atlantic over
the Leeward Islands. A deep layered trough over the west
Atlantic extends a mid to low level trough over the northwest
Caribbean. At the base of this low to mid level trough is a 1008
mb low centered off the coast of Nicaragua/Honduras near 16N83W.
A surface trough extends at 19/1500 UTC from the low east along
15N80W to 17N76W with a second surface trough extending south
from the low along 13N82W to Costa Rica near 10N83W. Scattered
showers and isolated thunderstorms are north of 11N west of 76W
to the above surface troughs. Scattered to numerous showers and
scattered thunderstorms are north of 14N to over Hispaniola and
Puerto Rico between 66W-75W. The low and surface troughs will
persist through the end of the week. A cold front will move into
the northwest Caribbean this weekend from the Gulf of Mexico.
The deep layered trough over the west Atlantic extends over the
island generating isolated to scattered showers over the island
of Hispaniola with possible isolated thunderstorms developing
later this afternoon. This could give the island showers and
possible thunderstorms through early Saturday.
A deep layered trough extends over the west Atlantic from 63W-
80W supporting the low and surface trough in the special
features above. The upper ridge over the Caribbean extends into
the central Atlantic from the Leeward Islands near 18N63W to
31N50W. This is providing difflunce aloft to enhance the
activity associated with the special features low/trough. A deep
layered trough over the north/central Atlantic is supporting a
remnant stationary front that extends to 32N34W where a surface
trough begins and continues along 29N41W to 23N48W. Isolated
showers are possible within 120 nm west of the surface trough.
A second weak surface trough is in the east Atlantic extending
from 30N31W to 27N23W. The special features low in the west
Atlantic will move northwest through late Thursday before
exiting off the east-northeast this weekend. Fresh to near gale
force winds will occur mainly on the northwest side of the low.
A cold front will move into the west Atlantic this weekend.
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